Funny Chemistry | Famous last words | The last words of a chemist

From: Mooseman#NoSpam.FATE.ohz.north.de (Bjoern "Mooseman" Harste)
(Blame JV for the translation from German.)
The last words of a chemist:
1. And now the tasting test.
2. May that become hot?
3. And now a little bit from this...
4. ... and please keep that test tube alone!
5. And now shake it a bit.
6. Why is there no label on this bottle?
7. In which glass was my mineral water?
8. The bunsen burner *is* out!
9. Why does that stuff burn with a green flame?!?
10. *H* stands for Nitrogen - and that does *not* burn...
11. Oh, now I have spilt something...
12. First the acid, then the water...
13. And now the detonating gas problem.
14. This is a completely safe experimental setup.
15. Where did I put my gloves?
16. O no, wrong beaker...
17. The fire alarm is just being tested.
18. Now you can take the protection window away...
19. And now keep ith constat at 24 degrees celsius, 25... 26... 27...20.
Peter can you please help me. Peter!?! Peeeeeteeeeer?!?!?!?
21. I feel it how long 15 seconds are!
22. Something is wrong here...
23. Where do all those holes in my kettle come from?
24. Trust me - I know what I am doing.
25. And now a cigarette...

2.From: roberts#NoSpam.ucunix.san.uc.edu (Michael A. Roberts)

Isaac Asimov said that if you want to find a chemist,
ask him/her todiscuss the following words:
mole
unionized
As he so eloquently put it, "If he starts talking about furry animals
and organized labor, keep walking."

3.Make it myself? But I'm a physical organic chemist!

4.From: Casandra Sheldon

okay so I came to the realization while I was riding in the Jeep with my
boyfriend:
I say to him You know when I Chemist says 'put it in a round
bottom' (you know round bottom flask) it doesn't mean what you think it
means.
I don't know maybe you just have to have a dirty mind to find this funny
hee hee

Joke 5
As one of our teaching assistants observed:
"The Chemistry Department is located near the Psychology Department for
good reason." ~Allisha Ray (2003)

6.From: John Bauer

Why I Am A Chemist, by Tom Walz
I am a chemist because when I was young I was told to look around and
see who had the kind of life I wanted to have. Then go do the same work.
What I found was that chemists are generally much better looking than
average. They test out smarter and have more friends. I heard about
some guys from a university who studied chemists in a bar. They found
that chemists get approached and generally get lucky about 43 times as
often as most folks.
Chemists win more at cards, catch more fish and are beloved by kids and
dogs. They can work their VCR and set the clock on the microwave.
Their kids are brighter, their lawns are greener and their cars run
better. Their daughters are prettier and their sons are better
athletes. Their spouses are sweeter and their mothers-in-law hardly
visit at all.
Chemists do things like save lives and generally make a better world.
Anyway, I looked around and it seemed to me that chemists were clearly
superior folk and I would be proud to be one. That is why I am a chemist.
That and all the good jobs were taken.


7.From: John Bauer

Quote:
"We had no doubts: we would be chemists, but our expectations and hopes
were quite different. Enrico asked chemistry, quite reasonably, for the
tools to earn his living and have a secure life. I asked for something
entirely different; for me chemistry represented an indefinite cloud of
future potentialities which enveloped my life to come in black volutes
torn by fiery flashes, like those which had hidden Mount Sinai. Like
Moses, from that cloud I expected my law, the principle of order in me,
around me, and in the world. I was fed up with books, which I still
continued to gulp down with indiscreet voracity, and searched for a key
to the highest truths; there must be a key, and I was certain that,
owing to some monstrous conspiracy to my detriment and the world's, I
would not get it in school. In school they loaded me with tons of
notions which I diligently digested, but which did not warm the blood in
my veins. I would watch the buds swell in spring, the mica glint in the
granite, my own hands, and I would say to myself: 'I will understand
this, too, I will understand everything, but not the way they want me
to. I will find a shortcut, I will make a lock-pick, I will push open
the doors.'
"It was enervating, nauseating, to listen to lectures on the problem of
being and knowing, when everything around us was a mystery pressing to be
revealed: the old wood of the benches, the sun's sphere beyond the
windowpanes and the roofs, the vain flight of the pappus down in the June
air. Would all the philosophers and all the armies of the world be able to
construct this little fly? No, nor even understand it: this was a shame
and an abomination, another road must be found. "We would be chemists,
Enrico and I. We would dredge the bowels of the mystery with our strength,
our talent: we would grab Proteus by the throat, cut short his inconclusive
metamorphoses from Plato to Augustine, from Augustine to Thomas, from
Thomas to Hegel, from Hegel to Croce. We would force him to speak."
~Primo Levi _The Periodic Table_ (1975) Translated by Raymond Rosenthal
(1984)

8.From: Norma van der Plaas

My daughter, not that long ago, made a basic error on a chemistry matter
in discussion with me, to which I replied, "Good heavens, you should
know that, you learnt it in the lab in your Yr 8 (first year High
School) Science class!"
She replied, "No I didn't"
I retorted, "Yes, you did!"
She replied, "No I didn't. How would *YOU* know what the dumb Science
teacher taught us, anyway?"
I replied, quietly, "Because, if you care to recall, I *WAS* your dumb
Yr 8 Science teacher"

9.Famous last words

Chemistry teacher: And if you combine the base and the acid just right, youcan safely drink it.
Chemist: What kind of tea is this?
Chemist: Why do they keep that under oil? It wil be much safer under water.

10.Top Ten ways to get thrown out of chemistry lab

10. Pretend an electron got stuck in your ear, and insist on describing the sound to others.
9. Give a cup of liquid nitrogen to a classmate and ask, "Does this taste funny to you?"
8. Consistently write three atoms of potassium as "KKK."
7. Mutter repeatedly, "Not again... not again... not again."
6. When it's very quiet, suddenly cry out, "My eyes!"
5. Deny the existence of chemicals.
4. Begin pronouncing everything your immigrant lab instructor says exactly the way he/she says it.
3. Casually walk to the front of the room and urinate in a beaker.
2. Pop a paper bag at the crucial moment when the professor is about to pour the sulfuric acid
1. Show up with a 55-gallon drum of fertilizer and express an interest in federal buildings.

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Chemistry Songs and poem

Song1

You better not weigh
You better not heat
You better not react
I'm telling you now
The Chemistry Teacher's coming to town.
He's collecting data
He's checking it twice
He's gonna find out
The heat of melting ice
The Chemistry Teacher's coming to town.
He sees you when you're decanting
He knows when you titrate
He knows when you are safe or not
So wear goggles for goodness sake.
Oh, you better not filter
And drink your filtrate
You better not be careless and spill your precipitate.
The Chemistry Teacher's coming to town.

2. I'm Dreaming of a White Precipitate

I'm dreaming of a white precipitate
just like the ones I used to make
Where the colors are vivid
and the chemist is livid
to see impurities in the snow.

I'm dreaming of a white precipitate
with every chemistry test I write
May your equations be balanced and right
and may all your reactions be bright.

3. Silent Labs
Silent labs, difficult labs
All with math, all with graphs
Observations of colors and smells
Calculations and graph curves like bells
Memories of tests that have past
Oh, how long will chemistry last
Silent labs, difficult labs
All with math, all with graphs
Lots of equations that need balancing
Gas pressure problems that make my head ring
Santa Chlorine's on his way
Oh, Please Santa bring me an 'A'.

