(a) Write any three methods of preparations of alkyl halides
(b) Write the following reactions
i) Williamsons synthesis of ethers ii) Reimer-Tiemann reaction
(a) Write any three methods of preparations of alkyl halides
(b) Write the following reactions
i) Williamsons synthesis of ethers ii) Reimer-Tiemann reaction
(a) 1. From alcohols: Alcohol on reaction with HX,PX3;PX5 OR SOCl2 form alkyl halide.
ROH+HClZncl2−−−→R−Cl+H2O
(b). By free radical halogenations:- Free radical chlorination or bromination gives mixture of isomeric mono and polyhalo alkanes.
CH3CH2CH2CH3 Cl2/urlightor heat CH3CH2CH2CH2Cl+CH3−CH−CH2−CH3 1-Chloro butane 2-Chlorobutane
(c ) . From alkene by addition of HX
CH2=CH2+HCl→CH3−CH2Cl
Alkene is converted to corresponding alkyl halide by reaction with HCl, HBr or HI.
(b) (i) Williamson’s synthesis of ether.
C2H5Cl+C2H5ONa→C2H5OC2H5+NaCl
When alkyl halide reacts with sodium alkoxide ethers are formed. This reaction can be used for the preparation of both symmetrical and unsymmetrical ether.
(ii) Reimer Tiemann Reaction
Phenol with chloroform in the presence sodium hydroxide gives a Salicylaldehyde, this reaction is called as Reimer – Tiemann reaction.
(a) 1. From alcohols: Alcohol on reaction with HX,PX3;PX5 OR SOCl2 form alkyl halide.
ROH+HClZncl2−−−→R−Cl+H2O
(b). By free radical halogenations:- Free radical chlorination or bromination gives mixture of isomeric mono and polyhalo alkanes.
CH3CH2CH2CH3 Cl2/urlightor heat CH3CH2CH2CH2Cl+CH3−CH−CH2−CH3 1-Chloro butane 2-Chlorobutane
(c ) . From alkene by addition of HX
CH2=CH2+HCl→CH3−CH2Cl
Alkene is converted to corresponding alkyl halide by reaction with HCl, HBr or HI.
(b) (i) Williamson’s synthesis of ether.
C2H5Cl+C2H5ONa→C2H5OC2H5+NaCl
When alkyl halide reacts with sodium alkoxide ethers are formed. This reaction can be used for the preparation of both symmetrical and unsymmetrical ether.
(ii) Reimer Tiemann Reaction
Phenol with chloroform in the presence sodium hydroxide gives a Salicylaldehyde, this reaction is called as Reimer – Tiemann reaction.
