Synthesis and Calibration of Two Radical Timing Devices: 2-Methyl-2-(1-naphthyl)- and 2-Methyl-2-(2-naphthyl)- 1-bromopropane.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
Marco Lucarini
Publications and source records attributed to Marco Lucarini.
Addition Reactions of Tris(trimethylsilyl)germyl Radicals to Unsaturated Compounds. An EPR and Product Study.
Tris(trimethylsilyl)germyl radicals, (TMS)(3)Ge(*), thermally or photochemically generated by means of suitable radical initiators, were reacted with a number of unsaturated compounds. The preparative scale reaction of (TMS)(3)GeH with a variety of alkynes proceeded stereo- and regioselectively affording exclusively 2-alkenylgermanes in excellent chemical yields. In the analogous reactions with alkenes, no addition products were obtained except in the case of 4-vinylpyridine. This behavior is explained in terms of the reversibility of germyl radical addition to olefines. The reaction with arylalkenes, ketones, quinones, azines, and nitroalkanes was instead carried out in the cavity of an EPR spectrometer. In most cases the corresponding radical adducts were observed; however, quite often the intensity of the spectra was lower than expected and with azines no EPR signals could be detected. These results have been interpreted as an indication that the addition reaction of tris(trimethylsilyl)germyl radicals to multiple bonds is less exothermic than that of trialkylgermyl radicals. With some of the investigated compounds, the addition of (TMS)(3)Ge(*) is thermoneutral or even endothermic and is therefore readily reversible.
Journal Article↗
Reactions of Substituted Boryl Radicals with Nitroalkanes. EPR, Kinetic, and Product Studies.
The radical-initiated reaction of amine-boranes and phosphine-boranes, LBH(3) (L = R(3)N, R(3)P) with aliphatic nitro compounds has been investigated in order to explore the possibility of reducing tertiary nitroalkanes to the corresponding hydrocarbons. In all the examined cases boroxy nitroxides, RN(O(*))OBLH(2), resulting from the addition of ligated boryl radicals, LBH(2)(*), to an oxygen atom of the nitro group were detected and characterized by EPR spectroscopy. This reaction occurs at room temperature with a rate constant of 1.5 x 10(7) M(-)(1) s(-)(1) for LBH(2)(*) = Me(3)NBH(2)(*) and RNO(2) = Me(3)CNO(2). The boroxy nitroxides from tertiary nitroalkanes decay by a fragmentation reaction occurring with cleavage of the nitrogen-oxygen bond, rather than of the carbon-nitrogen bond as would be required for the reduction to the corresponding alkane to take place. The Arrhenius parameters for this fragmentation have been determined in few cases.
Journal Article↗