Directed change in the selectivity of the action of catalysts in the process of hydrogenation of the dienone group Report 1. Hydrogenation of 6-methylheptadiene-3, 5-one-2 on nickel catalysts

Conclusions

• 1. The possibility of changing the selectivity of the action of a nickel catalyst in the process of hydrogenation of 6-methylheptadiene-3,5-one-2 was studied.

• 2. The hydrogenation proceeds nonselectively on skeletal nickel catalysts and in the presence of nickel catalysts on carriers: during the process of absorption of one mole of hydrogen two unsaturated ketones and a saturated ketone are formed.

• 3. It was proposed that the selective hydrogenation of the 3,4-double bond is accomplished by selective adsorption of dienone with the C=C-C=O group: by 1, 4-addition of hydrogen, or by direct hydrogenation of the 3, 4-double bond, in both cases with the participation of the C=O group. Considering this mechanism of hydrogenation and the catalytic peculiarities of zinc and cadmium, a composition of a Ni-ZnO-Cd catalyst was developed, in the presence of which the process occurs selectively: the 5,6-double bond is not hydrogenated.

• 4. The optimum conditions of the process, under which the yield of methylheptenone reaches 90% of the theoretical, were established. The proposed method of selective hydrogenation of dienone was checked on a continuous-action model setup.