X study has been ~n a d e of the decomposition of methanol vapor by I-Ig O(VJ1) atollis, ut~der static conditions, a t 25' C. A system constr~icted entirely of quartz was c~i~ployed to eliminate the darli rcactiori between methanol vapor and pyrex glass to for111 trimethyl borate. Etiiphasis it1 this investigation was placed ou the determin;itioli of the nature of the primary processes operative, and to this end, the reaction was studied ill some detail in the presence of nitric oxide.For pure methanol, the major primary proclucts were fou~id to be hydrogen and ethylene glycol. The primary quantum yield for hydrogen was 0.46. Millor products of primary origiri were formaldehyde (0.01), ethane (0.005), and dimethyl ether (O.OOB), with the numbers in parentheses showing the primary quantum yielcls.In the presence of nitric oside, thc major products became methyl nitrite, riitro~is oxide, a~i d water. The q u a n t u~n yield of methyl nitrite rose steadily with increasing NO concentrations. For a 1 :I C H 3 0 H : NO inisture, the primary quantunl yield for methyl nitrite was found to be 0.56. The behavior of the reaction in the presence of NO establishes fairly unec~uivocally that the ~iiajor primary process invol\~es 0-1-1 b o~l d scission to form methoxy radicals ancl H atoms. These primary radicals t1ie11 form hydrosy~netliyl radicals by abstraction reactions with the substrate. The ethylene glycol product arises by reconibi~iation of the secondary hydroxymethyl radicals. These conclusions were f~rrther substantiatecl by mass spectrometric alialysis of the products of the decomposition of CDsOFI. It w;ls shown that CD:rOIl is ;l significant product of the reaction.
ISTIZODUCTIOKThe reaction of methanol vapor with I-Ig Ci(3PI) atoms has been studied previously (1, 2), aiid in detail by Phibbs and Dar\vent (3) from 25-500'. From the fact that 1-12 (+ = 0.43) and I-IOCI-I2CI-1201-I were the inajor products a t 25', the). concluded (3) quite reasonably that the major primary process was:The observed products could also be explained by the two-step sequence:For both [I] ancl [S] the [-I atoms for~ned are nssunied to attack the methyl group of the substrate:I'hibbs and Darwe~it rejectecl [2] as a n important PI-inlary process since they found that CI-IBOD substrate produced little IID. I-Iowever, the results of a number of inore recent studies have indicated that the methanol reaction should be re-exainined. Thus Tal