16668-68-1Relevant articles and documents
The ultraviolet photochemistry of phenylacetylene and the enthalpy of formation of 1,3,5-hexatriyne
Sorkhabi,Qi,Rizvi,Suits
, p. 671 - 676 (2007/10/03)
The ultraviolet photochemistry of phenylacetylene was studied in a molecular beam at 193 nm. The only primary photofragments observed were HCCH (acetylene) and C6H4. Some of the C6H4 molecules were found to decompose to 1,3,5-hexatriyne and molecular hydrogen. An enthalpy of formation of ΔHf ≤ 160 ± 4 kcal mol-1 was determined for 1,3,5=hexatriyne from the energetic threshold for this process. This experimentally determined value agrees well with our ab initio calculations performed at the G2 level of theory. Angular distribution measurements for the HCCH + C6H4 channel yielded an i sotropic distribution and were attributed to a long-lived intermediate and ground-state dissociation. An exhaustive search yielded no evidence for the phenyl + ethynyl or, the atomic hydrogen elimination channels even though these were observed in the pyrolytic studies of phenylacetylene.
Reaction of diazoalkanes with unsaturated compounds: 13. A new method of preparation and [1+2]- and [3+2]-cycloaddition reactions of diazopropyne
Tomilov,Okonnishnikova,Shulishov,Shavrin,Nefedov
, p. 2208 - 2212 (2007/10/03)
A THF solution of diazopropyne was obtained in 60% yield by the reaction of a 30% aqueous solution of methylamine with N,N′-dinitroso-N,N′-dipropargylterephthalodiamide. The reactions of diazopropyne with methyl acrylate and methyl methacrylate giving var
The Energy Well of Diradicals, V. - 1,3,5-Cyclohexatriene-1,4-diyl and 2,4-Cyclohexadiene-1,4-diyl
Roth, Wolfgang R.,Hopf, Henning,Horn, Carina
, p. 1765 - 1780 (2007/10/02)
The energy profile of the Bergman rearrangement of (Z)-3-hexene-1,5-diyne (4) has been established from the NO and oxygen dependance of the trapping rate of the intermediate diradical 1 which leads to a heat of formation for 1,4-didehydrobenzene (1) of ΔH0f = 138.0 +/- 1.0 kcal * mol-1.By the same technique the heat of formation of 1,2,4-cyclohexatriene (2), generated by thermolysis of (Z)-1,3-hexadien-5-yne (10), gives ΔH0f = 105.1 +/- 1.0 kcal * mol-1 which indicates a high diradical character for 2. - Key Words: Diradicals / NO and O2 trapping / Heat of formation / Energy well / Rearrangements / Bergman cyclisation
Propargyl Stabilisation Energy
Roth, Wolfgang R.,Hopf, Henning,Horn, Carina
, p. 1781 - 1796 (2007/10/02)
For the alkynyl-substituted olefines 1 - 14 activation parameters for the geometrical isomerisation have been determined in the gasphase by the single-pulse shoke-tube technique.By comparison of these barriers with the corresponding one of the isolated double bonds, each corrected by the steric energy contribution of the ground and transition state, a value of 7.8 +/- 1.3 kcal * mol-1 for the propargyl stabilisation energy (PrSE) has been derived. - Key Words: Resonance energy / Stabilisation energy / Propargyl resonance / Force field calculation / Intrinsic rotational barrier / Single pulse shock tube / Gasphase kinetics / Heats of hydrogenation
Synthesis and characterization of cobalt and molybdenum complexes derived from linear conjugated diynenes, triynedienes and tetraynetrienes
Lindsell, W. Edward,Preston, Peter N.,Tomb, Peter J.
, p. 201 - 212 (2007/10/02)
Z-1,6-Bis(trimethylsilyl)hexa-1,5-diyn-3-ene (2a), E-hexa-1,5-diyn-3-ene (3b) and related compounds (3a, c and d) were synthesized by standard methods.The Grignard reagent (3e) derived from 1-phenylhexa-1,5-diyn-3-ene (3d) was coupled with E-1-chloro-4-ph
Alkine und Cumulene, XV. Ueber die Photodimerisierung konjugierter Enine
Eisenhuth, Ludwig,Siegel, Herbert,Hopf, Henning
, p. 3772 - 3788 (2007/10/02)
On irradiation in the presence of triplet sensitizers having a triplet energy >250 KJ/mol, vinylacetylene (1a) dimerizes to cis- and trans-1,2-diethynylcyclobutane (cis- and trans-2) as well as minor amounts of 4-ethynyl-1-vinylcyclobutene (3).The effect of substituents on the course of the reaction is investigated: whereas alkyl, vinyl, and phenyl substituents, respectively, in the 4-position of 1a do not influence the photoaddition, 2-substituted enynes yield the corresponding cyclobutanes in poor yields only.Finally, 1-substituted vinylacetylenes (besides the substituents mentioned above the influence of ethynyl, chloro, and methoxy groups has been investigated) do not provide photodimers; they are cis-trans-isomerized instead.The mechanism of the photoaddition is discussed.