4. Deck the Labs
Deck the labs with rubber tubing
Fa la la la la, la la la la.
Use your funnel and your filter
Fa la la la la, la la la la.
Don we now our goggles and aprons
Fa la la la la, la la la la.
Before we go to our lab stations
Fa la la la la, la la la la.
Fill the beakers with solutions
Fa la la la la, la la la la.
Mix solutions for reactions
Fa la la la la, la la la la.
Watch we now for observations
Fa la la la la, la la la la.
So we can collect our data
Fa la la la la, la la la la.

5. The Twelve Days of Chemistry
On the first day of chemistry
My teacher gave to me
A candle from Chem Study.
(second day) two asbestos pads
(third day) three little beakers
(fourth day) four work sheets
(fifth day) five golden moles
(sixth day) six flaming test tubes
(seventh day) seven unknown samples
(eighth day) eight homework problems
(ninth day) nine grams of salt
(tenth day) a ten page test
(eleventh day) eleven molecules
(twelfth day) a twelve point quiz
From: shaffer#NoSpam.morpheus.cis.yale.edu (Wendy Shaffer)

Just thought I'd post this little carol, which I wrote to celebratesuccesfully completing a recent Quantum Chemistry exam. Enjoy...5b.
The Twelve Days of Christmas
On the first day of Christmas, my professor gave to me: An exam in QuantumChemistry.
On the second day of Christmas, my professor gave to me:
adouble integral and an exam in Quantum Chemistry.
On the third day of Christmas, my professor gave to me:
three orbitals, adouble integral, and an exam in Quantum Chemistry.
On the fourth day of Christmas, my professor gave to me:
four harmonicoscillators, three orbitals, etc.
On the fifth day of Christmas, my professor gave to me:
Five HermitianOperators! Four harmonic ocillators, three orbitals, etc.
On the sixth day of Christmas, my professor gave to me:
six spin-orbitcouplings, etc.
On the seventh day of Christmas, my professor gave to me:
seven basisfunctions, etc.
On the eighth day of Christmas, my professor gave to me:
eight time dependentperturbations, etc.
On the ninth day of Christmas, my professor gave to me:
nine Slaterdeterminants, etc.
On the tenth day of Christmas, my professor gave to me:
ten electronstunneling, etc.
On the eleventh day of Christmas, my professor gave to me:
eleven photonsemitting, etc.
On the twelfth day of Christmas, my professor gave to me:
12 fermionsexchanging, etc.

6. Test Tubes Bubbling(to the tune of "Chestnuts Roasting On An Open Fire")
Test tubes bubbling in a water bath
Strong smells nipping at ypur nose.
Tiny molecules with their atoms all aglow
Will find it hard to be inert tonight.
They know that Chlorine's on its way
He's loaded lots of little electrons on his sleigh
And every student's slide rule is on the sly
To see if the teacher really can multiply.
And so I offer you this simple phrase
To chemistry students in this room
Although it's been said many times, many ways
Merry molecules to you.

7. O Little Melting Particle(to the tune of "O Little Town Of Bethlehem")
Para Dichloro Benzene
how do you melt so well?
The plateau of your cooling curve
is really something swell.
We think the heat of fusion
of water is so nice
Give up fourteen hundred cals per mole
and what you get is ice.

. We Wish You a Happy Halogen
We wish you a happy halogen
We wish you a happy halogen
We wish you a happy halogen
To react with a metal.
Good acid we bring to you and your base.
We wish you a merry molecule
and a happy halogen.

9. Chemistry Wonderland
Gases explode, are you listenin'
In your rest tube, silver glistens
A beautiful sight, we're happy tonight
Walking in a chemistry wonderland.
Gone away, is the buoyancy
Here to stay, is the density
A beautiful sight, we're happy tonight
Walking in a chemistry wonderland.
In the beaker we will make lead carbonate
and decide if what's left is nitrate
My partner asks "Do we measure it in moles or grams?"
and I'll say, "Does it matter in the end?"
Later on, as we calculate
the amount, of our nitrate
We'll face unafraid, the precipitates that we made
walking in a chemistry wonderland.
10. I Saw Teacher Kissing Santa Chlorine
I saw teacher kissing Santa Chlorine
under the chemistree last night
They didn't sneak me down the periodic chart
to take a peek
At all the atoms reacting in their beakers;
it was neat.
And I saw teacher kissing Santa Chlorine
under the chemistree so bright
Oh what a reaction there would have been
if the principal had walked in
With teacher kissing Santa Chlorine last night.

11. O Come All Ye Gases
O Come all yea gases
diatomic wonders
O come yea, o come yea
calls Avogadro. O come yea in moles
6 x 10 to the 23rd
O molar mass and molecules
O volume, pressure and temperature
O molar volume of gases at S.T.P.

12. We Three Students Of Chemistry Are
We three students of chemistry are
taking tests that we think are hard
Stoichiometry, volumes and densities
worrying all the time.
O room of wonder
room of fright
Room of thermites
blinding light:
With your energies
please don't burn us
Help us get our labs all right.

13. Iron the Red Atom Molecule(to the tune of "Rudolph The Red-Nosed Reindeer")
There was Cobalt and Argon and Carbon and Fluorine
Silver and Boron and Neon and Bromine
But do you recall
the most famous element of all?
Iron the red atom molecule
had a very shiny orbital
And if you ever saw him
You'd enjoy his magnetic glow
All of the other molecules
used to laugh and call him Ferrum
They never let poor Iron
join in any reaction games.
Then one inert Chemistry eve
Santa came to sayIron with your orbital so bright
won't you catalyze the reaction tonight?
Then how the atoms reacted
and combined in twos and threes
Iron the red atom molecule
you'll go down in Chemistry!

14. Lab Reports(to the tune of "Jingle Bells")
Dashing through the lab
with a tan page lab report
Taking all those tests
and laughing at them all
Bells for fire drills ring
making spirits bright
What fun it is to laugh and sing
a chemistry song tonight.
Oh, lab report, lab reports,
reacting all the way
Oh what fun it is to study
for a chemistry test today,
Hey! Chemistry test, chemistry test
isn't it a blast
Oh what fun it is to take a
chemistry test and pass.

15. Silver Nitrate(to the tune of "Silver Bells")
Silver nitrate, silver nitrate
it's chemistry time in the lab
Ding-a-ling, with a copper ring
soon it will be chemistry day.
Take your nitrate, in solution
Add your copper with style
In the beaker there's a feeling of reactions
silver forming, blue solution
Bringing ooh's ah's and wows
now the data procesing begins.
Get the mass, change to moles
what is the ratio with copper?
Write an equation, balance it
we're glad it's Chemistry Day.

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quotes in chemistry

Chemists are a strange class of mortals, impelled by an almost maniacalimpulse to seek their pleasures amongst smoke and vapour, soot and flames,poisons and poverty, yet amongst all these evils I seem to live so sweetlythat I would rather die than change places with the King of Persia." -- Johann Joachim Becher, Physica subterranea (1667)
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All that glitters may not be gold, but at least it contains free electrons. -- John Desmond Baernal (Irish physicist, 1901-1971) in a Lecture at Birkbeck college, University of London, 1960.
A tidy laboratory means a lazy chemist. -- Jöns Jacob Berzelius (Swedish chemist,1779-1848)

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... chemistry is a trade for people without enough imagination to bephysicists.--- Arthur C. Clarke & Michael Kube-McDowellin The Trigger, 1999, p. 410 (paperback edition)Note: Clarke was a chemist.

