Electronic Interpretation of the Uncatalyzed Reaction Between Resorcinol and Formaldehyde in Alcohols and Dioxane

Abstract

The condensation of resorci~iol and formaldehyde i11 aqueous alcollols and dioxane is interpreted on the basis of competing electrophilic react-ions of the hydroxyrnethyl carbonium ion with the resorcinol aronlatic ring and with the oxygen atoms of the resorci~lol and the solvents. The reaction of the carboniu~n ion and the alcohol groups leads to oxonium ions which may then form helniacetals. IntroductionRaff and Silverman (15, 1G) have determined the reaction rates of eqiiimolar proportions of resorcinol and formaldehyde in water and in the aqueous solutions of dioxane, methyl alcohol, ethyl alcohol, normal-propyl alcohol, ally1 alcohol, iso-propyl alcohol, and tertiary-butyl alcohol, a t GO°C, and a t pH values lying within the range of 3.5 to 4.0. The organic solvents were found to retard the condensation of resorcinol and formaldehyde and the effect of the alcohols was attributed to their reversible formation of hemiacetals with the formaldehyde.In this paper an attempt is made t o interpret all the reactions involved in terms of the electro~~ic theory of acids and bases (1,8,10). Resonance i n Molecular and Ionic ResorcinolA consideration of the most probable resonance structures of resorcinol is important in order to visualize the electronic distribution responsible for reaction.(a) Un-ionized resorcinol