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 (prenol): global production in 2001 can be estimated as 6–13 thousand tons. Isoprenol is produced by the reaction between isobutene (2-methylpropene) and formaldehyde, in what is arguably the simplest example of the Prins reaction. 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.