REACTIONS OF TRANS-HOCO STUDIED BY INFRARED-SPECTROSCOPY

trans-HOCO was produced by 193-nm photolysis of acrylic acid C2H3CO2H, and its reactions were studied using the rotational-vibrational trans itions of the nu1 O-H stretch. The thermal reaction rate constants for the reactions with O2 and NO show no isotope dependence (+/- 10 % unc ertainty) and have the following values: 1.9 (+/-0.2) X 10(-12) cm3 mo lecule-1 s-1 for O2 and 2.45 (+/-0.2) X 10(-12) cm3 molecule-1 s-1 for NO at 293 +/- 2 K. The lack of an H/D isotope dependence is interpret ed in terms of complex formation and dissociation, a mechanism in whic h hydrogen transfer is not the rate-limiting process. Product studies demonstrate the formation of trans-HONO from HOCO + NO. An upper limit of approximately 10(-14) cm3 molecule-1 s-1 has been set for the rate constants for the possible reactions of HOCO with CO, C2H4, and C2H2.