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Titolo:
PHOTOCHEMICAL C-C BOND-CLEAVAGE OF 1,2-DIARYLCYCLOPROPANES BEARING ANACETYLPHENYL GROUP - GENERATION AND OBSERVATION OF TRIPLET 1,3-BIRADICALS
Autore:
ICHINOSE N; MIZUNO K; OTSUJI Y; CALDWELL RA; HELMS AM;
Indirizzi:
UNIV OSAKA PREFECTURE,COLL ENGN,DEPT APPL CHEM SAKAI OSAKA 5998531 JAPAN UNIV OSAKA PREFECTURE,COLL ENGN,DEPT APPL CHEM SAKAI OSAKA 5998531 JAPAN UNIV TEXAS,DEPT CHEM RICHARDSON TX 75080
Titolo Testata:
Journal of organic chemistry
fascicolo: 10, volume: 63, anno: 1998,
pagine: 3176 - 3184
SICI:
0022-3263(1998)63:10<3176:PCBO1B>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
UV-LASER PHOTOCHEMISTRY; CROSSING RATE CONSTANTS; SINGLET BIRADICALS; ELECTRON-TRANSFER; ABINITIO MCSCF; LIFETIMES; STATE; TRIMETHYLENE; DIRADICALS; CHEMISTRY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
67
Recensione:
Indirizzi per estratti:
Citazione:
N. Ichinose et al., "PHOTOCHEMICAL C-C BOND-CLEAVAGE OF 1,2-DIARYLCYCLOPROPANES BEARING ANACETYLPHENYL GROUP - GENERATION AND OBSERVATION OF TRIPLET 1,3-BIRADICALS", Journal of organic chemistry, 63(10), 1998, pp. 3176-3184

Abstract

The photochemical properties of 1,2-diarylcyclopropanes bearing an acetylphenyl group were studied by product analysis and laser flash photolysis. All cyclopropanes showed efficient cis-trans photoisomerization followed by inefficient isomerization to 1,3-diarylpropenes. All theproducts were unquenched by the addition of triplet quencher, 2-methyl-1,3-butadiene (E-T similar or equal to 60 kcal mol(-1)), whereas molecular dioxygen gave oxygenated products. Triplet 1,3-biradicals generated from a short-lived acetophenone-like triplet (less than or similar to 1 ns) were observed as intermediates in these reactions through nanosecond laser flash photolysis. Polar substituent effects on the lifetime of the 1,3-biradicals were small, except for a heavy atom effectin the case of Br. Spin-orbit coupling calculations on model 1,3-biradicals show a negligible effect on polar substituent and thus predict a negligible effect on the intersystem crossing rate. Conjugated biradicals in general now seem unlikely to show the ''ionic character effect'' on intersystem crossing suggested by the work of Salem and Rowland.

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Documento generato il 02/12/20 alle ore 15:20:12