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प्रश्न
Which will undergo faster nucleophilic addition reaction?
Acetaldehyde or Propanone
उत्तर
Aldehydes are generally more reactive than ketones in nucleophilic addition reactions due to steric hindrance. As the electron density at the carbonyl carbon increases, the +I effect increases, which decreases the chances of attack by a nucleophile. Thus, acetaldehyde is more reactive than propanone.
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संबंधित प्रश्न
Arrange the following compound in increasing order of its reactivity in nucleophilic addition reactions.
Ethanal, Propanal, Propanone, Butanone.
Hint: Consider steric effect and electronic effect.
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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 the structure of the following derivative.
Acetaldehydedimethylacetal
Draw structure of the following derivative.
The ethylene ketal of hexan-3-one
