Isoprenol

Isoprenol, also known as 3-methylbut-3-en-1-ol, is a hemiterpene alcohol. It is produced industrially as an intermediate to 3-methylbut-2-en-1-ol : global production in 2001 can be estimated as 6–13 thousand tons.

Synthesis

Isoprenol is produced by the reaction between isobutene and formaldehyde, in what is arguably the simplest example of the Prins reaction.

Reactions

The thermodynamically preferred prenol, with the more substituted double bond, cannot be directly formed in the above reaction but is produced via a subsequent isomerisation:
This isomerisation reaction is catalyzed by any species which can form an allyl complex without excessive hydrogenation of the substrate, for example poisoned palladium catalysts.
Oxidation gives the aldehyde, which is used for the industrial synthesis of citral and other compounds. BASF achieves this transformation at scale using a silica-supported silver catalyst.

Uses

Isoprenol is primarily a feedstock used in the production of other more valuable chemicals. Its prenol and 3-methyl-3-butenal derivatives are used together in the formation of citral, which is used both as an aroma compound and as a starting material in the production of ionones such as vitamin E and vitamin A. Isoprenol is also used in the synthesis of some pyrethroid pesticides.