Full metadata record
DC Field | Value | Language |
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dc.contributor.author | 박준우 | - |
dc.date.accessioned | 2016-08-28T11:08:06Z | - |
dc.date.available | 2016-08-28T11:08:06Z | - |
dc.date.issued | 2002 | - |
dc.identifier.issn | 0253-2964 | - |
dc.identifier.other | OAK-1211 | - |
dc.identifier.uri | https://dspace.ewha.ac.kr/handle/2015.oak/219075 | - |
dc.description.abstract | This paper reports the photochemical reduction of benzil 1 to benzoin 2 and the reduction of 2 to hydrobenzoin 4 in deoxygenated solvents in the presence of triethylamine (TEA) and/or TiO2. Without TEA or TiO2, the photolysis of 1 resulted in very low yield of 2. The presence of TEA or TiO2 increased the rate of disappearance of 1 and the yield of 2, which were further increased considerably by the presence of water. The photoreduction of 1 to 2 proceeds through an electron transfer to 1 from TEA or hole-scavenged excited TiO2 followed by protonation. In the reaction medium of 88: 7: 2: 3 CH3CN/CH3OH/H2O/TEA with 2.5 mg/mL of TiO2, the yield of 2 was as high as 85% at 50% conversion of 1. The photolysis of 2 in homogeneous media resulted in photo-cleavage to benzoyl and hydroxybenzyl radicals, which are mostly converted to benzaldehyde. The reduction product 4 is formed in low yield through the dimerization of hydroxybenzyl radicals. The addition of TEA increased the conversion rate of 2 and the yield of 4 significantly. This was attributed to the scavenging effect of TEA for benzoyl radical to produce N,N-diethylbenzamide and the photoreduction of benzaldehyde in the presence of TEA. The ratio of (±) and meso isomers of 4 obtained from the photochemical reaction is about 1.1. This ratio is the same as that from the photochemical reduction of benzaldehyde in the presence of TEA. In the TiO2-sensitized photochemical reduction of 2, meso-4 was obtained in moderate yield. The reduction of 2 to 4 proceeds through two consecutive electron/proton transfer processes on the surface of the photocatalyst without involvement of α-cleavage. The radical 11 initially formed from 2 by one electron/proton process can also combine with hydroxy methyl radical, which is generated after hole trapping of excited TiO2 by methanol, to produce 1,2-diphenylpropenone after dehydration reaction. | - |
dc.language | English | - |
dc.title | Photochemical reductions of benzil and benzoin in the presence of triethylamine and TiO2 photocatalyst | - |
dc.type | Article | - |
dc.relation.issue | 9 | - |
dc.relation.volume | 23 | - |
dc.relation.index | SCI | - |
dc.relation.index | SCIE | - |
dc.relation.index | SCOPUS | - |
dc.relation.index | KCI | - |
dc.relation.startpage | 1229 | - |
dc.relation.lastpage | 1234 | - |
dc.relation.journaltitle | Bulletin of the Korean Chemical Society | - |
dc.identifier.wosid | WOS:000178759200014 | - |
dc.identifier.scopusid | 2-s2.0-0037145147 | - |
dc.author.google | Park J.W. | - |
dc.author.google | Kim E.K. | - |
dc.author.google | Park K.K. | - |
dc.contributor.scopusid | 박준우(35332923800) | - |
dc.date.modifydate | 20220119160750 | - |