How can alkyl halides be prepared from alkanes?

Question

Christian Anderson · Accepted Answer

#"Free radical halogenation........."#

Additionally, the reaction scheme is typically built as follows:

#i.# #"Initiation: "X_2 + hnu rarr 2dotX#

#ii.# #"Propagation(i): "dotX + H_3CR rarr HX + H_2dotCR#

#"Propagation(ii): "H_2dotCR+ X_2rarr H_2XCR+ dotX#

#iii.# #"Termination: the coupling of two radical species,"#

#H_2dotCR+dotXrarrH_2CXR#

#2H_2dotCRrarrH_2RC-CH_2R#

The radical mechanism proposed is well supported by the small amounts of, say, ethane found in the product mix of methane halogenation.

The propagation step involves a cascade-type process, whereby a radical species' reaction produces another radical species that can carry on the reaction's chain reaction.

Jacob Anderson · Answer

undefined Alkyl halides can be prepared from alkanes through free radical halogenation. In this process, an alkane is exposed to a halogen (e.g., chlorine or bromine) in the presence of ultraviolet (UV) light or heat. The halogen undergoes homolytic cleavage, generating free radicals that react with the alkane, resulting in the substitution of a hydrogen atom with a halogen atom.