Gas chromatographic verification of a mathematical model: product distribution following methanolysis reactions

Abstract

Kinetic and thermodynamic parameters of alcoholysis reactions have been carefully studied by gas chromatography. The methanolysis of diethyl acetal was studied by Juvet and Chiu (1) and later modified as a gas chromatography experiment for determination of the rate constants for the two-step reaction (2). Juvet and Wachi (3) reported equilibrium constants for the alcoholysis of propionate and butyrate esters, and estimated the precision of the gas chromatographic method to be about 1-2%. Rowland et al. (J, 5) extensively studied malonate transesterifications and provided kinetic, equilibrium thermodynamic, and mechanistic information; Johnson et al. ( 6) carefully studied the kinetics of the methanolysis of diethyl malonates. The application of binomial statistics to the chemical systems herein described is in many respects analagous to the recently developed theory of electron transfer with reactants having multiple electroactive centers (7).

Preparation of Oil of Wintergreen from Commercial Aspirin Tablets. A Microscale Experiment Highlighting Acyl Substitutions

“…The methyl salicylate product can be analyzed by 13 C or 1 H NMR spectroscopy as an excellent tool for instructing students on the use of the spectrometer and interpretation of spectra. The NMR spectra of methyl salicylate (23) demonstrate the concepts of deshielding, diamagnetic anisotropy, and molecular asymmetry.…”

Using Aspirin as a Teaching Tool

“…The most commonly employed reaction in these experiments is the Fischer esterification (1-9): the acid-catalyzed acyl substitution of a carboxylic acid with a nucleophilic alcohol to give an ester. While the Fischer esterification has been widely employed for the laboratory preparation of esters, the use of transesterification has been limited (11)(12)(13)(14). Acid-catalyzed transesterification is mechanistically related to the Fischer esterification but involves the acyl substitution of one ester with a nucleophilic alcohol to give a new ester.…”