1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation
The structure and protonation behaviour of four ortho-arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calc...
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| Format: | Article |
| Language: | English |
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Beilstein-Institut
2018-11-01
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| Series: | Beilstein Journal of Organic Chemistry |
| Subjects: | |
| Online Access: | https://doi.org/10.3762/bjoc.14.273 |
| _version_ | 1818963094814064640 |
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| author | A. S. Antonov A. F. Pozharskii P. M. Tolstoy A. Filarowski O. V. Khoroshilova |
| author_facet | A. S. Antonov A. F. Pozharskii P. M. Tolstoy A. Filarowski O. V. Khoroshilova |
| author_sort | A. S. Antonov |
| collection | DOAJ |
| description | The structure and protonation behaviour of four ortho-arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It has been shown that E-isomers of neutral imines can be stabilised by an intramolecular C=N−H···OMe hydrogen bond with a neighbouring methoxy group. Electron-donating OMe groups dramatically increase the basicity of the imino nitrogen, forcing the latter to abstract a proton from the proton sponge moiety in monoprotonated forms. The participation of the out-inverted and protonated 1-NMe2 group in the Me2N−H···NH=C hydrogen bond is experimentally demonstrated. It was shown that the number and position of OMe groups in the aromatic substituents strongly affects the rate of the internal hindered rotation of the NH2+ fragment in dications. |
| first_indexed | 2024-12-20T12:39:45Z |
| format | Article |
| id | doaj.art-a9dc122a86f3421da98ce6b51cd63e52 |
| institution | Directory Open Access Journal |
| issn | 1860-5397 |
| language | English |
| last_indexed | 2024-12-20T12:39:45Z |
| publishDate | 2018-11-01 |
| publisher | Beilstein-Institut |
| record_format | Article |
| series | Beilstein Journal of Organic Chemistry |
| spelling | doaj.art-a9dc122a86f3421da98ce6b51cd63e522022-12-21T19:40:31ZengBeilstein-InstitutBeilstein Journal of Organic Chemistry1860-53972018-11-011412940294810.3762/bjoc.14.2731860-5397-14-2731,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonationA. S. Antonov0A. F. Pozharskii1P. M. Tolstoy2A. Filarowski3O. V. Khoroshilova4Department of Organic Chemistry, Southern Federal University, Zorge str. 7, 344090 Rostov-on-Don, Russian FederationDepartment of Organic Chemistry, Southern Federal University, Zorge str. 7, 344090 Rostov-on-Don, Russian FederationInstitute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russian FederationFaculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, PolandInstitute of Chemistry, St. Petersburg State University, Universitetskii pr. 26, 198504 St. Petersburg, Russian FederationThe structure and protonation behaviour of four ortho-arylketimines of 1,8-bis(dimethylamonio)naphthalene with a different number of methoxy groups in an aromatic substituent were investigated in solution by NMR (acetone, DMSO, MeCN), in solid state by X-ray analysis and in the gas phase by DFT calculations. Both mono- and diprotonated species were considered. It has been shown that E-isomers of neutral imines can be stabilised by an intramolecular C=N−H···OMe hydrogen bond with a neighbouring methoxy group. Electron-donating OMe groups dramatically increase the basicity of the imino nitrogen, forcing the latter to abstract a proton from the proton sponge moiety in monoprotonated forms. The participation of the out-inverted and protonated 1-NMe2 group in the Me2N−H···NH=C hydrogen bond is experimentally demonstrated. It was shown that the number and position of OMe groups in the aromatic substituents strongly affects the rate of the internal hindered rotation of the NH2+ fragment in dications.https://doi.org/10.3762/bjoc.14.273hydrogen bondimineNMRproton spongesuperbase |
| spellingShingle | A. S. Antonov A. F. Pozharskii P. M. Tolstoy A. Filarowski O. V. Khoroshilova 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation Beilstein Journal of Organic Chemistry hydrogen bond imine NMR proton sponge superbase |
| title | 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation |
| title_full | 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation |
| title_fullStr | 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation |
| title_full_unstemmed | 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation |
| title_short | 1,8-Bis(dimethylamino)naphthyl-2-ketimines: Inside vs outside protonation |
| title_sort | 1 8 bis dimethylamino naphthyl 2 ketimines inside vs outside protonation |
| topic | hydrogen bond imine NMR proton sponge superbase |
| url | https://doi.org/10.3762/bjoc.14.273 |
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