Amino acids Fischer esterification

First law of thermodynamics, 24 645-648 First limiting amino acid, 2 601 First-order irreversible chemical kinetics, 25 286-287, 292-293 First-principle approach, in particle size measurement, 13 153 First sale doctrine, 7 793 Fischer, Emil, 16 768 Fischer carbene reaction, 24 35-36 Fischer esterification, 10 499 Fischer formula, 4 697 Fischer-Indole synthesis, 9 288 Fischer lock and key hypothesis, 24 38 Fischer-Tropsch (FT) synthesis, 6 791, 827 12 431... 

Carboxyl groups of amino acids and peptides are normally protected as esters. Methyl and ethyl esters are prepared by Fischer esterification. Deprotection of methyl and ethyl esters is accomplished by hydrolysis in base. Benzyl esters are a popular choice because they can also be removed by hydrogenolysis. Thus a synthetic peptide, protected at both... 

First all three ester bonds and both amide bonds are hydrolyzed to carboxylic acid groups by the aqueous acid. The mechanisms for these reactions are discussed in Section 19.5. The ester hydrolyses follow the exact reverse of the Fischer esterification mechanism shown in Figure 19.3, and the amide hydrolysis occurs by a very similar mechanism. The product of these hydrolysis steps has three carboxylic acid groups and one amino group. Two of these acid groups are attached to the same carbon so that one can be eliminated as carbon dioxide by the cyclic mechanism described in Section 20.4 for the malonic ester synthesis ... 

Amino acid esiers. The combination of methanol and thionyl chloride is recommended by Brenner for the esterification of amino acids (the Fischer procedure usually is troublesome). A mixture of the amino acid and methanol is treated... 

Fischer-Speier esterification to give a salt of an amino acid ester (by refluxing an alkanol with anhydrous HC1 or hot benzyl alcohol with toluene-/>-sulphonic acid) is straightforward. The fact that the nearby amino group is protonated when the carboxy group reacts to give a-amino acid esters does not slow the reaction down unduly a nearby positive site might have been expected to reduce the electrophilic character of the carboxy carbon atom. Without an acid catalyst, Walkylation can accompany esterification (Equation 4.6). 

Fischer esterification. See Esterification Esters Fischer projection formulas, 271-272, 278, 280, 292, 595 a-amino acids, 1056, 1103 carbohydrates, 973-974, 1007 of meso stereoisomer, 280 tartaric acids, 286... 

SYNTHESIS The first step involves the s)mthesis of the amino acid 7-benzyl-L-glutamate by a standard Fischer esterification reaction of L-glutamic acid with benzyl alcohol in the presence of strong acid. The amino acid is subsequently converted to the N-carboxyanhydride (NCA) monomer by reaction with phosgene gas, or by reaction with the less hazardous compound triphosgene.The NCA is polymerized by initiation with a variety compounds such as primary and secondary amines, and alkoxides. Typical comonomers include other amino acid NCAs. 

Many of the reactions of carboxylic acids and amines appear in the chemistry of amino acids. Acylation and Fischer esterification are two examples.There are some new reactions, however, that involve both the amino and the acid groups. Reaction with ninhydrin is an example. 

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