INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
artículos
Título:
Photolysis of an Asymmetrically Substituted Diazene in Solution and in the Crystalline State
Autor/es:
PABLO A. HOIJEMBERG; STEVE KARLEN; CARLOS SANRAMÉ; PEDRO F. ARAMENDÍA; MIGUEL GARCÍA GARIBAY
Revista:
Photochemical and Photobiological Sciences
Editorial:
Royal Society of Chemistry
Referencias:
Lugar: Cambridge; Año: 2009 vol. 8 p. 961 - 961
ISSN:
1474-905X
Resumen:
<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; text-autospace:none; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> In this work we study the product distribution in the steady state photolysis of a diazene, (1-biphenyl-4-yl-1-methyl-ethyl)-tert-butyl diazene, and a ketone, 2,4-bis-biphenyl-4-yl-2,4-dimethyl-pentan-3-one in the solid state and in solution. The two compounds yield 1-biphenyl-4-yl-1-methyl-ethyl (BME·) radicals upon photolysis. The ketone yields two units of this radical, whereas the diazene yields one BME· and one tert-butyl radical. Product analysis of the two compounds in solution makes it possible to differentiate their origin from their corresponding geminate cages, and from the different encounter pairs in the case of the asymmetrically substituted diazene photolysis. In this way we obtain a complete reaction scenery for the diazene, a compound with interesting features as a radical photoinitiator and as cage effect probe in fluid media. The reaction in cages containing two BME· radicals shows a decrease by a factor of 4 in the ratio of combination to disproportionation products upon going from the solid to the liquid phase. On the contrary, the reaction in cages containing a BME· and a tert-butyl radical shows a 30-fold increase in combination to disproportionation ratio in liquid compared to the crystal. We analyze the reasons for these differences considering the differences in the reactivity of the radicals and in cage rigidity.