Processes for preparing random polytrimethylene ether ester are provided. The processes include contacting 1,3-propanediol with a suitable polymerization catalyst, wherein the 1,3-propanediol comprises about 10 microg/g or less peroxide compounds, based on the weight of 1,3-propanediol, and about 100 microg/g or less carbonyl compounds based on the weight of the 1,3-propanediol.