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प्रश्न
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.
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उत्तर
\[\begin{array}{cc}\ce{C2H5 - CH - CH3}\\
|\phantom{.}\\\ce{Br}\end{array}\]
Mechanism:
\[\begin{array}{cc}
\ce{H}\phantom{.................}\ce{H}\\
|\phantom{..................}|\\
\ce{H3C - C - C2H5 ->[Slow step] C^⊕ + B\overset{⊖}{r}}\\
\phantom{...}|\phantom{................}/\phantom{...}\backslash\\
\phantom{.......}\ce{Br}\phantom{...........}\ce{H3C}\phantom{....}\ce{C2H5}
\end{array}\]
\[\begin{array}{cc}
\ce{H}\phantom{....................}\ce{H}\phantom{...............}\ce{H}\phantom{.......}\\
|\phantom{.....................}|\phantom{................}|\phantom{.......}\\
\ce{C^⊕ + O\overset{⊖}{H} ->[Fast] H3C - C - OH + HO - C - CH3}\\
/\phantom{..}\backslash\phantom{....................}|\phantom{.................}|\phantom{.........}\\
\ce{H3C}\phantom{...}\ce{C2H5}\phantom{...............}\ce{C2H5}\phantom{.............}\ce{C2H5}\phantom{........}
\end{array}\]
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संबंधित प्रश्न
Write the mechanism of the following reaction:
\[\ce{{n}BuBr + KCN ->[EtOH-H2O] {n}BuCN}\]
Out of C6H5CH2Cl and C6H5CHClC6H5, which is more easily hydrolysed by aqueous KOH.
The stability order for carbocation is _______.
(A) 2° > 3° > 1°
(B) 3° > 2° > 1°
(C) 3° > 1° > 2°
(D) 1° > 3° > 2°
In the reaction, \[\ce{R - X + NaOR' -> ROR’ + X}\] ( – ve ion). The main product formed is:
Most reactive halide towards SN1 reaction is ____________.
Optically active isomers but not mirror images are called ____________.
Which of the following alkyl halides will undergo SN1 reaction most readily?
A primary alkyl halide would prefer to undergo ______.
How do polar solvents help in the first step in SN1 mechanism?
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
