Diazonium Salts Preparation

We live in a colourful world. When everything around you is so vividly coloured, it’s hard to miss your neon-yellow clothing against the blue sky. Have you ever wondered how some of the clothes and materials we buy achieve such brilliant colours? Azo dyes, a class of organic molecules, play a vital part in helping to colour our environment with some beautiful colours, despite the fact that there are various explanations.

Organic compounds having nitrogen-nitrogen triple bonds and a side group are known as diazonium salts. The diazonium salt is an intermediary in the production of azo colours. Here, we will discuss the preparation of diazonium salts and the chemical reactions they can participate in. 

What are Diazonium Salts?

There are two nitrogen atoms in these compounds, one of which is positively charged. Diazonium salts include compounds such as benzenediazonium chloride and benzene diazonium hydrogen sulphate. Inorganic-organic combinations such as diazonium salts are some of the most versatile in the world of chemistry. RN2+X is the most common way to represent it. The organic group R is typically an aryl group, while the ionic group X is represented by the letter ‘X’. Diazonium and the anion X, such as bromide, are added to the parent hydrocarbon to form the salts’ names, which include the suffix diazonium.

Diazonium Salts Preparation

Diazonium salts are organic compounds that include nitrogen-nitrogen triple bonds and some other generic side group that could be either alkyl (an alkane derivative) or aryl (benzene ring). A chloride ion is a typical counter-ion for a positively charged nitrogen nucleus, which is why the chemical is referred to as a “salt” of diazo (di-nitrogen) in the name.

To make diazonium salts, the technique is very straightforward. Hydrochloric acid and sodium nitrite can be used to make either an alkyl or aryl primary amine, and the results are excellent. Reactions can typically be carried out at room temperature or even lower, depending on the situation.

Diazotization or dissociation is the process of turning an organic chemical, typically primary aromatic amines, into diazonium salts. The Diazonium group is highly unstable under normal conditions, hence it is usually used immediately after preparation rather than being kept in storage.

When nitrous acid and aromatic amines are mixed together, diazonium salt can be produced. Nitrous acid and aniline (aromatic amine) react to produce benzene diazonium chloride as a result of the reaction. Because nitrous acid is such a dangerous gas, it is often made in situ by reacting sodium nitrate dihydrate (NaNO2) with a mineral acid.

NaNO2+C6H5NH2 +2HCl (Temperature0–5°C)−−−−−−−−−−−→C6H7N2Cl +NaCl+2H2O

Temperature is another factor that affects product formation during the manufacture of diazonium salts; most salts are stable below 5°C. The Diazonium group will disintegrate to N2 if the reaction conditions are not kept below 5°C. Hence, it is crucial to maintain the low temperature. Aniline reacts with NaNO2 and hydrochloric acid to produce benzene diazonium chloride.

Properties of Diazonium Salts

1.     They have an ionic composition.
2.     They dissolve in water.
3.     As the name suggests, the crystals of aryl diazonium salts are colourless.
4.     Only when warmed does benzenediazonium chloride react with water.
5.     Water will not dissolve benzenediazonium fluoroborate. At room temperature, it is remarkably stable.

Importance of Diazonium Salts

1.       Dye and pigment industries use them, and they are also employed to make dyed fabrics.
2.     They are used in document reproduction because of their tendency to degrade when exposed to UV light.
3.       A wide range of chemical molecules can be synthesised using them, particularly aryl derivatives.
4.       In the dye and pigment industries, diazonium salts are used. They play a significant part in the production of coloured textiles.
5.       Reproducing documents with them is an option. This is due to the fact that they are able to decompose in UV light.
6.       A wide range of chemical molecules can be synthesised using them, particularly aryl derivatives.

Conclusion

The diazonium salt is formed when aniline (an aromatic amine) reacts with nitrous acid. You will find this salt in the form of benzene diazonium chloride. Toxic nitrous acid gas is extremely hazardous. NaNO2 and a mineral acid are commonly used to prepare the product during the reaction. The diazonium group can be used in a variety of ways. The mixing of organic and inorganic components has been a godsend for scientists, from the dyes and pigments sector to the synthesis of diverse organic substances.

Diazotization or dissociation is the process of making diazonium salts from an organic component. Diazonium groups are extremely unstable, thus we cannot keep them on hand. As a result, we tend to put them to use right away. To make diazonium salts, aromatic amines are often combined with nitrous acid.