🎁BACK-TO-SCHOOL DEAL. Subscribe Now to get 40% OFF at only 8.49 USD/month, only valid until Sep 30th, 2024

Question

Question
Predict the major product of the following sequence of reactions. OH 1) PBrz 2) Mg 3) CH2OH ? OCH OH

Asked By CrystalWaves53 at

Answered By Expert

Will

Expert · 2.6k answers · 2k people helped

Step 1/2

The objective of the question is to determine the product of the reaction of a `"1-cyclopentylethanol"` with `PBr_{3},\ Mg` and `CH_{3}OH` .

The substitution reactions are those in which a particular group in the compound gets replaced by a new group. If a nucleophile is the new group then the reaction is termed nucleophilic substitution.

Explanation:

A nucleophile can get substituted via two pathways, i.e., `S_{N}1` and `S_{N}2` . The former one involves a two-stepped mechanism whereas the latter one is a one-stepped reaction.

Step 2/2

The reaction of a `"1-cyclopentylethanol"` with `PBr_{3},\ Mg` and `CH_{3}OH` is given as follows:

Explanation:

In the reaction mechanism, The first step involves the nucleophilic attack of the `"O-atom"` of the `-OH` group on the electrophilic `"P-atom"` of ith `PBr_{3}` , one of ith `Br` is released as `Br^{-}` . Due to this, a positive charge is acquired by the `"O-atom"` . In the next step, the nucleophilic attack of `Br^{-}` occurs on the same `"C-atom"` containing `(OH^{+})PBr_{2}` group. This is an `S_{N}2` reaction, which produces `"1-bromoethyl cyclopentane"` and the removal of `(OH)PBr_{2}` is favored. The product formed then undergoes a reaction with `Mg` to form a Grignard reagent `"1-(cyclopentylethyl)magnesium bromide"` . The further reaction of this Grignard reagent with `CH_{3}OH` to give `"ethylcyclopentane"` and `CH_{3}O-MgBr` . It is an acid-base type of reaction in which `CH_{3}OH` is an acid that donates its `H^{+}` to the base (Grignard reagent) to synthesize an alkane.

Final Answer

The correct option is `(c)` as the product formed is an alkane.

🧑‍🏫 More Questions