Ethyl butyrate hydrolysis

Ethyl butyrate hydrolysis Hydrochloric acid 16,800 Steward and Bidwell, 1991... 

Pig pancreatic lipase added to a mixture of ethyl butyrate, ethyl isobutyrate, and ethyl pivalate in phosphate buffer (pH 8), and quenched with 10 M NaOH when reaction complete (pH-stat method) - butyric acid. Y 65% (> 95% purity). The enzyme only hydrolyzed straight-chain esters. F.e., preferential cleavage of functionalized esters, and comparison with horse liver acetonic powder, s. B. De Jeso et al., Synth. Commun. 18, 1699-705 (1988) preferential hydrolysis of dicarboxylic acid esters s. ibid. 1691-7. 

PROBLEM 18.54 In Section 18.8, we saw that aldehydes are avaUahle from the reduction of esters at low temperamre ( — 70 °C) hy diisohutylaluminum hydride (DIBAL-H see Fig. 18.38). If the reaction mixture is allowed to warm before hydrolysis, the yield of aldehyde drops appreciably. For example, reduction of ethyl butyrate with DIBAL-H at —70 °C followed by hydrolysis at —70 °C, affords a 90% yield of butyraldehyde. However, if the reaction mixture is allowed to warm to 0 °C before hydrolysis, the yield of aldehyde is less than 20%. 

Among the products under these conditions are ethyl butyrate (recovered starting material) and butyl alcohol (CH3CH2CH2CH2OH), formed from hydrolysis of CH3CH2CH2CH2O—AIR2 (R = isobutyl). Rationalize these observations with arrow formahsm mechanisms. 

The hydrolysis of ethyl butyrate is a ubiquitous phenomenon occurring in animal and plant tissues of many types. The enzyme responsible for the catalysis of this hydrolysis has been purified. In general, tissues contain one or more aliphatic esterases (or ali-esterases O which have a broad specificity for simple esters, possibly extending to esters of cholesterol and vitamin A. 

Trypsin, chymotrypsin, and carboxypeptidase, long thought to be specific only for the hydrolysis of peptide bonds also display a specific esterase activity. 2 Trypsin, for example, splits ammonia from benzoylargininamide and as well splits ethanol from benzoylarginine ethyl ester. No activity, however, is shown toward ethyl butyrate, a substrate for an aliphatic esterase. 

The formation of acyloins (a-hydroxyketones of the general formula RCH(OH)COR, where R is an aliphatic residue) proceeds best by reaction between finely-divided sodium (2 atoms) and esters of aliphatic acids (1 mol) in anhydrous ether or in anhydrous benzene with exclusion of oxygen salts of enediols are produced, which are converted by hydrolysis into acyloins. The yield of acetoin from ethyl acetate is low (ca. 23 per cent, in ether) owing to the accompanying acetoacetic ester condensation the latter reaction is favoured when the ester is used as the solvent. Ethyl propionate and ethyl ji-butyrate give yields of 52 per cent, of propionoin and 72 per cent, of butyroin respectively in ether. 

Amino alcohols can be resolved by a number of pathways including hydrolysis, esterification, and transesterification. For example, hydrolysis of Ai,0-diacet5l-2-amino-l-butanol with PPL followed by recrystallization results in (80a) with 95% ee (108). Hydrolysis of racemic acetates or butyrates of 2-[(aLkoxycarbonyl)amino]-l-aLkanols with PFL gives (R)-alcohol (81) with 95% ee (109). (3)-(81) can be obtained by transesterification of the racemic (81) with ethyl acetate which also serves as the reaction medium (109). 

These compounds yield, on hydrolysis, the free acids, which, like all acids containing two carbo.xyl groups attached to the same carbon atom, lose COj on heating. Thus, ethyl malonic acid yields butyric acid. In this way the synthesis of monobasic acids may be readily effected. Malonic ester, moreover, may be used in the preparation of cyclic compounds as well as of tetrabasic and also dibasic acids of the malonic acid series ( Perkin). To give one illustration malonic ester, and ethylene bromide in presence of sodium alcoholate, yield triniethyleiic dicarbo.xylic ester and tetramethylene tetracarbo.xylic ester. The first reaction takes place in two steps,... 

The 2-phenyl-2-ethyl-pentane-1,5-diacid-mononitrile-(1) of melting point 72° to 76°C, used as starting material in this process, can be produced for example from o-phenyl-butyric acid nitrile by condensation with acrylic acid methyl ester and subsequent hydrolysis of the thus-obtained 2-phenyl-2-ethyl-pentane-1,5-diacid-monomethyl ester-mononltrile-(l) of boiling point 176° to 185°C under 12 mm pressure. 

Hydrolysis, of 2 benzyl 2 carbometh oxycyclopentanone with lithium iodide m 2,4 6-colhdme, 46, 7 of 7 butyrolactone to ethyl y-bromo-butyrate with hydrogen bromide and ethanol, 46, 42 of 2,5 dicarbethoxy 1 4-cyclohexane-dione to 1,4 cyclohexanedione, 46, 25... 

E-values (E ) calculated using the equation E = [ln(l-c) (l-ees)]/[ln(l-c) (l + ees)] from data determined by gas chromatographic analysis on a chiral column from samples obtained after esterase-catalyzed hydrolysis of (R,S)-3-phenyl butyric acid ethyl ester [24]. 

These compounds are prepared starting from chloroace-tic acid or its ethyl ester. For chains longer than acetic, cya-noethylation and hydrolysis of the nitrile obtained leads to the propionic chain, alkylation with ethyl 4-bromobutyrate and saponification leads to the butyric chain. The propane-sulfonic chains are particularly accessible by means of ring opening of propane-sultone. 

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