Carbon-hydrogen bonds halogenation

The carbon-halogen bonds of aryl halides are both shorter and stronger than the carbon-halogen bonds of alkyl halides In this respect as well as m their chemical behavior they resemble vinyl halides more than alkyl halides A hybridization effect seems to be responsible because as the data m Table 23 1 indicate similar patterns are seen for both carbon-hydrogen bonds and carbon-halogen bonds An increase m s... 

Halogen dealkylation mimics O-dealkylation both in terms of mechanism and the commonality of the process. Virtually any drug that contains a carbon-hydrogen bond adjacent to a halogen atom will be subject to P450-catalyzed oxidative dehalogenation (Fig. 4.61). 

FHC=CHF adlayers. Results for the Pt (100) and (111) surfaces indicated that the first step of the surface reaction is the metallation of carbon-hydrogen bonds, the activation of which is much more efficient when halogen is substituted adjacent to the carbon-hydrogen bond. 

Heterocumulenes undergo insertion reactions with numerous substrates. In general, carbodiimides react faster than isocyanates and isothiocyanates, in that order. Insertions of carbodiimides into metal-hydrogen, metal-halogen, metal-mitrogen, metal-oxygen and metal-sulfur bonds are reported. Also insertions of carbodiimides into carbon-hydrogen bonds are known. 

The overall reaction results in the reduction of carbon-halogen bonds to carbon- hydrogen bonds. 

To start with, we can certainly say this the carbon-hydrogen bond is stretched but not entirely broken, and the hydrogen-halogen bond has started to form but is not yet complete. This condition could be represented as... 

Examination of the transition state shows that this is exactly what we would expect. As we saw before (Sec. 2.22), the hydrogen-halogen bond is partly formed and the carbon-hydrogen bond is partly broken. To the extent that the bond is... 

All contain an acyl group, R—c- bonded to another residue. The R substituent of the acyl group may be alkyl, aryl, alkenyl, or alkynyl the other substituent to which tlie acyl fragment is bonded may be a carbon, hydrogen, oxygen, halogen, nitrogen, sulfur, or other atom. 

---