Ion-molecule reactions in amines. Photoionization of propyl-, ethyl-, diethyl-, and triethylamine

Abstract

Photoinduced ion-molecule reactions of primary ions occurring in the ethylamines and propylamine have been investigated in the pressure range 1-20 mTorr using a Kr resonance lamp (10.03 and 10.6 eV) as the excitation source. Thermal rate constants (T = 298°K) have been determined for the reactions R3_"+NH" + R3-"NH" R3_"+NHn+i + R3_nNH"(-H) (fci) and R2_n(CH2)+NHn + R3-nNHn -R2-"(CH2)NHn(-H) + R3-n+NHn+i (k2) where = 0,1, and 2 for R = C2H5 and = 2 for R = C3H7. For the ethylamines the values for ki were found to be 18.3, 12.5, and 7.05 X 10-10 cm3 sec-1 and for k2, 19.7, 13.6, and 1.28 X 10-1°cm3 sec-1 for = 2,1, and 0, respectively. For propylamine the corresponding values for ki and k2 are 15.6 and 22.4 X 10~10 cm3 sec-1. The values of hi are slightly less than those previously reported for the methylamines and are shown to be consistent with the predictions for an ion-induced dipole model for ion-molecule reactions which assumes a collision complex in which the polar molecule is aligned with the ion and takes into account intrinsic differences in the N-H and C-H hydrogen-transfer rates. The observed change in k2 with increasing ethyl substitution is explained on the basis of the structure of the primary ion, R2_"(CH2)+NH".

Ion-Molecule reactions in methylamine and dimethylamine and trimethylamine systems

“…TI1t~low fract ional intensities of (CH 3hNH+ (m / z 59) and (CH 3hNH+ (mix 60) formed in reactions 11, ll, and 13 make the numerical simulation less sensitive to the assumed rate constant values, and therefore, the uncertainty in these values in Table 2 is higher than that in similar reactions (7)(8)(9) in the methyiamine jdimethylamine system. We estimate the uncertainty of rate constant values of reactions 11-13 at about 30%.…”

“…In any realistic kinetic study of nucleophilic displacement reactions one has to take into account the presence of these impurities, because even small amounts of dimethylamine or trimethylamines contributing to the formation of methylated ion products will play a crucial role in measurements of the rate constant of reaction 1. Some rate constants for proton transfer processes from methylamine molecular ion or its fragment ions to neutral methylamine to form the corresponding protonated ion species (m / z 32) have © 1991 American Society for Mass Spectrometry 1044-0305/91 /$3.50 been previously measured [2][3][4][5][6][7][8][9], and are summarized in Table 1. Clearly these rate constant values are scattered over a factor of two, which seems to be outside the normally admissible experimental error.…”

Gas phase ion–molecule reactions of dimethylsulphoxide

“…This mode of reaction requires an electronegative atom (oxygen) to which is attached a labile hydrogen atom. Recent reports on the ion-chemistry of sulphur (H2S, CH3SH, (CH3),S (21) and CH,SH, CD3SH (23,24)) and nitrogen (25)(26)(27) analogues show that similar reactions, at least in part, occur in these systems also.…”

Generalized selection rules: symmetry rules for molecules or chromophores in perturbing fields

“…If the projection is finite, then the projected operator product satisfies eq 10 and corresponds to a finite observable. In particular, if P° Pa = P'i (20) then the initial matrix element product may be replaced by the sum of matrix element products formed by substituting the ordered wave functions back into each term of the projected operator product sum. This will then lead directly to an observable.…”