Benzyl benzoate, hydrolysis

The production of both an alcohol and the sodium salt of an acid might easily be confused with the hydrolysis products of an ester (in the above instance benzyl benzoate). Such an error would soon be discovered (e.g., by reference to the b.p. and other physical properties), but it would lead to an unnecessary expenditure of time and energy. The above example, however, emphasises the importance of conducting the class reactions of neutral oxygen-containing compounds in the proper order, viz., (1) aldehydes and ketones, (2) esters and anhydrides, (3) alcohols, and (4) ethers. 

Yukawa and coworkers (1972)84 determined a0 values from the rate constants for alkaline hydrolysis of m- and p-substituted-benzyl benzoates in 70% (v/v) aqueous acetone at 25 °C. ap° values for SOMe and S02Me were found to be 0.573 and 0.749 respectively. These were compared with 0.564 and 0.721, respectively, for values determined from the rate constants of alkaline hydrolysis of substituted ethyl benzoates in 85% aqueous ethanol. From these values there is no evidence for any — R cross-conjugative effect of SOMe as a substituent in the benzoate moiety, which is eliminated when it is in the benzyl. However, both the values for SOMe are substantially higher than most of the ap values for SOMe which we have surveyed previously. For S02Me the order ap° > if significant,... 

The intermediates 74 and 76 can now lose OR to give the acid (not shown in the equations given), or they can lose OH to regenerate the carboxylic ester. If 74 goes back to ester, the ester will still be labeled, but if 76 reverts to ester, the 0 will be lost. A test of the two possible mechanisms is to stop the reaction before completion and to analyze the recovered ester for 0. This is just what was done by Bender, who found that in alkaline hydrolysis of methyl, ethyl, and isopropyl benzoates, the esters had lost 0. A similar experiment carried out for acid-Catalyzed hydrolysis of ethyl benzoate showed that here too the ester lost However, alkaline hydrolysis of substimted benzyl benzoates showed no loss. This result does not necessarily mean that no tetrahedral intermediate is involved in this case. If 74 and 76 do not revert to ester, but go entirely to acid, no loss will be found even with a tetrahedral intermediate. In the case of benzyl benzoates this may very well be happening, because formation of the acid relieves steric strain. Another possibility is that 74 loses OR before it can become protonated to 75. Even the experiments that do show loss do not prove the existence of the tetrahedral intermediate, since it is possible that is lost by some independent process not leading to ester hydrolysis. To deal with this possibility. Bender and Heck measured the rate of loss in the hydrolysis of ethyl trifluorothioloacetate- 0 ... 

Treatment of A-acyloxy-A-alkoxybenzamides 76a with dilute aqueous sodium hydroxide, at room temperature, resulted in the rapid formation of alkyl benzoates 67.40 A crossover experiment using A-acetoxy-A-butoxy-/ -chlorobenzamide 26e and A-acetoxy-A-benzyloxybenzamide 27a resulted in the exclusive formation of butyl / -chlorobenzoate (46%) and benzyl benzoate (43%) esters along with the hydrolysis products, / -chlorobenzoic acid and benzoic acid indicating that ester formation involves an intramolecular process. 

Benzyl benzoate is metabolized by rapid hydrolysis to benzoic acid and benzyl alcohol. Benzyl alcohol is then further metabolized to hippuric acid, which is excreted in the urine. 

Yukawa, Y., Tsuno, Y. and Sawada, M. (1972a). The Substituent Effect. I. Normal Substituent Constants from the Hydrolysis of Substituted-benzyl Benzoates. Bidl.Chem.Soc.Jap., 45,1198-1205. 

We have also developed a neutral low energy process for the hydrolysis of benzyl benzoate at high temperatures (>240°C) by heating benzyl benzoate with... 

Hydrolysis of 23 followed by debenzylation afforded demethyllasubine I (1) in 16% overall yield from 17. The configuration of the substituent at C-2 in 22 was inverted through two steps. Thus, hydrolysis of 22 followed by treatment with diethyl azodicarboxylate and triphenylphosphine in the presence of benzoic acid furnished the benzoate 24. Compound 24 was converted to demethyllasubine II (5) by sequential removal of the benzoyl and benzyl protecting groups the overall yield from 17 was 19%. 

Related oxidants that have been exploited to similar ends include l-(tert-butoxy)-l,2-benzoiodoxol-3(l//)-one292 and sodium bromate.293 Oxidation of benzyl ethers by l-(/erf-butoxy)-l,2-benzoiodoxol-3(l/f)-one followed by easy basic hydrolysis of the resultant benzoate ester provides a convenient alternative to the usual reductive deprotection. The reaction is carried out in the presence of alkali metal carbonates and the conditions are mild enough to be compatible with other hydroxyl protecting groups such as methoxymethyl, tetrahydropyranyl, TBS and acetate. 

As D-xylose and L-arabinose are 4-epimers, both, as well as mixtures of them (as provided by hemiceUulose), can be used to prepare enantiomerically pure synthetic intermediates the center C(4) of which is deoxy or sp -hybridized (alkenes, ketones). For instance, treatment of pure o-xylose with acetone under acidic conditions, followed by selective C(5) benzoylation, benzylation of the 3-alcoholic moiety, hydrolysis of the benzoate, and iodination furnishes the 5-iodo derivative... 

Kinetic studies of the alkaline hydrolysis of dimethyl and diethyl phthalate, ethyl benzoate, benzyl cinnamate, and diethyl malonate at 298-313 K in aqueous dioxane were reported. Activation parameters were determined for the alkaline hydrolysis of ethyl octanoate in various mixtures of PrOH-water."... 

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