The rate of esterification of isoamyl alcohol and glycol by dibasic acids

Abstract

The history of esterification begins with Berthelot and paen de St. Gilles, who in 1862 examined the reversible reaction between an acid and an alcohol. As the velocity of reaction was sufficiently slow for convenient study, it is not surprising to find that the relationship between the constitution of the acid and alcohol and the esterification process soon occasioned considerable research. At first the direct or auto catalytic method was used at high temperatures, but when it was shown that the reaction proceeded at a convenient rate at ordinary temperatures, provided a suitable catalyst were used, an indirect method was developed. Among the first investigations by the autocatalytic method may be mentioned the classical researches of Menschutkin, who showed that the replacement of the hydrogen atoms in the acetic acid molecule by alkyl groups, reduced the rate of esterification; for alcohols, the rate fell off with increasing complexity of the molecule; tertiary alcohols were less readily esterified than secondary, and the latter in turn less readily than the primary. Lichty Lichty. Amer, chem. J. 1895, 17,27; 1896 18,590. using the same method, found that the introduction of chlorine atoms increased the rate of esterification. Finally Rosanoff and Prager Rosanoff & Prager J. Am. C. S. 1908, 30, 1895. extended these investigations to the diortho substituted benzoic acids which resisted esterification by the catalytic method. Not only were these acids esterified, but it was further shown that their relative rates of esterification followed the same order as their dissociation constants. Certain other workers notably Goldschmidt and Michael Michael & Wohlgast. Ber. 1909, 42, 3157. have employed the direct method at ordinary temperatures, but only the stronger acids such as trichloracetic were found suitable for investigation.