Display options
Cite
Cai X, Cygon P, Goldfuss B, et al. Alpha-carbonyl substituent effect on the lifetimes of triplet 1,4-biradicals from Norrish-Type-II reactions. Chemistry. 2006;12(17):4662-7doi: 10.1002/chem.200600011.
Cai, X., Cygon, P., Goldfuss, B., Griesbeck, A. G., Heckroth, H., Fujitsuka, M., & Majima, T. (2006). Alpha-carbonyl substituent effect on the lifetimes of triplet 1,4-biradicals from Norrish-Type-II reactions. Chemistry (Weinheim an der Bergstrasse, Germany), 12(17), 4662-7. https://doi.org/10.1002/chem.200600011
Cai, Xichen, et al. "Alpha-carbonyl substituent effect on the lifetimes of triplet 1,4-biradicals from Norrish-Type-II reactions." Chemistry (Weinheim an der Bergstrasse, Germany) vol. 12,17 (2006): 4662-7. doi: https://doi.org/10.1002/chem.200600011
Cai X, Cygon P, Goldfuss B, Griesbeck AG, Heckroth H, Fujitsuka M, Majima T. Alpha-carbonyl substituent effect on the lifetimes of triplet 1,4-biradicals from Norrish-Type-II reactions. Chemistry. 2006 Jun 02;12(17):4662-7. doi: 10.1002/chem.200600011. PMID: 16557627.
Copy Download .nbib Format: NLM
Share it on

Chemistry. 2006 Jun 02;12(17):4662-7. doi: 10.1002/chem.200600011.

Alpha-carbonyl substituent effect on the lifetimes of triplet 1,4-biradicals from Norrish-Type-II reactions.

Chemistry (Weinheim an der Bergstrasse, Germany)

Xichen Cai, Peter Cygon, Bernd Goldfuss, Axel G Griesbeck, Heike Heckroth, Mamoru Fujitsuka, Tetsuro Majima

Affiliations

  1. Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan. [email protected]

PMID: 16557627 DOI: 10.1002/chem.200600011

Abstract

Triplet 1,4-biradicals were generated by Norrish-Type-II hydrogen transfer from alpha-heteroatom-substituted beta-branched butyrophenones 1-6 and detected by laser flash absorption measurements. For three oxy-substituted compounds 2-4 (R(alpha)=OH, OCOMe, OCOOEt) comparable lifetimes were determined in acetonitrile (roughly 1.5 micros). In benzene, divergent trends were observed: for the hydroxy compound 2 a lower lifetime of 790 ns was determined, whereas for 3 and 4 the lifetimes increased to 4.9 micros. Photolyses of the alpha-amino-substituted compounds 1 and 6 resulted in transient species with significant lower lifetimes (for 1 160 ns in benzene and 450 ns in acetonitrile; for 6 <100 ns in both solvents). The mesyloxy substrate 5 undergoes rapid C-O bond cleavage upon photolysis and no transient triplet species were detected. Computational (UB3 LYP/6-31G* and natural don orbital (NBO) analyses) results supported the assumption of a negative hyperconjugative interaction strongly stabilizing alpha-oxy-substituted over alpha-amino-substituted radicals.

Publication Types