How are alkenes obtained?

1 Answer
Apr 30, 2016

Alkenes are obtained by elimination reactions

Explanation:

Alkenes are obtained by elimination reactions Following are some examples.

  • Dehydration of Alcohol
    In this process alcohol is dehydrated
    (1) byheating with conc.H_2SO4 at 450KH2SO4at450K or by P_2O_5P2O5
    or (2) by passing alcohol vapor over heated Alumina,Al_2O_3Al2O3

Reaction
RCH_2CH_2OH->RCH=CH_2+ H_2ORCH2CH2OHRCH=CH2+H2O

  • Dehydrohalogenation
    In this process Alkyl halide except fluoride is reacted with alcoholic KOHKOH
    Reaction
    RCH_2CH_2X->RCH=CH_2+ HXRCH2CH2XRCH=CH2+HX (where X =Cl,Br,I)

- Dehalogenation
In this process vicinal or geminal dihalide except fluoride is heated with alcoholic ZnZn

Reaction
RCHXCH_2X+Zn->RCH=CH_2+ ZnX_2RCHXCH2X+ZnRCH=CH2+ZnX2 (where X =Cl,Br,I)

Other process like cracking of alkane is also there