THE PREDICTION OF ETHYLENE-OXIDE DISTRIBUTIONS IN MIXED ALCOHOL ETHOXYLATES

Supercritical fluid chromatographic analyses of ethoxylates of 2-ethylhexanol in the pure state and in mixtures were used to determine relative propagation-to-initiation ethoxylation rate constants. Earlier work with normal octanol was verified in that ethylene oxide distributions were found to be unaffected by the presence of other alcohols in the ethoxylation of mixed alcohols. An apparent decrease in the relative ethoxylation rates with increasing number of ethylene oxide monomers in ethoxylates is attributed to truncation of the measured distributions and is eliminated by adding small amounts of higher ethoxylates to the distribution. The Weibull-Tornquist effect of decreasing relative rate constants as the overall average ethylene oxide-to-alcohol ratio increases was again observed. Rate constants of the ethoxylation of 2-ethylhexanol and its ethylene oxide adducts relative to the ethoxylation of normal octanol were determined from the analysis of ethoxylates of their mixtures. A computer model using averaged relative rate constants was developed that effectively predicts the ethylene oxide distributions in ethoxylates of alcohol mixtures.