Advertisements
Advertisements
प्रश्न
Why are carboxylic acids more acidic than alcohols or phenols although all of them have hydrogen atom attached to a oxygen atom \[\ce{(-O-H)}\]?
Advertisements
उत्तर
The aliphatic carboxylic acids are stronger acids than alcohols and phenols. The difference in the relative acidic strengths can be understood if we compare the resonance hybrids of carboxylate ion and ethoxide phenoxide ion.
\[\ce{RCOOH ⇌ RCOO- + H+}\]
\[\ce{ROH ⇌ RO- + H+}\]
The resonance hybrids may be represented as:
\[\begin{array}{cc}
\phantom{.............}\ce{O^{δ-}}\\
\phantom{.........}//\\
\ce{R - C}\\
\phantom{........}\backslash\backslash\\
\phantom{............}\ce{O^{δ-}}\\
\end{array}\]
Carboxylate ion
Phenoxide ion
\[\ce{RO-}\]
(No resonance)
The resonance hybrids may be represented as: Carboxylate ion Phenoxide ion (No resonance)
The electron charge on the carboxylate ion is more dispersed in comparison to the phenate ion since there are two electronegative oxygen atoms in carboxylate ion as compared to only one oxygen atom in phenoxide ion. In other words, the carboxylate ion is relatively more stable as compared to phenate ion. Thus, the release of H+ ion from carboxylic acid is comparatively easier or it behaves as a stronger acid than phenol.
APPEARS IN
संबंधित प्रश्न
Write the products formed when CH3CHO reacts with the following reagents: CH3CHO in the presence of dilute NaOH
How will you convert ethanal into the following compound?
But-2-enal
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
Complete the synthesis by giving missing starting material, reagent or product.
\[\begin{array}{cc}
\ce{C6H5CHO}\phantom{............}\\
\phantom{........}\ce{+\phantom{......}\ce{->[dil.NaOH][\Delta]}}\phantom{...}\\
\ce{CH3CH2CHO}\phantom{............}
\end{array}\]
Give reasons Acetylation of aniline reduces its activation effect.
Write chemical equations of the following reaction :
Propanone is treated with dilute Ba (OH)2-.
Write a chemical equation for the following reaction:
Propanone is treated with dilute Ba( OH)2.
Cannizaro’s reaction is not given by ______.
Which of the following compounds do not undergo aldol condensation?
(i) \[\ce{CH3 - CHO}\]
(ii) 
(iii) \[\begin{array}{cc}
\phantom{}\ce{O}\\
\phantom{}||\\
\ce{CH3 - C - CH3}
\end{array}\]
(iv) \[\begin{array}{cc}
\phantom{}\ce{CH3}\\
|\phantom{...}\\
\ce{CH3 - C - CHO}\phantom{..}\\
|\phantom{...}\\
\phantom{}\ce{CH3}\\
\end{array}\]
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?
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.
\[\ce{CH3-CH2-CHO ->[dil][alkali] Product}\]
The product in the above reaction is:
Explain Aldol condensation of ethanal.
Which of the following does not give aldol condensation reaction?
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.
Write a note on the aldol condensation reaction of acetaldehyde.
What is aldol condensation? Explain it with suitable examples.
