Startseite Lebenswissenschaften DFT calculations on the Friedel-Crafts benzylation of 1,4-dimethoxybenzene using ZnCl2 impregnated montmorillonite K10 — inversion of relative selectivities and reactivities of aryl halides
Artikel
Lizenziert
Nicht lizenziert Erfordert eine Authentifizierung

DFT calculations on the Friedel-Crafts benzylation of 1,4-dimethoxybenzene using ZnCl2 impregnated montmorillonite K10 — inversion of relative selectivities and reactivities of aryl halides

  • Christophe Waterlot EMAIL logo , Daniel Couturier , Benoît Rigo , Alina Ghinet und Marc Backer
Veröffentlicht/Copyright: 28. September 2011
Veröffentlichen auch Sie bei De Gruyter Brill
Informationen für Autor*innen
Chemical Papers
Aus der Zeitschrift Chemical Papers Band 65 Heft 6

Abstract

Zinc was bound on montmorillonite K10 by cation exchange to obtain a catalyst named clayzic. In the Friedel-Crafts benzylation of 1,4-dimethoxybenzene, this catalyst was used for the synthesis of substituted diphenylmethanes using 4-chlorobenzyl chloride and 4-bromobenzyl bromide. During the reaction, sub-products from a second benzylation reaction process were observed. For a better understanding of their formation, reactions were carried out at different times to obtain data on the progress of benzylation and the relative ratio of each product was calculated using two different analytical methods. It was shown that the selectivity and reactivity of both aryl halides were reversed under these experimental conditions contrary to those obtained using the more conventional catalyst, zinc dichloride. These results were explained by geometrical and electronic considerations. It was found that the formation of transition states and Wheland intermediates from aryl bromide and chloride in the presence of clayzic can be explained in terms of preferential absorption. Moreover, the high percentage of 4-chlorobenzyl chloride conversion was attributed to its covalent radius, which is smaller than that of Br. At the same time it was shown that the presence of a Brönsted acid, due to the liberation of HCl during the benzylation, is responsible for the poisoning of the clayzic catalyst. Moreover, poisoning effect of the bromine anion could not be excluded.

Keywords: zinc; montmorillonite; diarylmethane; alkylation; orbital; DFT calculations

[1] Ahmed, O. S., & Dutta, D. K. (2005). Friedel-Crafts benzylation of benzene using Zn and Cd ions exchanged clay composites. Journal of Molecular Catalysis A: Chemical, 229, 227–231. DOI: 10.1016/j.molcata.2004.11.021. http://dx.doi.org/10.1016/j.molcata.2004.11.02110.1016/j.molcata.2004.11.021Suche in Google Scholar

[2] Bachari, K., & Cherifi, O. (2007). Benzylation of aromatics on tin-containing mesoporous materials. Applied Catalysis A: General, 319, 259–266. DOI: 10.1016/j.apcata.2006.12.010. http://dx.doi.org/10.1016/j.apcata.2006.12.01010.1016/j.apcata.2006.12.010Suche in Google Scholar

[3] Barlow, S. J., Bastock, T. W., Clark, J. H., & Cullen, S. R. (1993). Explanation of an unusual substituent effect in the benzylation of anisole and identification of the origin of the active site in Clayzic. Tetrahedron Letters, 34, 3339–3342. DOI: 10.1016/S0040-4039(00)73698-7. http://dx.doi.org/10.1016/S0040-4039(00)73698-710.1016/S0040-4039(00)73698-7Suche in Google Scholar

[4] Bidart, A. M. F., Borges, A. P. S., Chagas, H. C., Nogueira, L., Lachter, E. R., & Mota, C. J. A. (2006). Mechanistic aspects of Friedel-Crafts alkylation over FeY zeolite. Journal of the Brazilian Chemical Society, 17, 758–762. DOI: 10.1590/S0103-50532006000400018. http://dx.doi.org/10.1590/S0103-5053200600040001810.1590/S0103-50532006000400018Suche in Google Scholar

[5] Carey, F. A., & Tremper, H. S. (1968). Carbonium ion-silane hydride transfer reactions. I. Scope and stereochemistry. Journal of the American Chemistry Society, 90, 2578–2583. DOI: 10.1021/ja01012a023. http://dx.doi.org/10.1021/ja01012a02310.1021/ja01012a023Suche in Google Scholar