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"Every attempt to employ mathematical methods in the study of chemicalquestions must be considered profoundly irrational and contrary to thespirit of chemistry.... if mathematical analysis should ever hold aprominent place in chemistry -- an aberration which is happily almostimpossible -- it would occasion a rapid and widespread degeneration of thatscience." -- Auguste Comte, Cours de philosophie positive, 1830

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BUCKY BALL QUOTATIONS:"If it ain't tubes, we don't do it." -Richard Smalley, ACS Fullerene Satelite-Link Talk "We'd like to make it [bucky fiber] in a continuous fiber, roll it on adrum, and go fishing with it." -Richard Smalley, more of the same...
From: "Brenda L. Carroll" "Chemistry is all about getting lucky..." -Robert Curl

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From: kab4242#NoSpam.utxvms.cc.utexas.edu (Kevin Anthony Boudreaux) It is disconcerting to reflect on the number of students we have flunkedin chemistry for not knowing what we later found to be untrue.--quoted in Robert L. Weber, Science With a Smile (1992)

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From: scutchen#NoSpam.phoenix.phoenix.net (Steve Cutchen) Stephen Wright:(Referring to a glass of water:) I mixed this myself. Two parts H, onepart O. I don't trust anybody! They say we're 98% water. We're that close to drowning...(picks up hisglass of water from the stool)...I like to live on the edge... I bought some powdered water, but I don't know what to add to it.

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From: "Christopher Brown" Chemists are, on the whole, like physicists, only 'less so'.They don't makequite the same wonderful mistakes, and much what they do is an art, relatedto cooking, instead of a true science. They have their moments, and theirsources of legitimate pride. They don't split atoms, as the physicists do.They join them together, and a very praiseworthy activity that is.

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Anthony Standen, Science is a sacred cow (1958).

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chemistry jokes | organic chemistry jokes

A chemist walks into a pharmacy and asks the pharmacist, "Do you have any acetylsalicylic acid?""You mean aspirin?" asked the pharmacist."That's it, I can never remember that word."


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A physicist, biologist and a chemist were going to the ocean for the first time.
The physicist saw the ocean and was fascinated by the waves. He said he wanted to do some research on the fluid dynamics of the waves and walked into the ocean. Obviously he was drowned and never returned.
The biologist said he wanted to do research on the flora and fauna inside the ocean and walked inside the ocean. He too, never returned.
The chemist waited for a long time and afterwards, wrote the observation, "The physicist and the biologist are soluble in ocean water".

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A Chemical is a Substance that:
An organic chemist turns into a foul odor.An analytical chemist turns into a procedure.A physical chemist turns into a straight line.A biochemist turns into a helix.A chemical engineer turns into a profit.
Chemicals: Noxious substances from which modern foods are made.
Little Willie was a chemist,Little Willie is no more.What he thought was H2O,Was H2SO4.
Little Johnny took a drink,Now he shall drink no more.For what he thought was H2O,Was H2SO4.
Classification of Chemistry
Physical Chemistry: The pitiful attempt to apply y=mx+b to everything in the universe.Organic Chemistry: The practice of transmuting vile substances into publications.Inorganic Chemistry: That which is left over after the organic, analytical, and physical chemists get through picking over the periodic table.Chemical Engineering: The practice of doing for a profit what an organic chemist only does for fun.
Organic chemistry is the study of carbon compounds,biochemistry is the study of carbon compounds that wriggle.
If you're not part of the solution, you're part of the precipitate!
Ban Dihydrogen Monoxide! The Invisible Killer
Dihydrogen monoxide is colorless, odorless, tasteless, and kills uncounted thousands of people every year. Most of these deaths are caused by accidental inhalation of DHMO, but the dangers of dihydrogen monoxide do not end there. Prolonged exposure to its solid form causes severe tissue damage. Symptoms of DHMO ingestion can include excessive sweating and urination, and possibly a bloated feeling, nausea, vomiting and body electrolyte imbalance. For those who have become dependent, DHMO withdrawal means certain death.
Dihydrogen monoxide:
is also known as hydric acid, and is the major component of acid rain.
contributes to the "greenhouse effect."
may cause severe burns.
contributes to the erosion of our natural landscape.
accelerates corrosion and rusting of many metals.
may cause electrical failures and decreased effectiveness of automobile brakes.
has been found in excised tumors of terminal cancer patients.
CONTAMINATION IS REACHING EPIDEMIC PROPORTIONS!
Quantities of dihydrogen monoxide have been found in almost every stream, lake, and reservoir in America today. The pollution is global, and the contaminant has even been found in Antarctic ice. In the midwest alone DHMO has caused millions of dollars of property damage.
Despite the danger, dihydrogen monoxide is often used:
as an industrial solvent and coolant.
in nuclear power plants.
in the production of styrofoam.
as a fire retardant.
in many forms of cruel animal research.
in the distribution of pesticides. Even after washing, produce remains contaminated by this chemical.
as an additive in certain "junk-foods" and other food products.
Companies dump waste DHMO into rivers and the ocean, and nothing can be done to stop them because this practice is still legal. The impact on wildlife is extreme, and we cannot afford to ignore it any longer!
THE HORROR MUST BE STOPPED!
The American government has refused to ban the production, distribution, or use of this damaging chemical due to its "importance to the economic health of this nation." In fact, the navy and other military organizations are conducting experiments with DHMO, and designing multi-billion dollar devices to control and utilize it during warfare situations. Hundreds of military research facilities receive tons of it through a highly sophisticated underground distribution network. Many store large quantities for later use.
IT'S NOT TOO LATE!
Act NOW to prevent further contamination. Find out more about this dangerous chemical. What you don't know can hurt you and others throughout the world.
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What quote did Decartes come up with in his organic chemistry class?I think, therefore I amide.
Two molecules are walking down the street and they run into each other. One says to the other, "Are you all right?""No, I lost an electron!""Are you sure?" "I'm positive!"
Free radicals have revolutionized chemistry.
Rules of the lab
If an experiment works, something has gone wrong.
When you don't know what you're doing, do it neatly.
Experiments must be reproduceable, they should fail the same way each time.
First draw your curves, then plot your data.
Experience is directly proportional to equipment ruined.
Always keep a record of your data. It indicates that you have been working.
To do a lab really well, have your report done well in advance.
If you can't get the answer in the usual manner, start at the answer and derive the question.
In case of doubt, make it sound convincing.
Do not believe in miracles--rely on them.
Team work is essential, it allows you to blame someone else.
All unmarked beakers contain fast-acting, extremely toxic poisons.
No experiment is a complete failure. At least it can serve as a negative example.
Any delicate and expensive piece of glassware will break before any use can be made of it.
Chemist's last words
And now the tasting test...
And now shake it a bit...
In which glass was my mineral water?
Why does that stuff burn with a green flame?!?
And now the detonating gas problem.
This is a completely safe experimental setup.
Now you can take the protection window away...
Where do all those holes in my kettle come from?
And now a cigarette...
A physical chemist is a student who goes to university thinking he might want to be a physicist, but gets intimated by the math.
Chemistry Revisited
Some oxygen molecules help fires burn while others help to make water. So, sometimes it's brother against brother.
When you smell an odorless gas, it is probably carbon monoxide.
H2O is hot water, and CO2 is cold water.
Radioactive cats have 18 half-lives.
A super-saturated solution is one that holds more than it can hold.
To most people solutions mean finding the answers. But to chemists solutions are things that are still all mixed up.
Experiments should be reproducible. They should all fail in the same way.
ctivation Energy is the useful quantity of energy available in one cup of coffee.
How chemists do it...
Chemists do it reactively.Chemists do it in test tubes.Chemists do it in equilibrium.Chemists do it in the fume hood.Chemists do it in an excited state.Chemists do it periodically on table.Chemists do it organically and inorganically.Electrochemists do it with greater potential.Polymer chemists do it in chains.Pharmaceutical chemists do it with drugs.Analytical chemists do it with precision and accuracy.
You Might Be a Chemist if...
you carry your lab safety goggles around with you at all times, just in case...
you don't drink water, you drink H2O.
you start disagreeing with movies and TV shows on scientific aspects.
you carry a base solution around with you at all times, just in case one of those freak Hydrochloric acid spills happen.
you become very agitated when people refer to air as Oxygen, and proceed to list all of the components of air.
instead of writing ozone you write O3.
you start referring to the smell of nail polish remover as an acetone smell.
you no longer ask for Tylenol, you ask for acetaminophen.
you actually enjoy going to Chemistry class.
you think a mole is a unit of amount, rather than a small furry animal in your lawn.
you pronounce unionized as "un-ion-ized", instead of "union-ized".
you wash your hands before you go to the bathroom.
you start explaining the condensation of water vapour every time your soda can has water drops and people think water is coming out of the can.

