A Study on Electronic Spectra of Organic Compounds with S–Cl Group

Yamabe, Tokio; Nagata, Shinji; Kikuzono, Yasuo; Fukui, Kenichi

doi:10.1246/bcsj.48.1349

Cited by 6 publications

(3 citation statements)

References 10 publications

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“…O cloreto de benzenossulfenila é bem mais reativo que qualquer um dos compostos das outras classes de substratos estudadas, sendo cerca de 10 5 vezes mais reativo que o cloreto de benzoíla, cuja classe vem em segundo lugar na ordem de reatividade. Yamabe et al 30 propuseram, ainda, que a alta reatividade dos cloretos de arilsulfenila pode ser atribuída à fragilidade da ligação S-Cl devida, provavelmente, a uma forte repulsão entre os elétrons 3p dos átomos de enxofre e cloro, respectivamente.…”

Section: Cloretos De Arilsulfenilaunclassified

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

1997

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The experimental results for the 2-propanolysis of benzoyl, benzyl, benzene sulphenyl and benzene sulphonyl chlorides obtained by conductimetric technique were compared with estimates for chlorobenzene which is extremely unreactive as an electrophile. We thus obtained the following reactivity sequence: PhSCl>PhCOCl>PhSO 2 Cl>PhCH 2 Cl>PhCl with rate-coefficiente ratios (in the same order): 9.5 x 10 4 : 1: 7.14 x 10 -2 : 4.7 x 10 -3 : about 10 -26 . We have discussed these results in specific terms and with the aid of general conclusions which stem from our own classification of electrophiles.Keywords: 2-propanolysis; electrophilic carbon and sulphur centres; solvolysis mechanism. ARTIGO INTRODUÇÃONo campo da substituição nucleofílica, as pesquisas relativas às reatividades de substratos que têm como centro eletrofílico o carbono saturado 1,2 , o carbono carbonílico 3,4 e o carbono aromá-tico 5 têm recebido muita atenção; entretanto, estudos comparativos entre si são raros. Algumas comparações entre as reatividades dos carbonos: aromático e saturado, carbonílico e saturado, aromático e carbonílico, aromático, heteroaromático e sistema tropílico, carbonílico e imidoílico, e de arenos coordenados e não-coordenados são descritas na literatura [6][7][8][9][10][11][12][13][14][15] . Todavia, muito pouco é conhecido acerca da reatividade do enxofre como centro eletrofílico, embora haja uma quantidade razoável de trabalhos sobre centros sulfonílicos 16 e pouco sobre centros sulfenílicos.Estudos comparativos das reatividades relativas de compostos com carbono e enxofre como centros eletrofílicos, em solvólise nucleofílica, são, ainda, desconhecidos. Assim, no presente trabalho dispensou-se atenção aos cloretos de benzenossulfenila em reações de solvólise com 2-propanol e, para comparação, foram relacionadas reações de substituição nucleofílica nos grupos carbonila e sulfonila e nos carbonos saturado e aromático.A escolha do 2-propanol para o estudo da solvólise nucleofí-lica foi baseada na facilidade para seguir as reações usando uma técnica convencional (condutimetria), no nível conveniente de velocidade de reação, na escassez de dados de sua solvólise nucleofílica e no desejo de comparar os diferentes sistemas, sem as complicações introduzidas se algum deles reagisse por um mecanismo unimolecular (S N 1). Julgou-se que isso não ocorre em 2-propanol anidro para os compostos não substituídos e muito menos para os que possuem substituintes receptores de elé-trons no anel benzênico. Julgou-se, também, que entre as classes de compostos estudados, aquelas que oferecem maiores chances de operar por um mecanismo unimolecular são os sistemas benzílico e benzoílico. Entretanto, é muito relevante o fato de ter-se constatado que, mesmo na metanólise, nem cloreto de benzila e nem de benzoíla reagiu por um mecanismo S N 1 11,17 . Escolheram-se sistemas arílicos por conveniência e porque planejou-se estender os estudos cinéticos para incluir arenos eletrofí-licos. A escolha do cloreto como nucleófugo se deveu ao fato de ele se consti...

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Section: Cloretos De Arilsulfenilaunclassified

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

1997

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“…It belongs to the C s symmetry group with the symmetry plane containing the SQO double bond, and the electronic ground state is X 1 A 0 . Whereas until today only one early theoretical study exists on the electronic structure of SOCl 2 ground and excited electronic states, 8 experimentally the UV photolysis of the SOCl 2 molecule has been subject of several investigations. [9][10][11][12][13][14] The smooth absorption spectrum starts around 300 nm with distinct shoulders at 244 and 194 nm, as shown in Fig.…”

Section: A Introductionmentioning

confidence: 99%

Photodissociation dynamics of SOCl₂

Chichinin¹,

Einfeld²,

Gericke³

et al. 2005

Phys. Chem. Chem. Phys.

