Chlorination scission

Chlorine scission of 2-chloroheptyl 4-nitrophenyl sulfide or of the 2,4-dinitro analogue in presence of lithium perchlorate formed the explosive 2-chloroheptyl perchlorate in 5-7% yield. 

The conversion of some carbohydrate chlorosulfates into the corresponding fluorosulfates with silver fluoride in methanol,31 and the formation of a mono(azi-dosulfate) derivative on treatment of methyl 4,6-dichIoro-4,6-dideoxy-a-D-galac-topyranoside 2,3-di(chlorosulfate) (8) with sodium azide in N,N-dimethylform-amide at room temperature,32 are two other examples of reactions involving sulfur-chlorine scission. 

The fluorinated titanocycle related to (28) is not obtained from C H CMUCgF. Photolysis of CP2T1X2 always gives first scission of a Cp—Tibond. In a chlorinated solvent, the place vacated by Cp is assumed by Cl. In the absence of some donor, the radical dimerizes (298—299). 

Photocuring of commercial unsaturated polyester-styrene mixture was effectively done in the presence of the VOL2CI photoinitiator complex. The chlorine atom produced by the scission of V—Cl bond in the VOL2CI complex is proven to be the initiating species for the photocuring process 168]. 

Starnes et al.hl have also suggested that the head adduct may undergo p-scission to eliminate a chlorine atom which in turn adds VC to initiate a new polymer chain. Kinetic data suggest that the chlorine atom does not have discrete existence. This addition-elimination process is proposed to he the principal mechanism for transfer to monomer during VC polymerization and it accounts for the reaction being much more important than in other polymerizations. The reaction gives rise to terminal chloroallyl and 1,2-dichlorocthyl groups as shown in Scheme 4.8. 

Also for these substrates, chain scission is beheved to start from weak sites having the structure shown in Formula below [391], which possibly derived from the incompleteness of the chlorine atom substitutional processes in the... 

Photolysis of PVC in the presence of oxygen causes oxidation of the polymer. However, under most (perhaps all) conditions, in both the presence and absence of oxygen, the photodegradation is complicated by scissions of carbon-chlorine bonds. Such scissions may lead to the formation of conjugated polyene sequences via sequential dehydrochlorination (Equation 1). The polyenes... 

Another mechanism for alkanone-sensitized photodehydrochlorination comprises Norrish type I scission of the ketone, followed by ground-state reactions of radicals (19). However, the evidence for such a mechanism is based on experiments that were carried out in the vapor phase (19). Initiation of the photodegradation of PVC by hexachloroacetone has been suggested to involve the abstraction of hydrogen from the polymer by radicals resulting from the photolysis of the ketone s carbon-chlorine bonds (22). 

Significant volumes of low oxidized starch are used at the size press. These starches are made by treatment in alkaline suspension with sodium hypochlorite so that from 1 to 2% active chlorine acts on the starch. The reaction is simple to perform. However, the reaction products are complex. Chain scission occurs at the same time that carboxyl and carbonyl groups are formed in the starch. It is most desirable to prepare the highest ratio of carboxyl to carbonyl as possible and this reaction is a function of the pH in the slurry. 

Chlorine dioxide gas is unstable and can rapidly decompose at high concentrations. It also decomposes rapidly to chlorine and oxygen with exposure to mild heat. Chlorine dioxide will decompose upon exposure to sunlight (Vogt et al. 1986). The gas-phase absorption spectrum for chlorine dioxide is the same as in aqueous solution (Kaczur and Cawfield 1993). The primary photochemical reaction of CIO2 in the gas phase corresponds to homolytic scission of one of the chlorine-oxygen bonds (i.e., C102 CIO +... 

The hydroxyquinoline (39-2) provides the starting material for a quinolone that incorporates a hydrazine function. Reaction of (39-2) with 2,4-dintrophenyl O-hydroxylamine ether (41-1) in the presence of potassium carbonate leads to a scission of the weak N-O hydroxylamine bond by the transient anion from the quinolone the excellent leaving character of 2,4-dinitrophenoxide adds the driving force for the overall reaction, resulting in alkylation on nitrogen to form the hydrazine (41-2). The primary amine is then converted to the formamide (41-3) by reaction with the mixed acetic-formic anhydride. Alkylation of that intermediate with methyl iodide followed by removal of the formamide affords the monomethylated derivative (41-4). Chlorine at the 7 position is then displaced by A-methylpiperazine and the product saponified. There is thus obtained amifloxacin (41-6) [48]. 

In case of atomic oxygen reactions the formation of formaldehyde was found to be characteristic for all compounds studied (naturally except NH3 and CO). As a rule, but not always, the main reaction is the formation of formaldehyde. For example, for dichloroethane the reaction proceeds with scission of the carbon bond, but CH2O does not appear to be the main reaction product. As the dichloroethane molecule contains chlorine, the main product will be HC1. The formation of a... 

Studies with sulfated zirconia promoted with Pt309 and industrial chlorinated Pt on AI2O3 isomerization catalysts310 led to the same conclusion, namely, the intermolecular mechanism operative for M-butane isomerization. A significant difference, however, is that on the industrial catalysts extensive hydride and methyl shifts taking place in the intermediates prior to P scission do not lead to a random distribution of the labels. Instead, a binomial distribution with one and three 13C atoms is observed.310 This is indicative of the involvement of the 31 carbocationic intermediate. 

Hecht SM, Long EC, van Atta RB, De Vroom E, Carter BJ (1990) On the mechanism of bleomycin activation and polynucleotide strand scission. In Bleasdale C, Golding BT (eds) Mol. Mech. Bioorg. Processes, Conference Proceedings. Royal. Soc. Chem., London, pp 100-114 Held AM, Halko DJ, Hurst JK (1978) Mechanisms of chlorine oxidation of hydrogen peroxide. J Am Chem Soc 100 5732-5740... 

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