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Bredt's Rule | bridged systems

Bredt’s Rule states that bridged systems having a double bond at the bridgehead position cannot exist.
Thus according to this rule introduction of a double bond at the bridgehead of a fused ring system by any means is impossible.
A simple example, which illustrates Bredt’s Rule, is the dehydration of Norborneol (Bicyclo- [2,2,1] heptan-2-ol). This reaction is an elimination reaction wherein the substrate (norborneol) possesses two beta-carbons (the bridgehead methane carbon (C1) and methylene carbon (C3)), both of which bear hydrogen which can be competitively abstracted and thus the double bond may be oriented in either of the two ways to yield two products.
Thus the product as per Saytzeff’s Rule should be the major product. But this is not observed, as the product is not formed, as the elimination is not from the bridgehead carbon. The other product (alkene), which should be a minor product as per Saytzeff’s Ruleis, formed as the major product, which justifies Bredt’s Rule.
However there are many exception to Bredt’s Rule i.e., as the ring size of the bicyclic system increases, double bond can be introduced at the bridgehead with puckering of the rings. An example to this exception is Bicyclonene, which has a bridgehead double bond but is stable .In this compound the planarity of the pi-bond is accommodated by the puckering of the large ring.

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Cascade reaction in alkyne chemistry

Cascade reaction
A cascade reaction or tandem reaction or domino reaction is a consecutive series of intramolecular organic reactions which often proceed via highly reactive intermediates. It allows the organic synthesis of complex multinuclear molecules from a single acyclic precursor. The substrate contains many functional groups that take part in chemical transformations one at the time. Often a functional group is generated in situ from the previous chemical transformation. The definition includes the prerequisite intramolecular in order to distinguish this reaction type from a multi-component reaction. In this sense it differs from the definition of a biochemical cascade. The main advantages of a cascade reaction in organic synthesis are that the reaction is often fast due to its intramolecular nature, the reaction is also clean, displays high atom economy and does not involve workup and isolation of many intermediates.A cascade reaction is sometimes called a living reaction because it shares some characteristics with a living polymerization. In cascade reactions one can identify an initiation site, a relay moiety and a termination moiety. Examples of cascade reactions are numerous (e.g. the Aldol-Tishchenko reaction) and especially so in alkyne chemistry (the Banert cascade to name just one) or polyolefin polycycloisomerizations. Other alkyne coupling reactions are classified based on common features such as type of compound synthesised, for instance the spiro mode cascade.

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Ugi Reaction

Ugi Reaction
The Ugi four-component condensation (U-4CC) between an aldehyde, an amine, a carboxylic acid and an isocyanide allows the rapid preparation of α-aminoacyl amide derivatives. The Ugi Reaction products can exemplify a wide variety of substitution patterns, and constitute peptidomimetics that have potential pharmaceutical applications. This reaction is thus very important for generating compound libraries for screening purposes.

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Table showing 1-H NMR chemical shift | Type of proton.

Type of proton.
Table showing 1-H NMR chemical shift
Chemical shift (d ppm)
Alkyl, RCH3
0.8-1.0
Alkyl, RCH2CH3
1.2-1.4
Alkyl, R3CH
1.4-1.7
Allylic, R2C=CRCH3
1.6-1.9
Benzylic, ArCH3
2.2-2.5
Alkyl chloride, RCH2Cl
3.6-3.8
Alkyl bromide, RCH2Br
3.4-3.6
Alkyl iodide , RCH2I
3.1-3.3
Ether, ROCH2R
3.3-3.9
Alcohol, HOCH2R
3.3-4.0
Ketone, RCOCH3
2.1-2.6
Aldehyde, RCOH
9.5-9.6
Vinylic, R2C=CH2
4.6-5.0
Vinylic, R2C=CRH
5.2-5.7
Aromatic, ArH
6.0-9.5
Acetylenic, RC=CH
2.5-3.1
Alcohol hydroxyl, ROH
0.5-6.0a
Carboxylic, RCOOH
10-13a
Phenolic, ArOH
4.5-7.7a
Amino, R-NH2
1.0-5.0a

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pKa prediction by Hammett and Taft equations

. pKa prediction by Hammett and Taft equations

A more accurate prediction of pKa, but for a small class of compounds, may be made using Hammett equations. The atom typing above reflects the major factors influencing a site's disassociation constant, the atomic species of the site and the very local steric and electronic effects. However no account is made of the longer range electronic (inductive, mesomeric and electrostatic field effects). In 1940, L.P. Hammett demonstrated that the effects on pKa of meta- and para- substitued aromatic compounds (benzoic acids) were linear and additive.

This leads to the Hammett Equation for pKa:
pKa = pKa0 - Rho * Sum(Sigma)

Where Sigma is a constant assigned to a particular substituent, Rho is a constant assigned to the particular acid or base functional group and pKa0 is the pKa of the unsubstituted acid or base. For benzoic acids, pKa0 is 4.20 and Rho is defined to be 1.0.
In the original formulation, two constants need to assigned to each substituent, Sigmameta for meta-substitutions and Sigmapara for para-substitutions. This was soon extended to aliphatic systems by Taft, by introducing Sigmastar (also written Sigma*). Currently over 40 forms of sigma constant have been defined, but many of these corrolate extremely well with each other.
As a worked example, consider the pKa prediction of the compound shown below, 4-chloro-3, 5-dimethylphenol.

The Hammett equation for phenol has pKa0 = 9.92 and Rho = 2.23. The Sigmameta for -CH3 is -0.06 and the Sigmapara is 0.24. Hence the predicted value of the pKa is 9.92 - 2.23*(0.24-0.06-0.06) = 9.70. This compares extremely well with the experimental value of 9.71.
A major benefit of Hammet/Taft equations is their ability to handle special cases.
Tetronic acids (pKa ~3.39):The duck-billed platypus of organic chemistry?

6. Estimation of Sigma Constants
Unfortunately, the Achilles heel of Hammett and Taft based pKa prediction is the dependence upon large databases, both for the substituent constants and for the acid/base functional group under consideration. The functional groups can be supplemented by the atom type based approach described above. Missing sigma constants, however, are a more serious problem. In a recent analysis by Peter Ertl, showed that only 63 of the 100 common substituents (taken from the logpstar database) had measured sigma constants.

One common approach, is to extend the set of known substituents with sigma transmission equations. For example, Sigmastar of -CH2-R can be estimated as 0.41 * the Sigmastar for R. Similarly, -CH=CH- has transmission coefficient 0.51 and -C6H4- has coefficient 0.30. Similar schemes include the Exner-Fiedler method for aliphatic cycles, and the Dewar-Grisdale method for polyaromatic systems. However, this approach cannot be used when a terminal group in unparameterized.

