TRANSITION-METAL-CATALYZED OXIDATIVE CLEAVAGE OF UNSATURATED FATTY-ACIDS

The oxidative cleavage of the C=C-bond converts unsaturated fatty acid s to carboxylic and dicarboxylic acids. The only method currently used in oleochemistry is ozonolysis. The high energy consumption of ozonol ysis makes a transition-metal catalyzed alternative with a cheaper sec ondary oxidant attractive. Here we report new methods for ruthenium-, rhenium- and tungsten-catalyzed oxidations with peracetic acid and hyd rogen peroxide. Whereas the direct oxidative cleavage of internal C=C- bonds still lacks selectivity, two-step reactions are feasible. The fi rst possibility is to convert natural, internal unsaturated fatty acid s to omega-unsaturated ones. These omega-unsaturated fatty acids can b e cleaved by Ru/acac)(3)/CH3COOOH or Re2O7/H2O2 With yields up to 80%. In the second two-step procedure the fatty acid first is hydroxylated and the diol is cleaved; the overall yield for this method is 80%, to o.