Chlorine atoms hydrogen atom transfer

The use of benzene as a solvent eliminates the chlorinated organic products in Table II. This point and the products in the table are consistent with radical abstraction (hydrogen atom transfer) from the substrate, cyclohexene, by the high valent (and likely oxometal) intermediate form of the TMSP complexes, followed by chlorine abstraction from the solvent by intermediate organic radicals. Separation and analysis of the two phases after the reaction reveals that the polyoxometalate is intact. 

Hendry, D.G., Mill, T., Piszkiewicz, L., Howard, J.A., Eigenmann, H. K. (1974) Critical review of hydrogen-atom transfer in the liquid phase. Chlorine atom, alkyltrichloromethyl, alkoxy, and alkyl peroxy radicals. J. Phys. Chem. Ref. Data 3, 937-978. 

This approach has been taken for the reaction of chlorinated ethenes with Zn° [125,165] and Fe° [88,166], resulting in separate rate constants for all the reactions shown in Fig. 3. Care must be taken in using these parameters in predictive modeling, however, as it is not yet known how sensitive the relative values of these rate constants are to pH, thickness and composition of the oxide film, etc. The same caution applies where the approach represented by Eq. (25) is used to describe parallel mechanisms of transformation. For example, it has recently been reported that several experimental factors influence the relative contributions of dissociative electron transfer, hydrogen atom transfer, and reductive elimination to the dechlorination of carbon tetrachloride and TCE by Fe° [177],... 

Trialkyltin hydrides are effective hydrogen atom transfer agents, and trialkyltin radicals wiU abstract chlorine, bromine, or iodine atoms from alkyl halides. Together with a radical initiator, such as AIBN and trialkyltin hydrides, alkyl halides can give reduction or other radical-derived products (Scheme 4.27). 

There are no proven examples of 1,2-hydrogen atom shifts this can be understood in terms of the stereoelectronie requirements on the process. The same limitations are not imposed on heavier atoms (e.g. chlorine). The postulate309 that ethyl branches in reduced PVC are all derived from cbloroethyl branches formed by sequential 1,5-intramolecular hydrogen atom transfers as described for PE (Section 4,4.3.1) has been questioned.,6,6 It has been shown that many of these ethyl branches are derived from dichloroethyl groups. The latter are formed by sequential 1,2-chlorine atom shifts which follow a head addition (Section 4.3.1.2). 

It has been proposed that this reaction intermediate could decompose to produce HCN and CH3 [55], Chemiluminescence from alkanes can be greatly enhanced by addition of HC1. The proposed explanation is that energy transfer from active nitrogen dissociates HC1 to produce chlorine atoms, which have rapid hydrogen-atom abstraction reactions with alkanes,... 

In the HC1 molecule, the shared electrons are attracted more by the chlorine atom (electronegativity value 3.0) than by the hydrogen atom (electronegativity value 2.1). But the total transfer of electrons from hydrogen to chlorine does not happen because the electronegativity difference between hydrogen and chlorine is only 0.9, less than the 1.9 needed to form an ionic bond. 

Photodegradation of DDT by the protease-liberated flavo-protein from TX-20 resulted in the formation of TDE as the major product in addition to three other minor compounds. It has been well established that DDT conversion to TDE, anaerobically, is a reductive process involving replacement of a chlorine atom by hydrogen. On the other hand, it has been suggested that photo-lytic reactions involve a charge transfer from an amine to DDT and a subsequent pickup of a proton. Thus there is a possibility that the photochemical reaction involving flavoproteins undergoes a similar reaction scheme. Much more data are, however, needed to confirm this point. 

Conversion of alkanes means substitution of a hydrogen atom for a heteroatom. This is achieved at the anode by transfer of two electrons from a C—H bond to the electrode and reaction of the intermediate car-bocation with a nucleophile. Chemically in most cases either a chlorine or bromine... 

---