A second approach is to use molecular orbital methods to estimate sigma values when there is no experimental data. Using the strong corrolation between sigmameta and sigmapara and charges calculated with MOPAC's AM1 Hamiltonian, Peter Ertl of Novartis has been able to calculate sigma constants for over 80,000 organic functional groups.

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chemistry inventions

Chemistry Inventions, Discoveries and Patents

Invention
Inventor
Year
Short Description
Patent No.




Aluminum
Charles Hall
1888
Electrolytic method for extracting pure aluminum from its ore
US400,665




Anti-Leukemia Drugs
Gertrude Elion
1955
2-Amino-6-Mercaptopurine, or "Purinethol," the first major medicine to fight leukemia.
US2,884,667




Bakelite
Leo Baekeland
1907
Nonflammable material that was cheaper and more versatile than other known plastics. Used in everything from engine parts to jewelry to electronics.
US942,699




Bromine Extraction
Herbert Dow
1891
Entirely new method of extracting bromine from prehistoric brine.
US11,232




Carborundum
Edward Acheson
1897
Highly effective abrasive used in manufacturing.
US492,767US615,648




Catalytic Cracking
William Burton
1912
First commercially successful process for cracking crude oil into gasoline and other products.
US1,049,667




Cortisone (Synthetic)
Lewis Sarett
1945
Synthetic version of the hormone cortisone: an effective treatment against rheumatoid arthritis.
US2,462,133




Dynamite
Alfred Nobel
1866
Combination of nitroglycerin absorbed by a porous substance that enabled an easily handled, solid yet malleable explosive.
US78,317




HDPE and Polypropylene Plastics
Robert BanksPaul Hogan
1956
A method to produce HDPE in a low pressure situation.
US2,825,721




Isothiocyanate Compounds
Joseph BurckhalterRobert Seiwald
1958
Identification of antigens through the synthesis of fluorescein isothiocyanate (FITC)
US2,937,186




Kevlar
Stephanie Kwolek
1971
Polymer fiber five times stronger than the same weight of steel for bullet-resistant vests and many other applications.
US3,819,587




Nystatin
Rachel BrownElizabeth Hazen
1952
Antifungal / antibiotic cure for many disfiguring and disabling fungal infections of the skin, mouth, throat, and intestinal tract.
US2,797,183




Oral Contraceptives
Frank Colton
1951
Enovid, the first oral contraceptive
US2,691,028




Pasteurization
Louis Pasteur
1862
Process of heating food for the purpose of killing harmful organisms such as bacteria, viruses, protozoa, molds, and yeasts.
US135,245




Peanut Products
George Washington Carver
1923
Peanut cosmetics, paints and stains.
US1,522,176US1,541,478




Penicillin Production
Andrew Moyer
1945
By culturing the penicillium mold in a culture broth comprising corn steep liquor and lactose, penicillin yields could be increased many fold
US2,442,141US2,443,989




Penicillin Production
John Sheehan
1957
The first rational total and general synthesis of natural penicillin.
US3,939,151




Pentothal
Donalee TabernErnest Volwiler
1936
General anesthetic Pentothal, one of the most important agents in modern medicine
US2,153,729




pH Meter
Arnold Beckman
1935
Apparatus for testing acidity
US2,058,761




Photography
George Eastman
1885
The first commercial film was cut in narrow strips and wound on a roller device patented by Eastman and Walker
US226,503




Polymerase Chain Reaction (PCR)
Kary Mullis
1983
PCR amplifies specific DNA sequences from very small amounts of complex genetic material. The amplification produces an almost unlimited number of highly purified DNA molecules suitable for analysis or manipulation. Essential for screening genetic and infectious diseases, genetics, medicine, forensics and paternity testing.
US4,683,202




Polyurethane
William HanfordDonald Holmes
1939
Process that reacts polyols and related hydroxy compounds with di-isocyanates for making the multipurpose material polyurethane. Uses: upholstery, heat-insulation, artificial hearts, safety padding in modern automobiles and carpeting.
US2,284,896




Polyvinyl Chloride (PVC)
Waldo Semon
1926
A method to plasticize PVC by blending it with various additives rendering it a more flexible and more easily processed material that soon has become the world's second-best-selling plastic.
US1,929,453US2,188,396




Prozac
Bryan MolloyKlaus Schmiegel
1974
A class of aryloxyphenylpropylamines, which includes the active ingredient in Prozac®, the most widely used antidepressant.
US4,314,081




Scotchgard (TM) Textile Protector
Patsy ShermanSamuel Smith
1956
One of the most widely used and valuable products in stain repellency and soil removal.
US3,574,791




Synthetic Rubber
Julius Nieuwland
1928
A process by which monovinylacetylene were treated with hydrogen chloride and the resulting chloroprene polymerized, neoprene would result.
US1,811,959




Synthetic Rubber
Wallace Carothers
1930
A process that enabled the large-scale production of Neoprene, the first commercially successful synthetic rubber.
US2,130,947US2,130,948




Tagamet - Cimetidine
Graham DurantJohn EmmettCharon Ganellin
1974
Tagamet is one of the world's most essential drugs for its ability to heal stomach ulcers without surgery.
US3,950,333US4,024,271




Teflon
Roy Plunkett
1938
A synthetic fluoropolymer which has an extremely low coefficient of friction against polished steel and is used as a non-stick coating for pans and other cookware. It is very non-reactive, and so is often used in containers and pipework for reactive and corrosive chemicals.
US2,230,654




Tetracycline
Lloyd Conover
1953
Tetracycline one of the most prescribed broad spectrum antibiotic and is the drug of choice for a number of serious bacterial infections.
US2,699,054




Titanium
William Kroll
1932
"Kroll Process" enables the production of metallic ductile titanium by combining titanium tetrachloride with calcium.
US2,205,854




Transparent Silica
James Hyde
1934
A process for making fused silica, an impurity-free glass, using a method called “frame hydrolysis.”
US2,272,342




Vaccine for Hepatitis B
Baruch BlumbergIrving Millman
1963
Blumberg discovered an antigen in 1963 that detected the presence of hepatitis B in blood samples. Blumberg and Millman developed later a test that identified hepatitis B in blood samples and developed a vaccine against the virus.
US3,636,191US3,872,225




Vitamins
Max Tishler
1940
Process for the synthesis of riboflavin that would permit economical, large-scale production of the essential vitamin (B2).
US2,261,608US2,404,199




Vitamins
Robert Williams
1933
Isolation of vitamin B1 (thiamine) from a syrup of rice polishings.
US2,049,988




Vulcanization of Rubber
Charles Goodyear
1839
A process by which rubber is mixed with sulfur and heated - what came to be known as vulcanization strengthened rubber. Uses: a vast variety of industrial uses, including, eventually, automobile tires.
US3,633

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Ionic liquid | 1-butyl-3-methylimidazolium salts

Ionic liquid
An ionic liquid is a liquid that contains essentially only ions. Some ionic liquids, such as ethylammonium nitrate, are in a dynamic equilibrium where at any time more than 99.99% of the liquid is made up of ionic rather than molecular species. In the broad sense, the term includes all molten salts, for instance, sodium chloride at temperatures higher than 800 °C. Today, however, the term "ionic liquid" is commonly used for salts whose melting point is relatively low (below 100 °C). In particular, the salts that are liquid at room temperature are called room-temperature ionic liquids, or RTILs.


