Why allyl halides are more reactive towards nucleophilic substitution than Vinyl halides?

dear ankita 
aryl hallides are less reactive than alkyl hallides towards nucleophillic substitution reaction beacuse of 
1- resonance effect = the electron pair of halogen are in conjugation with pi-electron of the ring , this causes delocalisation of electron on C-X bond which acquires partial double bond charecter as a result cleavage in aryl hallides are difficult than alkyl hallides , 
2- instability of phenyl cation = the phenyl cation formed as a result of self ionisation will not be stabilised by resonance and therefore sn1 mechanism cannot occur at all . 
3- hybridisation = alkyl hallides are sp3 hybridised whereas aryl hallides are sp2 hybridised , 
HOPE IT CLEARS 
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