Aldehyde ketones & carboxylic Acid MCQs for NEET — Chemistry Questions with Answers

(b) Ketones can be prepared by the oxidation of secondary alcohols by using oxidising agent such as K₂Cr₂O₇/H₂SO_4.

     ${}_{{\mathrm{H}}_3\mathrm{C}}{}^{{\mathrm{H}}_3\mathrm{C}}>\mathrm{CHOH}$ + [O] $\to$  ${}_{{\mathrm{H}}_3\mathrm{C}}{}^{{\mathrm{H}}_3\mathrm{C}}>$C=O + H₂O

        2$°$ alcohol               Dimethyl ketone

In the aldol condensation reaction, two aldehydes or a ketone and an aldehyde undergo nucleophilic addition followed by dehydration to form a β-hydroxy aldehyde or a β-hydroxy ketone respectively. Therefore, the product formed is a β-hydroxy aldehyde or a β-hydroxy ketone.

(a) Clemmensen reduction Aldehydes and ketones are reduced to the corresponding alkanes by means of amalgamated zinc and HCl.

>C=O + 4[H]$\stackrel{\mathrm{Zn}-\mathrm{Hg}/\mathrm{HCl}}{\to }$>CH₂ + H₂O

(a) Aldol condensation in aldehydes is due to presence of $\mathrm{\alpha }$-hydrogen atoms. Those aldehydes which does not have $\mathrm{\alpha }$-hydrogen atom like HCHO, does not give aldol condensation reaction.                

(a) The -OH group of alcohol or the -COOH group of a carboxylic acid is replaced by -Cl using phosphorus pentachloride (i.e. PCl₅)

  ROH + PCl₅ $\to$RCl + POCl₃ + HCl

Alcohol

  RCOOH + PCl₅$\to$RCOCl + POCl₃ + HCl

   Acid

(d) ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{COOC}}_2{\mathrm{H}}_5\underset{\mathrm{Boiling}}{\overset{\mathrm{KOH}}{\to }}$   ${\mathrm{C}}_6{\mathrm{H}}_6\mathrm{COOK} + {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}$

    Ethyl benzoate

   ${\mathrm{C}}_6{\mathrm{H}}_6\mathrm{COOK}\stackrel{{\mathrm{H}}^{+}/{\mathrm{H}}_2\mathrm{O}}{\to }$  C₆H₅COOH
                                     (Benzoid Acid)

When malonic acid is heated with urea, it forms barbituric acid. This reaction is known as the Grimaux condensation reaction, where two molecules of malonic acid condense with one molecule of urea to form barbituric acid.

 CH₃COOCH₃ $\stackrel{{\mathrm{LiAlH}}_4}{\to }$CH₃CH₂OH + CH₃OH