Improvements in or relating to methods of converting a mixture of isomeric retinenes into trans, trans retinene

摘要

Mixtures of isomeric retinenes are converted into trans, trans-2,6-retinene by forming in the mixture a complex of the trans, trans retinene with a dihydroxy-benzene or halogen derivative thereof, and, simultaneously with such complex formation, converting the isomers other than trans, trans into the trans, trans retinene with an acid or iodine isomerization agent. The complex may be formed with pyrocatechol, tetrachloropyrocatechol or hydroquinone, and the isomerization may be effected with hydriodic acid, hydrobromic acid, hydrochloric acid, paratoluene sulphonic acid, nitric acid, sulphuric acid or elemental iodine. The complex is converted to trans, trans retinene by suspension in an alkaline solution, e.g. sodium hydroxide. Examples are given. Specifications 728,989, 728,990 and 935,006 are referred to.