Advertisements
Advertisements
Question
Give reasons for the following:
(CH3)3C–O–CH3 on reaction with HI gives (CH3)3C–I and CH3–OH as the main products and not (CH3)3C–OH and CH3–I.
Advertisements
Solution 1
Usually, iodide, being a big nucleophile, attacks on the group with low steric hindrance and the reaction proceeds by SN2 mechanism.
However, in this case, methanol, on leaving generates a tertiary carbocation, which is more stable. Hence, this reaction proceeds by SN1 mechanism and therefore, we get (CH3)3C-I and CH3-OH as the major products.
Solution 2
CH3)3-C–O–CH3 is an ether with two different alkyl groups, of which (CH3)3-C-, a tertiary alkyl group, on reaction with hydrogen halide (HI) forms a tertiary halide. This occurs as the reaction is an SN1 reaction. The reaction involves the formation of a stable carbocation. If the ether has a primary alkyl group, then the reaction follows the SN2 mechanism.
APPEARS IN
RELATED QUESTIONS
What are ambident nucleophiles? Explain with an example.
Write the structure of the major organic product in the following reaction:
\[\ce{CH3CH2Br + KCN ->[aq{.} ethanol]}\]
What happens when methyl chloride is treated with KCN?
What is the action of the following on ethyl bromide?
silver acetate
In a coordination entity of the type [PtCl2(en)2]2+ which isomer will show optical isomerism?
Which of the following is an optically active compound?
Which of the following undergoes nucleophilic substitution exclusively by SN1 mechanism?
Which of the following statements are correct about this reaction?
(i) The given reaction follows SN2 mechanism.
(ii) (b) and (d) have opposite configuration.
(iii) (b) and (d) have same configuration.
(iv) The given reaction follows SN1 mechanism.
Which of the following compounds will show retention in configuration on nucleophile substitution by OH− ion?
Consider the reactions,
(i) \[\begin{array}{cc}
\phantom{}\ce{\underset{}{(CH3)2CH - CH2Br} ->[C2H5OH] \underset{}{(CH3)2CH - CH2OC2H5 + HBr}}\\
\end{array}\]
(ii) \[\begin{array}{cc}
\phantom{}\ce{\underset{}{(CH3)2CH - CH2Br} ->[C2H5O-] \underset{}{(CH3)2CH - CH2OC2H5 + Br-}}\\
\end{array}\]
The mechanisms of reactions (i) and (ii) are respectively:
