General acid catalysed hydrolysis of benzaldehyde aryl methyl acetals
- 1 January 1975
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 10,p. 1113-1118
- https://doi.org/10.1039/p29750001113
Abstract
The kinetics of hydrolysis of substituted-benzaldehyde methyl phenyl acetals, XC6H4·CH(OMe)(OPh)(X =m-NO2, m-MeO, H, p-Me, or p-Meo), and of benzaldehyde methyl substituted-phenyl acetals, Ph·CH(OMe)-(OC6H4Y)(Y =m-NO2, m-Br, m-F, m-MeO, p-Me, or p-MeO), catalysed by pivalic, acetic, 3-chloropropionic, formic, and chloroacetic acid, and by hydronium ions have been studied. The reactions of the benzaldehyde methyl substituted-phenyl acetals have non-linear Hammett plots which were thought to arise from a shift in the structure of the transition state from one bearing a negative charge on the phenolic oxygen to one bearing a positive charge as the substituent changes from being electron withdrawing to electron releasing. The α values for these reactions become larger the more strongly electron releasing the substituent. The α values for the reactions of the substituted-benzaldehyde methyl phenyl acetals increase as the electron withdrawing power of the substituent increases. The mechanisms of these reactions are discussed with reference to the relevant More O'Ferrall–Jencks diagram.Keywords
This publication has 0 references indexed in Scilit: