66223-95-8Relevant academic research and scientific papers
Catalytic Asymmetric (3 + 3) Cycloaddition of Oxyallyl Zwitterions with α-Diazomethylphosphonates
Liu, Yan,Peng, Xian,Peng, Yungui,She, Rui,Zhou, Xin
supporting information, p. 7295 - 7300 (2021/10/01)
The unique structure of oxyallyls represents a significant challenge for their catalytic asymmetric applications. Herein, an unprecedented chiral imidodiphosphoric acid-catalytic enantioselective (3 + 3) cycloaddition between oxyallyl zwitterions generate
Primary and Secondary Kinetic Isotope Effects in the Decomposition of a Tertiary Alkoxide
Ibrahim, Sani,Msayib, Kadhum J.,Watt, C. Ian F.,Wilson, John M.
, p. 1703 - 1714 (2007/10/02)
Kinetic isotope effects have been determined for the elimination of toluene from the alkoxide of 1,2,3-triphenylpropan-2-ol (1a).In DMSO, the rate measurements on 1a and 1,2,3-triphenylpropanol (1b) at 30 deg C give kH4/kC4/
Micellar Systems as ''Supercages'' for Reactions of Geminate Radical Pairs. Magnetic Effects
Turro, Nicholas J.,Weed, Gregory C.
, p. 1861 - 1868 (2007/10/02)
The photochemistry of dibenzyl ketone (DBK) and other molecules capable of producing benzyl radicals and substituted benzyl radicals has been investigated in micellar systems.The cage effect (percent of unscavengeable radical pairs produced by photolysis) was measured under a variety of conditions, and the results are compared with those obtained in homogeneous organic solvents.For example, parameters such as mean occupancy of ketone, detergent type and concentration, O2 concentration, additives, temperature, applied magnetic field, and pressure have been varied and investigated as to their influence on the magnitude of cage effect.In addition to modifying its environment, structural modification of the DBK by incorporation of 2H and 13C isotopes, hydrophobic groups, and heavy atoms was performed to investigate the impact of these variations on the cage effect in micellar systems.Isotopic substitution of 2H or 13C leads to results on both the quantum yields for reactions and on the percent cage that were consistent with expectations of magnetic isotope effects.Hydrophobic groups substituted in the 4-position of DBK were found to cause a substantial increase in the cage effect and yet retain the magnetic-field-dependent character found in the parent DBK.Incorporation of Br in the 4-position of DBK was found to enhance the cage effect but at the same time cause the cage effect to become magnetic field independent.Substitution of α-naphthyl for phenyl in DBK also produced magnetic-field-independent behavior, in addition to a dramatic decrease in the efficiency of photolysis.
Thermolysis of Model Compounds for Coal. 3. Radical Chain Decomposition of 1,3-Diphenylpropane and 1,4-Diphenylbutane
Poutsma, Marvin L.,Dyer, Catherine W.
, p. 4903 - 4914 (2007/10/02)
Cracking of 1,3-diphenylpropane (1) at 345-425 deg C to give toluene and styrene proceeded much more rapidly than expected from the strength of its weakest C-C bond.Styrene was rapidly consumed in secondary reactions, one of which was addition to 1 to from 1,3,5-triphenylpentane.The kinetic order at low conversion over a 103 variation in initial concentration from neat liquid through solutions in biphenyl to gas at 20 kPa was 1.59 +/- 0.03.The activation energy for the neat liquid was 52.3 +/- 1.3 kcal*mol-1.Toluene product from 1-1,1,3,3-d4 contained no detectable deuterium in the aromatic ring.Combination of these experimental data with thermochemical kinetic estimation procedures demonstrates that the rate "acceleration" results from a free-radical chain decomposition mechanism involving steps 5 and 6, in which k6 >>k5, rather than from a concerted retro-ene cleavage.The failure of such a chain to develop for 1,2-diphenylethane is a consequence of the dependence of ΔH0 for radical β scission on structure.Cracking of 1,4-diphenylbutane (2) gave both toluene plus allylbenzene and ethylbenzene plus styrene.The ratio between these competitive pathways increased nonlinearly with concentration from 0.185 at 100-110 kPa to 0.82 in the neat liquid.This behavior is interpreted in terms of chain reaction steps 22-26.The key step is the interconversion of 1,4-diphenyl-1-butyl radical (6) and its 2-isomer (7) by hydrogen abstraction from 2, a process which is competitive with β scission.Thermochemical kinetic estimates lead to a set of rate constants which are consistent with the observed product ratio behavior.Use of the hydrogen atom donor tetralin as the solvent had only minor effects on the rates of thermolysis of 1 and 2 but dampened the product ratio dependence from 2.Tetralyl radicals are too reactive as hydrogen abstractors at 350-400 deg C to serve as chain-inhibiting species.These α,ω-diphenylalkanes, Ph(CH2)nPh, serve as models for aliphatic bridges between aromatic units in coal.The implications of the demonstrated chain character of their thermolysis when n is more or equal to 3 for modeling the thermal decomposition of coal are discussed.
