Chemistry - GOC Question with Solution | TestHub
Use arrow pushing to explain the following reactions (heterolytic-type reaction mechanisms). The reaction types of (a), (b) and (c) respectively are :
(a) 
(b) 
(c) 
Options:
Answer:
Solution:
(a) This is an example of an SN2 reaction mechanism, converting an alkyl iodide (iodomethane) to an alkyl nitrile (acetonitrile). The arrow pushing is illustrated below:
(b) This is an example of a Claisen rearrangement, which occurs through a concerted reaction mechanism. Concerted mechanisms can be described by the movement of either electron pairs or single electrons. However, they are generally represented by the movement of electron pairs using double-barbed arrows, similar to heterolytic reaction mechanisms. The arrow pushing is illustrated below:
(c) This is an example of a cation-π cyclization. Unlike the previously described heterolytic reaction mechanisms, this reaction is influenced by a positive charge. This reaction also shares some characteristics with concerted mechanisms, as the formation of new bonds occurs almost simultaneously. The arrow pushing is illustrated below:
Answer: (C).
