Patent GB-413754-A (GB)
Title: Improvements in the manufacture and production of aldehydes
IPC: C07C45/48
Filed: 1933-01-26
Abstract: For the production of unsaturated aldehydes from mixtures of formic acid with unsaturated acids containing at least 10 carbon atoms, decarboxylation catalysts are employed which may be difficulty reducible metal oxides, such as calcium, barium, strontium, manganese, chromium, titanium, aluminium, and thorium oxides or mixtures or compounds thereof, and like difficulty reducible compounds such as phosphates; also metals such as iron, copper, cobalt, nickel or their alloys and like base heavy metals. Carriers such as alkali-bearing pumice, kieselguhr, asbestos, alumina, aluminium, and the metals mentioned above may be used. In examples: (1) pumice is sprayed with manganese carbonate and then with water, heated in vacuo to 250 DEG  C. in a vertical copper vessel, and then reduced with methanol vapour to produce manganous carbonate; (2) pumice is treated in vacuo with manganese nitrate solution, dried at 500 DEG  C., and reduced with hydrogen at 400 DEG  C.; (3) fossil flour, after extraction with hydrochloric acid, is made into a paste with manganese nitrate solution, pelleted, dried, and heated in a current of air at 500 DEG  C. and then treated with hydrogen at 400 DEG  C.ALSO:Unsaturated aldehydes are obtained by passing unsaturated carboxylic acids containing at least 10 carbon atoms or their esters, anhydrides or halides, mixed with formic acid or its esters, over decarboxylation catalysts, the partial pressure of the unsaturated acid or its derivative being kept at not more than \ba1/20\be and preferably not more than \ba1/30\be of an atmosphere.  Suitable unsaturated acids are undecylenic, oleic, linoleic, ricinoleic and abietic acids, and naphthenic acids containing at least 10 carbon atoms, and the acid mixtures obtained from vegetable and animal oils such as castor, linseed, Chinawood and train or fish oils.  The formic acid or its ester is preferably used in excess, for instance 3 to 6 molecules to one of p  oleic acid.  The low partial pressure of the unsaturated acid may be obtained by working in vacuo or by adding further quantities of formic acid or by adding inert gases such as carbon dioxide, methane, or nitrogen.  Suitable partial pressures are \ba1/50\be or \ba1/100\be of an atmosphere.  The catalysts may be difficultly reducible metal oxides such as calcium, barium, strontium, manganese, chromium, titanium, aluminium, and thorium oxides or mixtures or compounds thereof and like difficultly reducible compounds such as phosphates; also metals such as iron, copper, cobalt, nickel or their alloys and like base heavy metals. Carriers such as alkali-bearing pumice, kieselguhr, asbestos, alumina, aluminium, and the metals mentioned above may be used. The temperature may be 250--400 DEG  C.  In examples: (1) pumice is sprayed with manganese carbonate and then with water, heated in vacuo to 250 DEG  C. in a vertical copper vessel, and then reduced by methanol vapour to produce manganous carbonate; oleic and formic acid vapours are passed over this catalyst at 40--60 mm. pressure; (2) pumice is treated in vacuo with manganese nitrate solution, dried at 500 DEG  C., and reduced with hydrogen at 400 DEG  C.; oleic and formic acid vapours together with carbon dioxide are passed over this catalyst at atmospheric pressure; (3) fossil flour, after extraction with hydrochloric acid, is made into a paste with manganese nitrate solution, pelleted, dried, and heated in a current of air at 500 DEG C. and then treated with hydrogen at 400 DEG  C.; a mixture of oleic and formic acid vapours with carbon monoxide and hydrogen is passed over this catalyst at 310--315 DEG  C. The opening statement refers to the production of saturated aldehydes from saturated acids and formic acid, and of hexylenic aldehyde from hexylenic acid and formic acid by treatment with manganous oxide.