Photochemical cyanation of aromatic compounds

Photoinduced three-component coupling reactions of electron deficient alkenes, dienes and active methylene compounds

The irradiation of aqueous acetonitrile solutions, containing electron deficient alkenes, dienes and active methylene compounds along with sodium or cesium carbonate and catalytic amounts of phenanthrene or pyrene, gives rise to the formation of novel three-component coupling products and diene dimers. Cinnamonitrile and benzylidenemalononitrile and its derivatives serve as electron-acceptors; 2,5-dimethyl-2,4-hexadiene and malononitrile anion serve as electron donors in this process. Based on the results of UV-vis absorption spectroscopy and the calculated ΔG values for single electron transfer (SET), mechanisms are proposed for the coupling reaction involving photoinduced electron transfer (PET) between the electron deficient alkenes and dienes or malononitrile anion via direct excitation of electron deficient alkenes or redox photosensitization using phenanthrene or pyrene serving as a photosensitizer.

Acetalization allows the photoheterolysis of the Ar-Cl bond in chlorobenzaldehydes and chloroacetophenones

The nonaccessibility of phenyl cations by irradiation of electron-poor aryl chlorides was circumvented by transforming the carbonyl group of aromatic ketones or aldehydes into the corresponding 1,3-dioxolanes and the carboxyl group of benzoate ester into an orthoester functionality. This transformation allowed the heterolytic photoactivation of the Ar-Cl bond in protic media and the generation of phenyl cations. In the presence of π-bond nucleophiles, arylated products were obtained in good to excellent yields.

Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)

Abstract: The second edition of the Glossary of Terms Used in Photochemistry [Pure Appl. Chem.68, 2223-2286 (1996); <http://www.iupac.org/publications/pac/1996/pdf/6812x2223.pdf>] has been both corrected and updated. Terms have been added related to molecular anisotropy, the use of polarized radiation, nonlinear optical phenomena, and the emerging field of computation of excited species. Some changes have been introduced in this "Glossary" regarding the terms related to radiation energy to make this collection fully compatible with internationally agreed-upon terms. Many links are included to various Web pages listing quantities relevant to the work of photochemists and scientists using photochemical tools.