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प्रश्न
Arrange the compounds of the following set in order of reactivity towards SN2 displacement:
2-Bromo-2-methylbutane, 1-Bromopentane, 2-Bromopentane
उत्तर
The SN2 reaction involves the formation of a transition state with the carbon atom surrounded by 5 additional atoms (groups). A transition state requires minimum steric interactions. The most suitable substrates for SN2 reactions are 1° alkyl halides, followed by 2° and 3° alkyl halides. The order of reactivity towards SN2 is 1° > 2° > 3°> aryl halide. Based on this, the order will be
\[\begin{array}{cc}
\phantom{.....................}\ce{Br}\phantom{...........................}\ce{Br}\\
\phantom{...................}|\phantom{.............................}|\\
\ce{\underset{1-Bromopentane}{H3C - (CH2)3 - CH2Br} > \ce{\underset{2-Bromopentane}{CH3 - CH - (CH2)2 - CH3}} > \ce{CH3 - C - CH2 - CH3}}\\
\phantom{.................................................}|\\
\phantom{....................................................}\ce{\underset{2-Brmo-2-methylbutane}{CH3}}\
\end{array}\]
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संबंधित प्रश्न
Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction
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.
Which alkyl halide from the following pair would you expect to react more rapidly by an SN2 mechanism? Explain your answer.
CH3CH2CH2CH2Br or \[\begin{array}{cc}
\ce{CH3CH2CHCH3}\\
\phantom{...}|\\
\phantom{....}\ce{Br}\
\end{array}\]
Which compound in the following pair will react faster in SN2 reaction with OH−?
(CH3)3CCl or CH3Cl
What happens when ethyl chloride is treated with aqueous KOH?
Given reasons: SN1 reactions are accompanied by racemization in optically active alkyl halides.
What is the action of the following on ethyl bromide:
moist silver oxide
Which compound in the following pair reacts faster in SN2 reaction with OH–?
- CH3Br or CH3
- CH3Cl, (CH3)3CCl
Most reactive halide towards SN1 reaction is ____________.
Which of the following is the correct order of decreasing SN2 reactivity?
An important chemical method to resolve a racemic mixture makes use of the formation of ______.
Which of the following compounds will give a racemic mixture on nucleophilic substitution by OH ion?
1-Bromoethane, 1-Bromopropane, 1-Bromobutane, Bromobenzene
Which of the following statements are correct about the kinetics of this reaction?
(i) The rate of reaction depends on the concentration of only (b).
(ii) The rate of reaction depends on concentration of both (a) and (b).
(iii) Molecularity of reaction is one.
(iv) Molecularity of reaction is two.
Match the reactions given in Column I with the types of reactions given in Column II.
| Column I | Column II | |
| (i) |  |
(a) Nucleophilic aromatic substitution |
| (ii) | \[\begin{array}{cc} \ce{CH3 - CH = CH2 + HBr -> CH3 - CH - CH3}\\ \phantom{............................}|\phantom{}\\ \phantom{.............................}\ce{Br}\phantom{} \end{array}\] |
(b) Electrophilic aromatic substitution |
| (iii) |  |
(c) Saytzeff elimination |
| (iv) |  |
(d) Electrophilic addition |
| (v) | \[\begin{array}{cc} \ce{CH3 CH2 CH CH3 ->[alc.KOH] CH3 CH = CH CH3}\\ \phantom{}|\phantom{..........................}\\ \phantom{}\ce{Br}\phantom{........................} \end{array}\] |
(e) Nucleophilic substitution (SN1) |
Which of the following is the definition of chirality?
Convert bromoethane to propanamine.
An organic compound A with the molecular formula (+) C4H9Br undergoes hydrolysis to form (+) C4H9OH. Give the structure of A and write the mechanism of the reaction.
Identify the product in the following reaction: 
Explain why Grignard reagents should be prepared under anhydrous conditions.
