PURPOSE: To obtain the title compound in high yield without corrosion of an apparatus, by the contact of 3-methyl-2-buten-1-ol with an aqueous solution of boric acid.

CONSTITUTION: The title compound is obtained by the contact of 3-methyl-2- buten-1-ol with an aqueous solution of boric acid at 20-200°C. The starting material is easily obtained by the isomerization of 3-methyl-3-buten-1-ol by-produced in the synthesis of isoprene from isobutene and formalin, etc. Concentration of the aqueous solution of boric acid is generally 0.1-60 wt.%. Concentration of the starting material to an aqueous solution of boric acid in a reaction mixture is preferably low, and generally below 50 wt.%. Preferably, the reaction is carried out while heating the aqueous solution of boric acid in a distillation column, supplying the starting material thereto, and distilling off the title compound from the top of the column.

USE: Raw material of medicines, agricultural chemicals, perfumes, etc., especially intermediate for syntheses of terpenoid compounds such as carotinoids