1-butyl-3-methylimidazolium salts or bmim
//
History
Whereas the date of discovery, as well as discoverer, of the "first" ionic liquid is disputed, one of the earlier known ionic liquids was [EtNH3]+ [NO3]- (m.p. 12 °C), the synthesis of which was published in 1914.Much later, series of ionic liquids based on mixtures of 1,3-dialkylimidazolium or 1-alkylpyridinium halides and trihalogenoaluminates, initially developed for use as electrolytes, were to follow.An important property of the imidazolium halogenoaluminate salts was that they were tuneable – viscosity, melting point and the acidity of the melt could be adjusted by changing the alkyl substituents and the ratio of imidazolium or pyridinium halide to halogenoaluminate.
A major drawback was their moisture sensitivity and, though to a somewhat lesser extent, their acidity/basicity, the latter which can sometimes be used to an advantage. In 1992, Wilkes and Zawarotko reported the preparation of ionic liquids with alternative, 'neutral', weakly coordinating anions such as hexafluorophosphate ([PF6]-) and tetrafluoroborate ([BF4])-, allowing a much wider range of applications for ionic liquids It was not until recently that a class of new, air- and moisture stable, neutral ionic liquids, was available that the field attracted significant interest from the wider scientific community.
More recently, people have been moving away from [PF6]- and [BF4]- since they are highly toxic, and towards new anions such as bistriflimide [(CF3SO2)2N]- or even away from halogenated compounds completely. Moves towards less toxic cations have also been growing, with compounds like ammonium salts (such as choline) being just as flexible a scaffold as imidazole.
Characteristics
Ionic liquids are electrically conductive and have extremely low vapor pressure. (Their noticeable odours are likely due to impurities.) Their other properties are diverse. Many have low combustibility, excellent thermal stability, a wide liquid range, and favorable solvating properties for diverse compounds. Many classes of chemical reactions, such as Diels-Alder reactions and Friedel-Crafts reactions, can be performed using ionic liquids as solvents. Recent work has shown that ionic liquids can serve as solvents for biocatalysis . The miscibility of ionic liquids with water or organic solvents varies with sidechain lengths on the cation and with choice of anion. They can be functionalized to act as acids, bases or ligands, and have been used as precursor salts in the preparation of stable carbenes. Because of their distinctive properties, ionic liquids are attracting increasing attention in many fields, including organic chemistry, electrochemistry, catalysis, physical chemistry, and engineering; see for instance magnetic ionic liquid.
Despite their extremely low vapor pressures, some ionic liquids can be distilled under vacuum conditions at temperatures near 300 °C.Some ionic liquids (such as 1-butyl-3-methylimidazolium nitrate) generate flammable gases on thermal decomposition. Thermal stability and melting point depend on the components of the liquid.
The solubility of different species in imidazolium ionic liquids depends mainly on polarity and hydrogen bonding ability. Simple aliphatic compounds are generally only sparingly soluble in ionic liquids, whereas olefins show somewhat greater solubility, and aldehydes can be completely miscible. This can be exploited in biphasic catalysis, such as hydrogenation and hydrocarbonylation processes, allowing for relatively easy separation of products and/or unreacted substrate(s). Gas solubility follows the same trend, with carbon dioxide gas showing exceptional solubility in many ionic liquids, carbon monoxide being less soluble in ionic liquids than in many popular organic solvents, and hydrogen being only slightly soluble (similar to the solubility in water) and probably varying relatively little between the more popular ionic liquids. (Different analytical techniques have yielded somewhat different absolute solubility values.)
Room temperature ionic liquids
Room temperature ionic liquids consist of bulky and asymmetric organic cations such as 1-alkyl-3-methylimidazolium, 1-alkylpyridinium, N-methyl-N-alkylpyrrolidinium and ammonium ions. A wide range of anions is employed, from simple halides, which generally inflect high melting points, to inorganic anions such as tetrafluoroborate and hexafluorophosphate and to large organic anions like bis-trifluorsulfonimide, triflate or tosylate. There are also many interesting examples of uses of ionic liquids with simple non-halogenated organic anions such as formate, alkylsulfate, alkylphosphate or glycolate. As an example, the melting point of 1-butyl-3-methylimidazolium tetrafluoroborate or [bmim][BF4] with an imidazole skeleton is about -80 °C, and it is a colorless liquid with high viscosity at room temperature.
It has been pointed out that in many synthetic processes using transition metal catalyst, metal nanoparticles play an important role as the actual catalyst or as a catalyst reservoir. It also been shown that ionic liquids (ILs) are an appealing medium for the formation and stabilization of catalytically active transition metal nanoparticles. More importantly, ILs can be made that incorporate co-ordinating groups, for example, with nitrile groups on either the cation or anion (CN-IL). In various C-C coupling reactions catalyzed by palladium catalyst, it has been found the palladium nanoparticles are better stabilized in CN-IL compared to non-functionalized ionic liquids; thus enhanced catalytic activity and recyclability are realized.
Low temperature ionic liquids
Low temperature ionic liquids (below 130 kelvins) have been proposed as the fluid base for an extremely large diameter spinning liquid mirror telescope to be based on the earth's moon.Low temperature is advantageous in imaging long wave infrared light which is the form of light (extremely red-shifted) that arrives from the most distant parts of the visible universe. Such a liquid base would be covered by a thin metallic film that forms the reflective surface. A low volatility is important for use in the vacuum conditions present on the moon.
Food science
The application range of ionic liquid also extends to food science. [bmim]Cl for instance is able to completely dissolve freeze dried banana pulp and the solution with an additional 15% DMSO lends itself to Carbon-13 NMR analysis. In this way the entire banana compositional makeup of starch, sucrose, glucose, and fructose can be monitored as a function of banana ripening.
Safety
Due to their non-volatility, effectively eliminating a major pathway for environmental release and contamination, ionic liquids have been considered as having a low impact on the environment and human health, and thus recognized as solvents for green chemistry. However, this is distinct from toxicity, and it remains to be seen how 'environmentally-friendly' ILs will be regarded once widely used by industry. Research into IL aquatic toxicity has shown them to be as toxic or more so than many current solvents already in use . A review paper on this aspect has been published in 2007. Available research also shows that mortality isn't necessarily the most important metric for measuring their impacts in aquatic environments, as sub-lethal concentrations have been shown to change organisms' life histories in meaningful ways. According to these researchers balancing between zero VOC emissions, and avoiding spills into waterways (via waste ponds/streams, etc.) should become a top priority. However, with the enormous diversity of substituents available to make useful ILs, it should be possible to design them with useful physical properties and less toxic chemical properties.
With regard to the safe disposal of ionic liquids, a 2007 paper has reported the use of ultrasound to degrade solutions of imidazolium-based ionic liquids with hydrogen peroxide and acetic acid to relatively innocuous compounds.
Despite their low vapor pressure many ionic liquids have also found to be combustible and therefore require careful handling . Brief exposure (5 to 7 seconds) to a flame torch will ignite these IL's and some of them are even completely consumed by combustion.

