29075-95-4

Upstream product

• 15520-32-8 isopropoxide 
• 74-86-2 acetylene 
• 16331-65-0 t-butoxide 
• 62268-73-9 diphenylcarbene 
• 54128-17-5 trifluoromethanide 

Downstream Products

• 74-86-2 acetylene 
• 16331-65-0 t-butoxide 
• 74-99-7 prop-1-yne 
• 15520-32-8 isopropoxide 

Relevant academic research and scientific papers

Unusual ionic hydrogen bonds: Complexes of acetylides and fluoroform

Ion-molecule complexes of substituted acetylides, RCC- (R = tert-butyl, H, phenyl, p-tolyl), and fluoroform, HCF3, were studied using Fourier transform ion cyclotron resonance mass spectrometry. These complexes, RCC-·HCF3, all have complexation energies of approximately -19 kcal/mol and are, therefore, hydrogen bonded. The acetylides vary in basicity over a 6 kcal/mol range, but all have the same complexation energy with fluoroform. The structure of these complexes was verified by deuterium isotopic exchange reactions and equilibrium fractionation experiments. The relationship between acid-base thermochemistry and hydrogen bond stability is discussed.

Bond strengths of ethylene and acetylene

Negative ion photoelectron spectroscopy and gas-phase proton transfer kinetics were employed to determine the CH bond dissociation energies of acetylene, ethylene, and vinyl radical: D0(HCC-H) = 131.3 ± 0.7 kcal mol-1, D0(CH2CH-H) = 109.7 ± 0.8 kcal mol-1, and D0(CH2C-H) = 81.0 ± 3.5 kcal mol-1. The strengths of each of the other CH and CC bonds in acetylene and ethylene and their fragments were derived. The energy required to isomerize acetylene to vinylidene was also determined: HC≡CH → H2C=C: ΔHisom,0 = 47.4 ± 4.0 kcal mol-1. As part of this study, proton transfer kinetics in a flowing afterglow/selected-ion flow tube apparatus were used to refine the acidities of ethylene, acetylene, and vinyl. The gas-phase acidity of acetylene was tied to the precisely known values for hydrogen fluoride, ΔGacid,298(HF) = 365.6 ± 0.2 kcal mol-1, and water, ΔGacid,298(H2O) = 383.9 ± 0.3 kcal mol-1, yielding ΔGacid,298(HCC-H) = 369.8 ± 0.6 kcal mol-1. The gas-phase acidity equilibria of acetylene with isopropyl alcohol and tert-butyl alcohol were also measured. Combined with relative acidities from the literature, these measurements yielded improved acidities for the alcohols, ΔGacid,298((CH3)2CHO-H) = 370.1 ± 0.6 kcal mol-1, ΔGacid,298((CH3)3CO-H) = 369.3 ± 0.6 kcal mol-1, ΔGacid,298(C2H5O-H) = 372.0 ± 0.6 kcal mol-1, and ΔGacid,298(CH3O-H) = 375.1 ± 0.6 kcal mol-1. The gas-phase acidity of ethylene was measured relative to ammonia, ΔGacid,298(NH3) = 396.5 ± 0.4 kcal mol-1, giving ΔGacid,298(C2H4) = 401.0 ± 0.5 kcal mol-1. The gas-phase acidity of vinyl radical was bracketed, 375.1 ± 0.6 kcal mol-1 ≤ ΔGacid,298(CH2C-H) ≤ 380.4 ± 0.3 kcal mol-1. The electron affinities of ethynyl, vinyl, and vinylidene radicals were determined by photoelectron spectroscopy: EA(HCC) = 2.969 ± 0.010 eV, EA(CH2CH) = 0.667 ± 0.024 eV, and EA(CH2C) = 0.490 ± 0.006 eV.

Generation, Thermodynamics, and Chemistry of the Diphenylcarbene Anion Radical (Ph2C.-)

Dissociative electron attachment with Ph2C=N produced Ph2C.- (m/z 166).The reactions of Ph2C.- with potential proton donors of known gas-phase acidity were used to bracket PA(Ph2C.-) = 380 +/- 2 kcal mol-1 from which ΔHf0(Ph2C.-) = 81.8 +/- 2 kcal mol-1 was calculated.The reactions of Ph2C.- with CH3OH and C2H5OH proceeded with major and minor amounts, respectively, of a H2.+-transfer channel, forming Ph2CH2, RCHO, and an electron.The kinetic nucleophilicity of Ph2C.- in SN2 displacement reactions with CH3X and C2H5X molecules was shown to be medium, which requires a significant intrinsic barrier in these reaction.The reactions of Ph2C.- with various aldehydes, ketones, and esters were fast and established two principal product-forming channels: (1) H+ transfer if the neutral reactant contains activated C-H bonds and (2) carbonyl addition followed by radical β-fragmentation of one of the groups originally attached to the carbonyl carbon.The order for the ease of radical β-fragmentation in the tetrahedral intermediates was RO > alkyl >> H, and CO2CH3 > CH3.Since the reactions of Ph2C.- with the simple esters HCO2CH3 and CH3CO2CH3 were fast, it should now be possible to examine the reactions of carbonyl-containing organic molecules, which are expected to react slower than these esters and obtain their relative reactivities.