Present commercial processes for making glycols involve the hydrolysis of alkylene oxides, using a large excess of water with the application of heat with or without a catalyst. Generally, these processes obtain only about 88 percent yield of the monoglycol with the remainder going to make the higher di-, tri-, and tetraglycols. One disadvantage of the present commercial process is that there is a large excess of water which must be evaporated off in order to obtain pure glycol. This is highly energy intensive. A British patent suggests that alkylene glycols can be made from alkylene oxides using only a small amount of water in the presence of carbon dioxide under 10 to 180 atmospheres of pressure and at temperatures of 80.degree. to 220.degree. C. and in the presence of a catalyst, for example, an alkali metal halide such as potassium iodide or sodium iodide. It is theorized in this reference, British Pat. No. 1,177,877, that the reaction takes place through formation of the carbonate which then hydrolyzes to the glycol. Greater than 90% yields to the mono-glycol are claimed for this process. The present invention uses ethylene carbonate as a starting material together with slightly greater than stoichiometric quantities of water over an alumina catalyst to achieve 98% yields of the mono-glycol.
USPTO Backgrounds
USPTO Backgrounds