GB490211A - Method of converting aliphatic polyhydric alcohols to alcohols of lower molecular weight - Google Patents

Abstract

Aliphatic polyhydric alcohols containing three or more carbon atoms and three or more hydroxyl groups are converted to alcohols of fewer carbon atoms by catalytic hydrogenation in the presence of an initially added substantially anhydrous mono- or di-hydric aliphatic alcohol containing less than five carbon atoms as vehicle at a pressure not above 3000 lb./sq. in. and at a temperature above 150 DEG C. The initial alcohols include sucrose, dextrose, maltose, lactose, levulose, pentosans, starches, dextrins, cellulose, sorbitol, mannitol, and crude sugars or hydrolysis products of starch or cellulose. The products may be used as anti-freeze agents. The amount of hydrogen is controlled in accordance with the product desired. The best yield of anti-freeze is obtained with absorption of not more than 5 1/2 moles of hydrogen per mole of sucrose or 2,75 moles per mole of dextrose. Substantially less hydrogen results in unreacted sugar and sorbitol. More hydrogen gives large amounts of ethyl alcohol. In an example, sucrose mixed with methanol, and a copper-chromium-barium catalyst is treated with hydrogen at 250 DEG C. and 2000 lb./sq. in. or less until 5,1 moles have been introduced per mole of sucrose. The proportion of the product boiling above 125 DEG C., mainly propylene glycol and glycerine, is used as an anti-freeze. The portion volatile below 125 DEG C containing the original methanol and lower alcohols formed in the reaction may be used again as the vehicle in a further reaction. In another example dextrose is treated until 2,3 moles of hydrogen are absorbed. Reference has been directed by the Comptroller to Specification 430,576.