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प्रश्न
What is meant by the following term? Give an example of the reaction in the following case.
Ketal
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उत्तर
Ketals are cyclic products formed by the reaction of ketones with ethylene glycol in the presence of dry HCl gas.
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संबंधित प्रश्न
Write balanced chemical equations for action of ammonia on - formaldehyde
How are the following compounds prepared?
benzaldehyde from benzene
Write the structures of the main products when acetone (CH3 − CO − CH3) reacts with the following reagent :
H2N − NHCONH2/H+
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.
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.
Predict the product of the following reaction:
Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.
PhMgBr and then H3O+
Predict the products formed when cyclohexanecarbaldehyde reacts with the following reagents.
Semicarbazide and weak acid
Give plausible explanation for the following:
There are two −NH2 groups in semicarbazide. However, only one is involved in the formation of semicarbazones.
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 
Write the main product formed when propanal reacts with the following reagents:
2 moles of 3 CH OH in presence of dry HCl
Write a test to differentiate between pentan-2-one and pentan-3-one.
Paraldehyde is formed as a result of polymerisation:-
Which of the following is most reactive in nucleophilic addition reactions?
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 structure of the following derivative.
Acetaldehydedimethylacetal
Draw the structure of the following derivative.
Acetaldehydedimethylacetal
Draw structure of the following derivative:
Acetaldehydedimethylacetal
Draw structure of the following derivative.
The ethylene ketal of hexan-3-one
