Copper chromite diols

Barium copper chromite Diols from dicarboxylic acids... 

Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

Lactones can be hydrogenolyzed on copper chromite catalysts.23 Diol formation is favored at lower temperatures, whereas higher temperatures give cyclic ethers. This process is not widely used, however, because of experimental difficulties. 

Acyloins were converted to mixtures of stereoisomeric vicinal diols by catalytic hydrogenation over copper chromite [972]. More frequently they were reduced to ketones by zinc (yield 77%) [913, 914], by zinc amalgam (yields 50-60%) [975], by tin (yields 86-92%) [173], or by hydriodic acid by refluxing with 47% hydriodic acid in glacial acetic acid (yields 70-90%) [916], or by treatment with red phosphorus and iodine in carbon disulfide at room temperature (yields 80-90%) [917] Procedure 41, p. 215). Since acyloins are readily accessible by reductive condensation of esters (p. 152) the above reductions provide a very good route to ketones and the best route to macro-cyclic ketones [973]. 

Esters may alternatively be reduced to primary alcohols either using hydrogen under pressure in the presence of a copper chromite catalyst,56 or with lithium aluminium hydride (Expt 5.38), but not with sodium borohydride which is insufficiently reactive. However it has been found recently that sodium borohydride in mixed solvents (methanol/tetrahydrofuran) reduces /1-ketoesters to 1,3-diols, and this method offers a convenient route to this type of compound.57... 

The use of copper chromite at 40°C and atmospheric pressure was not very effective for selective carbonyl group hydrogenation. Unsaturated alcohols were produced from unsaturated aldehydes in low yields at low conversions and not at all from methyl vinyl ketone. 28 With unconjugated, unsaturated aldehydes, copper chromite is effective as a selective hydrogenation catalyst. Hydrogenation of 46 at 140°-160°C and 200 atmospheres gave better than 70% of the diene diol, 47. Increasing the temperature to 240°C resulted in the complete saturation of 46 (Eqn. 18.28). 29... 

Many methods are known for its manufacture, e.g., dehydrogenation of 2,3-butane -diol with a copper chromite catalyst [22]. Biotechnological production on an industrial scale is referred [23]. It is used mainly in aromas for butter and roast notes. Large quantities are used for flavoring margarine small amounts are used in perfumes. 

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