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New theoretical and experimental results for the ultraviolet photodissociation dynamics of thionyl chloride (SOCl2) are presented and combined with existing data from a variety of sources in order to provide a unified view of the photodissociation dynamics of SOC12. Time-dependent density functional theory on the basis of the hybrid-type B3LYP functional was employed to calculate vertical excitation energies for the SOCl2 parent molecule up to 6.3 eV. Three-dimensional (3D) imaging of photofragments was performed for a dissociation wavelength of 235 nm. Atomic chlorine fragments were observed in the 2P(3/2) ground state [Cl] and the 2P(1/2) excited spin-orbit state [Cl*] by employing resonance enhanced multi-photon ionization (REMPI) and time-of-flight (TOF) techniques. State-specific speed distributions and the speed dependence of the beta anisotropy parameter were obtained from the full 3D momentum vector distribution by appropriate projection methods. Bimodal speed distributions for both spin-orbit states are evidence of a competition between the radical (SOCl2 --> SOCl + Cl/Cl*) and the three-body decay channel (SOCl2 --> SO + 2 Cl/Cl*). No evidence of the molecular fragmentation channel (SOCl2 --> SO + Cl2) was found. With increasing fragment speed the beta anisotropy parameter increases from 0.1 to 0.85 and 0.68 for Cl and Cl*, respectively, suggesting fragmentation via an excited A' state for slow fragments and via an A" state for fast fragments. The calculations allow for the first time to interpret all previous and new experimental data for the ultraviolet photodissociation of SOCl2 by assuming simultaneous excitation of several excited electronic states giving rise to competing dissociation channels.

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“…26 The distinct shoulder at 40 000 cm À1 (250 nm) and the pronounced absorption maximum above 50 000 cm À1 (below 200 nm) were assigned to overlapping electronic transitions: the s* SCl n S and the p* SO n S transitions from a non-bonding lone pair electron on the sulfur atom to the anti-bonding molecular orbitals of the S-Cl or the S-O bond, and, at higher excitation energies, the corresponding transitions from a non-bonding n Cl electron out of the Cl(3p) manifold. 24,27 Photodissociation studies have been performed at wavelengths of 193 nm, 235 nm, and 248 nm, [20][21][22][23][24]28 corresponding to excitation in the short wavelength absorption maximum and the long wavelength shoulder, respectively. The dissociation dynamics differ remarkably for dissociation at 193 nm and at the longer wavelengths.…”

Section: A Introductionmentioning

confidence: 99%

Competitive channels in the photodissociation of thionyl chloride

Roth

Maul

Gericke

2002

Phys. Chem. Chem. Phys.

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The photodissociation dynamics of thionyl chloride are investigated by a one-dimensional resonance enhanced multi-photon/time-of-flight technique (REMPI/TOF) at a dissociation wavelength around 235 nm. Nascent sulfur monoxide molecules and chlorine atoms were detected state-specifically under collision-free conditions for parallel and perpendicular polarisation geometries. Dissociation and detection were performed using the same laser. Polarisation-dependent and state-specific TOF profiles were converted into kinetic energy distributions using a least squares fitting method taking into account velocity-dependent spatial fragment anisotropies. Kinetic energy distributions are narrow and structureless for SO and bimodal for both spin-orbit states of Cl. The bimodality reflects the competition between two-and three-body decay: SOCl 2 + hn ! SOCl + Cl and SOCl 2 + hn ! SO + 2 Cl. Chlorine atoms are preferentially released along the polarisation vector of the dissociation laser. The spatial distribution of Cl is characterised by an anisotropy parameter of 0.8 AE 0.2 for the two-body decay and 0.2 AE 0.2 for the three-body decay. SO molecules are isotropically released with low kinetic energy together with two ground state chlorine atoms. These products are most likely to be generated in a sequential three-body decay on a potential energy surface of A 0 symmetry. Another surface of A 00 symmetry instantaneously produces fast chlorine atoms in a two-body decay process to equal amounts in the ground and the excited spin-orbit states. The corresponding SOCl fragment carries about 50% of the available energy as internal energy.

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A Study on Electronic Spectra of Organic Compounds with S–Cl Group

Cited by 6 publications

References 10 publications

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

Photodissociation dynamics of SOCl₂

Competitive channels in the photodissociation of thionyl chloride

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A Study on Electronic Spectra of Organic Compounds with S–Cl Group

Cited by 6 publications

References 10 publications

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

Reatividade Relativa em Solvólise Nucleofílica de Cloretos de Arilsulfenila, Arilcarbonila, Arilsulfonila, Arilmetila e de Arila

Photodissociation dynamics of SOCl2

Competitive channels in the photodissociation of thionyl chloride

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Photodissociation dynamics of SOCl₂