- Kinetics and mechanism of alkaline hydrolysis of Y-substituted phenyl phenyl carbonates
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Second-order rate constants (kOH-) have been measured spectrophotometrically for alkaline hydrolysis of Y-substituted phenyl phenyl carbonates (2a-j) and compared with the kOH- values reported previously for the corresponding reactions of Y-substituted phenyl benzoates (1a-j). Carbonates 2a-j are 8 ～ 16 times more reactive than benzoates 1a-j. The Hammett plots correlated with σ- and σo constants exhibit many scattered points, while the Yukawa-Tsuno plot results in excellent linear correlation with ρ = 1.21 and r = 0.33. Thus, the reaction has been concluded to proceed through a concerted mechanism in which expulsion of the leaving group is advanced only a little. However, one cannot exclude a possibility that the current reaction proceeds through a forced concerted mechanism with a highly unstable intermediate.
- Kim, Song-I,Hwang, So-Jeong,Jung, Eun-Mi,Um, Ik-Hwan
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experimental part
p. 2015 - 2018
(2010/12/19)
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- Process for the preparation of alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydroxybenzoic acid
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Alkali metal salts of hydroxybenzoates are claimed which are substantially anhydrous and free from hydrobenzoic acid and have the formula STR1 in which R1 denotes alkyl, alkenyl, cycloalkyl or aralkyl, R2 and R3 are identical or different and represent hydrogen, halogen, hydroxyl, amino, alkylamino, alkyl, alkoxy, aralkyl or aryl and Me denotes an alkali metal. Furthermore a process for the preparation of the said alkali metal salts of hydroxybenzoates, which are substantially anhydrous and free from hydrobenzoic acid, characterized in that a solution or suspension of a hydroxybenzoate of the formula STR2 in which R1, R2 and R3 have the abovementioned meaning, is neutralized with an alkali metal hydroxide at -10° to +50° C. until the degree of neutralization is 0.95 to 1.05, a degree of neutralization of 1.00 denoting the end point of the neutralization of the phenolic OH group by the alkali metal hydroxide, and the resulting solution or suspension of the alkali metal salt of the hydroxybenzoate is passed to a mild drying operation which does not damage the product and is in itself known, after a time such that the content of hydroxybenzoic acid or the alkali metal salt thereof in this solution or suspension does not reach the value of 1% by weight, relative to the amount of alkali metal salt of hydroxybenzoate contained in this solution or suspension.
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