[6] Chouday, B. M., Vally, V. L. K., & Durga Prasad, A. (1991). A novel montmorillonite — KMnO4 system for the oxidation of alkenes under triphase conditions. Synthetic Communications, 21, 2007–2013. DOI: 10.1080/00397919108019806. http://dx.doi.org/10.1080/0039791910801980610.1080/00397919108019806Suche in Google Scholar

[7] Choudhary, V. R., & Jana, S. K. (2002). Benzylation of benzene and substituted benzenes by benzyl chloride over InCl3, GaCl3, FeCl3 and ZnCl2 supported on clays and Si-MCM-41. Journal of Molecular Catalysis A: Chemical, 180, 267–276. DOI: 10.1016/S1381-1169(01)00447-2. http://dx.doi.org/10.1016/S1381-1169(01)00447-210.1016/S1381-1169(01)00447-2Suche in Google Scholar

[8] Choudhary, V. R., & Jana, S. K. (2001). Highly active and low moisture sensitive supported thallium oxide catalysts for Friedel-Crafts type benzylation and acylation reactions: Strong thallium oxide-support interactions. Journal of Catalysis, 201, 225–235. DOI: 10.1006/jcat.2001.3245. http://dx.doi.org/10.1006/jcat.2001.324510.1006/jcat.2001.3245Suche in Google Scholar

[9] Choudhary, V. R., & Jha, R. (2008). GaAlClx-grafted Mont.K10 clay: Highly active and stable solid catalyst for the Friedel-Crafts type benzylation and acylation reactions. Catalysis Communications, 9, 1101–1105. DOI: 10.1016/j.catcom.2007.10.014. http://dx.doi.org/10.1016/j.catcom.2007.10.01410.1016/j.catcom.2007.10.014Suche in Google Scholar

[10] Choudhary, V. R., & Mantri, K. (2002). Thermal activation of a clayzic catalyst useful for Friedel-Crafts reactions: HCl evolved with creation of active sites in different thermal treatments to ZnCl2/Mont-K10. Catalysis Letters, 81, 163–168. DOI: 10.1023/A:1016564603798. http://dx.doi.org/10.1023/A:101656460379810.1023/A:1016564603798Suche in Google Scholar

[11] Clark, J. H. (1994). Catalysis of organic reactions by supported inorganic reagents (pp. 126). New York, NY, USA: Wiley. Suche in Google Scholar

[12] Clark, J. H., Cullen, S. R., Barlow, S. J., & Bastok, T. W. (1994). Environmentally friendly chemistry using supported reagent catalysts: structure-property relationships for clayzic. Journal of the Chemical Society, Perkin Transactions, 2, 1117–1130. DOI: 10.1039/P29940001117. 10.1039/P29940001117Suche in Google Scholar

[13] Clark, J. H., Kybett, A. P., & Macquarrie, D. J. (1992). Supported reagents: Preparation, analysis and applications (pp. 152). New York, NY, USA: Wiley. Suche in Google Scholar

[14] Clark, J. H., Kybett, A. P., Macquarrie, D. J., Barlow, S. J., & Landon, P. (1989). Montmorillonite supported transition metal salts as Friedel-Crafts alkylation catalysts. Journal of the Chemical Society, Chemical Communications, 18, 1353–1354. DOI: 10.1039/C39890001353. http://dx.doi.org/10.1039/c3989000135310.1039/C39890001353Suche in Google Scholar

[15] Clark, J. H., & Macquarrie, D. J. (1996). Environmentally friendly catalytic methods. Chemical Society Reviews, 25, 303–310. DOI: 10.1039/CS9962500303. http://dx.doi.org/10.1039/cs996250030310.1039/cs9962500303Suche in Google Scholar

[16] Cornélis, A., Dony, C., Laszlo, P., & Nsunda, K. M. (1991a). Inversion of the relative reactivities of mesitylene and toluene in clay-catalyzed Friedel-Crafts alkylations. Tetrahedron Letters, 32, 2901–2902. DOI: 10.1016/0040-4039(91)80643-K. http://dx.doi.org/10.1016/0040-4039(91)80643-K10.1016/0040-4039(91)80643-KSuche in Google Scholar

[17] Cornélis, A., Dony, C., Laszlo, P., & Nsunda, K. M. (1991b). Synergistic acceleration of reactions having clay-based catalysts. Tetrahedron Letters, 32, 1423–1424. DOI: 10.1016/0040-4039(91)80347-9. http://dx.doi.org/10.1016/0040-4039(91)80347-910.1016/0040-4039(91)80347-9Suche in Google Scholar

