45581-66-6Relevant academic research and scientific papers
Unimolecular rearrangements of carbanions in the gas phase. 2. Cyclopropyl anions
Chou, Phillip K.,Dahlke, Gregg D.,Kass, Steven R.
, p. 315 - 324 (1993)
We have examined the gas-phase unimolecular rearrangements of a series of substituted cyclopropyl anions (CHXCH2CY-; X - H, Y = Ph, CHO, and CM; X = Y = CO2CH3) with a variable temperature flowing afterglow device. The ring-opening barriers range from 19 to ≥36 kcal mol-1 and are well reproduced by ab initio molecular orbital calculations. An analysis of eight monosubstituted cyclopropyl anions reveals that the flexibility (ease of inversion) and thermodynamic stability of these ions account for their tendency to isomerize.
The Ever-surprising chemistry of boron: Enhanced acidity of phosphine·boranes
Hurtado, Marcela,Yanez, Manuel,Herrero, Rebeca,Guerrero, Andres,Juan Z. Davalos,Jose-Luis, M. Abboud,Khater, Brahim,Guillemin, Jean-Claude
supporting information; experimental part, p. 4622 - 4629 (2009/12/29)
The gas-phase acidity of a series of phosphines and their corresponding phosphine·borane derivatives was measured by FT-ICR techniques. BH 3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol-1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High- level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH 2PH2·BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl- is kinetically favored with respect to loss of Cl - in a typical SN2 process. Hence, ClCH2PH 2·BH3 is the only phosphine·borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
Gas-Phase Acidity of Aliphatic Alcohols
Boand, Genevieve,Houriet, Raymond,Gaeumann, Tino
, p. 2203 - 2206 (2007/10/02)
The gas-phase acidities of aliphatic alcohols containing up to nine carbon atoms have been determined by the method of dissociation of proton-bound dimers.Alkyl substituent effects on acidity are discussed in terms of dipolar, polarizability, and hyperconjugation effects.The latter seems to account for the unexpected higher acidity observed for secondary alcohols with respect to the isomeric tertiary alcohols.The influence of through-space dipolar interactions is involved to account for the increasing acidity of the higher linear homologues.
