Regioselective isomerization at carbon atom vicinal to doubly bonded tertiary carbon atom by sulfur dioxide catalysis
AssigneeAllied Chemical Corporation
InventorsDivakaran Masilamani, Milorad M. Rogic
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Abstract
Beta pinene is converted to alpha pinene in liquid sulfur dioxide. The process is a regioselective isomerization of organic compounds having a carbon-carbon double bond at a tertiary carbon atom, by sulfur dioxide-induced allylic rearrangement of a hydrogen atom and/or replacement of a proton in the allylic position by a deuteron. The organic compound is contacted with sulfur dioxide at temperatures between about 0.degree. and 70.degree. C. for a time sufficient to effect such isomerization to a more stable isomer; and if deuteration is to take place D.sub.2 O is provided in the solution.
Claims14
A method for conversion of beta-pinene to alpha-pinene comprising:
- (a) dissolving beta-pinene in sulfur dioxide;
- (b) allowing the resulting solution to react for a time sufficient to isomerize to alpha-pinene;
- and
- (c) separating the alpha-pinene from the sulfur dioxide.
A method for isomerizing beta-pinene to alpha-pinene comprising maintaining said beta-pinene in solution in dry liquid sulfur dioxide whereby allylic rearrangement of the bond, attaching a hydrogen nucleus to a carbon atom vicinal to the tertiary double bonded carbon atom of beta-pinene, takes place, resulting in the alpha-isomer of beta-pinene.
A method for isomerizing an olefinic compound having a hydrogen nucleus or isotope thereof attached to a carbon atom vicinal to a tertiary double bonded carbon atom comprising:
- maintaining said compound as solution in dry liquid sulfur dioxide whereby allylic rearrangement of a hydrogen bond takes place.
Dependencies are inferred from the claim text.