[18] Cornélis, A., Laszlo, P., & Wang, S. (1993). On the transition state for “clayzic”-catalyzed Friedel-Crafts reactions upon anisole. Tetrahedron Letters, 34, 3849–3852. DOI: 10.1016/S0040-4039(00)79244-6. http://dx.doi.org/10.1016/S0040-4039(00)79244-610.1016/S0040-4039(00)79244-6Suche in Google Scholar

[19] Cseri, T., Békássy, S., Figueras, F., & Rizner, S. (1995). Benzylation of aromatics on ion-exchanged clays. Journal of Molecular Catalysis A: Chemical, 98, 101–107. DOI: 10.1016/1381-1169(95)00016-X. http://dx.doi.org/10.1016/1381-1169(95)00016-X10.1016/1381-1169(95)00016-XSuche in Google Scholar

[20] Dewar, M. J. S., Zoebish, E. G., Healy, E. F., & Stewart, J. J. P. (1985). AM1: A new general purpose quantum mechanical molecular model. Journal of the American Chemistry Society, 107, 3902–3909. DOI: 10.1021/ja00299a024. http://dx.doi.org/10.1021/ja00299a02410.1021/ja00299a024Suche in Google Scholar

[21] Friesner, R. A. (1991). New methods for electronic structure calculations on large molecules. Annual Review of Physical Chemistry, 42, 341–367. DOI: 10.1146/annurev.pc.42.100191.2013. http://dx.doi.org/10.1146/annurev.pc.42.100191.00201310.1146/annurev.pc.42.100191.002013Suche in Google Scholar PubMed

[22] Gribble, G. W., Leese, R. M., & Evans, B. E. (1977). Reactions of sodium borohydride in acidic media; IV. Reduction of diarylmethanols and triarylmethanols in trifluoroacetic acid. Synthesis, 3, 172–176. DOI: 10.1055/s-1977-24308. http://dx.doi.org/10.1055/s-1977-2430810.1055/s-1977-24308Suche in Google Scholar

[23] Koltunov, K. Y., Walspurger, S., & Sommer, J. (2004). Super-electrophilic activation of polyfunctional organic compounds using zeolites and other solid acids. Chemical Communications, 15, 1754–1755. DOI: 10.1039/B404074K. http://dx.doi.org/10.1039/b404074k10.1039/b404074kSuche in Google Scholar

[24] Laszlo, P. (1987). Chemical reactions on clays. Science, 235, 1473–1477. DOI: 10.1126/science.235.4795.1473. http://dx.doi.org/10.1126/science.235.4795.147310.1126/science.235.4795.1473Suche in Google Scholar

[25] Laszlo, P., & Mathy, A. (1987). Catalysis of Friedel-Crafts alkylation by a montmorillonite doped with transitionmetal cations. Helvetica Chimica Acta, 70, 577–586. DOI: 10.1002/hlca.19870700310. http://dx.doi.org/10.1002/hlca.1987070031010.1002/hlca.19870700310Suche in Google Scholar

[26] Miller, J. M., Wails, D., Hartman, J. S., & Belelie, J. L. (1997). Friedel-Crafts catalysis using supported reagents. Synthesis, characterization and catalytic applications of sol-gel-derived aluminosilicates. Journal of the Chemical Society, Faraday Transactions, 93, 2439–2444. DOI: 10.1039/A701746D. http://dx.doi.org/10.1039/a701746d10.1039/a701746dSuche in Google Scholar

[27] Miller, J. M., Wails, D., Hartman, J. S., Schebesh, K., & Belelie, J. L. (1998). Friedel-Crafts catalysis using supported reagents. Synthesis, characterization, and catalytic application of sol-gel-derived silica. Canadian Journal of Chemistry, 76, 382–388. DOI: 10.1139/v98-025. 10.1139/v98-025Suche in Google Scholar

[28] Olah, G. A. (1973). Carbocations and electrophilic reactions. Angewandte Chemie International Edition, 12, 173–212. DOI: 10.1002/anie.197301731. http://dx.doi.org/10.1002/anie.19730173110.1002/anie.197301731Suche in Google Scholar

[29] Olah, G. A. (1963). Friedel-Crafts and related reactions (Vol. 1, pp. 68–72). New York, NY, USA: Wiley-Interscience. Suche in Google Scholar

[30] Olah, G. A., Arvanaghi, M., & Ohannesian, L. (1986). Synthetic methods and reactions; 126. Trifluoromethanesulfonic acid/triethylsilane: A new ionic hydrogenation reagent for the reduction of diaryl and alkyl aryl ketones to hydrocarbons. Synthesis, 1986, 770–772. DOI: 10.1055/s-1986-31773. http://dx.doi.org/10.1055/s-1986-31773Suche in Google Scholar

