Influence of chain length on the rate of hydrolysis of polyoxymethylene ethers

Abstract

SynopsisFour series of polyoxymethylene ethers (polyformals) [RO(CH20)&] where R is isopropyl, ethyl, methyl, or methoxyethyl and n = 1-3 have been prepared, examined by GLC, separated by fractional distillation, and characterized by NMR. Rate constants for the aqueous acid hydrolysis of all the compounds have been determined. The isopropyl series appears to be a special case, and as reported in the literature (but in aqueous dioxane), all members of this series hydrolyze a t the same rate. In the other series, there is a definite increase in rate, which never exceeds fourfold, in going from n = 1 to n = 2. This increase differs considerably from the 100-fold increase reported by others in going from CII30CH20CHa to CH,O(CHzO)?CH3. In all series, the n = 3 compound hydrolyses at practically the same rate as the n = 2 compound.

High Purity Oligomeric Oxymethylene Ethers as Diesel Fuels

“…However, this approach is significantly less developed than the other strategies. Typical catalysts for the synthesis of OMEs are solid acids such as zeolites, ion exchange resins, metal oxides, or heteropoly acids , , . The mentioned synthesis routes have in common that mixtures of oligomeric OMEs are produced which comprise predominantly DMM/OME 2 – 5 and only low amounts of higher OMEs.…”

A Computational Investigation of OME‐synthesis through Homogeneous Acid Catalysis

“…Different catalysts, such as acidic zeolites, homogeneous acids such as sulfuric acid as well as ion exchanged sieves, have been explored for this process. A central challenge is that the reaction usually yields a thermodynamic equilibrium mixture of OMEs, while it would be desirable to steer the product distribution towards OMEs in the range of OME3 to OME5 ,.…”

“…[1a,c,h] Alternative approaches are therefore being investigated, amongst which are the use of trioxane (TOX) instead of FA and OME1 instead of methanol as an endcapping group as shown in Scheme 1. [3] Different catalysts, such as acidic zeolites, [4] homogeneous acids such as sulfuric acid [5] as well as ion exchanged sieves [3a,6] have been explored for this process. A central challenge is that the reaction usually yields a thermodynamic equilibrium mixture of OMEs, while it would be desirable to steer the product distribution towards OMEs in the range of OME3 to OME5.…”