Methyl 2-hydroxy benzoate, hydrolysis

This has been achieved, for solution-phase flow calorimeters, through the use of a chemical test and reference reaction the base-catalysed hydrolysis of methyl 4-hydroxy-benzoate (methyl paraben). 

Preparation by hydrolysis of 2-(2-hydroxy-4,6-dimethoxy-phenyl)-2-oxoethyl benzoate in pyridine with aqueous sodium hydroxide under nitrogen atmosphere at r.t. for 1 h (80%) [5118]. Also obtained by degradation of 2-[2-(2-hydroxy-4,6-dimethoxyphenyl)-2-oxoethoxy]-2-methyl-propionic acid in refluxing mixture of concentrated hydrochloric acid/methanol (1 vol/5 vol) for 1 h (42%) [5119]. 

In order to gain more informations on the nature of the complex borohydride Na(PEGBH2), the reduction of esters was examined using NaBH in PEG 200, 300 and monomethoxy PEG. From these results it appears that methyl benzoate is completely reduced in PEG 200, whereas the same reduction in PEG 300 is complicated by a partial hydrolysis of the ester to benzoic acid. Finally, if one of the two hydroxy groups of PEG is blocked as ether no reduction at all takes place (Scheme 7). 

R-[ H]oleate. For complete characterization of this enzymic reaction, it would be useful have available the enantiomeric specifically tritiated oleate. The Mitsunobu reaction uses triphenyl phosphine together with dimethylazodicarboxylate to form the benzoate ester of methyl ricinoleate with inversion of configuration [9]. Hydrolysis of the benzoate ester provided the 12-(R)-hydroxy-9-octadecenoate. Methylation and tosylation provided the appropriate precursor for nucleophilic displacement with NaBT4 to obtain the methyl 12-(R)-[ H]oleate. 

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