[31] Orlovic, A. M., Janackovic, D. T., Drmanic, S., Marinkovic, Z., & Skala, D. U. (2001). Alumina/silica aerogel with zinc chloride as an alkylation catalyst. Journal of the Serbian Chemical Society, 66, 685–695. 10.2298/JSC0110685OSuche in Google Scholar

[32] Pai, S. G., Bajpai, A. R., Deshpande, A. B., & Samant, S. D. (1997). Friedel-Crafts benzylation of arenes using FeCl3 impregnated montmorillonite K10. Synthetic Communications, 27, 2267–2273. DOI: 10.1080/00397919708003381. http://dx.doi.org/10.1080/0039791970800338110.1080/00397919708003381Suche in Google Scholar

[33] Phukan, A., Ganguli, J. N., & Dutta, D. K. (2003). ZnCl2− Zn2+-montmorillonite composite: efficient solid acid catalyst for benzylation of benzene. Journal of Molecular Calysis A: Chemical, 202, 279–287. DOI: 10.1016/S1381-1169(03)00211-5. http://dx.doi.org/10.1016/S1381-1169(03)00211-510.1016/S1381-1169(03)00211-5Suche in Google Scholar

[34] Price, C. C. (1946). Organic reactions (Vol. 3 (1), pp. 1–82). New York, NY, USA: Wiley. Suche in Google Scholar

[35] Rhodes, C. N., Franks, M., Parkes, G. M. B., & Brown, D. R. (1991). The effect of acid treatment on the activity of clay supports for ZnCl2 alkylation catalysts. Journal of the Chemical Society, Chemical Communications, 12, 804–807. DOI: 10.1039/C39910000804. http://dx.doi.org/10.1039/c3991000080410.1039/c39910000804Suche in Google Scholar

[36] Schrödinger, Inc. (1991–2000). Jaguar 4.1 [computer software]. Portland, OR, USA: Schrödinger, Inc. Suche in Google Scholar

[37] Singh, D. U., & Samant, S. D. (2004). Comparative study of benzylation of benzene using benzyl chloride in the presence of pillared bentonite; ion-exchanged and pillaring solution impregnated montmorillonite K10. Journal of Molecular Catalysis A: Chemical, 223, 111–116. DOI: 10.1016/j.molcata.2003.09.042. http://dx.doi.org/10.1016/j.molcata.2003.09.04210.1016/j.molcata.2003.09.042Suche in Google Scholar

[38] Tyagi, O. D., & Yadav, M. (1990). A textbook of organic reaction mechanism. New Dehli, Delhi, India: Anmol Publications Pvt. Ltd. Suche in Google Scholar

[39] Vanden Eynde, J. J., Mayence, A., & Van Haverbecke, Y. (1995). Ultrasound-promoted benzylation of arenes in the presence of zinc chloride mixed with a K10 clay. Tetrahedron Letters, 26, 3133–3136. DOI: 10.1016/0040-4039(95)00472-O. http://dx.doi.org/10.1016/0040-4039(95)00472-O10.1016/0040-4039(95)00472-OSuche in Google Scholar

[40] Waterlot, C., & Couturier, D. (2010). Reduction of dissolved oxygen in boiler water using new redox polymers. Journal of Applied Polymer Science, 118, 7–16. DOI: 10.1002/app.32267. 10.1002/app.32267Suche in Google Scholar

[41] Waterlot, C., Couturier, D., De Backer, M., & Rigo, B. (2000a). A study of hydrogenation of benzhydrols in the presence of catalytic amount of triflic acid. Canadian Journal of Chemistry, 78, 1242–1246. DOI: 10.1139/v00-082. http://dx.doi.org/10.1139/v00-08210.1139/v00-082Suche in Google Scholar

[42] Waterlot, C., Couturier, D., Debacker, M., & Rigo, B. (2000b). 1H and 13C NMR determination of polysubstituted diphenylmethane dimers. Mechanism of their formation by reduction of polymethoxylated benzophenones. Spectroscopy Letters, 33, 755–775. DOI: 10.1080/00387010009350156. http://dx.doi.org/10.1080/0038701000935015610.1080/00387010009350156Suche in Google Scholar

