Advertisements
Advertisements
Question
Describe the following:
Cross aldol condensation
Advertisements
Solution
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.

APPEARS IN
RELATED QUESTIONS
Write the products formed when CH3CHO reacts with the following reagents: CH3CHO in the presence of dilute NaOH
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.
- Methanal
- 2-Methylpentanal
- Benzaldehyde
- Benzophenone
- Cyclohexanone
- 1-Phenylpropanone
- Phenylacetaldehyde
- Butan-1-ol
- 2, 2-Dimethylbutanal
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.
How will you bring about the following conversion in not more than two steps?
Ethanol to 3-Hydroxybutanal
What is substituted imine called?
Explain aldol condensation reaction in detail.
Which product is formed when the compound
is treated with concentrated aqueous \[\ce{KOH}\] solution?
Why is there a large difference in the boiling points of butanal and butan-1-ol?
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.
Give reasons to support the answer:
Presence of Alpha hydrogen in aldehydes and ketones is essential for aldol condensation.
Convert the following:
Acetaldehyde to But-2-enal
Explain Aldol condensation of ethanal.
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?
Write a note on the aldol condensation reaction of acetaldehyde.
