Synthesis of 1,128‐Octacosahectanediol and Its Sharp Thermoresponse in Solution with Concomitant Structural Change

Abstract

Abstract1,128‐Octacosahectanediol, which has an extremely long polymethylene chain, was synthesized. The heptaene C128 intermediate with both ends silylated was synthesized by the sequence of the Wittig reaction and acetal deprotection in a two‐directional manner. The unsaturated compound was converted to a saturated disilyl ether by homogeneous hydrogenation under toluene reflux, and was subsequently desilylated under THF/toluene/12 M HCl refluxing conditions to yield a C128 diol. High‐temperature conditions were employed to dissolve the substrates, and cooling liberated the products, which were isolated by filtration. 1,128‐Octacosahectanediol showed a sharp increase in solubility in organic solvents with temperature changes of 10 K along with thermal hysteresis, which was ascribed to the concomitant structural change. The extended structure in the solid state was converted to a globular structure in solution, which involved large enthalpic loss and entropic gain.