Xi-Kui Jiang

N-Perhalofluoroalkylation of secondary amines by the reactions of the amines and amides with perhalofluoroalkanes. Halophilic attack on nitrogen nucleophile on CBr bond.

Abstract Secondary amines and amides react spontaneously with perhalofluoroalkanes CF 2 BrCFBrX(X = F, Cl, CF 3 ) to afford N-perhalofluoroalkylated tertiary amines in fair to good yields. Evidence for an anionic chain process initiated by the bromophilic attack of nitrogen nucleophiles on CBr bonds is given.

The chemistry of diacyl peroxides - VIII. The reactions between polyfluorodiacyl peroxides and 2-nitro-2-nitrosopropane--Generation of bis(polyfluoroalkyl) nitroxides

Abstract Thermal decomposition of 2-nitro-2-nitrosopropane (4) in F113 (CCl2F-CClF2) solution involves C-NO bond fission and forms acetone as the major product. In the presence of polyfluorodiacyl peroxide (3), the oxidation of 4 by 3 to 2,2-dinitropropane (5) is the predominant reaction and bis(polyfluoroalkyl) nitroxide(1) is generated as one of the by-products.

The chemistry of diacyl peroxides IX. An ESR study of the reduction of polyfluorodiacyl peroxides by copper (O) in the presence of 2-nitro-2-nitrosopropane: The generation of polyfluoroalkyl nitroalkyl nitroxides

Abstract Polyfluoroalkyl radicals generated by one-electron reduction of polyfluorodiacyl peroxides by copper (O) were trapped by 2-nitro-2-nitrosopropane to yield polyfluoroalkyl nitroalkyl nitroxides, R F N(O)CMe 2 NO 2 .

Distinctive and solvent-dependent behaviour of some per(chloro, fluoro)ethanes in their reactions with PhSNa . Competing mechanistic pathways in halophilic reactions

Abstract Per(chloro, fluoro)ethanes CF 2 XCCl 2 Y ( 1 ) react spontaneously with PhSNa at room temperature or below to give PhSCF 2 CCl 2 Y ( 2 ) in fair to good yield, which as well as the by-products PhSCF 2 CCl ( 3 ) and PhSCFCCl 2 ( 4 ) (for 1b and 1c ) are most probably produced by an anionic chain process initiated by the chlorophilic attack of PhS − on CCl bonds. In case of 1c , the coexistence of two competitive reaction pathways is indicated by the two products 2b and PhSCCl 2 CF 3 ( 10 ). The reaction rates and the product distribution have been found to be highly solvent-dependent. Products 2b , 4 and 10 all react further with PhSNa to afford multi-substituted ethylenes PhSCFC(Cl)SPh ( 7 ) (PhS) 2 CC(Cl)SPh ( 8 ) and (PhS) 2 CC(SPh) 2 ( 9 ).

Correlation analysis of UV spectral data of some phenylhydrazones and semicarbazones by the dual-parameter equation. Observation of three types of behaviors of the ?max values induced by the polar effects of substituents

The K-band λmax values of the UV spectra of five types of p-Y-benzaldehyde derivatives, namely phenylhydrazones (1-Ys), 2,4-dinitrophenylhydrazones (2-Ys), 4-nitrophenylhydrazones (3-Ys), semicarbazones (4-Ys) and N-phenylsemicarbazones (5-Ys), were measured and the corresponding wavenumbers (νmax) calculated. Correlation analyses of the νmax values by the dual-parameter equation show that the νmax values of these compounds are affected, albeit to different degrees, by both spin-delocalization effects (σ˙) and polar effects (σx) of the substituents. The spin-delocalization effects of substituents always facilitate bathochromic shifts of the λmax values (ρ˙ negative). However, polar effects of the substituents on these λmax data depend on the mode of polarization of these hydrazone or semicarbazone molecules, i.e. electron-pair acceptor substituents (Ys) facilitate bathochromic shifts for 1-Ys (ρx negative), but hypsochromic shifts for 2-Ys and 3-Ys (ρx positive), and induce very small shifts for 4-Ys and 5-Ys. As expected, donor Ys facilitate hypsochromic shifts for 1-Ys and bathochromic shifts for 2-Ys and 3-Ys and induce very small shifts for 4-Ys and 5-Ys. Possibly, a higher degree of polarization of the substrate molecule would demand a higher degree of polar assistance from the substituents at the transition states.

