G. I. MackayR. HemsworthDiethard K. Böhme
The flowing afterglow technique has been employed in measurements of the rate and equilibrium constants at 296 ± 2 K for reactions of the type[Formula: see text]and[Formula: see text]where R 1 and R 2 may be H, CH 3 , or C 2 H 5 . The equilibrium constant measurements provided absolute values for the intrinsic (gas-phase) acidities of the Brønsted acids CH 3 NH 2 , C 2 H 5 NH 2 , (CH 3 ) 2 NH, and (CH 3 ) 3 N, the heats of formation of their conjugate bases, and the electron affinities of the corresponding radicals R 1 R 2 N. Proton removal energies, ΔG 0 298 /(kcal mol −1 ), were determined to be 395.7 ± 0.7 for [Formula: see text] 391.7 ± 0.7 for [Formula: see text] 389.2 ± 0.6 for [Formula: see text] and > 396 for [Formula: see text] Heats of formation, ΔH 0 f.,298 , were determined to be 30.5 ± 1.5 for CH 3 NH − , 21.2 ± 1.5 for C 2 H 5 NH − , and 24.7 ± 1.4 for (CH 3 ) 2 N − . Electron affinities (in kcal mol −1 ) were determined to be 13.1 ± 3.5 for CH 3 NH, 17 ± 4 for C 2 H 5 NH, and 14.3 ± 3.4 for (CH 3 ) 2 N. These results quantify earlier conclusions regarding the intrinsic effects of substituents on the gas-phase acidity of amines and provide an experimental assessment of recent molecular orbital calculations of proton removal energies for alkylamines.
Paolo SebastianelliPablo M. ComettoRodolfo G. Pereyra
Eiken HaussühlS. HaussühlЕ. Тиллманнс
G. C. PapavassiliouIoannis KoutselasAris TerzisCatherine P. Raptopoulou
Mung-Dar LiChung‐Cheng ChangMichael Y. ChiangShiu-Tzung Liu