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types of cyclodextrins. | History of cyclodextrins

Cyclodextrins (sometimes called cycloamyloses) make up a family of cyclic oligosaccharides, composed of 5 or more α-D-glucopyranoside units linked 1->4, as in amylose (a fragment of starch). The 5-membered macrocycle is not natural. Recently, the largest well-characterized cyclodextrin contains 32 1,4-anhydroglucopyranoside units, while as a poorly characterized mixture, even at least 150-membered cyclic oligosaccharides are also known. Typical cyclodextrins contain a number of glucose monomers ranging from six to eight units in a ring, creating a cone shape. thus denoting: α-cyclodextrin: six sugar ring molecule β-cyclodextrin: seven sugar ring molecule γ-cyclodextrin: eight sugar ring molecule Cyclodextrins are produced from starch by means of enzymatic conversion. Over the last few years they have found a wide range of applications in food, pharmaceutical and chemical industries as well as agriculture and environmental engineering. It is also the chief active compound found in Procter and Gamble's deodorizing product "Febreze".
Chemical structure of the three main types of cyclodextrins. // History of cyclodextrins Cyclodextrins, as they are known today, were called "cellulosine" when first described by A. Villiers in 1891. Soon after, F. Schardinger identified the three naturally occurring cyclodextrins -α, -β, and -γ. These compounds were therefore referred to as "Schardinger sugars". For 25 years, between 1911 and 1935, Pringsheim in Germany was the leading researcher in this area, demonstrating that cyclodextrins formed stable aqueous complexes with many other chemicals. By the mid 1970's, each of the natural cyclodextrins had been structurally and chemically characterized and many more complexes had been studied. Since the 1970s, extensive work has been conducted by Szejtli and others exploring encapsulation by cyclodextrins and their derivatives for industrial and pharmacologic applications. [1] Structure
γ-CD toroid structure showing spatial arrangement. Typical cyclodextrins are constituted by 6-8 glucopyranoside units, can be topologically represented as toroids with the larger and the smaller openings of the toroid exposing to the solvent secondary and primary hydroxyl groups respectively. Because of this arrangement, the interior of the toroids is not hydrophobic, but considerably less hydrophilic than the aqueous environment and thus able to host other hydrophobic molecules. On the contrary the exterior is sufficiently hydrophilic to impart cyclodextrins (or their complexes) water solubility. The formation of the inclusion compounds greatly modifies the physical and chemical properties of the guest molecule, mostly in terms of water solubility. This is the reason why cyclodextrins have attracted much interest in many fields, especially pharmaceutical applications: because inclusion compounds of cyclodextrins with hydrophobic molecules are able to penetrate body tissues, these can be used to release biologically active compounds under specific conditions. In most cases the mechanism of controlled degradation of such complexes is based on pH change of water solutions, leading to the cleavage of hydrogen or ionic bonds between the host and the guest molecules. Alternative means for the disruption of the complexes take advantage of heating or action of enzymes able to cleave α-1,4 linkages between glucose monomers. Synthesis The production of cyclodextrins is relatively simple and involves treatment of ordinary starch with a set of easily available enzymes. Commonly cyclodextrin glycosyltransferase (CGTase) is employed along with α-amylase. First starch is liquified either by heat treatment or using α-amylase, then CGTase is added for the enzymatic conversion. CGTases can synthesize all forms of cyclodextrins, thus the product of the conversion results in a mixture of the three main types of cyclic molecules, in ratios that are strictly dependent on the enzyme used: each CGTase has its own characteristic α:β:γ synthesis ratio. Purification of the three types of cyclodextrins takes advantage of the different water solubility of the molecules: β-CD which is very poorly water soluble (18.5 g/l or 16.3mM) (at 25C???) can be easily retrieved through crystallization while the more soluble α- and γ-CDs (145 and 232 g/l respectively) are usually purified by means of expensive and time consuming chromatography techniques. As an alternative a "complexing agent" can be added during the enzymatic conversion step: such agents (usually organic solvents like toluene, acetone or ethanol) form a complex with the desired cyclodextrin which subsequently precipitates. The complex formation drives the conversion of starch towards the synthesis of the precipitated cyclodextrin, thus enriching its content in the final mixture of products. The precipitated cyclodextrin is easily retrieved by centrifugation and is later separated from the complexing agent.
Uses
Crystal structure of a rotaxane with an α-cyclodextrin macrocycle.[2] Cyclodextrins are able to form host-guest complexes with hydrophobic molecules given the unique nature imparted by their structure. As a result these molecules have found a number of applications in a wide range of fields. Other than the above mentioned pharmaceutical applications for drug release, cyclodextrins can be employed in environmental protection: these molecules can effectively immobilise inside their rings toxic compounds, like trichloroethane or heavy metals, or can form complexes with stable substances, like trichlorfon (an organophosphorus insecticide) or sewage sludge, enhancing their decomposition. In the food industry cyclodextrins are employed for the preparation of cholesterol free products: the bulky and hydrophobic cholesterol molecule is easily lodged inside cyclodextrin rings that are then removed, leaving behind a "low fat" food. Other food applications further include the ability to stabilize volatile or unstable compounds and the reduction of unwanted tastes and odour. Reportedly cyclodextrins are used in alcohol powder, a powder for mixing alcoholic drinks. The strong ability of complexing fragrances can also be used for another purpose: first dry, solid cyclodextrin microparticles are exposed to a controlled contact with fumes of active compounds, then they are added to fabric or paper products. Such devices are capable of releasing fragrances during ironing or when heated by human body. Such a device commonly used is a typical 'dryer sheet'. The heat from a clothes dryer releases the fragrance into the clothing. The ability of cyclodextrins to form complexes with hydrophobic molecules has led to their usage in supramolecular chemistry. In particular they have been used to synthesize certain mechanically-interlocked molecular architectures, such as rotaxanes and catenanes, by reacting the ends of the threaded guest. Derivatives Both β-cyclodextrin and MβCD remove cholesterol from cultured cells. The methylated form MβCD was found to be more efficient than β-cyclodextrin. The water-soluble MβCD is known to form soluble inclusion complexes with cholesterol, thereby enhancing its solubility in aqueous solution. Methyl-β-cyclodextrin are employed for the preparation of cholesterol-free products: the bulky and hydrophobic cholesterol molecule is easily lodged inside cyclodextrin rings that are then removed. It is also employed to disrupt lipid rafts by removing the cholesterol from the membrane in research.

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Hammett equation

Hammett equation



The Hammett equation in organic chemistry describes a free-energy relationship relating reaction rates and equilibrium constants for many reactions involving benzoic acid derivatives with meta- and para-substituents to each other with just two parameters: a substituent constant and a reaction constant . This equation was developed and published by Louis Plack Hammett in 1937 as a follow up to qualitative observations in a 1935 publication
The basic idea is that for any two reactions with two aromatic reactants only differing in the type of substituent the change in free energy of activation is proportional to the change in Gibbs free energy . This notion does not follow from elemental thermochemistry or chemical kinetics and was introduced by Hammett intuitively
//
Hammett equation
The basic equation is:
relating the equilibrium constant K for a given equilibrium reaction with substituent R and the reference K0 constant with R=H to the substituent constant σ which depends only on the specific substituent R and the reaction constant ρ which depends only on the type of reaction but not on the substituent used.
The equation also holds for reaction rates k of a series of reactions with substituted benzene derivatives:
In this equation k0 is the reference reaction rate of the unsubstituted reactant and k that of a substituted reactant.
A plot of log(K/K0) for a given equilibrium versus log(k/k0) for a given reaction rate with many differently substituted reactants will give a straight line.
Substituent constants
The starting point for the collection of the substituent constants is a chemical equilibrium for which both the substituent constant and the reaction constant are arbitrarily set to 1: the ionization of benzoic acid (R and R' both H) in water at 25°C.

