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प्रश्न
Give plausible explanation for the following:
Cyclohexanone forms cyanohydrin in good yield but 2, 2, 6 trimethylcyclohexanone does not.
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उत्तर
Due to the presence of three methyl groups at α-places, nucleophilic attack of CN– ions does not occur. This steric hindrance is absent in cyclohexane. Hence, nucleophilic attack of CN– ions occurs quickly. Hence, cyclohexanone cyanohydrin is obtained in good yield.
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संबंधित प्रश्न
Arrange the following in the increasing order of their reactivity towards nucleophilic addition reaction:
C6H5COCH3, CH3-CHO, CH3COCH3
Arrange the following compound in increasing order of its reactivity in nucleophilic addition reactions.
Benzaldehyde, p-Tolualdehyde, p-Nitrobenzaldehyde, Acetophenone.
Hint: Consider steric effect and electronic effect.
What is meant by the following term? Give an example of the reaction in the following case.
Imine
Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN)
Complete the synthesis by giving missing starting material, reagent or product.
What is the action of the following reagents on ethanoic acid?
1) `LiAlH_4"/"H_3O^+`
2) `PCl_3 , "heat"`
3) `P_2O_5, "heat"`
Give a simple chemical test to distinguish between 
How will you convert benzoic acid to m-bromobenzoic acid?
Which of the following compounds is most reactive towards nucleophilic addition reactions?
Which of the following is the correct representation for intermediate of nucleophilic addition reaction to the given carbonyl compound (A):
(i) 
(ii) 
(iii) 
(iv) 
Reaction of aqueous sodium hydroxide on chlorobenzene gives which of the following products?
A Idol condensation will not be observed in
Acetaldehyde and acetone differ in their reaction with
Paraldehyde is formed as a result of polymerisation:-
What is the action of sodium hypoiodite on acetone?
What happens when ethanal is treated with excess ethanol and acid?
The following questions are case-based questions. Read the passage carefully and answer the questions that follow:
| The carbon-oxygen double bond is polarised in aldehydes and ketones due to higher electronegativity of oxygen relative to carbon. Therefore, they undergo nucleophilic addition reactions with a number of nucleophiles such as HCN, NaHSO3, alcohols, ammonia derivatives and Grignard reagents. Aldehydes are easily oxidised by mild oxidising agents as compared to ketones. The carbonyl group of carboxylic acid does not give reactions of aldehydes and ketones. Carboxylic acids are considerably more acidic than alcohols and most of simple phenols. |
Answer the following:
(a) Write the name of the product when an aldehyde reacts with excess alcohol in the presence of dry HCl. (1)
(b) Why carboxylic acid is a stronger acid than phenol? (1)
(c) (i) Arrange the following compounds in increasing order of their reactivity towards CH3MgBr: (1)
CH3CHO, \[\begin{array}{cc}
\ce{(CH3)3C-C-CH3}\\
\phantom{....}||\\
\phantom{....}\ce{O}
\end{array}\], \[\begin{array}{cc}
\ce{CH3-C-CH3}\\
||\\
\ce{O}
\end{array}\]
(ii) Write a chemical test to distinguish between propanal and propanone. (1)
OR
(c) Write the main product in the following: (2)
| (i) |  |
| (ii) |  |
Draw structures of the given derivatives.
The ethylene ketal of hexan-3-one
Draw the structure of the given derivative.
The ethylene ketal of hexan-3-one
