Screen Shot 2017-12-03 at 1.2348 A- Search Which mechanism step is not required

Question

Screen Shot 2017-12-03 at 1.2348 A- Search Which mechanism step is not required for the following Gabriel synthesis? image1.jpeg Search 1.KOH/EIDH The first sop of the reaction is PHOTON TRANSFER as te imide protos Co I-CO) is acidic(acd bass raction) 2. Br 3. KOH, Ho H, e, Proton han L Nucleophile elimination IL Proton transfer I. Electrophile elimination V. Nucleophilic addition H,o Expert Answer H of Anonymous answered this 121 answers proton transfer Hide comments (1). Untitled CHEGG is providing 3 different answers here. Which one is correct?! Anonymous Electrophile elimination (Correct Answer) y nosted 2 wnars th ATTEMPT

Explanation / Answer

The mehanism which is given in the question explains the three different reactions taking place so as to yield the final product. The first reaction is a proton transfer reaction which is aided by the reagents KOH/EtOH. In order to clarify any doubts let me assert that abstraction of a proton by a base is considered as proton transfer.

Now, if we do not add the second reagent, i.e. the (bromomethyl)cyclopropane, the reaction does not proceed further. However, on addition of this reactant, the reaction continues leading to a substitution reaction (SN2). It must be noted that this step involves substitution and not elimination reaction.

In the final step, it involves, an attack of a nucleophile (i.e. H2O), leading to the final product as shown in the reaction mechanism. We must not forget that cyclopropylmethanamine is also a nucleophile and it is eliminated in this last step. In this step, the mechanism is slightly tricky: It appears as though it is a substitution reaction; however, the step is a two step process i.e. firstly the initial attack by a nucleophile, then followed by an elimination reaction where cyclopropylmethanamine is produced. So this step is also known as both a nucleophilic addition as well as nucleophilic elimination.

Now, in conclusion lets recollect what we have discussed above and sort out the steps involved in the entire synthetic pathway. Here, the steps involved were: PROTON TRANSFER, SN2(substitution reaction), NUCLEOPHILIC ADDITION and NUCLEOPHILIC ELIMINATION.

So, if we were told to sort the odd one out from the choices given in the question we can confidently say that in Gabriel synthesis the mechanism which is not required is ELECTROPHILE ELIMINATION.

Hope that your doubts are clarified now!

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.