Explain this reaction with example ( methods of preparation of haloalkanes : from alcohol)
Dear Student,
Choloroalkane can be formed easily with the help of PCl3.For example when ethanol reacts with PCl3 ,it forms chloroethane.The reaction is as follows:
3CH3CH2OH+PCl3------>3CH3CH2Cl+H3PO3
But we cannot form Bromoalkane or Iodoalkane with the above method because PBr3 and PI3 are not stable compounds. Hence this reaction takes place in the presence of red phosphorus where this red phosphorus forms freshly prepared PBr3 and PI3 by reacting with bromine or iodine.
R--OH reacts in the presence red phosphorus/Br2 to form R-Br(bromoalkane).
CH3CH2OH+red P/Br2------> CH3CH2Br
R--OH reacts in the presence red phosphorus/I2 to form R-I(Iodoalkane).
CH3CH2OH+red P/I2------> CH3CH2​​​​​​​I
Here R-any alkyl group
Regards
Choloroalkane can be formed easily with the help of PCl3.For example when ethanol reacts with PCl3 ,it forms chloroethane.The reaction is as follows:
3CH3CH2OH+PCl3------>3CH3CH2Cl+H3PO3
But we cannot form Bromoalkane or Iodoalkane with the above method because PBr3 and PI3 are not stable compounds. Hence this reaction takes place in the presence of red phosphorus where this red phosphorus forms freshly prepared PBr3 and PI3 by reacting with bromine or iodine.
R--OH reacts in the presence red phosphorus/Br2 to form R-Br(bromoalkane).
CH3CH2OH+red P/Br2------> CH3CH2Br
R--OH reacts in the presence red phosphorus/I2 to form R-I(Iodoalkane).
CH3CH2OH+red P/I2------> CH3CH2​​​​​​​I
Here R-any alkyl group
Regards