Selective Hydrogenations in the Presence of Other Unsaturated Functions

4 Selective Hydrogenations in the Presence of Other Unsaturated Functions 

Blout and Silverman selectively hydrogenated nitrocinnamic acids and esters (5 g) to the corresponding amino compounds over Raney Ni (2-3 g, wet) in ethanolic suspension (50 ml) at 20-30°C and 0.2-0.3 MPa H2.144 The rate of hydrogen absorption dropped to between 0.3 and 0.01 of its former value after the uptake of 3 equiv of hy- 

Among the sulfides of molybdenum, cobalt, nickel, iron, rhodium, rhenium, osmium, and ruthenium, only the polysulfide of cobalt153 and the sulfide of ruthenium showed good selectivities. Optimum conditions over cobalt polysulfide included temperatures of 85-120°C, hydrogen pressures of 2.8-6.9 MPa, substrate concentrations of up to 25%, and substrate catalyst ratios of 50-80 1 (g of feed/g of Co). A typical run is shown in eq. 9.64. The hydrogenation over ruthenium disulfide was successful 

TABLE 9.7 Selectivity of Transition Metal Catalysts in Hydrogenation of 3-Nitrophenylacetylene (NPA)  

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