C-Cl bond formation

One example of C — Cl bond formation by cleavage of a C — Hg bond with chlorine has been reported.The yield was moderate. 

The gas-phase reaction of hydrochloric acid and ethylene to give chloroethane was investigated in the framework of spin-coupled theory. The authors found little evidenee supporting the occurrence of a four-membered transition state. AIM confirmed that the breaking of the H-Cl bond occurs before the C-Cl bond formation. 

Figure 27.17 SchematicdiagramoftheeLectron-induced reaction of chlorobenzene with Si(lll)-7 x 7 interatomic distances are to scale. In (a) the chlorobenzene molecule is absorbed on a middle ad-atom (M) with the Cl atom weakly bound to a neighbouring cornerad-atom(C). Electron impact induces a concurrent breaking of a C—Cl bond formation of Si—Cl at the neighbouring corner ad-atom. Reproduced from Lu etal, J. Chem. Phys., 1999, 111 9905, with permission ofthe American Institute of Physics...

Whitfield and Sanford investigated C-Cl bond formation from two isolated Pd complexes. PhICl2 and A-chlorosuccinimide were used to oxidize (phpy)2Pd to form stable Pd species 44 and 45 (Eq. 38) [70]. These complexes were stable in solution for several hours at room temperature and were characterized by H and C NMR spectroscopy and X-ray crystallography (45). 

Finally, Arnold and Sanford have reported C-Cl bond formation from the Pd N-heterocyclic carbene complex 50 (Eq. 41) [71]. Complex 50 was prepared by oxidation of 49 with PhICl2 at —35°C in CH3CN and was characterized by and C NMR spectroscopy and X-ray crystallography. This complex could... 

In 2010, we reported a study regarding the role of the dinuclear core during C-Cl reductive elimination from 62, an analog of the dinuclear Pd complexes that have been proposed in catalysis (Fig. 35) [96,119]. Experimental results established that reductive elimination from 62 proceeds without fragmentation of the dinuclear core C-Cl bond formation proceeds from a dinuclear complex. 

Stoichiometric amounts of Pd(II) and exchange of the CuCl by CaClj led to no chlorohydrin formation. Jira proposed a reaction sequence of oxypalladation to AJ as observed in the Wacker process and oxidative-induced reductive C-Cl bond formation of the Pd alkyl intermediate AK (Scheme 16.41). 

Step 3 is bimolecular because two species, the carbocation and chloride ion, react together. Figure 4.9 is a potential energy diagram for this step, and Figure 4.10 shows the orbitals involved in C—Cl bond formation. 

To visualize bond formation by an outer atom other than hydrogen, recall the bond formation in HF. One valence p orbital from the fluorine atom overlaps strongly with the hydrogen 1 S orbital to form the bond. We can describe bond formation for any outer atom except H through overlap of one of its valence p orbitals with the appropriate hybrid orbital of the inner atom. An example is dichloromethane, CH2 CI2, which appears in Figure 10-11. We describe the C—H bonds by 5 -I S overlap, and we describe the C—Cl bonds by 5 - 3 p... 

Once UV photons have been absorbed by the polymer, excited states are formed they disappear by various routes, one of them leading to the formation of free radicals by cleavage of the C-Cl bonds. The very reactive Cl radicals evolved are most likely to abstract an hydrogen atom from the surrounding CHC1 sites to generate a-B,B ... 

An unusual template reaction leads to the Ni11 complex of a tetrabenzo-N2S2 macrocyclic ligand (676) via C—Cl bond cleavage and C—S bond formation according to Equation (25).1701... 

There is no reason to believe that any of these reactions involve formation of an intermediate acylium ion (Bentley et al., 1984) but the extent of C—Cl bond breaking probably increases markedly with increasing electron release from a substituent. Kinetic primary chloride isotope effects show that C—Cl bond breaking increases with increasing electron release in hydrolyses of 4-substituted benzoyl chlorides in aqueous acetone (Fry, 1970)... 

There are two possible pathways for formation of biphenyl. One is cleavage of C-Cl bond followed by H addition ... 

CHCI3. Similar 2 1 adducts were formed quantitatively when 122 was treated with CCl4, CH2CI2, or benzyl chloride.However, product 131 was obtained exclusively via silylene insertion into the C—Cl bond when 122 was allowed to react with tert-butyl chloride.It is proposed that the formation of 130 is a result of the initial halophihc interaction between the silylene and halocarbon. 

It was shown in 1941 that C —Cl bonds adjacent to C = C bonds could be converted readily to C —F bonds (like those in the side chains of arenes), e.g. formation of 2 from 1. 

The rate function was shown to vary with light intensity or energy absorbed and also with the hexachloroacetone concentration, rising with the amount of energy absorbed (as measured by the amount of CO formed) and decreasing with increase in hexachloroacetone pressure. An explanation advanced for this phenomenon is that there is a further alternative primary step in which a C-Cl bond is ruptured with the formation of chlorine atoms. These react with CCI3 radicals and increase the rate of formation of carbon tetrachloride. 

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