Question: Distinguish between (i) \[{\mathbf{phCOEt}}\] and (ii) \[{\mathbf{p}} - {\mathbf{Me}}{{\mathbf{C}}_{...

Question

Distinguish between (i) ${\mathbf{phCOEt}}$ and (ii) ${\mathbf{p}} - {\mathbf{Me}}{{\mathbf{C}}_{\mathbf{6}}}{{\mathbf{H}}_{\mathbf{4}}}{\mathbf{COMe}}$ by a chemical method:
A. i does not undergo haloform reaction whereas ii does
B. ii does not undergo reaction with tollens reagent whereas i does
C. i does not undergo reaction with Fehling’s solution whereas ii does
D. none of these

Answer 1

Solution

in the given question we have to differentiate between the two compounds through identification of their chemical reaction. In the reaction three test has been performed to detect the compound, the reactions are Fehling’s and tollens reagent there by performing the reaction.

Complete step by step solution: Any compounds containing the $C{H_3}C = O$ group or the $C{H_3}CH\left( {OH} \right)$ group give a positive result with the iodoform test. So, the iodoform test can therefore be used to identify aldehydes and ketones and also this test can also be used to identify alcohols.
The haloform reaction is a chemical reaction test which is done where a haloform that is a halogen and is produced by the comprehensive halogenation of a methyl ketone $\left( {RCOC{H_3}} \right)$ where $R$ can be either a hydrogen atom, an alkyl or an aryl group, in the presence of a base in the reaction.
As soon as the halogen used is iodine, the haloform reaction might be used to classify methyl ketones as iodoform is a yellow solid with a distinctive odor. Thus the test is known as the iodoform test or haloform test.
${\mathbf{phCOEt}}$ and ${\mathbf{p}} - {\mathbf{Me}}{{\mathbf{C}}_{\mathbf{6}}}{{\mathbf{H}}_{\mathbf{4}}}{\mathbf{COMe}}$ can be distinguished by haloform reaction. ${\mathbf{p}} - {\mathbf{Me}}{{\mathbf{C}}_{\mathbf{6}}}{{\mathbf{H}}_{\mathbf{4}}}{\mathbf{COMe}}$ is a methyl ketone and gives positive haloform test ${\mathbf{phCOEt}}$ is not a methyl ketone Hence, it does not gives the haloform test .

Hence option D is correct.

Note: Haloform reaction mechanism occurs with the disproportionation of the halogen with the presence of the hydroxide ion when it takes place. The haloform reaction forms the source of the iodoform test which was commonly used in the past as a chemical test to govern the presence of a methyl ketone, or a secondary alcohol oxidizable to a methyl ketone.