${\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-\mathrm{COOH} \underset{1 \mathrm{mole}}{\overset{{\mathrm{Br}}_2/\mathrm{Red} \mathrm{P}}{\to }} \mathrm{A} \stackrel{\mathrm{aq}. \mathrm{KOH}}{\to } \mathrm{B} \underset{∆}{\overset{\mathrm{Conc}. {\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\mathrm{C}.$

Common name of ‘C’ is

Organic Chemistry Reaction Sequence

CH₃ - CH₂ - CH₂ - COOH → A → B → C

Step 1: Starting compound is butanoic acid (CH₃-CH₂-CH₂-COOH)

Step 2: Treatment with Br₂/Red P (Hell-Volhard-Zelinsky reaction)

• Alpha bromination occurs at the carbon next to the carboxyl group
• Product A: CH₃-CH₂-CHBr-COOH (2-bromobutanoic acid)

Step 3: Treatment with aqueous KOH

• Nucleophilic substitution replaces Br with OH
• Product B: CH₃-CH₂-CH(OH)-COOH (2-hydroxybutanoic acid)

Step 4: Treatment with concentrated H₂SO₄ with heat

• Dehydration occurs, forming a double bond
• Product C: CH₃-CH=CH-COOH

Common name of C:Crotonic acid

Crotonic acid is the common name for but-2-enoic acid, an unsaturated carboxylic acid with a double bond between the second and third carbon atoms.