Photoisomerization of alfa calcidol by a sensitized quantum chain reaction
The production of vitamin D3 is a pharmaceutically relevant process, producing high added-value products. Precursors are extracts from vegetal origin but bearing mainly an E geometry in the 5,6 double bond. The synthesis of vitamin D3 (5-E-α-calcidol) with the correct Z stereochemistry in the 5,6 do...
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2012
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paper:paper_00318655_v88_n4_p769_Estruch2023-06-08T14:57:25Z Photoisomerization of alfa calcidol by a sensitized quantum chain reaction Aramendía, Pedro Francisco 1,4 diazabicyclo[2.2.2]octane anthracene anthracene derivative colecalciferol ethylamine oxygen piperazine derivative triethylamine chemical structure chemistry conference paper high performance liquid chromatography isomerism kinetics photochemistry quantum theory solution and solubility spectroscopy synthesis thermodynamics ultraviolet radiation Anthracenes Cholecalciferol Chromatography, High Pressure Liquid Ethylamines Isomerism Kinetics Models, Molecular Oxygen Photochemical Processes Piperazines Quantum Theory Solutions Spectrum Analysis Thermodynamics Ultraviolet Rays The production of vitamin D3 is a pharmaceutically relevant process, producing high added-value products. Precursors are extracts from vegetal origin but bearing mainly an E geometry in the 5,6 double bond. The synthesis of vitamin D3 (5-E-α-calcidol) with the correct Z stereochemistry in the 5,6 double bond from the E isomer using anthracene and triethylamine (TEA) as the sensitizer system was studied from the kinetic and mechanistic point of view. The sensitized isomerization of E-calcidol by irradiation of anthracene takes place only in deoxygenated solution and yields the Z isomer in ca 5% yield in the photostationary state. When TEA is added to the system, the E-Z reaction is not inhibited by oxygen any more, the quantum yield of photoisomerization to the Z isomer grows linearly with the concentration of E-calcidol, while conversions higher than 95% to the Z isomer are reached in the photostationary state and E-Z quantum yields as high as 45 at [E-calcidol] = 25 mm are reached. If TEA is replaced by 1,4-diazabicyclo[2.2.2]octane, the reaction rate drops to one-third at the same amine concentration. The observations can be explained by a quantum chain reaction mechanism. The high conversion achieved eliminates the need of isomer separation. © 2012 Wiley Periodicals, Inc. Fil:Aramendía, P.F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2012 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00318655_v88_n4_p769_Estruch http://hdl.handle.net/20.500.12110/paper_00318655_v88_n4_p769_Estruch |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
1,4 diazabicyclo[2.2.2]octane anthracene anthracene derivative colecalciferol ethylamine oxygen piperazine derivative triethylamine chemical structure chemistry conference paper high performance liquid chromatography isomerism kinetics photochemistry quantum theory solution and solubility spectroscopy synthesis thermodynamics ultraviolet radiation Anthracenes Cholecalciferol Chromatography, High Pressure Liquid Ethylamines Isomerism Kinetics Models, Molecular Oxygen Photochemical Processes Piperazines Quantum Theory Solutions Spectrum Analysis Thermodynamics Ultraviolet Rays |
| spellingShingle |
1,4 diazabicyclo[2.2.2]octane anthracene anthracene derivative colecalciferol ethylamine oxygen piperazine derivative triethylamine chemical structure chemistry conference paper high performance liquid chromatography isomerism kinetics photochemistry quantum theory solution and solubility spectroscopy synthesis thermodynamics ultraviolet radiation Anthracenes Cholecalciferol Chromatography, High Pressure Liquid Ethylamines Isomerism Kinetics Models, Molecular Oxygen Photochemical Processes Piperazines Quantum Theory Solutions Spectrum Analysis Thermodynamics Ultraviolet Rays Aramendía, Pedro Francisco Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| topic_facet |
1,4 diazabicyclo[2.2.2]octane anthracene anthracene derivative colecalciferol ethylamine oxygen piperazine derivative triethylamine chemical structure chemistry conference paper high performance liquid chromatography isomerism kinetics photochemistry quantum theory solution and solubility spectroscopy synthesis thermodynamics ultraviolet radiation Anthracenes Cholecalciferol Chromatography, High Pressure Liquid Ethylamines Isomerism Kinetics Models, Molecular Oxygen Photochemical Processes Piperazines Quantum Theory Solutions Spectrum Analysis Thermodynamics Ultraviolet Rays |
| description |
The production of vitamin D3 is a pharmaceutically relevant process, producing high added-value products. Precursors are extracts from vegetal origin but bearing mainly an E geometry in the 5,6 double bond. The synthesis of vitamin D3 (5-E-α-calcidol) with the correct Z stereochemistry in the 5,6 double bond from the E isomer using anthracene and triethylamine (TEA) as the sensitizer system was studied from the kinetic and mechanistic point of view. The sensitized isomerization of E-calcidol by irradiation of anthracene takes place only in deoxygenated solution and yields the Z isomer in ca 5% yield in the photostationary state. When TEA is added to the system, the E-Z reaction is not inhibited by oxygen any more, the quantum yield of photoisomerization to the Z isomer grows linearly with the concentration of E-calcidol, while conversions higher than 95% to the Z isomer are reached in the photostationary state and E-Z quantum yields as high as 45 at [E-calcidol] = 25 mm are reached. If TEA is replaced by 1,4-diazabicyclo[2.2.2]octane, the reaction rate drops to one-third at the same amine concentration. The observations can be explained by a quantum chain reaction mechanism. The high conversion achieved eliminates the need of isomer separation. © 2012 Wiley Periodicals, Inc. |
| author |
Aramendía, Pedro Francisco |
| author_facet |
Aramendía, Pedro Francisco |
| author_sort |
Aramendía, Pedro Francisco |
| title |
Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| title_short |
Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| title_full |
Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| title_fullStr |
Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| title_full_unstemmed |
Photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| title_sort |
photoisomerization of alfa calcidol by a sensitized quantum chain reaction |
| publishDate |
2012 |
| url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00318655_v88_n4_p769_Estruch http://hdl.handle.net/20.500.12110/paper_00318655_v88_n4_p769_Estruch |
| work_keys_str_mv |
AT aramendiapedrofrancisco photoisomerizationofalfacalcidolbyasensitizedquantumchainreaction |
| _version_ |
1768542071468064768 |