2.2.2- Trichloroethyl ester

Zn, THF-H2O, pH 4.2, 25°, 4 h. The authors suggest that selective cleavage should be possible by this method, since, at pH 4.2, 25°, 2,2,2-trichloroethyl esters are cleaved in 10 min, 2,2,2-trichloroethyl carbamates are cleaved in 30 min, and the 2,2,2-trichloroethyl carbonate of estrone, formed in 87% yield from estrone and the acid chloride, is cleaved in 4 h (97% yield). 

TBAF, THF or DMSO or DMF, 72-98% yield. 4-Nitrobenzyl and trichloroethyl esters of amino acids are also cleaved. 

Cd-Pb, AcOH, 89-94% yield.This reagent also cleaves trichloroethyl esters and carbonates. 

Electrolysis at a Hg cathode, -0.5 to -0.6 V, LiC104, CH3CN, Pyr. The trichloroethyl ester, which requires a greater reduction potential for cleavage, is retained under these conditions." ... 

If only the O-H, as opposed to the carbonyl, of a carboxyl group has to be masked, it can be readily accomplished by esterification. Alkaline hydrolysis is the usual way for regenerating the acid. t-Butyl esters, which are readily cleaved by acid, can be used if alkaline conditions must be avoided. 2,2,2-Trichloroethyl esters, which can be reductively cleaved with zinc, are another possibility.267 Some esters can be cleaved by treatment with anhydrous TBAF. These reactions proceed best for esters of relatively acidic alcohols, such as 4-nitrobenzyl, 2,2,2-trichloroethyl, and cyanoethyl.268... 

The use of protecting groups is common in penicillin chemistry the amino function is normally protected by a triryl, benzyloxycarbonyl. p-nitrobenzyloxycarbonyl. tridlloroethyloxycarbonyl. or trimethylsilyl group and the carboxylic acid is usually protected as a benzyl, p-nitrobenzyl. p-methoxybenzyl. or trichloroethyl ester. Acylations may thus be carried out... 

Alley, C.C., Brooks, J.B., and Choudhary, G., Electron capture gas-liquid chromatography of short chain acids as their 2,2,2-trichloroethyl esters, Anal. Chem., 48, 387, 1976. 

Mierzwa, S. and Witek, S., Gas-liquid chromatographic method with electron-capture detection for the determination of residues of some phenoxyacetic acid herbicides in water as their 2,2-trichloroethyl esters, J. Chromatogr., 136, 105, 1977. 

Trichloroethyl esters were proposed for the sensitive analysis of aromatic acids [152]. 

Chlorophenoxy acids are chromatographed after esterification. Methyl esters [498] and propyl esters [499] prepared by transesterification from methyl esters by heating for 5 min with n-propanol and sulphuric acid are often used. For a very sensitive analysis, Mierzwa and Witek [500] proposed the following procedure. They esterified acids with 20% of 2,2,2-trichloroethanol in TFA anhydride in the presence of sulphuric acid by heating at 100°C for 15 min (or several hours at room temperature) and analysed the derivatives on a column packed with 15% of QF-1 plus 10% of DC-200 (1 1) at 195°C. Trichloroethyl esters permit down to hundredths of 1 ppb of chlorophenoxy acids to be... 

BIS(2,2,2-TRICHLOROETHYL) AZODICARBOXYLATE [Diazenedicarboxylic acid, bis(2,2,2-trichloroethyl) ester]... 

Hydrazine hydrate Hydrazine monohydrate (8, 9) (7803-57-8) 2,2,2-Trichloroethyl chloroformate Formic acid, chloro-, 2,2,2-trichlor-ethyl ester (8) Carbonochloridic acid, 2,2,2-trichloroethyl ester (9) (17341-93-4)... 

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