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15th of March 2017
Chemistry
Q:

Why unsaturated hydrocarbons show addition reactions but not sustitution reaction?

Sayon Ghosh - CBSE - Class X

Tuesday, March 14, 2017 at 19:24:PM

A:

Hi Sayon,

In unsaturated hydrocarbons valency of carbon is fulfilled by double or triple bond there is space to add another substituent in place of multiple bonds between one carbon and other carbon of the same compound
In saturated compounds all carbons are attached through 4 single bonds, which means there is no space to add another substituent , if they undergo addition that would mean a particular carbon will be having 5 single bonds which is not desirable. They can only replace one of their groups with a new one.  That's why they always undergo substitution.

Wednesday, March 15, 2017 at 17:47:PM