Synthesis and Liquid Crystal Properties of Dimethylene Linked Compounds Incorporating the Cyclobutane or Spiro[3.3]heptane Rings

Abstract

The preparation of sixteen dimethylene linked compounds is described [14 incorporating the cyclobutane ring and 2 incorporating the spiro[3.3]heptane ring], and a comparison is made between the transition temperatures of these compounds and those of the corresponding esters.¹ This comparison once again highlights the fact that the cyclobutane ring should be regarded, in terms of its ability to promote nematic thermal stability, as a “chain stiffener” rather than as a ring system.

A comparison is also made of the nematic thermal stabilities of the trans-cyclobutane and the spiro[3.3]heptane systems and of the trans-cyclohexane and the spiro[5.5]undecane systems.