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प्रश्न
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.
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उत्तर
The possible products of aldol condensation from propanal and butanal are:
(i) \[\begin{array}{cc}
\phantom{..............................}\ce{OH}\phantom{...}\ce{CH3}\\
\phantom{...........................}|\phantom{.....}|\\
\ce{\underset{Propanal}{2CH3CH2CHO}->[dil.\overset{-}{O}H]\underset{3-Hydroxy-2-methylpentanal}{H3C - CH2 - CH - CH - CHO}}\\
\end{array}\]
(ii) \[\begin{array}{cc}
\phantom{.......................................}\ce{OH}\phantom{..}\ce{CH2CH3}\\
\phantom{................................}|\phantom{.....}|\\
\ce{\underset{Butanal}{2CH3(CH2)2CHO}->[dil.\overset{-}{O}H]\underset{2-Ethyl-3-hydroxyhexanal}{H3C - (CH2)2 - CH - CH - CHO}}\
\end{array}\]
(iii) When butanal acts as an electrophile and propanal as a nucleophile:
\[\begin{array}{cc}
\phantom{...........................................}\ce{OH}\\
\phantom{.........................................}|\\
\ce{\underset{Butanal}{H3C - (CH2)2CHO} + \underset{Propanal}{CH3CH2CHO}->[\overset{-}{O}H]H3C - (CH2)2 - CH - CH - CHO}\\
\phantom{.....................................................}|\\
\phantom{.........................................................}\ce{\underset{3-Hydroxy-2-methylhexanal}{CH3}}\
\end{array}\]
(iv) When propanal serves as an electrophile and butanal as a nucleophile:
\[\begin{array}{cc}
\phantom{............................................}\ce{OH}\phantom{...}\ce{C2H5}\\
\phantom{.........................................}|\phantom{......}|\\
\ce{CH3CH2CHO + CH3(CH2)2CHO -> \underset{2-Ethyl-3-hydroxypentanal}{H3C - CH2 - CH - CH - CHO}}\
\end{array}\]
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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 :
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
How will you convert ethanal into the following compound?
But-2-enal
How will you bring about the following conversion in not more than two steps?
Ethanol to 3-Hydroxybutanal
Describe the following:
Cross aldol condensation
Write chemical equations of the following reaction :
Benzoyl chloride is hydrogenated in the presence of `"Pd"/(BaSO_4)`
Write a chemical equation for the following reaction:
Propanone is treated with dilute Ba( OH)2.
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?
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.
Which of the following gives aldol con~ensation reaction?
Convert the following:
Acetaldehyde to But-2-enal
Explain the aldol condensation of ethanal.
Why is the α-hydrogens of aldehydes and ketones are acidic in nature?
Assertion (A): The final product in Aldol condensation is always α, β-unsaturated carbonyl compound.
Reason (R): α, β-unsaturated carbonyl compounds are stabilised due to conjugation.
When acetaldehyde is treated with dilute NaOH, the following reaction is observed.
\[\begin{array}{cc}
\ce{2CH3 - CHO ->[dil.NaOH] CH3 - CH - CH2 - CHO}\\
\phantom{...............}|\\
\phantom{.................}\ce{OH}
\end{array}\]
- What are the functional groups in the product?
- Can another product be formed during the same reaction? (Deduce the answer by doing atomic audit of reactant and product).
- Is this an addition reaction or condensation reaction?
What is aldol condensation? Explain it with suitable examples.
