Chapter 4, Problem 4.81EP

Interpretation Introduction

Interpretation:

The compounds that will react with the Tollen’s solution has to be chosen from the given options.

Concept Introduction:

In organic chemistry, oxidation reaction is referred to the number $\text{C}-\text{O}$ bonds increase and/or number of $\text{C}-\text{H}$ bonds decrease.

In organic chemistry, reduction reaction is referred to the number $\text{C}-\text{O}$ bonds decrease and/or number of $\text{C}-\text{H}$ bonds increase.

Alcohols undergo oxidation reaction and reduction reaction.  This depends upon the number of hydrogen atoms that is bonded to the alpha carbon atom.  Primary and secondary alcohol undergoes oxidation reaction while tertiary alcohol does not undergo oxidation reaction.  Primary alcohols undergo oxidation to give aldehyde and carboxylic acid as product.  Secondary alcohol undergoes oxidation to give ketone as the product.

Aldehyde undergoes oxidation to give carboxylic acid as the product while ketone does not undergo oxidation reaction.

Tollen’s test:

This is also known as silver mirror test.  The reagent that is used in Tollen’s test is silver nitrate and ammonia in water.  Aldehyde reacts with Tollen’s reagent, where the silver ion is reduced to silver metal and the aldehyde is oxidized to carboxylic acid.

Ketone does not undergo Tollen’s test to deposit silver metal.

Benedict’s test:

This test is also similar to Tollen’s test.  In this test, ${\text{Cu}}^{\text{2+}}$ metal ion is used as oxidizing agent.  The ${\text{Cu}}^{\text{2+}}$ ion is reduced to ${\text{Cu}}^{\text{+}}$ ion while the aldehyde is oxidized to carboxylic acid.  ${\text{Cu}}_{\text{2}}\text{O}$ is precipitated as brick-red solid.  Ketone does not answer the Benedict’s test.  This is because ketone are not oxidized.