Answer to Question #284563 in Organic Chemistry for Reens

Question

using fmo model explain why in thermal condition disrotatory motion would necessary for cyclization of 1,3,5- hexatriene and conrotatory of 2,4- hexadiene

Answer 1

An electrocyclic reaction can either be classified as conrotatory or disrotatory based on the rotation at each end of the molecule. In conrotatory mode, both atomic orbitals of the end groups turn in the same direction (such as both atomic orbitals rotating clockwise or counter-clockwise).