Preparations of Methylcyclopentenes using Zeolite Catalyst and their Reactions

Abstract

Methylcyclopentenes, which are useful intermediates for the synthesis of five membered alicyclic compounds, were prepared by means of thermal isomerization of cyclohexene over natural zeolite (clinoptilolite type) at 430440°C in good yield (cf. Table 1). Similarly, cyclohexanol was dehydrated and isomerized directly over zeolite at 430 °C to yield 1-and 3-methylcyclopentenes (cf. Table 2).
The zeolite was quite active in these reactions. It was also active in establishing equilibrium between these hydrocarbons which are differing only in the position of a double bond. The ratio of 1-and 3-methylcyclopentenes was always about 73 : 27 under these reaction conditions (cf. Table 3). The isomerized methylcyclopentenes were converted to the corresponding trans glycols by oxidation with hydrogen peroxide in formic acid.