Isolongifolanone is a mixture of isomer liquid with persistent woody and earthy odors, and it smells like the odor of patchouli and rock orchid. There are two preparation methods. One is to isomerize longifolene, the sesquiterpenes composition of heavy turpentine oil, into Isolongifolene under acidic conditions, and then through Hydrogen peroxide oxidation reaction in the presence of formic acid to produce Isolongifolanone. The other preparation process of Isolongifolanone is to oxidize low concentration hydrogen peroxide in the presence of formic acid. It is widely used in fragrance formulation.
According to U.S. Patent No.3718698 that Isolongifolanone can be oxidized with sodium dichromate in acetic acid to provide a mixture of saturated and unsaturated ketones. It was further suggested in this Netherlands specification that the mixture of compounds so obtained could be used in perfume compositions. The mixture so formed contained relatively small amounts of saturated ketone.
The other process is the preparation of a sesquiterpene ketone, e.g. cedranone, isolongifolanone and thujopsanone, wherein a C15H24 sesquiterpene hydrocarbon having an endocyclic double bond, e.g. cedrene, isolongifolene and thujopsene, is reacted with hydrogen peroxide in the presence of a C1-5 alkyl formate. ( learn more about U.K.Patent No.1434035 )