Pressure ethoxylation in dense gases to produce hydroxyalkyl ester monomer

摘要

A pressure process for preparing a hydroxyalkyl ester monomer and oligomer that can be used to prepare a polyester such as polyethylene terephthalate (PET) is disclosed. The process includes the steps of reacting, by ethoxylation, dicarboxylic acid and alkylene oxide in the presence of a compressed gas medium to form a specified mixture of monohydroxyalkyl ester and bishydroxyalkyl ester. The reaction pressure is such that the density of the gas medium is greater than or equal to half the critical density of the compressed gas medium. The mole ratio of the alkylene oxide to the dicarboxylic acid is less than about 2:1, and preferably 1.1:1.2. The DP of all reaction products is less than 5. The reactant product may be polymerized into a polyester. The process may optionally employ catalysts such as amines or amino acids. The compressed gas medium can be a solvent and an optional cosolvent. The temperature of reaction is from about 100° C. to 240° C. at a pressure of 50-5000 psi.