The alkaline catalysts commonly applied to alkoxylation are characterized by a limited spectrum of activity caused by an irreversible termination of the polyether chains. The presented results show that double metal cyanide (DMC) catalysts reduce or eliminate the aforementioned adverse rearrangement of hydroxyl groups. Moreover, DMC catalysts indicate high activity at low concentrations (ppm range), as expressed by high polymerization rates. It was demonstrated that decreased concentrations of DMC catalyst irreversibly influence its reactivity and the dispersity of the obtained products, as exemplified by the production and determination of selected polyoxypropylenediols at different concentrations of the catalyst. Because of their unique advantages, the DMC catalysts are a very attractive alternative to conventional alkaline catalysts for the polyaddition of oxiranes. The phenomenon was discussed and explained by an alteration of reaction rate coefficients at subsequent polyaddition stages.

Ethoxylation of alcohols, alkylphenols, and alkylamines has been studied in the presence of a few catalytic systems. Distribution constants were computed. Broad‐range distributed ethoxylates are formed in the presence of NaOH, and the distribution constants increase up to the homologue containing six oxyethylene units. Narrow‐range distributed ethoxylates are formed in the presence of calcium‐based catalysts. It is reflected in the values of the distribution constants because an increase with the growing number of oxyethylene units in successive homologue is not observed.

The effect of reagent molar ratio and temperature upon the composition of oxyethylated fatty acid methyl esters and surface tension reduction at air/water interfaces was studied. It was found that oxyethylation of fatty acid methyl esters carried out in the presence of calciumbased catalyst gives narrow range distributed products. The distribution depends on temperature, and more narrow products are obtained at higher temperatures. Oxyethylated fatty acid methyl esters contain less unreacted hydrophobic starter than oxyethylated alcohols. The pressure drop in the batch process can be satisfactorily modeled, assuming the reaction proceeds in the liquid phase and estimating the concentration of the ethylene oxide in the liquid phase from vaporliquid equilibrium. The modeling supports the important role of ethylene oxide diffusion from the gas to the liquid phase. The distribution of the polyoxyethylene chain in hydrophilic oxyethylated fatty acid methyl esters has only a minor effect upon the surface tension reduction and the values of characteristic adsorption coefficients. The effect of the synthesis temperature is not reflected in the surface tension reduction.