PALLADIUM-CATALYZED CARBONYLATION OF TERT-BUTYL ALCOHOL TO ESTERS OF ISO-VALERIC ACID

Tert-butyl alcohol was carbonylated to esters of iso-valeric acid in t he presence of a deneacetone)dipalladium(0)-triphenylphosphine-p-Ts ca talytic system without any halogen promoter or other extreme condition s. Typical reaction conditions are: temperature 120-160 degrees C; p(C O) = 4.0-7.0 MPa; tert-butyl alcohol/ROH/Pd = 400/3280/1; [Pd] = 4.3 X 10(-3) mol/l; Pd/PPh(3)/p-Ts = 1/24/65; reaction time 6-24 h. Under t hese experimental conditions a high yield (98.9%) and selectivity (99. 2%) for esters are obtained. The carbonylation of other similar alcoho ls were studied using this catalyst system. The mechanism of this reac tion has also been discussed.