Thiapyrylium Salts Research Articles

A mechanistic study on photocatalysis by thiapyrylium salts. Photodegradation of dimethoate, alachlor and pyrimethanil under simulated sunlight

Photodegradation of dimethoate, alachlor, and pyrimethanil using a thiapyrilium salt (TPTP+) as photocatalyst was performed under simulated sunlight. The photocatalyst removes preferentially pyrimethanil (45% after 60min of irradiation), followed by dimethoate (20%) and alachlor (13%). In the three cases, an important to moderate decrease of the fluorescence intensity upon addition of the pollutants was observed. The active participation of the singlet excited state in the photodegradation of the pollutants was demonstrated; the corresponding dynamic quenching rate constants were found to be 1.9×1010M−1s−1 (pyrimethanil), 6.7×109M−1s−1 (dimethoate) and 9.1×109M−1s−1 (alachlor). Moreover, a decrease in the signal corresponding to the triplet excited state was observed immediately after the laser pulse; again a good correlation was observed between the missing fraction of triplets and the photodegradation rates under solar light. Detection of TPTP+, the reduced species derived from the photocatalyst, as well as Rehm–Weller calculations on the free energy changes, strongly support an electron transfer mechanism occurring from the singlet excited state.

Involvement of triplet excited states in the electron transfer photodegradation of cinnamic acids using pyrylium and thiapyrylium salts as photocatalysts

The mechanistic pathway for degradation of cinnamic acids using 2,4,6-triphenylpyrylium as well as 2,4,6-triphenyl(thia)pyrylium salts (,) as solar photocatalysts has been unambiguously established. Results obtained in steady-state experiments have been correlated with time-resolved photophysical studies. High percentages of photodegradation (60-70%) were achieved when aqueous solutions of caffeic and ferulic acids (,) as model pollutants were submitted to irradiation in the presence of ,. Electron-transfer quenching of both the singlet and triplet excited states of , by , has been proved, and the quenching rate constants (close to diffusion control) have been determined. However, the percentages of singlet quenching by ,, even at relatively high concentrations of the model pollutants, is lower than 5%. In addition to this, growth of the signal corresponding to the pyranyl radical occurs in the microsecond timescale, incompatible with the singlet state as precursor. Thus, photodegradation of , mainly involves the triplet state of the photocatalysts.

Emission of substituted pyrylium and thiapyrylium salts: Phosphorescence and delayed fluorescence emission in polymeric matrices

Pyrylium and thiapyrylium salts show interesting emission properties when incorporated in a rigid PMMA matrix. In addition to a strong prompt fluorescence emission, the 18 compounds studied show a delayed fluorescence which cannot be observed in solution, even at 77 K. The delayed fluorescence/phosphorescence ratio increases with the temperature. The activation barrier as well as the intersystem crossing from the lowest excited triplet state to the lowest excited singlet state have been measured for compounds 4, 8, 11, and 17. An absence of crossing point between the potential energy surfaces of the two excited states is put forward to explain the low value (ca. 10 3 s −1) of the intersystem crossing rate constant.

Synthesis and some transformations of 4H-pyrano[3,2-d]pyrazoles

The ability of the amide carbonyl group of the pyrazolone ring to participate in the heterocyclization of oxopropyl-5-pyrazolones under the influence of polyphosphoric acid (PPA) or phosphorus polysulfide in dioxane with the formation of 4H-pyrano[ 3,2-d]pyrazole derivatives is demonstrated. Ionic hydrogenation of the pyranopyrazoles leads to 5,6-dihydropyrano[3,2-d]pyrazoles, while the action of phosphorus polysulfide in xylene leads to pyrazolo[5,4-b]thiapyrylium salts.

