Question

The order of reactivity of halides towards ${S_N}1\;$ mechanism is:
(A) $benzyl > allyl > {1^o}{2^o} > {3^o} > Me$
(B) $Me > {1^o} > {2^o} > {3^o} > allyl > benzyl$
(C) ${3^o} > {2^o} > {1^o} > Me > allyl > benzyl$
(D) $benzyl > allyl > {3^o} > {2^o} > {1^o} > Me$

Answer 1

Hint : The response is a replacement nucleophilic unimolecular response. It is a two-venture response. In the initial step, the carbon-halogen bond breaks heterolytically with the halogen holding the recently shared pair of electrons.

Complete Step By Step Answer:
The ${S_N}1$ response is a replacement response in natural science, the name of which alludes to the Hughes-Ingold image of the instrument. " ${S_N}$ " Means "nucleophilic replacement", and the "1," says that the rate-deciding advance is unimolecular. In this manner, the rate condition frequently appeared as having first-request reliance on electrophile and zero-request reliance on nucleophile. This relationship holds for circumstances where the measure of nucleophile is a lot more prominent than that of the transitional. All things being equal, the rate condition might be all the more precisely depicted utilizing consistent state energy.
The response includes a carbocation middle of the road and is usually found in responses of optional or tertiary alkyl halides under firmly essential conditions or, under unequivocally acidic conditions, with auxiliary or tertiary alcohols. With essential and optional alkyl halides, the option ${S_N}2$ response happens. In inorganic science, the ${S_N}2$ response is regularly known as the dissociative system. This separation pathway is very much depicted by the cis impact. A response component was first proposed by Christopher In gold in 1940.
This response doesn't rely much upon the strength of the nucleophile, in contrast to the SN2 instrument. This kind of system includes two stages. The initial step is the ionization of alkyl halide within the sight of watery or ethyl liquor. This progression gives a carbocation as a middle of the road.

Note :
The request for reactivity of responses relies upon the dependability of carbocation middle of the road framed during nucleophilic replacement response. So pi bonds and cumbersome alkyl bunches build the strength of carbocations.