Effect of formaldehyde on the rate constants for the reactions of isoprene, dimethylvinylcarbinol, and dimethylallyl alcohol in aqueous perchloric and sulfuric acid solutions

Abstract

1. Study has been made of the kinetics of the hydration of isoprene to equilibrated mixtures of dimethylvinylcarbinol and dimethylallyl alcohol, and of the hydration and condensation of these alcohols with formaldehyde in aqueous sulfuric and perchloric acid solutions. 2. Dimethylvinylcarbinol and dimethylallyl alcohol react rapidly and reversibly to form polyformals in acid solutions containing formaldehyde. 3. Determination has been made of: a) the sum of the rate constants for conversion of equilibrated mixtures of DMVC, DMAA, and their polyformals to 3-methyl-1,3-butanediol and formaldehyde condensation products, with eventual formation of 4,4-dimethyl-5-hydroxymethyl-1,3-dioxane and 5-(2-hydroxy-2-propyl)-1,3-dioxane; and b) the rate constant for isoprene hydration to an equilibrated DMVC-DMAA mixture. 4. Formaldehyde promotes the hydration of isoprene to DMVC and DMAA. The catalytic activity of formaldehyde is due to the ability of the\(\begin{array}{*{20}c} {\backslash \backslash } \\ {//} \\ \end{array} CH - 0\) ion to transfer an OH group and an H+ ion to the reactant, and of the H2COH+ ion to cleave an OH group and an H+ ion from the reactant molecule. The catalytic activity of formaldehyde is determined by the anion concentration and the acidity of the solution.