68525-40-6

Upstream product

• 70712-85-5 1-phenyl-2,2-dimethyl-1-propyl bromide 
• 107557-73-3 meso-Bis(2,2-dimethyl-1-phenylpropyl)diazen 
• 100-17-4 4-methoxynitrobenzene anion radical 
• 92-24-0 2,3-benzanthracene radical anion 
• 119-61-9 benzophenone radical anion 
• 1499-10-1 9,10-diphenylanthracene anion radical 
• 103-33-3 azobenzene anion radical 
• 84-65-1 9,10-anthraquinone radical anion 
• 1009-61-6 1,4-diacetylbenzene anion radical 

Relevant academic research and scientific papers

The Nucleophilicity of Superoxide towards Different Alkyl Halides Estimated from Kinetic Measurements

Values of the rate constant ksub are measured for the substitution reaction between superoxide O2 anion-radical and the alkyl halides butyl chloride, 2-butyl chloride, benzyl chloride, ethyl bromide, butyl bromide, 2-butyl bromide, neopentyl bromide, benzyl bromide, (1-bromo-2,2-dimethylpropyl)benzene and 1-iodoadamantane.These rate constants are compared with the expected rate constant kET for the electron transfer reaction between the same alkyl halides and an aromatic anion radical A anion-radical with the same standard oxidation potential as O2 anion-radical.The ksub/kET ratios show that the mechanism of the substitution reaction amy shift from SN2-like to ET-like on changes in the steric hindrance and the acceptor ability of the alkyl halide.The influence on ksub/kET of the difference in self-exchange reorganization energy λ(0) between O2 anion-radical/O2 and A anion-radical/A is discussed.

Application of Force Field Calculations, 7. - Synthesis and Thermolysis of 1,1'-Disubstitueted trans-Azoneopentanes. - Steric and Resonance Effects of the Substituents on the Thermal Stability of Secondary Azoalkanes

A number of secondary azoalkanes 1, R1R2CH-N=N-CHR1R2, R1 = t-C4H9, R2 = aryl (meso- and D,L-1a-i) and R2 = cyclo-C6H11 (D,L-1k), have been synthesized by partial catalytic hydrogenation of the corresponding ketazines.The configuration of 1 was elucidated by photolysis of crystalline samples of 1, which yielded the dimers 6 with retention of configuration.The kinetics of thermal fragmentation of 1a-k and of 1n (R1 = CH3, R2 = C6H5) into the radicals 7 was followed by DSC.The activation parameters were determined by fitting theoretical curves to the experimental data with the help of a computer program. - The rate of decomposition of 1 with R1, R2 = alkyl is sterically accelarated by increasing size of the substituents (back strain), but the fragmentation of 1a-i (R2 = aryl) is sterically inhibited, e.g. k 2 = C6H5, R1 = t-C4H9)>/k 2 = C6H5, R1 = CH3)> = 10-2.The strain enthalpies Hs of 1 and 7 were calculated by the force field method.The results show that both steric effects are a result of the change in strain during the reaction s = 2Hs(7) - Hs(1)>.A fraction of 0.5 - 0.6 of Ds contributes to ΔG excit. (150 deg C), thus effecting the rate of the reaction.The large positiv value of Ds for R2 = aryl e.g.Ds (1a) = 7.8 kcal/mol, results from a strong repulsion between R1 and R2 in 7 due to the coplanar arrangement of the aryl ring with the radical center. - The resonance effect on the rate of thermolysis has a similar magnitude for R2 = phenyl, p-X-C6H4 (X = Cl, OCH3, t-C4H9, C6H5) and 2-naphthyl, but is considerable stronger for R2 = 1-naphthyl.The measured effect corresponds to a resonance stabilisation of 1-naphthylmethyl radicals by additional 4.5 kcal/mol, compared to benzyl radicals.