Ethoxylation

The translation of the potentially hazardous, highly exothermic alkoxylation reaction to the rapid, safe and completely reliable industrial technology that it is today has been a noteworthy development. Commercially, the reactions of ethylene oxide with fatty acids are conducted in the presence of alkaline catalysts at temperatures above 100 C. The reaction proceeds in two steps. The first step is relatively slow and the product is predominantly ethylene glycol monoester. The second step occurs after approximately one mole ethylene oxide is reacted and all of the fatty acid is consumed. An increase in the ethylene oxide addition rate is observed, and polyethylene glycol esters are formed. Rapid transesterification also occurs, and the molar proportions of monoester, diester, and free polyol in the product approaches those predicted by the equilibrium assuming random esterification of the polyethylene glycol hydroxyl groups. The composition of polyoxyethylated fatty acids is similar to that obtained by the direct esterification of fatty acid with polyethylene glycol. The distribution of the ethylene oxide chain lengths in the polyethylene glycol portion of the product can be approximated assuming random addition of the epoxide.