| Abstract: | The kinetics of the gas phase pyrolyses of methyl 2-bromopropionate and 2-bromopropionic acid were studied in a seasoned, static reaction vessel and under maximum inhibition of the free radical suppressor toluene. The working temperature and pressure range was 310–430°C and 26.5–201.5 torr, respectively. The reactions proved to be homogeneous, unimolecular, and obeys a first-order rate law. The rate coefficients are expressible by the following equations: for methyl 2-bromopropionate, log k1(s?1) = (13.10 ± 0.34) ? (211.4 ± 4.4)kJ mol?1(2.303RT)?1; for 2-bromopropionic acid, log k1(s?1) = (12.41 ± 0.29) ? (180.3 ± 3.4)kJ mol?1(2.303RT)?1. The bromoacid yields acetaldehyde, CO and HBr. Because of this result, the mechanism is believed to proceed via a polar five-membered cyclic transition state. |
