5667-66-3Relevant academic research and scientific papers
Length- and direction-specific solute-solvent interactions as determined from Norrish II reactions of p-alkylalkanophenones in ordered phases of n-butyl stearate
He, Zhiqiang,Weiss, Richard G.
, p. 5535 - 5541 (2007/10/02)
The photochemistry of a series of p-alkylalkanophenones (1) has been investigated in the ordered and isotropic phases of n-butyl stearate (BS). By varying the total length of the ketones and the relative position of the benzoyl group within ketones of constant length, the solvent-related factors responsible for Norrish II product selectivity and reactivity have been identified. Specifically, the location of the hydroxy 1,4-biradical intermediates from 1 with respect to the carboxyl groups of neighboring BS molecules and the orientation of the biradical centers within a BS layer appear to control the nature and efficiency of product formation. Infrared spectra of models of the hydroxy 1,4-biradicals in BS and eicosane support the hypotheses. Differential scanning calorimetric data indicate that the ketones exhibiting the lowest product selectivity or least reactivity are not incorporated well within the BS anisotropic phases.
Type II Photochemistry of Ketones in Liquid Crystalline Solvents. The Influence of Ordered Media on Biradical Dynamics
Hrovat, David A.,Liu, Jerry H.,Turro, Nicholas J.,Weiss, Richard G.
, p. 7033 - 7037 (2007/10/02)
The Norrish type II photochemistry of five alkylphenones, PhCO(CH2)nH (1a, n=4; 1b, n=10; 1c, n=17; 1d, n=19; 1e, n=21), 10-nonadecanone (2), and 2-undecanone (3) was studied in the isotopic, smetic, and solid phases of n-butyl stearate.The ratio of elimination-to-cyclization products for ketones 1c-e and 2 exhibits a strong phase dependence with a 7-8-fold increase in the smectic phase relative to the isotropic phase.The ratio of isomeric cyclobutanols from 2 shows a similar change.Further increases in the elimination-to-cyclization ratio are observed for 1d in the solid phase.The product ratios for ketones 1a, 1b, and 3 are the same in all the phase studied.Transient absorption studies on the intermediate 1,4-biradical produced from laser flash photolysis of 1d yield lifetimes of 64 +/- 5 and 70 +/- 5 ns in the isotopic and smectic phases, respectively.These results are explaned in terms of the structures of the various phases of n-butyl stearate and the accepted behavior of Norrish type II biradicals.
