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प्रश्न
Describe the following:
Cross aldol condensation
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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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संबंधित प्रश्न
What is meant by the following term? Give an example of the reaction in the following case.
Aldol
Write structural formulas and names of four possible aldol condensation products from propanal and butanal. In each case, indicate which aldehyde acts as nucleophile and which as electrophile.
Why is alpha (α) hydrogen of carbonyl compounds acidic in nature?
Write chemical equations of the following reaction :
Propanone is treated with dilute Ba (OH)2-.
Explain aldol condensation reaction in detail.
Cannizaro’s reaction is not given by ______.
Compounds A and C in the following reaction are:
\[\ce{CH3CHO ->[(i) CH3MgBr][(ii) H2O] (A) ->[H2SO4, Δ] (B) ->[Hydroboration oxidation] (C)}\]
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?
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.
When liquid ‘A’ is treated with a freshly prepared ammoniacal silver nitrate solution, it gives bright silver mirror. The liquid forms a white crystalline solid on treatment with sodium hydrogensulphite. Liquid ‘B’ also forms a white crystalline solid with sodium hydrogensulphite but it does not give test with ammoniacal silver nitrate. Which of the two liquids is aldehyde? Write the chemical equations of these reactions also.
Give reasons to support the answer:
Presence of Alpha hydrogen in aldehydes and ketones is essential for aldol condensation.
Cross aldol condensation occurs between
Convert the following:
Acetaldehyde to But-2-enal
Which of the following does not give aldol condensation reaction?
Which of the following compounds will undergo self-condensation in the presence of dilute NaOH solution?
Why is the α-hydrogens of aldehydes and ketones are acidic in nature?
Identify A and B:
Write a note on the aldol condensation reaction of acetaldehyde.
