An allylic rearrangement or allylic shift is an organic reaction in which the double bond in an allyl chemical compound shifts to the next carbon atom. It is encountered in nucleophilic substitution.
In reaction conditions that favor a SN1 reaction mechanism the intermediate is a carbocation for which several resonance structures are possible. This explains the product distribution (or product spread) after recombination with nucleophile Y. This type of process is called an SN1' substitution.
Alternatively, it is possible for nucleophile to attack directly at the allylic position, displacing the leaving group in a single step, in a process referred to as SN2' substitution. This is likely in cases when the allyl compound is unhindered, and a strong nucleophile is used. The products will be similar to those seen with SN1' substitution. Thus reaction of 1-chloro-2-butene with sodium hydroxide gives a mixture of 2-buten-1-ol and 1-buten-3-ol.
In this video Mr. Lalit Sardana (IIT-JEE AIR 243) is explaining students about allylic carbon, thionyl chloride, darzens reagent, N bromo succinimide. Mr. Lalit Sardana knows the supreme art to awaken joy in creative expression and knowledge. So experience the same through his online teaching. The allylic substitution of alkene is a very important topic which is asked in 11th CBSE, 12th CBSE, JEE Mains, JEE Advanced, VITEEE, MPPET, AIPMT, WBJEE, KCET engineering, AFMC, etc.
