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प्रश्न
What is meant by the following term? Give an example of the reaction in the following case.
Schiff’s base
उत्तर
Aldehydes and ketones react with primary aliphatic or aromatic amines to form azomethine or Schiff's base.
\[\ce{\underset{Aldehyde}{R - CH = O} + \underset{1° amine}{H2N - R'} ->[H+][Heat] \underset{Schiff’s base}{R - CH = N - R'} + H2O}\]
APPEARS IN
संबंधित प्रश्न
Draw the structure of the semicarbazone of ethanal.
Write the products formed when CH3CHO reacts with the following reagents : HCN
Predict the product of the following reaction:
\[\begin{array}{cc}
\phantom{..............}\ce{O}\\
\phantom{..............}||\\
\ce{R - CH = CH - CHO + NH2 - C - NH - NH2 ->[H+]}\end{array}\]
Give plausible explanation for the following:
Cyclohexanone forms cyanohydrin in good yield but 2, 2, 6 trimethylcyclohexanone does not.
How are the following compounds prepared?
acetophenone from benzene
Give a simple chemical test to distinguish between 
Acetone, Acetaldehyde, Benzaldehyde, Acetophenone – reactivity towards addition of HCN.
Grignard reagent on reaction with acetone forms.
Write the name of product formed, when acetone is treated with 2, 4-dinitrophenyl hydrazine.
What is the action of sodium hypoiodite on acetone?
What happens when ethanal is treated with excess ethanol and acid?
The product "P" in the above reaction is:
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 structure of the following derivative.
The ethylene ketal of hexane-3-one
Draw structure of the following derivative.
Acetaldehydedimethylacetal
Why dissociation of HCN is suppressed by the addition of HCL?
Draw structures of the following derivative.
The ethylene ketal of hexan-3-one
Draw structure of the following derivative.
The ethylene ketal of hexan-3-one
Draw structures of the given derivatives.
The ethylene ketal of hexan-3-one
