Question

Which of the following is obtained when chloral is boiled with NaOH?
A) \[C{H_3}Cl\]
B) \[CHC{l_3}\]
C) \[CC{l_4}\]
D) None of these

Answer 1

Hint: NaOH is a strong base. The formula of chloral is \[C{l_3}CCHO\]. The C=O bond in choral is polar bond so that it is easy for OH to attack the bond. Choral when reacted with alcohol or water gives chloral hydrates which are unstable.

Complete step-by-step answer:When chloral mixed with a strong base like $NaOH$ forms the sodium salt of chloral hydrate, \[NaC{l_3}C{H}OH\]. It is unstable and decomposes on standing. At last, it forms trichloromethane which is generally known as chloroform. The reaction is shown below.
$\,C{l_3}CCHO{\text{ }} + {\text{ }}NaOH{\text{ }} \to {\text{ }}C{l_3}CH{\text{ }} + {\text{ }}HCOONa$

Therefore, chloroform is obtained when chloral is boiled with NaOH.

Option ‘B’ is correct

Additional Information:Chloroform is a thick, white liquid that is dense and heavily manufactured as a precursor to PTFE. It is a trihalomethane and one of the four chloromethanes. When breathed or swallowed, it is a potent anesthetic.

Note:The chloral is formed as intermediate in the haloform test using chlorine. It forms when methyl carbonyl compound reacts with chlorine and strong base such as sodium hydroxide, calcium hydroxide and potassium hydroxide. Due to its instability, this intermediate compound break to give positive haloform test by forming chloroform. The similar type of reaction can happen with compound with molecular formula \[C{l_3}CCRO\], where R is an alkyl group.