40489-75-6

Upstream product

• 24973-59-9 2,4,6-tri-tert-butyl-1-nitrosobenzene 
• 109-99-9 tetrahydrofuran 
• 4497-05-6 1-phenyl-tetradecan-1-one 
• 112-12-9 methyl nonyl ketone 

Relevant academic research and scientific papers

Spin-trapping evidence for the formation of alkyl, alkoxyl, and alkylperoxyl radicals in the reactions of dialkylzincs with oxygen

The reactions of dialkylzincs (Me2Zn, Et2Zn, and nBu2Zn) with oxygen have been investigated by EPR spectroscopy using spin-trapping techniques. The use of 5-diethoxyphosphoryl-5-methyl-1-pyrrroline N-oxide (DEPMPO) as a spin-trap has allowed the involvement of alkyl, alkylperoxyl, and alkoxyl radicals in this process to be probed for the first time. The relative ratio of the corresponding spin-adducts depends strongly on the nature of the R group, which controls the C-Zn bond dissociation enthalpy, and on the experimental conditions (excess of spin-trap compared with R 2Zn and vice versa). The results have demonstrated that Et 2Zn and, to a lesser extent, nBu2Zn are much better traps for oxygen-centered species than Me2Zn. When the dialkylzincs were used in excess with respect to the spin-trap, the concentration of the oxygen-centered radical adducts of DEPMPO was much lower for Et2Zn and nBu2Zn than for Me2Zn. A detailed reaction mechanism is discussed and C-Zn, O-Zn, and O-O bond dissociation enthalpies for the proposed reaction intermediates were calculated at the UB3LYP/6-311++G(3df,3pd)/ /UB3LYP/6-31G(d,p) level of theory to support the rationale. All trapped! The reactions of dialkylzincs with oxygen (see scheme) have been investigated with EPR spectroscopy by using spin-trapping techniques. The use of DEPMPO as a spin-trap has allowed the involvement of alkyl, alkylperoxyl, and alkoxyl radicals in this process to be probed for the first time. A detailed mechanism is discussed in the light of theoretical calculations of the C-Zn, O-Zn, and O-O bond dissociation enthalpies of the proposed reaction intermediates.

EPR/Spin-trapping study of free radical intermediates in the photolysis of trifluoromethyl ketones with initiators

Photolysis of trifluoromethyl ketones (TFMKs) 1a-1e versus the non-fluorinated ketones 2a-2b in the presence of radical initiators by electron paramagnetic resonance spectroscopy has been studied for the first time. The transient radicals generated after irradiation of the ketones were identified by trapping with 2-methyl-2-nitrosopropane (MNP) and 2,4,6-tritert- butylnitrosobenzene (TTBNB) as spin traps. TTBNB is a powerful, particularly useful spin trap in these kinds of processes producing anilino and nitroxyl spin adducts due to the ambivalent reactivity on the N and O atoms. In the presence of t-butylperoxide, short-chain TFMKs, such as 1,1,1-trifluoroacetone (1d) and hexafluoroacetone (1e), give rise to detection of the elusive trifluoromethyl radical. In contrast, long-chain TFMKs did not provide clues to prove formation of the trifluoromethyl radical but instead to radicals derived by abstraction of one α-methylene proton to the carbonyl. Although TFMKs are quite stable to photodegradation in the absence of initiator, methyl ketone 2b and phenyl ketone 3 produce radicals resulting from abstraction of a γ-hydrogen to the carbonyl group. Copyright