Reactions of polysubstituted thiopyrans with proton acids and structural studies of the resulting thiacyclohexanes

Depending on the number and nature of substituting groups, 4H-thiopyrans under the influence of perchloric and trifluoroacetic acids either undergo disproportionation or form thiapyrylium salts in quantitative yields with the participation of air oxygen; in the case of ionic hydrogenation with CF3COOH-SiHEt3 they are converted to thiacyclohexanes, regardless of their structure. To ascertain the reason for the difference in the mechanisms of the reaction of polysubstituted thiopyrans with proton acids the structures of the polysubstituted thiacyclohexanes were investigated jointly by NMR spectroscopy and x-ray diffraction analysis; this made it possible to form a judgment regarding the effect of the degree and character of substitution of 4H-thiopyrans on the mechanism of their reaction with proton acids. The tetrahydrothiopyran ring has a chair conformation. The phenyl substituents are equatorially oriented, while the methyl substituents are axially oriented.

Electron-donating properties of oxygen vs. sulfur. Redox potentials for some pyrylium and thiapyrylium salts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron-donating properties of oxygen vs. sulfur. Redox potentials for some pyrylium and thiapyrylium saltsF. D. Saeva and G. R. OlinCite this: J. Am. Chem. Soc. 1980, 102, 1, 299–303Publication Date (Print):January 1, 1980Publication History Published online1 May 2002Published inissue 1 January 1980https://doi.org/10.1021/ja00521a047RIGHTS & PERMISSIONSArticle Views915Altmetric-Citations52LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (534 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: OXIDATIVE SYNTHESIS OF THIAPYRYLIUM SALTS FROM POLYSUBSTITUTED THIOPYRANS

Chemischer InformationsdienstVolume 10, Issue 36 Heterocyclic Compounds ChemInform Abstract: OXIDATIVE SYNTHESIS OF THIAPYRYLIUM SALTS FROM POLYSUBSTITUTED THIOPYRANS V. G. KHARCHENKO, V. G. KHARCHENKOSearch for more papers by this authorN. I. KOZHEVNIKOVA, N. I. KOZHEVNIKOVASearch for more papers by this authorN. V. VORONINA, N. V. VORONINASearch for more papers by this author V. G. KHARCHENKO, V. G. KHARCHENKOSearch for more papers by this authorN. I. KOZHEVNIKOVA, N. I. KOZHEVNIKOVASearch for more papers by this authorN. V. VORONINA, N. V. VORONINASearch for more papers by this author First published: September 4, 1979 https://doi.org/10.1002/chin.197936247Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume10, Issue36September 4, 1979 RelatedInformation

Oxidative formation of thiapyrylium salts by polysubstituted thiopyrans

Oxidative formation of thiapyrylium salts by polysubstituted thiopyrans

The reactivity of C-nucleophilic compounds and of pyrylium and thiapyrylium salts in particular, I (author's transl)

AbstractDas Reaktionsverhalten von C‐nukleophilen Pyrylium‐ und Thiapyryliumsalzen gegenüber γ‐Pyronderivaten wird untersucht, wobei die Verbindungen 3,5‐12, 15, 17, 20a‐20f, 21, 22 erhalten werden.

New Applications of Malononitrile in Organic Chemistry - Part I

Recent applications of malononitrile in organic chemistry are reviewed; an overview of the chemistry of substituted malononitriles is also included. New trends, mechanisms and synthetic methods employing malononitriles are discussed. Among other topics, this survey includes new information on malononitrile dimers and trimers, new Knoevenagel and Michael condensation reactions, reactions with cyclic polyketones, quinones, sulfur and organometallic compounds, and the synthesis of new heterocycles, pesticides, charge-transfer complexes, and solvatochromic dyes. 1. Introduction 2. Scope of the Review 3. Methods of Preparation 4. Toxicity and Handling 5. Physical Properties 6. Spectral Properties 7. Chemical Reactivity 8. Analysis 9. Dimerization 10. Trimerization 11. The Knoevenagel and Related Reactions 12. Syntheses via the Michael Reaction 13. Reaction of Cyclic Polyketones with Malononitrile 14. Reaction of Quinones with Malononitrile 15. Quinodimethanes 16. Pyrans, Thiapyrans, and Pyrylium and Thiapyrylium Salts 17. Reactions of Tropones, Tropolones, and Tropylium Salts with Malononitrile 18. Reaction of Cyclooctatrienone with Malononitrile 19. Miscellaneous Applications 20. Industrial Applications 21. Addenda

ChemInform Abstract: SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF THIAPYRYLIUM SALTS

