Question

What is Tollen's reagent ?

Answer 1

An attempt to this question can be made by determining the composition of tollen's reagent. Try to identify the class of compounds that react with tollen's reagent and give a positive result of tollen's reagent. Based on that you can determine the structure of the compounds. The name should be determined in accordance with IUPAC nomenclature.

Complete step by step answer:
Tollens reagent is a chemical reagent mainly used to determine the presence of aldehyde and aromatic aldehyde functional groups.
The reagent consists of a solution of silver nitrate, ammonia and small portions of sodium hydroxide. Sodium hydroxide is added to the solution to mainly maintain the pH of the solution.
A positive test with Tollens reagent is confirmed by the precipitation of elemental silver on the walls of the test tube. It is often seen as a silver mirror on the inner surface of the reaction vessel.
Tollens reagent plays an important role in qualitative and quantitative analysis of salts in chemistry. It is used as a confirmatory test for the presence of aldehydes. In a solution containing carbonyl compounds, aldehydes can be separated from ketones using the Tollens reagent.
The complex formed by the reaction of silver nitrate with ammonia and sodium hydroxide is used as Tollens reagent. The final product is shown below:
$2\text{ AgN}{{\text{O}}_{3}}\text{ + 2 NaOH }\to \text{ A}{{\text{g}}_{2}}\text{O(s) + 2 NaN}{{\text{O}}_{3}}\text{ + }{{\text{H}}_{2}}\text{O}$
$\text{A}{{\text{g}}_{2}}\text{O(s) + 4 N}{{\text{H}}_{3}}\text{ + 2 NaN}{{\text{O}}_{3}}\text{ + }{{\text{H}}_{2}}\text{O }\to \text{ 2 }\\!\\![\\!\\!\text{ Ag(N}{{\text{H}}_{3}}{{\text{)}}_{2}}\text{ }\\!\\!]\\!\\!\text{ N}{{\text{O}}_{3}}\text{ + 2 NaOH}$

Note: It is important to know that along with aldehydes, Tollens reagent given positive results with alpha-hydroxy ketone. This is because alpha-hydroxy ketone tautomerizes reversibly to give an aldehyde.