Edited Invalid date
21 Carboxylic Acid Derivatives -- Part 16
Racemic products are produced by all of the laboratory products described in Section 24-5.
The l enantiomers are biologically active.
It is possible that the d enantiomers are toxic.
If the product is to have the activity of the natural material, pure l enantiomers are needed.
We must be able to resolve a racemic acid into its enantiomers.
The methods we have already discussed can be used to resolve amino acids.
Two diastereomeric salts are formed if a racemic amino acid is converted to a salt.
The salts can be separated by physical means.
Pure enantiomers are regenerated from the separated diastereomeric salts.
Strychnine and brucine are naturally occurring bases, and tartaric acid is used to resolve racemic mixtures.
There are specific catalytic activities for the kerosines.
The acyl group can be cleaved from just the molecule having the natural (l) configuration by an acylase.
The d-amino acids are unaffected because the enzyme doesn't recognize them.
The mixture of the two acids is easy to separate.
There is a hog kidneys acylase that deacylates only the natural l-amino acid.
Both amines and carboxylic acids undergo many standard reactions.
The conditions for some of these reactions must be carefully selected so that the carboxyl group reaction is not interfered with.
Two of the most useful reactions are acylation and esterification of the carboxyl group.
These reactions can be used to protect either the carboxyl group or the amino group while the other group is being modified.
There are specific reactions that occur to the a@amino acid structure.
Section 24-7C discusses the formation of a colored product on treatment with ninhydrin.
Like monofunctional carboxylic acids, amino acids are esterified by treatment with a large excess of alcohol and an acidic catalyst.
It does not interfere with esterification.
The following example shows the process of esterification.
The carboxyl group can be prevented from reacting in a way that is undesirable with the use of derivatives of amino acids.
The most common protecting groups are ethyl and benzyl.
Aqueous acid hydrolyzes the ester.
The benzyl group is converted to toluene and left with the deprotected amino acid.
The ease of formation of benzylic intermediates is what determines the mechanism of hydrogenolysis.
There is a mechanism for acid-catalyzed hydrolysis.
Give equations for the formation and hydrogenolysis.
As an acylating agent, decarboxylation is similar to the alcohol esterification of the carboxyl group of an amino acid.
Acylation is done to protect biological processes.
There is a wide variety of acid chlorides and anhydrides used for acylation.
The decarboxyl carbonyl derivative is often used as a protecting group in the synthesis of peptides.
The amide half of a carbamate ester is more easily protected than most other amides.
The half of this urethane that undergoes hydrogenolysis is a benzyl ester.
benzyloxycarbonyl amino acid gives an unstable acid that quickly decarboxylates.
The purple dye produced by ninhydrin is the same as the original one.
The side chain is lost as an aldehyde.
A wide range of substrates can be detected with the reaction of ninhydrin.
If a kidnapper touches a ransom note with his fingers, the ridges on his fingers will leave traces of a substance from his skin.
Treatment of the paper with ninhydrin and pyridine causes it to turn purple.
There is a negative charge in the purple anion.
There are many common reactions of amines and acids.
There are two monomers that combine to form polymers.
The various types of proteins are essential to life.
The formation of peptide bonds is the most important reaction.
The loss of water can cause amines and acids to form amides.
Industrial processes often make amides by mixing acid and amine and heating the mixture to drive off water.
Review flashcards and saved quizzes
Getting your flashcards
You're all caught up!
Looks like there aren't any notifications for you to check up on. Come back when you see a red dot on the bell!
Privacy & Terms