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MODEL PAPER 9 — Chemistry STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceChemistryMODEL PAPER 91 Mark
Question
Assertion (A): In comparison to ethyl chloride it is difficult to carry out nucleophilic substitution on vinyl chloride.
Reason (R): Vinyl group is electron-donating.
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Answer

(c) A is true but R is false.
Explanation: $CH _2= CH - Cl$ has some partial double bond character between carbon and a chlorine atom. So, nucleophilic substitution is difficult to carry as it is difficult to break the partial double bond in vinyl chloride than ethyl chloride $CH _3 CH _2$
→ Cl where there is no double bond character.
The vinyl group is not electron-donating. The carbon halogen bond in vinyl halides has some double-bond character and thus a little difficult to break.

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