Seiko Nakagawa

Degradation of halogenated carbons in alkaline alcohol

Abstract 1,1,2-Trichloro-trifluoroethane, 1,2-dibromo-tetrafluoroethane, 2,3,4,6-tetrachlorophenol, 1,2,4-trichlorobenzene, and 2,4,6-trichloroanisole were dissolved in alkaline isopropyl alcohol and irradiated with 60 Co gamma rays after purged with pure nitrogen gas. The concentration of the hydroxide ions and the parent molecules decreased with the dose, while that of the halide ions and the organic products, with less halogen atoms than the parent, increased. Chain degradation will occur in alkaline isopropyl alcohol.

Reactivity of solvent alcohol on degradation of CFC113

1,1,2-Trichloro-trifluoroethane (CFC113) was dissolved in alkaline 1-butanol, 2-butanol, iso-butyl alcohol, and phenyl ethyl alcohol and irradiated with 60Co gamma rays after purged with pure nitrogen gas. In all these solvents, the concentration of CFC113 and hydroxide ion decreased and that of chloride ion increased with a dose observed in 2-propanol solution. The reaction efficiency increases in order of 1-butanol<iso-butyl alcohol<phenyl ethyl alcohol<2-butanol<2-propanol. The solvent effect will depend on the binding energy of the αC–H of the alcohol molecule and electron affinity and dipole moment of the ketones or aldehydes produced from the alcohols.

Negative chemical ionization mass spectrometric study on the electron attachment to CFxCl4−x(x=1,2) and CBryCl4−y(y=1,2)

Abstract The temperature dependence of the formation of negative ions from CFCl 3 , CF 2 Cl 2 , CBrCl 3 , and CBr2Cl2 was studied using negative chemical ionization mass spectrometry. For CFxCl4−x(x=1,2), chloride ion was observed and the activation energy agreed with previous data. For CBryCl4−y(y=1,2), Cl− and Br− were observed when the concentration of the sample was 0.01 mol%. The branching ratio of Cl− increases and that of Br− decreases with increasing temperature for CBrCl3. Otherwise, the temperature dependence of the branching ratio was lower for CBr2Cl2. For the higher concentrations of CBrCl3, BrCl− was observed. Not only BrCl− but also Br2− was observed for CBr2Cl2. CBrCl2− and CCl3− or CBr2Cl−, whose production path is electron attachment to the radicals produced from electron attachment to the parent molecules were also observed. Based on these results, the relative ratio of the electron attachment reactions can be estimated.

The branching ratio of anions in thermal electron attachment to halogenated fluorocompounds

Abstract The temperature dependence of the formation of negative ions from C 6 F 5 X , C 6 F 4 X 2 ( X = Cl , Br , I ) , XC 6 F 4 Br ( X = Cl , CF 3 , BrC 6 F 4 , CN ) , and NC5F4Br was studied using negative chemical ionization mass spectrometry. Cl− and the parent negative ion for chlorofluorobenzene, Br − , ( M – Br ) − (M=parent molecule), and the parent negative ion for bromofluorocarbon, and I− and (M–I)− for iodofluorobenzene were observed. The intensity of (M–X)− and the parent negative ion relative to that of halide ion changes with temperature. The relative intensity, C 6 F 4 X − / X − ( X = Br , I ) of 1,2-C6F4X2 is smaller than that of 1,4-C6F4X2. It seems that the heat of formation of (M–X)−+X relative to that of (M–X)+X− in 1,2-C6F4X2 would be higher than in 1,4-C6F4X2 and C6F5X. The temperature dependence of the relative ratio, (M–Br)−/Br−, can lead the relative trend of the electron affinity of M–Br, as C6F4CN>CF3C6F4>C6F4C6F4Br>C5F4N>C6F4Cl>C6F4Br>C6F5. This is correlated with the atomic charge distribution of (M–Br)− calculated using the Hartree–Fock method.

Improvement of the method to estimate the relative reaction rate constants of hydroxyl radical with polyphenols using ESR spin trap: X-ray irradiation of water with a flowing system

Abstract UV-photolysis of hydrogen peroxide is a useful technique to produce hydroxyl radical. However, it is not an appropriate method to estimate the reactivity of polyphenols with hydroxyl radicals because many of the polyphenol derivatives also absorb the UV-light to generate hydroxyl radicals. In this study, X-ray irradiation of water with a flowing system was applied to estimate the reactivity of hydroxyl radicals with polyphenols using electron spin resonance (ESR) spin trap. The obtained relative reaction rates reasonably agreed with previous data by pulse radiolysis. This method will be a useful technique to estimate the reactivity of antioxidants including polyphenols with hydroxyl radicals.