Carbon tetrachloride radiolysis

Reaction Scheme of CMS Resists. The transient absorption spectrum shown in Figure 6 and observed for irradiated CMS films is mainly composed of two components as based on pulse radiolysis data of solid films of CMS and polystyrene, and CMS and polystyrene solutions in cyclohexane, chloroform, and carbon tetrachloride. An absorption with a maxima at 320 nm and 500 nm as due to the charge transfer radical-complex of the phenyl ring of CMS and chlorine atom (see Figure 14) and an absorption with maxima at 312 and 324 nm is due to benzyl type radicals (see Figure 11). 

The pulse radiolysis studies of liquid alkanes have relevance to the radiolysis of polyethylene and related polymers. In liquid alkanes at ambient temperature, the reaction intermediates such as alkane radical-cations, olefin radical-cations, olefine dimer-cations, excited states, and alkyl radicals have been observed after the electron-pulse irradiation [90-93]. According to the nanosecond and subnanosecond studies by Tagawa et al., the observed species were alkane radical cations, excited states, and alkyl radicals in n-dodecane excited states and cyclohexyl radical were observed in cyclohexane, and only radicals in neopentane [91, 93]. Olefin radical-cations were also detected in cyclohexane containing carbon tetrachloride [92],... 

Another example is the use of solvent mixtures to study protonation reactions. Thus, pulse radiolysis of acetone/2-propanol/carbon tetrachloride has been shown to produce HCl within approximately 100 ns, and this system has been used to measure rates of fast protonation reactions [43]. 

Carbon tetrachloride probably represents the simplest example of radiolysis of a halogen compound. Studies with both X-rays - and Co y-rays - ... 

Phosgene is formed, in addition to chlorine and hexachloroethane, when carbon tetrachloride is irradiated in the presence of oxygen . Mund et have reported on the effect of a-radiation on carbon tetrachloride. Zimin and Egorova have found that carbon tetrabromide, like carbon tetrachloride, produces free halogen upon radiolysis. 

Tn the y radiolysis of glasses of carbon tetrachloride containing various solutes, the positive ions of these solutes are formed by electron transfer to the positive ion of the host, (CCh) (10). Recent experiments in the y irradiation at 20 °K. of 3-methylpentane glasses with 1 mole % of CCI4 show that the species Cl2 is formed (5). No evidence of the positive ion of carbon tetrachloride with an absorption maximum at 4800 A. was obtained at 20°K., although this species is observed at higher temperatures (5,12). 

The pulse radiolysis of carbon tetrachloride and solutions of carbon tetrachloride shows that transient species are produced with absorption spectra from 3000 to 7000 A. (3). These species have been assigned to chlorine atom-solute charge transfer complexes (4). No assignment was made to positive ions as in the glassy state. 

The nanosecond pulse radiolysis technique has been described (8, 14). Carbon tetrachloride was purified as follows Matheson Research grade CC14 was dried over anhydrous potassium carbonate for several days, and subsequently distilled, discarding initial and final fractions. However, untreated research grade CCLj gave identical results to that treated as above. Zone refined naphthalene, anthracene, biphenyl, and N,N,N, N -tetramethyl-paraphenylenediamine (TMPD) were used pyrene, 1 2 benzanthracene were recrystallized from absolute alcohol, and aniline was purified as described in an earlier paper (6). Normal hexane, cyclohexane, 3-methylpentane, benzene, and toluene were Matheson research grade methanol and ethyl alcohol were analytical grade. 

Figure 10. CICN production (Curves 1 and 2) and chlorine production (Curves 1 and 2 ) as a function of absorbed dose during the y-radiolysis of nitrogen solutions in tetra-chloroethylene (Curves 1 and 1 ) and in carbon tetrachloride (Curves 2 and 2 ) at 30°C. Nitrogen pressure above solution was 120 atm.

Styrene and a-Methylstyrene in Organic Solvents. Pulse radiolysis studies have been made on styrene and a-methylstyrene dissolved in methanol, benzene, carbon tetrachloride, dioxane, tetrahydrofuran, hexane, and cyclohexane (9, 24, 29, 30, 31). The results are easiest to understand for the aliphatic hydrocarbons and especially for the styrene in cyclohexane, which has been studied the most (31). For such solutions, two absorption bands were seen after the pulse by Keene, Land, and Swallow (24) and Schneider and Swallow (30) with peaks at 320 and 390 m/. The absorption at 320 m/u disappeared slowly by complex kinetics, and the 390-m/x absorption was very short lived, decaying by second-order kinetics with k/c = 4-7 X 10 cm. sec.-1. The relative intensities of the two peaks were quite variable. Chambers et al. saw the long lived absorption at 320 m/, but did not see a separate peak at 390 m/a, although it was observed that the absorption at 375 mfi decayed rapidly with k/e = 2.6 X 106 cm. sec.-1. 

The use of pulse radiolysis and scavenging techniques has identified the electron in liquid hydrocarbons [116]. In these non-polar media, interaction between the electron and the solvent is, of course, very small and it is doubtful whether such electrons can properly be described as solvated. The pulse radiolysis of hexane or 3-methyl hexane gave rise to a short lived transient species absorbing at Xm ax = 1500 nm. Rate coefficients for reaction in hydrocarbon solutions at 193°K are given in Table 10. Baxendale et al. [117] have studied the pulse radiolysis of liquid methylcyclohexane and obtained rate coefficients for the reactions of the electron with carbon tetrachloride and pyrene at 293° K. Relative rate coefficients have been obtained by irradiation of hydrocarbons containing two electron scavengers [118]. 

Thus in the presence of halogenated compounds, the radiolytically produced electron may preferentially react with the halogenated molecules. Also, the free radical moiety produced from the halogenated molecule, e.g., the free radicals formed in reaction (R-20), may participate in the reactions leading to the formation of several new products. For example, radiolysis of cyclohexane in the presence of carbon tetrachloride was reported to lead to a chain reaction [Henglein et al., 1963 Stone and Dyne, 1964]. 

In another radiation technique, pulse radiolysis, high-energy electrons formed in a Van de Graaff generator lead to cation radical reactions in solution with very short periods of irradiation. Solvent ions or radicals are formed which may next remove an electron from the solute. For example, TMPD and some triarylaminc cation radicals have been made in carbon tetrachloride solution [(66) and (67)] by... 

The above theories invoke essentially the physical properties of the grafting system to explain the observed copolymerization phenomenon. Swelling either from the solvent or monomer or both is also an important factor in these reactions. However if the data in Figures 1 and 2 are considered, a further theory would appear to be necessary to explain the solvent properties observed, especially the trend in the alcohol data to n-octanol and also the benzene, pyridine, chloroform and carbon tetrachloride results. Thus, as previously proposed for radiation grafting processes, it is necessary to consider the radiation chemistry of the system and in particular the radiolysis products of the solvent in any complete analysis of the copolymerization process. It has been suggested that a contribution to the mechanism of the acceleration effect of methanol can be due to the radiolytic scavenging properties of styrene and hence the relative numbers of styrene... 

The peroxyl radical that has been most extensively studied for its interactions with antioxidants is the trichloromethyl peroxyl radical (CCI3O ), which is produced during the metabolism of CCLt via reaction of the trichloromethyl radical (CCI3) with oxygen [69] and is known to cause hepatoxicity and other types of tissue injury. Pulse radiolysis is normally used to generate this radical and in primarily aqueous solutions it is prepared in air saturated solutions by adding carbon tetrachloride, 2-propanol and acetone and is produced via the following reactions [70]. 

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