Which of the following reactions gives `H_2C = C = C = CH_2 `

Options

A. `CH_2Br- CHBr = CH_2 overset(Zn// CH_3OH)to`
B. `HC -= C = CH_2 - COOH overset(aq. Na_2CO_3)to `
C. `BrCH_3 - C -= C -CH_2Br overset(Zn, "heat")to `
D. `2CH_2 = CH- CH_2I + Zn overset("heat")to`

Answer

C

Explanation

a) `CH_2Br - CHBr = CH_2 overset(Zn// CH_3OH)to CH_2 = CH=CH_2 + ZnBr_2`
b) `HC -= C - CH_2 - COOH overset(aq. Na_2CO_3)to`
`HC-=C-CH_2-COONa overset(Delta)to HC -= C - CH_3`
C) `BrCH_3 - C -= C-CH_2 Br overset("Zn, heat")to H_2C = C = CH_2+ ZnBr_2`
D) `2CH_2 = CH - CH_2I + Zn overset("heat")to`
`CH_2 = CH-CH_2 - CH_2 - CH = CH_2 + ZnI_2`