Search results for "β-propiolactone"

1973

The thermal degradation of poly(oxycarbonylethylene) (poly-β-propiolactone) has been investigated within a temperature range of 180–220°C and under various pressures. The degradation begins with a considerable decrease in molecular weight, followed by an accelerating formation of acrylic acid. The reaction involves the following steps: 1 Random chain scission of polymer chains by typical ester pyrolysis with the formation of fragments one of which containing a carboxylic group the other one a CC-double bond at the chain end (Eq. (1)). 2 Formation of the volatile acrylic acid by scissions at the chain end, the amount of acrylic acid or the weight-loss increasing with the number of fragmentat…

A theoretical study on the decomposition mechanism of β-propiolactone and β-butyrolactone

1998

Abstract The reaction mechanism associated with the decomposition of β-propiolactone and β-butyrolactone in the gas phase to form carbon dioxide and ethylene or propene, respectively, has been theoretically characterized by using analytical gradients at the B3LYP/6-31G**, B3LYP/6-31++G**, MP2/6-31G** and MP2/6-31++G** calculation levels, as well as by single point calculations at QCISD(T)/6-31++G**//MP2/6-31++G**. A detailed analysis of the results points out that the reaction pathway can be described as an asynchronous concerted process. The geometrical parameters and the components of the transition vector are weakly dependent on the computational method. By applying transition state theo…