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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

Describe the following: Cross aldol condensation

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प्रश्न

Describe the following:

Cross aldol condensation

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लघु उत्तर
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उत्तर

When aldol condensation is carried out between two different aldehydes and/or ketones, it is called cross aldol condensation. If both of them contain a-hydrogen atoms, it gives a mixture of four products. This is illustrated below by the aldol reaction of a mixture of ethanal and propanal.

Ketones can also be used as one component in the cross-aldol reactions.

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पाठ 8: Aldehydes, Ketones and Carboxylic Acids - Exercises [पृष्ठ २५६]

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एनसीईआरटी Chemistry Part 1 and 2 [English] Class 12
पाठ 8 Aldehydes, Ketones and Carboxylic Acids
Exercises | Q 8.16 (iii) | पृष्ठ २५६

संबंधित प्रश्‍न

A compound 'A' of molecular formula C2H3OCl undergoes a series of reactions as shown below. Write the structures of A, B, C and D in the following reactions :


What is meant by the following term? Give an example of the reaction in the following case.

Aldol


Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither? Write the structures of the expected products of aldol condensation and Cannizzaro reaction.

  1. Methanal
  2. 2-Methylpentanal
  3. Benzaldehyde
  4. Benzophenone
  5. Cyclohexanone
  6. 1-Phenylpropanone
  7. Phenylacetaldehyde
  8. Butan-1-ol
  9. 2, 2-Dimethylbutanal

How will you bring about the following conversion in not more than two steps?

Benzaldehyde to 3-Phenylpropan-1-ol


Give reasons  Acetylation of aniline reduces its activation effect.


Write chemical equations of the following reaction :
Benzoyl chloride is hydrogenated in the presence of `"Pd"/(BaSO_4)`


Cannizaro’s reaction is not given by ______.


Compounds A and C in the following reaction are:

\[\ce{CH3CHO ->[(i) CH3MgBr][(ii) H2O] (A) ->[H2SO4, Δ] (B) ->[Hydroboration oxidation] (C)}\]


Which of the following conversions can be carried out by Clemmensen Reduction?

(i) Benzaldehyde into benzyl alcohol

(ii) Cyclohexanone into cyclohexane

(iii) Benzoyl chloride into benzaldehyde

(iv) Benzophenone into diphenyl methane


Compound ‘A’ was prepared by oxidation of compound ‘B’ with alkaline \[\ce{KMnO4}\]. Compound ‘A’ on reduction with lithium aluminium hydride gets converted back to compound ‘B’. When compound ‘A’ is heated with compound B in the presence of \[\ce{H2SO4}\] it produces fruity smell of compound C to which family the compounds ‘A’, ‘B’ and ‘C’ belong to?


Why are carboxylic acids more acidic than alcohols or phenols although all of them have hydrogen atom attached to a oxygen atom \[\ce{(-O-H)}\]?


Assertion: The α-hydrogen atom in carbonyl compounds is less acidic.

Reason: The anion formed after the loss of α-hydrogen atom is resonance stabilised.


Assertion: Aromatic aldehydes and formaldehyde undergo Cannizaro reaction.

Reason: Aromatic aldehydes are almost as reactive as formaldehyde.


Predict the reagent for carrying out the following transformations:

Ethanal to 3-hydroxy butanal


The major product of the following reaction is:


Explain Aldol condensation of ethanal.


Which of the following does not give aldol condensation reaction?


Write a note on the aldol condensation reaction of acetaldehyde.


Which one of the following undergoes reaction with 50% sodiumhydroxide solution to give the corresponding alcohol and acid:


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