Naphthalene tetrachlorides and related compounds. Part 7. Products of methanolysis of a 1-p-tolylnaphthalene tetrachloride; evidence for a rapid bimolecular elimination of methanol from the 2,3-dichloro-1-methoxy-1-p-tolyl-1,2-dihydronaphthalenes

Abstract

Unimolecular methanolysis of r-1,c-2,t-3,t-4-tetrachloro-1-p-tolyltetralin gives two isomeric 1-methoxy-1-p-tolyl-2,3,4-trichlorotetralins, each of which undergoes bimolecular elimination in two defined stages having similar rates, and giving 2,3-dichloro-1-p-tolylnaphthalene as the nearly exclusive final product. The intermediate 2,3-dichloro-1-methoxy-1-p-tolyl-1,2-dihydronaphthalenes, which can be characterised through signals in their 1H n.m.r. spectra, must, therefore, undergo bimolecular elimination of methanol at rates which can be estimated from the rates of build-up of their precursors. The theoretical implications of these results are discussed; it is suggested that this elimination must be far on the E1cb side of the spectrum of bimolecular eliminations.