HYDROLYZES OF TERPENOID DIPHOSPHATES - EFFECTS OF AZIDE ION ON PRODUCTS OF HYDROLYSIS

Hydrolysis of geranyl diphosphate (GPP) at pH 7 in water gives largely linalool (LOH) + geraniol (GOH) in the ratio of 3:1. Added N3- generates mixed acylic allylic azides and increases the LOH GOH ratio to 15:1 in 2 M NaN3, but does not speed up the overall reaction. Hydrolysis of neryl diphosphate (NPP) gives largely alpha-terpineol (TOH) + LOH, but their ratio is not very sensitive to NaN3 concentration although acyclic azide and small amounts of alpha-terpinyl azide (TN3) are formed. Hydrolysis of alpha-terpinyl diphosphate (TPP) gives large amounts of the cyclic alkenes, limonene and terpinolene. Added N3- does not change the amount of elimination, but increases the ratio of limonene to terpinolene, and diverts some substitution product to TN3. Trapping of carbocationic species from GPP by N3- is sharply increased by addition of Mn2+, Which also catalyzes the overall reaction. Products of reaction of GPP are derived from acyclic intermediates and of NPP from acyclic and cyclic intermediates, and ionizations of the three substrates do not generate common carbocationic species.