No abstract

Absolute rate constants for the reactions of rert-butoxyl radicals with some organic aldehydes have been measured in solution by using laser flash photolysis techniques. At 297 K, the rate constants are 8.9, 6.8, 1.0, and 0.05 X 107 M-1 s-1 for EtCHO, C6H5CHO, Me2NCHO, and EtOCHO, respectively. Arrhenius parameters were determined for benzaldehyde. Polar effects are very important in determining the reactivity of organic aldehydes toward tert-butoxyl radicals. The EPR spectra are described for a number of furoyl, thenoyl, and pyrroyl radicals (ArCO) which were generated photolytically over a wide range of temperatures. Conformational isomers were detected and their structural assignment obtained from the magnitude of the hyperfme splittings of the ring protons, by comparison with the conformers of the parent aldehydes, and from the solvent dependence.

No abstract

No abstract

The polar fractions decomposed rapidly and could not be studied satisfactorily. Photooxygenation of 1 g of 3b in acetone at 10 °C for 1 h gave 418 mg (36%) and photooxygenation of 1.5 g of 3b in acetone at 78 °C gave 279 mg (31% based on recovered diene) at 19b. l-Methyl-4,5-dihydronaphtho[2,l-b]furan (20a). Reaction of 0.2 g of 19a in 15 mL of THF with 0.4 g of FeS04-7H20 in 20 mL of H20 at room temperature for 2 h followed by the usual workup and chromatography over 20 g of silica gel gave 0.16 g (88%) of 20a: