Question

The formula of chloral is:
(A) $CHC{l_3}$
(B) $C{H_2}ClCHO$
(C) $CC{l_3}CHO$
(D) $CHC{l_2}CHO$

Answer 1

As the name suggests, chloral has chlorine atoms in its structure. Chloral will give a positive Silver mirror test and Fehling’s test. It reacts with water to form chloral hydrate, which has geminal diol in its structure.

Complete answer:
- As the name suggests you can relate Chloral to a compound that has an aldehyde functional group as it also contains the suffix ‘-al’ in its name. So, option (A) cannot be a true answer as it does not contain an aldehyde group.
- Chloral is actually trichloroethanal. That means the carbon atom that is bonded with carbonyl carbon has three chlorine atoms.
- In option (B) and (D), there are one and two chlorine atoms respectively, so they are not true.
- $CHC{l_3}$ is known as Chloroform.
Therefore, option (C) $CC{l_3}CHO$ is the correct answer.
So, the correct answer is “Option C”.

Additional Information:
- Chloral is a colourless oily liquid. It has an irritating and a pungent odour. Water reacts with Chloral to give Chloral hydrate which was used as a sedative and hypnotics material.
- Chloral is produced industrially from Chloral hydrate. First ethanal is allowed to react with Chlorine gas in presence of hydrochloric acid that gives Chloral hydrate and then Chloral hydrate is allowed to react with concentrated sulfuric acid which hydrolyzes the Chloral hydrate to give Chloral.
$C{H_3}CHO + 3C{l_2} + {H_2}O \to \mathop {C{l_3}CCH{{(OH)}_2}}\limits_{{\text{Chloral hydrate}}} + 3HCl$
$\mathop {C{l_3}CCH{{(OH)}_2}}\limits_{{\text{Chloral hydrate}}} \xrightarrow{{{H_2}S{O_4}}}\mathop {CC{l_3}CHO}\limits_{Chloral} + {H_2}O$

Note: Do not get confused with Chloral ($CC{l_3}CHO$) and Chloroform ($CHC{l_3}$). Remember that only trichloroethanal is known as Chloral and monochloroethane and dichloroethane are not known as Chloral.