Generation of 15N labelled bis(polyfluoroalkyl) nitroxides and their hydrogen-abstraction reactions with alkanes, alkylbenzenes and aldehydes

Abstract Blue solutions containing 15 labelled bis(polyfluoralkyl) nitroxides and spin traps, polyfluoronitrosoalkanes, were conveniently made from the reactions of Na 15 NO 2 with polyfluoro-compounds, (R F CO 2 ) and R F SO 2 Br in F113. It has been found that the nitroxides effected fast H-abstraction from alkanes, alkylbenzenes, aldehydes and the radicals derived from the substrates were in turn effectively trapped by R F 15 NO to give 15 N labelled spin adducts detectable by ESR. The bigger a N (15 N ) values as well as much simpler splittings of both the nitroxides and the spin adducts have made the kinetic studies of the H-abstraction and other radical reactions quite feasible.

ESR studies of ω-hydroperfluoroalkyl 1-methyl-2-substituted-pyrrolyl-5-carbonyl nitroxides and dual-parameter correlation analysis of their hyperfine splitting constants

Abstract Two series of ω-hydroperfluoroalkyl 1-methyl-2-substituted-pyrrolyl-5-carbonyl nitroxides, i.e., 5 and 6 generated in the H-abstraction/spin trapping reaction of twelve 1-methyl-2-substituted-pyrrolyl-5-carbaldehydes 1 with the H-abstracting agent RfN(O⋅)Rf (2) and the spin-trapping agent RfNO (4), were studied by ESR. Correlation analysis of the aN values of 5 and 6 with polar and spin-delocalization substituent constants shows that aN values are mainly affected by the polar effect, but the spin-delocalization effect also exists.

How does an alkoxy group at the benzylic carbon affect the transition state of the hydrogen-atom abstraction reaction? Correlation analysis of relative rates for 14 p-Y-substituted α,α-ethylenedioxytoluenes

Correlation analysis of the relative rates for the H-atom abstraction reaction of 14 2-(4-Y-phenyl)dioxolanes (p-Y-substituted α,α-ethylenedioxytoluenes, 1-Y) by N-bromosuccinimide (NBS) shows that the spin-delocalization effect is also operating at the transition state of the H-atom abstraction reaction and that the ethylenedioxy group at the benzylic carbon makes the spindelocalization more observable than do two methyl groups.

The electrophilic trifluoromethyl radical cf3 application of the dual-parameter equation to the correlation analysis of relative rates of the trifluoromethylbromo addition reactions to 14 p-y-substituted phenylacetylenes

Abstract A rigorous procedure was applied to the measurement of the relative rates, i.e., kr(Y) = kY/kH, of the trifluoromethylbromo addition reactions to 14p-Y-substituted phenylacetylenes (1-Y, with Y =F, Cl, Br, Me, Bu, OMe, SMe, SiMe3, CF3, CN, NO2, SOMe, COMe and CO2Me). The reaction was run in cyclohexane under nitrogen at 55 ±0.5 °C and was initiated by di-t-butylperoxy-oxalate. Correlation analysis of the data suggests that a spin effect is also operating at the transition state of this addition reaction and that the dual-parameter equation is applicable to this reaction.

Study of the electron-transfer initiated reaction of N,N-dichloro-5-iodo-3-oxa-octafluoropentane sulfonyl amide and carbomethoxydifluoromethane sulfonyl azide with 2-methyl-2-nitrosopropane

Abstract The reactions of N,N-dichloro-5-iodo-3-oxa-octafluoropentane sulfonyl amide (1) and carbomethoxydifluoromethane sulfonyl azide (2) with 2-methyl-2-nitrosopropane (3) have been studied by EPR spectroscopy. Our results suggest that these reactions are initiated by electron transfer (ET) between the perfluoroalkane sulfonyl compounds and the donor 3. The reaction of the dichloroamide 1 with 3 yields either one of two products, i.e., the unsymmetrical nitroxide 4 or the symmetrical nitroxide 5, depending on the nature of the solvent and the amount of 1 used. Possible mechanistic paths are discussed.