Interaction between the carbonyl group and an α-sulphur atom. Part I. Infrared and ultraviolet spectra of some α-(alkylthio)thioesters

Wladislaw, Blanka; Viertler, Hans; Demant, Ekke

doi:10.1039/j29710000565

Cited by 8 publications

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“…No definite conclusions can be reached without a refined quantum-mechanical calculation and this is yet to be carried out. A similar observation is made for methyl 3-thiabutanoate (4 (Fig. 2).…”

Section: Resultssupporting

confidence: 57%

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On the photoelectron and ultraviolet spectra of molecules containing a divalent sulfur atom and a carbonyl group separated by a methylene group

Olivato¹,

Viertler²,

Wladislaw³

et al. 1976

Can. J. Chem.

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Can. J. Chem. 54, 3026 (1976).Photoelectron spectra show that in CH3SCH2COCH3 the sulfur and carbonyl lone pair orbitals (S,O) are both stabilized with respect to the compounds containing S or CO only. This is in keeping with the observed values of the basicity constants. The ultraviolet absorption spectra contain the expected T * c 0 and a* t S bands and give evidence for a significant amount of mixing between the excited orbitals. P. R. OLIVATO, H. VIERTLER, B. WLADISLAW, K. C. COLE et C. SANDORFY. Can. J. Chern. 54, 3026 (1976).Nous avons mis en evidence par la mesure de spectres photoelectroniques que dans la molecule CH3SCH2COCH3 les orbitales des doublets libres du soufre et du carbonyle sont toutes deux stabilisies par rapport B leur valeur dans les molecules respectives qui ne contiennent que S ou CQ. Cela esten accord avec les valeurs observies des constantes de basiciti. Les frequences des bandes T * + 0 et U * t S dans le spectre d'absorption ultraviolet indiquent qu'il se produit un melange apprkiable entre les orbitales excities.

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Section: Resultssupporting

confidence: 57%

“…Previously this problem has been examined by ultraviolet, infrared and nmr spectroscopic measurements (1)(2)(3)(4)(5)(6). We now present the He(1) photoelectron spectra of the following molecules: CI13SCH2CH2CH3 (I), CH3COCH2CH2CH3 (2), CH3SCH2COCH3 (3), CH30CH2COCH3 (4), CH3CH2CH2COOCH3 (5), CH30CH2COOCH3 (ti), and CH3SCH2COOCH3 (7).…”

Section: Introductionmentioning

confidence: 99%

On the photoelectron and ultraviolet spectra of molecules containing a divalent sulfur atom and a carbonyl group separated by a methylene group

Olivato¹,

Viertler²,

Wladislaw³

et al. 1976

Can. J. Chem.

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“…The C-S bond cleavage is accelerated when the methoxycarbonyl group is introduced to 9,9-bis(ethylthio)fluorene (1). Compounds (2)-44) reacted more than 20 times faster than (1) and compounds (6)-- (8) reacted with measurable rates, whereas (5) hardly reacted at all under these conditions. The second ethylthio group in (1)--(4) plays an important role in the reaction.…”

Section: Resultsmentioning

confidence: 87%

Chemical consequences of the intramolecular interaction between a sulphur atom and a methoxycarbonyl group in fluorene systems

Nakanishi¹,

Kusuyama²,

Ikeda³

et al. 1986

J. Chem. Soc., Perkin Trans. 2

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The intramolecular interaction between a sulphur atom and a methoxycarbonyl group was found to affect their chemical reactivity. The rates of C-S bond cleavage in methyl 9,9-bis( ethy1thio)fluorene-xcarboxylate, where x is 1, 2, or 3, with sodium ethanethiolate show that the rate is minimal, though comparable with the others, when x = 1, because of steric effects. In contrast, methyl 9-(ethy1thio)fluorene-x-carboxylates, where x is 1 , 2, or 3, exhibit the maximum rate when x = 1. The rates of ester exchange in the presence of toluene-p-sulphonic acid indicate that the reaction is accelerated by the presence of two ethylthio groups at the 9-position of methyl fluorene-1-carboxylate but no significant effect is detected if there is only one ethylthio group. The hydrolysis of the thioketal group in 9,9-bis(ethylthio)fluorene is also accelerated by the presence of a 1 -methoxycarbonyl group. The implications of these results are discussed with the use of a model compound.Carbonyl compounds carrying an alkyl(or ary1)thio group at the a-position can be reduced by soft bases, including thiolate anions2 During the course of a study of the enhanced reactivity of these compounds towards soft bases, we encountered a C-S bond cleavage in the reaction of 9,9-bis(ethylthio)fluorene (1) with ethanethiolate in methanol to give 9-(ethy1thio)fluorene (5) and diethyl disulphide. We have examined various sulphides which should give stable anions on cleavage of the C-S bond. As a result, it has become apparent that: (i) if there is no assistance of a carbonyl group, cleavage of the C-S bond requires a leaving group whose conjugate acid has a pK, of less than 20; and (ii) the C-S bonds in a-alkyl(or ary1)thio carbonyl compounds react easily, irrespective of their rather high ~K , s . ~The cause of this facile C-S bond cleavage in these compounds is worth investigation.If a sulphur atom and a carbonyl group are placed in proximity to each other, there should be a charge-transfer-type interaction, as has been found in thiacyclo-octan-5-0ne.~ Similar interactions have been studied by u.v.,' i.r.,6 n.m.~-.,~*' and photoelectron spectroscopy.' The importance of 1,3through-space interactions was pointed out by lnamoto and Masuda to explain "C n.m.r. chemical shifts.' We have looked for model compounds which might exhibit enhanced rates of C-S bond scission as a result of a through-space interaction between a sulphur atom and a carbonyl group. This paper reports one such example, methyl 9-(ethylthio) fluorene-1carboxylate. (It was, however, not possible to completely erase the inductive and mesomeric effects of the carbonyl group.) Enhanced rates of ester exchange and hydrolysis of the thioketal group in methyl 9,9-bis(ethylthio) fluorene-1carboxylate were also observed. These reactions provide another intriguing example of the chemical consequences of intramolecular interactions.

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“…These shifts cannot be due to the inductive effect alone as it should lead to the positive values only. However, the frequency shifts correlates well with the substituents' inductive parameters (0,) and the polarizability of the C-X bonds (G), as shown in equation (2).…”

Section: O X O H H 4 H H Gxmentioning

confidence: 76%

“…It may be seen in the Table 4 that the n + x* transition energy for fluoroacetone (2) is almost the same as for the unsubstituted ketone (1) and a small hypsochromic effect is observed. This is not in accord with the i.r.…”

Section: Ref 15mentioning

confidence: 84%

Conformational studies of α-substituted carbonyl compounds. Part 1. Conformation and electronic interaction in hetero-substituted acetones by infrared and ultraviolet spectroscopy

Guerrero¹,

BARROS²,

Wladislaw³

et al. 1983

J. Chem. Soc., Perkin Trans. 2

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Interaction between the carbonyl group and an α-sulphur atom. Part I. Infrared and ultraviolet spectra of some α-(alkylthio)thioesters

Cited by 8 publications

References 0 publications

On the photoelectron and ultraviolet spectra of molecules containing a divalent sulfur atom and a carbonyl group separated by a methylene group

On the photoelectron and ultraviolet spectra of molecules containing a divalent sulfur atom and a carbonyl group separated by a methylene group

Chemical consequences of the intramolecular interaction between a sulphur atom and a methoxycarbonyl group in fluorene systems

Conformational studies of α-substituted carbonyl compounds. Part 1. Conformation and electronic interaction in hetero-substituted acetones by infrared and ultraviolet spectroscopy

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