Question

Provide chemical equations for reactions such as Aldol Condensation, Cross Aldol Condensation, Wurtz Reaction, Fittig Reaction, and Hoffmann Bromamide Reaction.

Hint:

Hofmann bromamide reaction shortens the carbon chain by one carbon — a key exam point.

Answer 1

Concept: Named organic reactions help in understanding reaction mechanisms and synthetic pathways. Below are standard chemical equations for each reaction.
1. Aldol Condensation: Occurs between two molecules of aldehyde or ketone having \( \alpha \)-hydrogen in presence of dilute base. \[ 2CH_3CHO \xrightarrow{\text{dil. NaOH}} CH_3CH(OH)CH_2CHO \] On heating (dehydration): \[ CH_3CH(OH)CH_2CHO \rightarrow CH_3CH=CHCHO + H_2O \]
2. Cross Aldol Condensation: Occurs between two different carbonyl compounds. Example: Acetaldehyde + Formaldehyde \[ CH_3CHO + HCHO \xrightarrow{\text{NaOH}} CH_3CH(OH)CH_2CHO \]
3. Wurtz Reaction: Coupling of alkyl halides using sodium metal in dry ether to form higher alkanes. \[ 2R-X + 2Na \xrightarrow{\text{dry ether}} R-R + 2NaX \] Example: \[ 2CH_3Br + 2Na \rightarrow C_2H_6 + 2NaBr \]
4. Fittig Reaction: Coupling of aryl halides with sodium in dry ether to form biaryl compounds. \[ 2Ar-X + 2Na \xrightarrow{\text{dry ether}} Ar-Ar + 2NaX \] Example: \[ 2C_6H_5Cl + 2Na \rightarrow C_6H_5{-}C_6H_5 + 2NaCl \]
5. Hoffmann Bromamide Reaction (Hofmann Rearrangement): Conversion of amide to primary amine with one less carbon using bromine and alkali. \[ RCONH_2 + Br_2 + 4NaOH \rightarrow RNH_2 + Na_2CO_3 + 2NaBr + 2H_2O \]