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".
Photoinduced ion-molecule reactions of the primary ions occurring in a number of thiols and alkyl sulfides have been investigated over the pressure range 1-20 mTorr using a Kr resonance lamp (10.03 and 10.6 eV) as the excitation source. Rate coefficients at 298 K have been determined for the reaction R2_"+SHn + R2_nSH" -* R,_"+SHn+1 + R2-"SHri (-H) (ki), n = 0,1. For the mercaptans values of kx were found to be 14.1,12.5,11.3, and 5.7 X 10"10 cm3 s"1 for R = CH3, C,H5, C3H7, and (CH3)3C. These values agree with the general trend established for the analogous reactions in amines. In the case of (CH3)2S and (C2H5)2S, no hydrogen transfer was observed. Photoionization of C2H5SH in CH3OH could indicate that mercaptans behave as hydrogen atom acceptors rather than as proton donors. However, for fert-butyl mercaptan, the proton transfer reaction (CH3)3C+ + (CH3)3CSH -»• (CH3)2CCH2 + (CH3)3CS+H2 (k2) was also observed.
Mit Hilfe eines Hochdruck‐Quadrupolmassenspektrometers (1‐20m Torr) mit einer Kr‐Resonanzlampe (10,03 und 10,6 eV) als Photoionisationsquelle werden die Geschwindigkeitskonstanten der Reaktionen A bestimmt.
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