[43] Waterlot, C., Couturier, D., & Hasiak, B. (2000c). Friedel-Crafts benzylation of 1,4-dialkoxybenzenes — cleavage and rearrangement of esters and methoxymethyl ethers in ZnCl2 montmorillonite K10 clay. Journal of Chemical Research, Part S Synopsis, 3, 100–101. DOI: 10.3184/030823400103166715. http://dx.doi.org/10.3184/03082340010316671510.3184/030823400103166715Suche in Google Scholar

[44] Waterlot, C., Couturier, D., & Hasiak, B. (2001a). Synthesis of new electron transfer polymers for the reduction of dissolved oxygen in water. Journal of Applied Polymer Science, 80, 223–229. DOI: 10.1002/1097-4628(20010411)80:2〈223::AIDAPP1090〉3.0.CO;2-D. http://dx.doi.org/10.1002/1097-4628(20010411)80:2<223::AID-APP1090>3.0.CO;2-D10.1002/1097-4628(20010411)80:2<223::AID-APP1090>3.0.CO;2-DSuche in Google Scholar

[45] Waterlot, C., Hasiak, B., Couturier, D., & Rigo, B. (2001b). On the synthesis of dimethoxybenzyl cinnamates, monomers for electron transfer polymers. Tetrahedron, 57, 4889–4901. DOI: 10.1016/S0040-4020(01)00417-3. http://dx.doi.org/10.1016/S0040-4020(01)00417-310.1016/S0040-4020(01)00417-3Suche in Google Scholar

[46] Wavefunction, Inc. (1999). Spartan, version 5.1.3 [computer software]. Irvine, CA, USA: Wavefunction Inc. Suche in Google Scholar

[47] Wheland, G. W. (1942). A quantum mechanical investigation of the orientation of substituents in aromatic molecules. Journal of the American Chemical Society, 64, 900–908. DOI: 10.1021/ja01256a047. http://dx.doi.org/10.1021/ja01256a04710.1021/ja01256a047Suche in Google Scholar

[48] Yadav, G. D., & Thorat, T. S. (1996). Role of benzyl ether in the inversion of reactivities in Friedel-Crafts benzylation of toluene by benzyl chloride and benzyl alcohol. Tetrahedron Letters, 37, 5405–5408. DOI: 10.1016/0040-4039(96)01057-X. http://dx.doi.org/10.1016/0040-4039(96)01057-X10.1016/0040-4039(96)01057-XSuche in Google Scholar

[49] Yadav, G. D., Thorat, T. S., & Kumbhar, P. S. (1993). Inversion of the relative reactivities and selectivities of benzyl chloride and benzyl alcohol in Friedel-Crafts alkylation with toluene using different solid acid catalysts: An adsorption related phenomenon. Tetrahedron Letters, 34, 529–532. DOI: 10.1016/0040-4039(93)85119-H. http://dx.doi.org/10.1016/0040-4039(93)85119-H10.1016/0040-4039(93)85119-HSuche in Google Scholar

Published Online: 2011-9-28
Published in Print: 2011-12-1

© 2011 Institute of Chemistry, Slovak Academy of Sciences

Artikel in diesem Heft

  1. Determination of four trace preservatives in street food by ionic liquid-based dispersive liquid-liquid micro-extraction
  2. Optimisation and validation of liquid chromatographic and partial least-squares-1 methods for simultaneous determination of enalapril maleate and nitrendipine in pharmaceutical preparations
  3. Chemiluminescence parameters of peroxynitrous acid in the presence of short-chain alcohols and Ru(bpy)32+
  4. Investigation of multi-layered silicate ceramics using laser ablation optical emission spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron microprobe analysis
  5. Simultaneous analysis of three catecholamines by a kinetic procedure: comparison of prediction performance of several different multivariate calibrations
  6. Enzymatic saccharification of cellulose in aqueous-ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate-DMSO media
  7. Statistical and evolutionary optimisation of operating conditions for enhanced production of fungal l-asparaginase
  8. Extraction of phytosterols from tall oil soap using selected organic solvents
  9. Dynamic simulations of waste water treatment plant operation
  10. Influence of recycling and temperature on the swelling ability of paper
  11. Zirconium(IV) 4-sulphophenylethyliminobismethylphosphonate as an efficient and reusable catalyst for one-pot synthesis of 3,4-dihydropyrimidones under solvent-free conditions
  12. Toxicity reduction of 2-(5-nitrofuryl)acrylic acid following Fenton reaction treatment
  13. Synthesis and characterisation of alkaline earth-iron(III) double hydroxides
  14. Effect of cyclodextrins on pH-induced conformational transition of poly(methacrylic acid)
  15. Polyamine-substituted epoxy-grafted silica for aqueous metal recovery
  16. Helical silica nanotubes: Nanofabrication architecture, transfer of helix and chirality to silica nanotubes
  17. DFT calculations on the Friedel-Crafts benzylation of 1,4-dimethoxybenzene using ZnCl2 impregnated montmorillonite K10 — inversion of relative selectivities and reactivities of aryl halides
  18. Facile synthesis of 3-aryl-1-((4-aryl-1,2,3-selenadiazol-5-yl)sulfanyl)isoquinolines
  19. Influence of trimethoxy-substituted positions on fluorescence of heteroaryl chalcone derivatives
  20. A simple and efficient one-pot synthesis of Hantzsch 1,4-dihydropyridines using silica sulphuric acid as a heterogeneous and reusable catalyst under solvent-free conditions
  21. Methylprednisolone release from agar-Carbomer-based hydrogel: a promising tool for local drug delivery
  22. 2-Alkylsulphanyl-4-pyridinecarbothioamides — inhibitors of oxygen evolution in freshwater alga Chlorella vulgaris
https://doi.org/10.2478/s11696-011-0073-7
Schlagwörter für diesen Artikel
zinc; montmorillonite; diarylmethane; alkylation; orbital; DFT calculations

