- Photolysis of Matrix-Isolated Acryloyl Chloride: 1,3 Chlorine Migration and Further Evolutions
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Photolysis, at λ ≥ 310 nm (ΔE -1), of acryloyl chloride 1 isolated in argon matrixes at 10 K yields 3-chloro-1,2-propenone 4 through 1,3-chlorine migration. There is no evidence of cyclopropenone or propadienone formation. 4 is also synthesized by irradiation of 3-chloropropanoyl chloride (λ ≥ 230 nm) isolated in argon matrix at 10 K. Identification is performed by comparison of experimental FT-IR spectrum with calculated ones (ab initio calculations at the 6-31G** level). Irradiation of 1 at λ ≥ 230 nm induces the photolysis of 4 which breaks into CO and the postulated transient 2-chloroethylidene 5 and/or into propadienone 2 complexed by HCL The transient 5 collapses to form ground-state vinyl chloride 6 by 1,2 hydrogen migration. In the next step, 2 loses CO to form a new transient assumed to be vinylidene 7 which yields ethyne by intramolecular isomerization process and vinyl chloride by intermolecular reaction with HCl trapped in the same cage. CO, HCl, ethyne, and vinyl chloride are the final reaction products. Modeling of the 1,3 chlorine migration process from 1 using ab initio calculations at the MP2/6-31G* level is performed in the ground state (S0) and the first singlet excited state (S1). The reaction energy value for an S1 (509 kJ/mol) state process is higher than for an S0 process (207.2 kJ/mol), these theoretical results suggesting the reaction take place in the ground state.
- Pietri, Nathalie,Monnier, Maurice,Aycard, Jean-Pierre
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- Conformational analysis and photolysis of matrix isolated 3-chloropropanoyl chloride monitored by FTIR spectroscopy
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Fourier transform infrared spectra of 3-chloropropanoyl chloride 1, both as a neat liquid and isolated in an argon matrix at 10 K, have been analyzed. These spectra reveal the existence of three conformers, the SA conformer (φ(1(C3C2C10)) = 0°and φ(2(C1C2C3C13)) = 180°) being the most stable. The semi-empirical PM3 and ab initio 6-31G* methods were used to evaluate the relative stability of these conformers, and to calculate the infrared spectra. Irradiation of 3-chloropropanoyl chloride, at λ > 230 nm, yields 3-chloro-1,2-propenone 2 and acryloyl chloride 3 as primary photoproducts. Photolysis of these compounds induces the formation of CO, HCl, vinyl chloride and ethyne as final products. The shifts of the ν(HCl) stretching mode, below the frequency of monomeric HCl in argon matrix, are indicative of the formation of HCl: CO and HCl: ethyne complexes. The identification of the reaction products is performed by comparison of experimental FTIR spectra and literature data.
- Pietri, Nathalie,Piot, Jerome,Aycard, Jean-Pierre
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p. 163 - 173
(2007/10/03)
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