Process for Producing 1,2-Alkanediol From the Corresponding Alkene and Hydrogen Peroxide

A process for preparing an 1,2-alkanediol from the corresponding alkene and hydrogen peroxide, comprising the steps of:

• a) reacting the alkene with hydrogen peroxide in the presence of a catalytic amount of at least one tungsten polyoxometalate and at least one tetraalkylammonium cation,
• wherein the reaction is carried out in a biphasic reaction mixture comprising an aqueous phase having a pH of at most 6 and an organic phase,
• wherein the tetraalkylammonium cation has the general formula N+R1R2R3R4, wherein R1, R2, R3, and R4 are alkyl groups which each independently may be the same or different, wherein, when all of R1, R2, R3, and R4 are the same, the tetraalkylammonium cation has in total at least 32 carbon atoms in the alkyl groups, or, when at least one of R1, R2, R3, and R4 is different from the others, the tetraalkylammonium cation has in total at least 37 carbon atoms in the alkyl groups;
• b) separating the biphasic mixture from step a) into an aqueous phase P1 and an organic phase P2;
• c) optionally recycling alkene oxide which may be present in the separated organic phase P2 into reaction step a);
• and
• d) separating 1,2-alkanediol from the aqueous phase P1 separated in step b).