17675-09-1Relevant academic research and scientific papers
Proton Affinity and Heat of Formation of Silylene
Shin, Seung Koo,Beauchamp, J. L.
, p. 1507 - 1509 (2007/10/02)
Using the techniques of Fourier transform ion cyclotron resonance spectroscopy, we determined the proton affinity of silylene to be 201 +/- 3 kcal*mol-1 from a study of the kinetics and thermochemistry of proton transfer from SiH3+ to a series of n-donor bases with well-established gas-phase base strengths.This value leads to ΔHfo298(SiH2) = 69 +/- 3 kcal*mol-1, which is 11 kcal*mol-1 higher than the previously accepted value (Wals, R.Acc.Chem.Res. 1981, 14, 246-252), but in excellent agreement with the recent theoretically recommended value of 68.1 kcal*mol-1 (Ho, P.; Coltrin, M.E.; Binkely, J.S.; Melius, C.F.J.Phys.Chem. 1985, 89, 4647-4654).
RING SIZE EFFECTS ON THE GAS PHASE PROTONATION OF CYCLIC KETONES
Bouchoux, G.,Houriet, R.
, p. 5755 - 5758 (2007/10/02)
Experimental proton affinities of cyclic ketones are determined showing evidence for a larger strain energy in protonated vs. neutral cyclic ketones.
Carbon-Hydrogen Bond Dissociation Energies in Alkylbenzenes. Proton Affinities of the Radicals and the Absolute Proton Affinity Scale
Meot-Ner (Mautner), Michael
, p. 5 - 10 (2007/10/02)
Rate constants (k) were measured for proton-transfer reactions from alkylbenzene ions RH+ to a series of reference bases B, i.e., RH+ + B -> BH+ + R*.For exothermic reactions (ΔH -1.For example, the reaction C6H5CH3+ + B -> BH+ + C6H5CH2* is fast (reaction efficiency = k/kcol >/= 0.5) when B = MeO-t-Bu or stronger bases, but k/kcol is significantly smaller when B is n-Pr2O or weaker bases.From the falloff curve of reaction efficiency vs.PA(B), we find PA(n-Pr2O) = PA(C6H5CH2*) + 0.8 kcal mol-1 = 200.0 kcal mol-1.Since PA(C6H5CH2*) is obtained from known thermochemical data, this relation defines the absolute PA of n-Pr2O.Through a ladder of known PA, we then obtain PA(i-C4H8) = 186.8 kcal mol-1; we also obtain the absolute PAs of other oxygen bases.Falloff curves of reaction efficiencies of 3-FC6H4CH3+, C6H5C2H5+, C6H5-n-C3H7+, and C6H5-i-C3H7+ with these reference bases give then the following PAs of R* and R-H bond dissociation energies (Do) (all in kcal mol-1) as R*, PA(R*), Do(R-H): 3-FC6H4CH2*, 197.2, 89.4; , 197.9, 86.2; , 199.1, 86.1; , 199.6, 86.1.In similar manner, rate constants for H+ transfer from C6H5NH2+ to reference pyridines and amines yield PA(C6H5NH*) = 221.5 and Do(C6H5NH-H) = 85.1 kcal mol-1 (1 kcal mol-1 = 4.18 kJ mol-1).
