Reactions of some p-substituted triphenylmethyl chlorides with alcohols, alkali-metal alcoholates, and tributylamine

Abstract

The p-methoxylated triphenylmethyl chlorides (4a–c), when heated with alcohols, give mixtures of the corresponding triarylmethanes (5a–c)(via the hydride transfer to the corresponding triarylmethylium cations) and the alkyl (substituted triphenylmethyl) ethers (7a–c)(via polar substitution reactions). Part or all of the ether (7c) may be further converted into the substituted triphenylmethanol (6c). In the reaction of the mono-p-methoxylated halides (4a) and (4c) with methanol, the substitution products (7a) and (7c)[and/or (6c)] are formed as the main products, while the main product of the reaction of the di-p-methoxylated halide (4b) with methanol is the substituted triphenylmethane (5b). When the methanol is replaced by [2H4] methanol, no reduction product is formed from the halide (4c). Reaction of halide (4c) with ethanol furnishes exclusively the substituted triphenylmethane (5c). The p-chlorophenyl(diphenyl)methyl chloride (4d) gives, with methanol, mainly or exclusively the ether (7d), and with ethanol, under mild conditions, gives the ether (9d). However, under vigorous conditions, the substituted triphenylmethane (5d) is formed. The reduction of the p-methoxylated triphenylmethyl chloride (4c) by alcohols as well as its conversion into alkyl (p-methoxylated triphenylmethyl) ethers are accompanied, to a certain degree, by exchange of the p-methoxy group of the substrate and the alkoxy group of the alcohol; no similar exchange of the p-chlorine atom of halide (4d) was observed. Explanations for all observed differences are offered.The reactions of the substituted triphenylmethyl chlorides (4b–d) with alkoxides in the corresponding alcohols give the corresponding alkyl (substituted triphenylmethyl) ethers (7b), (7c), (9c), and (9d), respectively, in excellent yields.The reaction of the triarylmethyl chloride (4d) with potassium t-butoxide in THF in the presence of acetone led, among other products, to the formation of oligomeric material which indicates the operation of single-electron-transfer induced processes. Reaction of the same chloride (4d) with tributylamine in refluxing cumene or t-butylbenzene led to the exclusive formation of a series of products [(5d) and (14)–(17)] all of which may be derived from the intermediacy of the substituted triphenylmethyl radical (18); the latter, in turn, is thought to arise as a result of dissociative electron transfer from tributylamine to chloride (4d).