Question

Write I.U.P.A.C. name of Acetaldehyde. Write chemical equations of its reaction with (A) NaHSO$_3$, (B) NaOH, (C) NH$_2$NH$_2$, and (D) HCN.

Hint:

Aldehydes readily undergo nucleophilic addition reactions at the carbonyl carbon.

Answer 1

Step 1: IUPAC name.
Acetaldehyde = Ethanal (CH\(_3\)CHO). Step 2: Reaction with NaHSO\(_3\).
\[ CH_3CHO + NaHSO_3 \rightarrow CH_3CH(OH)SO_3Na \] Step 3: Reaction with NaOH.
Aldol condensation: \[ 2CH_3CHO \xrightarrow{NaOH} CH_3CH(OH)CH_2CHO \ (\beta\text{-hydroxybutanal}) \] Step 4: Reaction with NH\(_2\)NH\(_2\).
\[ CH_3CHO + NH_2NH_2 \rightarrow CH_3CH=NNH_2 + H_2O \] Step 5: Reaction with HCN.
\[ CH_3CHO + HCN \rightarrow CH_3CH(OH)CN \ (\text{acetaldehyde cyanohydrin}) \] Step 6: Conclusion.
Thus, acetaldehyde shows addition and condensation reactions due to its –CHO group.