Advertisements
Advertisements
प्रश्न
Write the structure of the major organic product in the following reaction:
\[\ce{CH3CH2Br + KCN ->[aq{.} ethanol]}\]
Advertisements
उत्तर
\[\ce{\underset{Bromoethane}{CH3CH2Br} + KCN ->[aq{.} ethanol][(nucleophilic substitution)] \underset{Propanenitrile}{CH3CH2CN} + KBr}\]
APPEARS IN
संबंधित प्रश्न
Given reasons: C–Cl bond length in chlorobenzene is shorter than C–Cl bond length in CH3–Cl.
What are ambident nucleophiles? Explain with an example.
Write the structure of the major organic product in the following reaction:
\[\ce{CH3CH2CH2OH + SOCl2 ->}\]
Arrange the compounds of the following set in order of reactivity towards SN2 displacement:
1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3-methylbutane
Out of C6H5CH2Cl and C6H5CHClC6H5, which is more easily hydrolysed by aqueous KOH.
What happens when chlorobenzene is subjected to hydrolysis?
What happens when ethyl chloride is treated with aqueous KOH?
AgCN reacts with haloalkanes to form isocyanide. Haloalkanes react with KCN to form alkyl cyanides as the main product. Why?
Which of the following is optically inactive?
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.
Elimination reactions (especially β-elimination) are as common as the nucleophilic substitution reaction in case of alkyl halides. Specify the reagents used in both cases.
Aryl halides are extremely less reactive towards nucleophilic substitution. Predict and explain the order of reactivity of the following compounds towards nucleophilic substitution:
| (I) |  |
| (II) |  |
| (III) |  |
Give reason for the following:
The product formed during SN1 reaction is a racemic mixture.
In which reaction mechanism carbocation is formed?
Which of the following compounds will show retention in configuration on nucleophile substitution by OH− ion?
Convert bromoethane to propanamine.
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
Discuss the mechanism of alkaline hydrolysis of methyl bromide.
Explain why Grignard reagents should be prepared under anhydrous conditions.