Having obtained a value for K0, a series of equilibrium constants (K) are now determined based on the same process but now with variation of the para substituent for instance p-Hydroxybenzoic acid (R=OH, R'=H) or 4-aminobenzoic acid (R=NH2, R'=H). These values combined in the Hammett equation with K0 and remembering that ρ = 1 give the para substituent constants compiled in table 1 for amine, methoxy, ethoxy, dimethylamino, methyl, fluorine, bromine, chlorine, iodine, nitro and cyano substituents. Repeating the process with meta-substituents afford the meta substituent constants. This treatment does not include ortho-substituents which would introduce steric effects.
The δ values displayed in table 1 [6] reveal certain substituent effects. With ρ = 1 the group of substituents with increasing positive values, notably cyano and nitro cause the equilibrium constant to increase compared to the hydrogen reference meaning that the acidity of the carboxylate anion (depicted on the right of the equation) has increased. These substituents stabilize the negative charge on the carboxylate oxygen atom by an electron-withdrawing inductive effect (-I) and also by a negative mesomeric effect (-M).
The next set of substituents are the halogens for which the substituent effect is still positive but much more modest. The reason for this is that while the inductive effect is still positive, the mesomeric effect is negative causing partial cancellation. The data also that for these substituents the meta effect is much larger than the para effect and this is due to the fact that the mesomeric effect is cancelled in a meta substituent.
This effect is depicted in scheme 3 where in a para substituted arene 1a, one resonance structure 1b is a quinoid with positive charge on the X substituent releasing electrons and thus destabilizing the Y substituent. This destabilizing effect is not possible when X has a meta orientation.

Other substituents like methoxy and ethoxy can even have opposite signs for the substituent constant as result of opposing inductive and mesomeric effect. Only alkyl and aryl substituents like methyl are electron-releasing in both respects.
Of course when the sign for the reaction constant is negative (next section) only substituents with a likewise negative substituent constant will increase equilibrium constants.
Reaction constants
With knowledge of substituent constants it is now possible to obtain reaction constants for a wide range of organic reactions. The archetypal reaction is the alkaline hydrolysis of ethyl benzoate (R=R'=H) in a water/ethanol mixture at 30°C. Measurement of the reaction rate k0 combined with that of many substituted ethyl benzoates ultimately result in a reaction constant of +2.498 [2].

Reaction constants are known for many other reactions and equilibria, a selection of those provided by Hammett himself (with their values in parenthesis):
the hydrolysis of substituted cinnamic acid ester in ethanol/water (+1.267)
the ionization of substituted phenols in water (+2.008)
the acid catalyzed esterification of substituted benzoic esters in ethanol (-0.085)
the acid catalyzed bromination of substituted acetophenones (Ketone halogenation) in an acetic acid/water/hydrochloric acid (+0.417)
the hydrolysis of substituted benzyl chlorides in acetone-water at 69.8°C (-1.875).
Hammett modifications
Other equations now exist that refine the original Hammett equation: the Swain-Lupton equation, the Taft equation and the Yukawa-Tsuno equation. An equation that address stereochemistry in aliphatic systems is also known.

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मिसेल्लेस

Micelles 2
Introduction:
A micelle is formed when a variety of molecules including soaps and detergents are added to water. The molecule may be a fatty acid, a salt of a fatty acid (soap), phospholipids, or other similar molecules.
The molecule must have a strongly polar "head" and a non-polar hydrocarbon chain "tail". When this type of molecule is added to water, the non-polar tails of the molecules clump into the center of a ball like structure, called a micelle, because they are hydrophobic or "water hating". The polar head of the molecule presents itself for interaction with the water molecules on the outside of the micelle.
Structure of Dodecylphosphocholine (DPC):
An example of a micelle uses DPC is a synthetic phosphodiester. The phosphoric acid group has ester bonds between 1) choline, (CH3)3N(CH2)2OH, and 2) dodecyl (or lauryl) alcohol, CH3(CH2)11OH.
The choline, which contains a quaternary amine with a positive charge, and the phosphate are ionic and polar. The dodecyl part is the non-polar hydrocarbon chain.
Quiz: Which part of the molecule is soluble in water?
Answer: “water is polar,” so it interacts with; the choline and; phosphate group.

Which part of the molecule is insoluble in water?
Answer: Water is polar,” long HC chain; is non-polar; and insoluble.

Structure of a Micelle:
The theoretical model shows 54 molecules of dodecylphosphocholine (DPC) and about 1200 H2O molecules. Each lipid has a polar head group (phosphocholine) and a hydrophobic tail (dodecyl = C12).
The graphic on the left represents a cross section of a micelle.
The gray spheres on the interior represent the long hydrocarbon chains of the dodecyl groups, which are massed together because they are non-polar.
The polar head groups of the phosphate are shown as red and orange spheres. The amine nitrogen is shown in blue surrounded by the gray methyl groups.
The water molecules are represented as red and white spheres surrounding the outside of the micelle and penetrate all of the spaces in the head group region.
The hydrophobic tails are shown Spacefill. H2O is excluded from this entire interior volume. The hydrocarbon chains vary in their individual conformations (e.g. trans/gauche configuration at each carbon-carbon bond), but adapt so as to fill all of the interior space.

Single DPC and Surrounding Molecules:
The close-up of a DPC molecule (spacefill) in the micelle is shown in the graphic on the left. Other DPC neighbor molecules are shown in thick wire form. The rest of the micelle is white sticks.
The DPC is in contact with 10-15 H2O's (red/white spheres) that make favorable H-bond or ion-dipole interactions (<3.5 Å).
Neighboring DPC molecules that are within 4.0 Å of each DPC are thicker Sticks; the atoms on each that can make favorable van der Waals interactions are colored yellow.
Note: In contrast to protein crystal structures where interior atoms are relatively fixed. ON the other hand, the micelle interior is highly dynamic, i.e. each lipid may have 4-8 contacting neighbor lipids at any instant, but these partners change several times every nanosecond on average.

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Structure of Cryptand

Structure of cryptand encapsulating a potassium cation (purple). At crystalline state, obtained with an X-ray diffraction.
Cryptands are a family of synthetic bi- and polycyclic multidentate ligands for a variety of cations. The Nobel Prize for Chemistry in 1987 was given to Donald J. Cram, Jean-Marie Lehn, and Charles J. Pedersen for their efforts in discovering and determining uses of cryptands and crown ethers, thus launching the now fluorishing field of supramolecular chemistry.The term cryptand implies that this ligand binds substrates in a crypt, interring the guest as in a burial. These molecules are three dimensional analogues of crown ethers but are more selective and complex the guest ions more strongly. The resulting complexes are lipophilic.
Structure of Cryptand
The most common and most important cryptand is N[CH2CH2OCH2CH2OCH2CH2]3N; the formal IUPAC (International Union of Pure and Applied Chemistry) name for this compound is 1,10-diaza-4,7,13,16,21,24-hexaoxabicyclo[8.8.8]hexacosane. So it is easy to see why the common name of "cryptand" was preferable. This compound is termed [2.2.2]cryptand, where the numbers indicate the number of ether oxygen atoms (and hence binding sites) in each of the three bridges between the amine nitrogen "caps". Many cryptands are commercially available under the tradename "Kryptofix." All-amine cryptands exhibit particularly high affinity for alkali metal cations, which has allowed the isolation of salts of K-.
Properties
The three-dimensional interior cavity of a cryptand provides a binding site - or nook - for "guest" ions. The complex between the cationic guest and the cryptand is called a cryptate. Cryptands form complexes with many "hard cations" including NH4+, lanthanides, alkali metals, and alkaline earth metals. In contrast to typical crown ethers, cryptands bind the guest ions using both nitrogen and oxygen donors. Their three-dimensional encapsulation mode confers some size-selectivity, enabling discrimination among alkali metal cations (e.g. Na+ vs. K+).
Uses of Cryptand
Cryptands although they are more expensive and more difficult to prepare offer much better selectivity and strength of binding than other complexants for alkali metals, such as crown ethers. They are able to extract otherwise insoluble salts into organic solvents. Cryptands increase the reactivity of anions in salts since they effectively break up ion-pairs. They can be also be used as phase transfer catalysts by transferring ions from one phase to another. Cryptands enabled the synthesis of the alkalides and electrides. They have also been used in the crystallization of Zintl ions such as Sn92−.

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