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A dihalogen derivative X of a hydrocarbo...

A dihalogen derivative X of a hydrocarbon witn three carbon atom react with alocholic `KOH` and produces another hydrocarbon which forms a red precipitate with ammoniacal `Cu_2 Cl_2 * X` gives 'an aldehyde on reaction with aqueous KOH. The compound `X` is

A

a) 1,3 - dichloropropane

B

b) 1,2 - dichloropropane

C

c) 2,2 -dichloropropane

D

d) 1,1 -dichloropropane

Text Solution

Verified by Experts

The correct Answer is:
D
X is a three carbon compound with two halogenatom , so its molecular formula is `C_(3)H_(6)Cl_(2)` . Only terminal alkynes give red ppt with ammoniacal `Cu_(2)Cl_(2)` , so the hydrocarbon produced by the reaction of .X. with alc KOH , must be a terminal alkyne (ie , `CH_(3)C-=CH)`
`C_(3)H_(6)Cl_(2)overset("Alc KOH")toCH_(3)C-=CHoverset("Amm"Cu_(2)Cl_(2))tounderset("Red ppt")(CH_(3)C-=)C Cdarr`
Compound (X) gives an aldehyde when reacts with aqueous KOH .This suggests that both the halogens are present on same terminal carbon atom . Thus , the formula of compound (X) is

and the reactions are as follows :

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