Principle of Diazotisation titration

Diazotization titration is a type of volumetric analysis in which an unknown organic compound is titrated with a standard solution of sodium nitrite in the presence of an acid to form a diazonium salt. The principle of diazotization titration is based on the reaction between primary aromatic amines and sodium nitrite in an acidic solution to form diazonium ions. These diazonium ions then react with various types of compounds, such as phenols or amines, to form colored azo dyes.

The principle of diazotization titration can be explained by the following reactions:

1. The primary aromatic amine is first converted to its diazonium salt by the action of sodium nitrite and hydrochloric acid:

R-NH2 + NaNO2 + HCl → R-N2+Cl- + NaCl + H2O

2. The diazonium salt reacts with the compound being titrated, which could be a phenol or an amine, to form a colored azo compound:

R-N2+Cl- + HOC6H5 → R-C6H4-N=N-C6H5 + HCl + H2O

The intensity of the resulting color is directly proportional to the concentration of the compound being titrated, allowing for the determination of the unknown compound’s concentration.

Diazotization titration is a sensitive and specific method for determining the concentration of phenols and primary aromatic amines in a sample. However, care must be taken to ensure that the diazonium salt is not decomposed before it reacts with the compound being titrated, and that the reaction between the diazonium salt and the compound being titrated is complete.

First Year B Pharm Notes, Syllabus, Books, PDF Subjectwise/Topicwise

Suggested readings:

• 301T Pharmaceutical Organic Chemistry II Theory
• Oral Rehydration Salt Pharmaceutics I Practical
• Identification tests for anions and cations Pharmaceutical Chemistry Practical
• Neutralization curves: Pharmaceutical Analysis
• Assay of Benzyl penicillin