18282-77-4Relevant articles and documents
Direct identification of photofragment structures formed in the 193 nm photodissociation of thiophene
Hsu,Liao,Ma,Ng
, p. 1760 - 1767 (1995)
An experimental scheme which involves vacuum ultraviolet photoionization mass spectrometric sampling of laser photodissociation products in a pulsed supersonic molecular beam has been used to identify the isomeric structures of the 193 nm photofragments from thiophene. The primary products observed are vinylacetylene (H2C=CH-C≡CH), acetylene (C2H2), and thioketene (H2C=C=S). Using the 2 + 1 resonance-enhanced multiphoton (REMPI) scheme, we find that S atoms are produced predominantly (≥96%) in 3PJ states with a fine structure distribution of 3P2:3P1:3P0 = 0.82 ± 0.03:0.15 ± 0.03:0.03 ± 0.03. These experimental results indicate that the major dissociation channels are CH2=CH-C≡CH + S(3P) and CH=CH + CH2=C=S. Ab initio multiconfiguration self-consistent-field calculations have been made to rationalize these experimental observations.
HCl Elimination from Ethanesulfenyl Chloride and Chlorodimethyl Sulfide
Maier, Guenther,Floegel, Ulrich,Reisenauer, Hans Peter,Hess, B. Andes,Schaad, Lawrence J.
, p. 2609 - 2612 (2007/10/02)
Thioacetaldehyde (5) is prepared by matrix photolysis of ethanesulfenyl chloride (3) or thiirane (4) and by flash pyrolysis of allyl ethyl sulfide (6).Matrix irradiation of 3 or 5 with 222-nm light results in a dehydrogenation, and a mixture of thiirene (7), ethynethiol (8), and thioketone (9) is formed.Flash pyrolysis of chlorodimethyl sulfide ((1) yields ethenethiol (11) together with thiirane (4), whereas ethanesulfenyl chloride (2) gives ethene under the same conditions.The identification of thioacetaldehyde (5) is based on the comparison between the experimental and calculated IR spectra. Key Words: Matrix isolation / Elimination of HCl, photochemically / Flash pyrolysis / Calculations, ab initio / Photochemistr
Photochemistry of Low-Temperature Matrices Containing Carbonyl Sulfide: Reactions of Sulfur Atoms with the Phosphorus Trihalides PF3 and PCl3 and the Hydrocarbons CH4, C2H4, and C2H2
Hawkins, Michael,Almond, Matthew,Downs, Anthony J.
, p. 3326 - 3334 (2007/10/02)
Exposure of a solid argon matrix containing the molecules OCS and PX3 (X = F or Cl) at ca. 20 K to broad-band ultraviolet radiation leads to the formation of CO and the corresponding thiophosphorus(V) halides SPX3, as witnessed by the infrared spectrum of the matrix.Photolysis of a solid methane matrix containing OCS at 13-20 K on exposure to radiation with wavelengths near 230 nm gives rise to CO, methanethiol, CH3SH, thioformaldehyde, H2C=S, and carbon disulfide, CS2, as the only products to be detected by their infrared spectra.Yet there is no sign of either CH3SH or H2C=S on photolysis of OCS in a CH4-doped argon matrix with the composition Ar:CH4:OCS = 100:20:1.Evidently the photolysis of OCS generates 1D sulfur atoms which add to an adjacent CH4 molecule with the formation of a vibrationally activated intermediate *; this relaxes to give CH3SH or decomposes to give H2C=S.Similar experiments have been carried out with solid argon matrices including OCS and either C2H4 or C2H2.In the presence of C2H4 there is no hint of C-H insertion; instead the C2H4 undergoes sulfur atom addition at the double bond to give thiirane, , as the sole product to be identified by its infrared spectrum.By contrast, C2H2 yields thioketene, H2C=S, ethynethiol, HCCSH, and carbon disulfide, CS2, as the main products, as well as thiirane, , as a minor product.The response of the hydrocarbon molecules in argon matrices can be interpreted in terms of the diffusion and reaction of ground-state 3P sulfur atoms but not of 1D sulfur atoms which are too short-lived to undergo significant migration.It appears that 3P sulfur atoms react with both C2H4 and C2H2 to yield a triplet diradical: that derived from C2H4 favors cyclization, whereas that derived from C2H2 rearranges preferentially to H2C=C=S and this in turn enters into secondary reactions to give HCCSH and CS2.
