Zur photolyse von 1,2,3-thiadiazolen I

Zeller, Klaus‐Peter; Meier, Herbert; Müller, Eu.

doi:10.1016/s0040-4039(01)96489-5

Cited by 30 publications

(27 citation statements)

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“…Also, as mentioned earlier, it was claimed that the existence of the 1,3-diradical ( 11 ) is still not experimentally confirmed. 24,25,68,69 Our computational results based on the RASSCF study suggest that the energy difference among Int-2 , TS-4 , and 11 is not much (∼15 kcal/mol), and the activation barriers from 11 to the final photoproducts ( 8 , 9 , and 10 ) are not much as well (at most 23 kcal/mol). These facts strongly imply that the 1,3-diradical 11 is kinetically unstable and may rearrange spontaneously to the stable minima if 11 is produced.…”

Section: Resultsmentioning

confidence: 78%

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Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

2018

ACS Omega

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The restricted active space self-consistent field method in the 26-electron/27-orbital active space and the 6-311(d) basis set has been used to investigate the mechanisms of the photochemical isomerization reactions concerning the model systems of 1,2,3-thiadiazole and 1,2,3-selenadiazole. The computational works suggest that the preferred reaction paths for both 1,2,3-thiadiazole and 1,2,3-selenadiazole are as follows: reactant → Franck–Condon region → conical intersection → intermediate → transition states → photoproducts. As a result, the structures of the conical intersections, which play a decisive role in these photoisomerization reactions, are obtained. In particular, the present theoretical evidences demonstrate that the potential energy surfaces for the formation of 1,3-diradicals are quite flat. This may explain why their experimental detections are so difficult.

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Section: Resultsmentioning

confidence: 78%

“…This could be the reason why the spectroscopic signals of 11 have still not been experimentally detected yet. 24,25,68,69…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

2018

ACS Omega

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“…Only 1,4-dithiins have been reported in the literature but, in their photolysis studies on substituted thiadiazoles, Zeller et al (13) postulated the transient existence of 1,2-dithiins in order to explain the mode of formation of some of the products. The 1,2-dithiin structure for product 18 is consistent with the above spectral data and also with kinetic mechanistic considerations (vide infra).…”

Section: / \mentioning

confidence: 99%

Thiirene formation in the reactions of sulfur atoms with alkynes

Verkoczy¹,

Sherwood²,

Safarik³

et al. 1983

Can. J. Chem.

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The gas phase reactions of S(1D2) and S(3PJ) atoms with alkynes have been studied by photolyzing COS in the presence of CH≡CH, CF3C≡CH, and CF3C≡CCF3. In the reactions with CH≡CH, CS2, benzene, and thiophene were formed; with CF3C≡CH, eight products were found with disubstituted thiophenes and trisubstituted benzenes as the major products. In the case of CF3C≡CCF3, only perfluorotetramethylthiophene was detected at low conversion but at long photolysis several new products were observed. Many of the reaction products characterized here have not been reported before.The formation and distribution of the reaction products could be rationalized by an overall mechanism in which the formation of the highly reactive primary adducts, thiirene and thioformylmethylene, is followed by bimolecular reactions yielding the principal end products. The formation of minor products could be explained by secondary photoisomerizations, secondary photolysis, and by secondary decompositions and the secondary reactions of sulfur atoms with primary products.

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“…Scheme 1 gives a survey of the formation of these heterocycles from four-to seven-membered rings. [2][3][4][5][6][7][8][9][10][11][12] (The examples given in refs. 2-12 are typically early established reaction examples.)…”

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confidence: 99%

“…Its nitrogen and sulfur content corresponded largely to intact 1,2,3-thiadiazole rings and a complete alkylation of all phenolic OH groups. The photocrosslinking of the polymers 1c¢ and 1i¢ could be per-Scheme 1 Formation of S-heterocycles by ring cleavage of 1,2,3thiadiazoles 1: 2,4-dialkylidene-1,3-dithietanes 6, 2 3,5-dialkylidene-1,2,4-trithiolanes 7, 3,4 3,6-dialkylidene-1,2,4,5-tetrathianes 8, 3 2-alkylidene-1,3-dithioles 9, 5-10 thiophenes 10, 3,6,7,9,11,12 1,4-dithiines 11, 5,6,7,9 formed in solution (benzene or dichloromethane) or in thin neat films, which were spin-coated or produced by evaporation of saturated solutions. The absorption maxima of 1c¢ and 1i¢ occur at 260 nm; additionally to this p→p* transitions, n→p* transitions appear in the form of an extended shoulder at about 310 nm (CH 2 Cl 2 ).…”

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confidence: 99%

1,2,3-Thiadiazoles with Unsaturated Side Chains; Synthesis, Polymerization, and Photocrosslinking

Al-Smadi¹,

Hanold²,

Kalbitz³

et al. 2009

Synthesis

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1,2,3-Thiadiazoles with polymerizable functionalities in the 4-position were synthesized as potential negative photoresists. The polymerization to soluble, film-forming materials must leave the heterocyclic rings intact, because they are needed for photocrosslinking reactions to give insoluble materials. 1,2,3-Thiadiazoles 1 cycloeliminate N 2 on irradiation. The resulting 1,3-diradicals 2 have various options for stabilization processes leading to alkynes 3 or to higher heterocycles 5-12. The generation of atomic sulfur and its involvement in these subsequent reactions must be avoided. Therefore, systems like model compound 1a, in which the 1,3diradicals form 2-methylene-1,3-dithioles (dithiafulvenes) 9 were selected here. Optimization gave ultimately two materials for application as photoresists. Monomer 1c could be polymerized in the presence of boron trifluoride to soluble 1c¢, which on irradiation formed 1c¢¢ as a cross-linked insoluble polymer. Furthermore, thiadiazole 1f was attached to polystyrene 26. The resulting soluble polymer 1i¢ yielded the insoluble material 1i¢¢ on irradiation.

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Zur photolyse von 1,2,3-thiadiazolen I

Cited by 30 publications

References 4 publications

Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

Mechanistic Investigations on the Photoisomerization Reactions of Five-Membered Ring Heterocyclic Molecules Containing Sulfur and Selenium Atoms

Thiirene formation in the reactions of sulfur atoms with alkynes

1,2,3-Thiadiazoles with Unsaturated Side Chains; Synthesis, Polymerization, and Photocrosslinking

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