Chemischer InformationsdienstVolume 7, Issue 21 Heterocyclic Compounds ChemInform Abstract: SYNTHESIS AND ANTIMICROBIAL ACTIVITY OF THIAPYRYLIUM SALTS V. G. KHARCHENKO, Search for more papers by this authorS. N. CHALAYA, Search for more papers by this authorM. V. NORITSINA, Search for more papers by this authorL. K. KULIKOVA, Search for more papers by this author V. G. KHARCHENKO, Search for more papers by this authorS. N. CHALAYA, Search for more papers by this authorM. V. NORITSINA, Search for more papers by this authorL. K. KULIKOVA, Search for more papers by this author First published: May 25, 1976 https://doi.org/10.1002/chin.197621226AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume7, Issue21May 25, 1976 RelatedInformation

Reactions of 1,5-diphenyl-2,4-dimethyl-1,5-pentanedione with hydrogen sulfide

1,5-Diphenyl-2,4-dimethyl-1,5-pentanedione reacts with hydrogen sulfide in the presence of boron trifluoride etherate or 70% perchloric acid to give the corresponding thiapyrylium salts and 2,6-diphenyl-3,5-dimethyldihydrothiopyran; complete disproportionation to give 2,6-diphenyl-3,5-dimethylthiacyclohexane and 2,6-diphenyl-3,5-dimethylthiapyrylium bromide occurs in the presence of hydrogen bromide. The possibility of catalytic hydrogenation in the presence of 10% Pd/C of compounds with a thiopyran ring was established.

Thiapyrylium salts (review)

The literature data touching upon the synthesis of thiapyrylium salts and the stability of the thiapyrylium cation as compared with its isoelectronic analogs, as well as the nucleophilic, oxidation, anion-exchange, and other reactions of the salts with substituted and unsubstituted thiapyrylium cations are examined in this review.

ChemInform Abstract: THE SYNTHESIS OF 1,2-DIAZEPINES FROM THIAPYRYLIUM SALTS

Umsetzung der Thiapyryliumsalze (I) mit Hydrazin (II) liefert die 4H-Diazepine (III); mit Methylhydrazin (Va) werden aus (I) die lH-Diazepine (IV) erhalten.

The Synthesis of 1, 2-Diazepines from Thiapyrylium Salts

The reactions of thiapyrylium salts 3a–c with hydrazine and methylhydrazine yield the 3,5,7-triphenyl-1,2(4H)-diazepines 4a–c and 1-methyl-3,5,7-triphenyl-1,2(1H)-diazepines 5a–c in good to excellent yields. Although numerous 1-acyl-1,2(1H)-diazepines are now known, compounds 5a–c represent the first examples of 1-alkyl-1,2(1H)-diazepine derivatives. With a slight variation in work up conditions, the reaction of thiapyrylium salts 3a and 3c with methylhydrazine leads to the formation of the pyrazoline derivatives 6a and 6c, respectively; on the other hand, only pyrazolines 9a and 9b can be obtained from the corresponding reaction with phenylhydrazine. Pyrolysis of the pyrazolines 6a, 6c, 9a, and 9b provides the pyrazoles 7a, 7c, 10a, and 10b, respectively. The mechanism of some of these transformations is briefly discussed.

Reaction of thiapyrylium salts with malononitrile

Journal of Heterocyclic ChemistryVolume 8, Issue 2 p. 301-302 Note Reaction of thiapyrylium salts with malononitrile G. A. Reynolds, G. A. Reynolds Research Laboratories, Eastman Kodak Company Rochester, New York 14650Search for more papers by this authorJ. A. Vanallan, J. A. Vanallan Research Laboratories, Eastman Kodak Company Rochester, New York 14650Search for more papers by this author G. A. Reynolds, G. A. Reynolds Research Laboratories, Eastman Kodak Company Rochester, New York 14650Search for more papers by this authorJ. A. Vanallan, J. A. Vanallan Research Laboratories, Eastman Kodak Company Rochester, New York 14650Search for more papers by this author First published: April 1971 https://doi.org/10.1002/jhet.5570080223Citations: 6AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume8, Issue2April 1971Pages 301-302 RelatedInformation