CO₂ laser‐induced decomposition of propan‐2‐ol, butan‐2‐ol, pentan‐2‐ol, pentan‐3‐ol, and hexan‐2‐ol

Abstract

The pulsed COz laser-induced decompositions of propan-2-01, butan-2-01, pentan-2-01, pentan-3-01, and hexan-2-01 in the gas phase have been investigated. Like ethanol which we examined previously [l] the absorption cross section of propan-2-01 for pulsed 9R14 radiation increases with pressure at low pressures, an effect attributed to rotational hole-filling. In contrast the absorption cross section of butan-2-01 (lOR24) has only a small pressure dependence and those of pentan-2-01 (9R26), pentan-3-01 (10R14), and hexan-2-01 (9P20) show little or no variation with pressure in the range 0.1-5.0 torr.Decomposition products have been investigated at low pressure where the excitation of the alkanols was essentially collision free. The observed products for all the alkanols can be rationalized on the basis of primary dehydration and C-C fission channels, with minor contributions from other molecular eliminations. 0 1994 John Wiley & Sons, Inc. *This article is dedicated to the memory of Bob Back, a personal friend and colleague over many years who is sadly missed and to whom we were indebted for valuable discussions during the progress of the work described.t Present address,

Characterization of the Unimolecular Water Elimination Reaction from 1-Propanol, 3,3,3-Propan-1-ol-d3, 3,3,3-Trifluoropropan-1-ol, and 3-Chloropropan-1-ol

“…Dehydration processes can be more easily observed from thermal activation of 2-propanol and 2-methyl-2-propanol than 1-propanol, because the E 0 for dehydration is reduced for secondary and tertiary alcohols, just as is the case for HX (X = F, Cl, Br) elimination reactions. − Several pyrolysis studies exist for 2-propanol, and a recent theoretical analysis concluded that dehydration is an important channel for most temperatures and pressures. Thermal activation studies of 1-propanol, , which are not so common, seem to be dominated by free-radical chain reactions.…”