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प्रश्न
In which reaction mechanism carbocation is formed?
पर्याय
SN1
SN2
Both SN1 and SN2
None of them
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उत्तर
SN1
APPEARS IN
संबंधित प्रश्न
How do you convert the following:
Ethanol to propanenitrile
Write the main products when methyl chloride is treated with AgCN.
Which would undergo SN2 reaction faster in the following pair and why ?
Write the isomers of the compound having the formula C4H9Br.
Which compound in the following pair will react faster in SN2 reaction with OH−?
CH3Br or CH3I
Which compound in the following pair will react faster in SN2 reaction with OH−?
(CH3)3CCl or CH3Cl
How will you bring about the following conversion?
Toluene to benzyl alcohol
SN1 reactions are accompanied by racemization in optically active alkyl halides.
Which would undergo SN2 reaction faster in the following pair and why ?
CH3 – CH2 – Br and CH3 – CH2 – I
What is the action of the following on ethyl bromide?
moist silver oxide
Answer the following question.
Write one stereochemical difference between SN1 and SN2 reactions.
Which of the following is optically inactive?
Most reactive halide towards SN1 reaction is ____________.
In the SN1 reaction, racemization takes place. It is due to:
Optically active isomers but not mirror images are called ____________.
The process of separation of a racemic modification into d and l-enantiomers is called ____________.
Which of the following is a chiral compound?
Which of the following compound will undergo racemisation when reacts with aq. KOH?
(i)
(ii)
CH3CH2CH2Cl
(iii)
\[\begin{array}{cc}
\ce{CH3}\phantom{..}\\
|\phantom{....}\\
\ce{CH3-CH-CH2Cl}
\end{array}\]
(iv)
\[\begin{array}{cc}
\phantom{..}\ce{H}\\
\phantom{..}|\\
\ce{CH3-C-Cl}\\
\phantom{..}|\\
\phantom{.....}\ce{C2H5}
\end{array}\]
The reaction of C6H5–CH=CH–CH3 with HBr produces:
Assertion: KCN reacts with methyl chloride to give methyl isocyanide.
Reason: CN– is an ambident nucleophile.
How do polar solvents help in the first step in SN1 mechanism?
Why are aryl halides less reactive towards nucleophilic substitution reactions than alkyl halides?
Which of the following is the definition of chirality?
CCl4 is insoluble in water because:-
The following questions are case-based questions. Read the passage carefully and answer the questions that follow:
|
Nucleophilic Substitution: Influences of solvent polarity: The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. Hence the level of solvent polarity has an influence on both SN1 and SN2 reactions but with different results. Generally speaking, a weak polar solvent is favourable for SN2 reaction, while a strong polar solvent is favourable for SN1. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example ethanol containing water). |
Answer the following questions:
(a) Why racemisation occurs in SN1? (1)
(b) Why is ethanol less polar than water? (1)
(c) Which one of, the following in each pair is more reactive towards SN2 reaction? (2)
(i) CH3 – CH2 – I or CH3CH2 – Cl
(ii)
OR
(c) Arrange the following in the increasing order of their reactivity towards SN1 reactions: (2)
(i) 2-Bromo-2-methylbutane, 1-Bromo-pentane, 2-Bromo-pentane
(ii) 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3- methylbutane
Which alkyl halide from the following pair would you expect to react more rapidly by an SN2 mechanism? Explain your answer.
\[\begin{array}{cc}
\ce{CH3CHCH2CH2Br}\\
|\phantom{.............}\\
\ce{CH3}\phantom{..........}\\
\end{array}\] or \[\begin{array}{cc}
\ce{CH3CH2CHCH2Br}\\
|\\
\phantom{...}\ce{CH3}\\
\end{array}\]
HCI, Major product ______.
The compound that will undergo SN1 reaction with the fastest rate is:
