Applications of Oxidation Reaction

Aldehydes, ketones, and carboxylic acids may be oxidised, and this process has several industrial uses. For instance, the creation of carboxylic acids, which are extensively employed in the pharmaceutical and food sectors, is accomplished via the oxidation of aldehydes and ketones. Carbon dioxide, a crucial gas utilised in several industrial processes, is created by the oxidation of carboxylic acids.

Tollen’s Reagent

Together with various alpha-hydroxy ketones that can tautomerize into aldehydes, Tollens’ reagent is a chemical reagent used to differentiate between aldehydes and ketones. The reagent is made up of silver nitrate, ammonia, and sodium hydroxide solution.

 Tollens test uses a chemical reagent called Tollens reagent, which has a mild oxidising effect. Silver ions are coupled to ammonia in the form of the diamine-silver (I) complex [Ag(NH₃)₂]⁺ in this colourless, basic, and aqueous solution. A two-step process is used to make Tollens’ reagent. Two things happen during the process. Initially, carbon dioxide is created from the aldehyde. Second, the Ag+ ions are converted to Ag metal, leaving a shiny look inside the test tube to signify a successful reaction.

Tollen’s Test

A qualitative laboratory test called the Tollens’ test also referred to as the silver-mirror test, is used to distinguish between an aldehyde and a ketone. It makes use of the fact that aldehydes can oxidise more quickly than ketones. Aldehydes and -hydroxy ketones, such as hydroxy acetone, cannot be distinguished by this test.

R-CHO +   2[Ag(NH₃)₂]⁺OH^–  +  H₂O →  R-COOH + 2Ag   +   4NH₃   +  2H₂O

Fehling’s Test

• One of the most popular tests for determining whether a substance is a reducing or non-reducing sugar is the Fehling test.
• To identify the different types of carbohydrates present in a solution or to determine their presence.

Fehling’s solution: The Fehling Solution is created by combining two different solutions. The first is Rochelle salt produced strongly with sodium hydroxide, which is a colourless solution and is known as Fehling A solution. The second is copper sulphate, which is a deep blue aqueous solution and is known as Fehling B solution. The Fehling Solution is created by combining the Rochelle salt and copper sulphate from the A and B solutions. Also, each of the solutions A and B is prepared independently and stored during the evaluation. The active chemical in this reaction is the tartrate complex, which acts as an oxidising agent.

Reactions

Fehling’s solution, the reaction between copper(II) ions and an aldehyde is stated as,

RCHO+2Cu²⁺+5OH⁻→RCOO⁻+Cu₂O+3H₂O

After Tartrate is introduced,

RCHO+2Cu(C₄H₄O₆)₂⁻² + 5OH⁻→ RCOO⁻+ Cu₂O + 4C₄H₄O₂⁻⁶ + 3H₂O

Haloform Reaction

Carboxylates and trihalomethane, often known as haloforms, are the end products. Up until the 3 H has been substituted, the reaction continues at the alpha position through a series of quicker halogenations. As a chemical test, this reaction is also carried out to identify methyl ketones using iodine.

In the process of halogenating a methyl ketone in a basic solution, the halogen takes the place of all three -hydrogen atoms. When this trihaloketone reacts further, a carbon-carbon bond is broken. A carboxylic acid and a trihalomethane compound known as haloform are the byproducts of acidification.

3 R-C(CH₃)₂(C=O)R’ + X₂ + 4NaOH → R-CX₃ + R’COO-Na+ + 2 CH₃COONa + 3H₂O

The reaction of ethyl methyl ketone with chlorine and sodium hydroxide yields chloroform

3CH₃COC₂H₅ + 3Cl₂ + 4NaOH → CHCl₃ + C₂H₅COONa + 5NaCl + 3H₂O

Baeyer-Villiger Oxidation

Using the Baeyer-Villiger The process of oxidation, which changes ketones into esters and cyclic ketones into lactones, involves the oxidative cleavage of a carbon-carbon bond next to a carbonyl. You can perform the Baeyer-Villiger with peracids like MCBPA or with hydrogen peroxide and a Lewis acid.

Ketone + Peroxy Acid  = Ester

R₂C=O + RCO₃H → R₂C(OH)OR’ (ester) + HO₂CR’

Cycloketone + Peroxy Acid  =  Lactone

R₂C=O + RCO₃H → R₂C(OH)OR’ (lactone) + HO₂CR’

A carbonyl group (-C=O) is found at the end of a carbon chain, which distinguishes aldehydes from other organic molecules. They are often present in nature and have significant uses across several sectors. In this assignment, the structure, characteristics, and reactivity of aldehydes will be covered.