Artikel in diesem Heft

  1. Determination of four trace preservatives in street food by ionic liquid-based dispersive liquid-liquid micro-extraction
  2. Optimisation and validation of liquid chromatographic and partial least-squares-1 methods for simultaneous determination of enalapril maleate and nitrendipine in pharmaceutical preparations
  3. Chemiluminescence parameters of peroxynitrous acid in the presence of short-chain alcohols and Ru(bpy)32+
  4. Investigation of multi-layered silicate ceramics using laser ablation optical emission spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron microprobe analysis
  5. Simultaneous analysis of three catecholamines by a kinetic procedure: comparison of prediction performance of several different multivariate calibrations
  6. Enzymatic saccharification of cellulose in aqueous-ionic liquid 1-ethyl-3-methylimidazolium dimethylphosphate-DMSO media
  7. Statistical and evolutionary optimisation of operating conditions for enhanced production of fungal l-asparaginase
  8. Extraction of phytosterols from tall oil soap using selected organic solvents
  9. Dynamic simulations of waste water treatment plant operation
  10. Influence of recycling and temperature on the swelling ability of paper
  11. Zirconium(IV) 4-sulphophenylethyliminobismethylphosphonate as an efficient and reusable catalyst for one-pot synthesis of 3,4-dihydropyrimidones under solvent-free conditions
  12. Toxicity reduction of 2-(5-nitrofuryl)acrylic acid following Fenton reaction treatment
  13. Synthesis and characterisation of alkaline earth-iron(III) double hydroxides
  14. Effect of cyclodextrins on pH-induced conformational transition of poly(methacrylic acid)
  15. Polyamine-substituted epoxy-grafted silica for aqueous metal recovery
  16. Helical silica nanotubes: Nanofabrication architecture, transfer of helix and chirality to silica nanotubes
  17. DFT calculations on the Friedel-Crafts benzylation of 1,4-dimethoxybenzene using ZnCl2 impregnated montmorillonite K10 — inversion of relative selectivities and reactivities of aryl halides
  18. Facile synthesis of 3-aryl-1-((4-aryl-1,2,3-selenadiazol-5-yl)sulfanyl)isoquinolines
  19. Influence of trimethoxy-substituted positions on fluorescence of heteroaryl chalcone derivatives
  20. A simple and efficient one-pot synthesis of Hantzsch 1,4-dihydropyridines using silica sulphuric acid as a heterogeneous and reusable catalyst under solvent-free conditions
  21. Methylprednisolone release from agar-Carbomer-based hydrogel: a promising tool for local drug delivery
  22. 2-Alkylsulphanyl-4-pyridinecarbothioamides — inhibitors of oxygen evolution in freshwater alga Chlorella vulgaris
Jetzt anmelden und 20% sparen
Institutioneller Zugang
Wie funktioniert Authentifizierung?
Haben Sie eine Idee, wie wir unsere Website verbessern können?
Bitte schreiben Sie uns.
© 2026 De Gruyter Brill
Heruntergeladen am 20.1.2026 von https://www.degruyterbrill.com/document/doi/10.2478/s11696-011-0073-7/html?lang=de
Button zum nach oben scrollen