Curious about what makes your red woollen socks so vibrant? It's probably thanks to amines! These versatile compounds have many uses in organic chemistry, which we'll explore in this article. First, let's cover what amines actually are. Then, we'll dive into real-life examples of how they're used in industry, including quaternary ammonium salts and azo compounds. Ready to learn more about the fascinating world of amines?

What are amines?

In Amines, we introduced you to a new type of organic molecule: amines. These are ammonia derivatives, characterised by a nitrogen atom bonded to at least one organic hydrocarbon R group. Amines can be further divided into three different types: Primary amines contain a nitrogen atom bonded to just one R group and have the general formula NH2R.Secondary amines contain a nitrogen atom bonded to two R groups and have the general formula NHR2.Tertiary amines contain a nitrogen atom bonded to three R groups and have the general formula NR3.

‍

You can also get quaternary ammonium cations. These consist of a nitrogen atom bonded to four R groups. The nitrogen atom bonds to the fourth R group using a dative covalent bond. Quaternary ammonium ions are an important part of quaternary ammonium salts.

‍

Properties of amines

Let's take a quick look at some key properties of amines. These molecules are polar and can form hydrogen bonds with other amine molecules and water. This high level of intermolecular bonding leads to a higher melting and boiling point, and shorter-chain amines are soluble in water. Amines can also act as both nucleophiles and bases, which allows for a wide range of reactions. To learn more about the fascinating world of amines, check out our detailed guide Amines. For an in-depth look at their reactions as nucleophiles and bases, head to Amines Basicity.

Uses of amines in daily life

Now that we know what amines are, we can look at some of their day-to-day applications. After that, we'll consider their uses in industry.

Amines are found in every cell in your body in the form of proteins. Proteins are condensation polymers, made up of repeating units called amino acids. Each amino acid has both a carboxyl functional group and an amine functional group, and they join together to form a long polymer chain. This chain then folds into a specific 3D shape that is unique to each protein. Another type of polymer involving amines is polyamides. These include nylon, Kevlar, and a variety of plastics. Many common drugs and pharmaceuticals are amines. These include the analgesic morphine, the decongestant ephedrine, and the antidepressant amoxapine. Amines play a role in cosmetics, such as shampoos, soaps, and shaving creams. We'll look at how they are made in just a second. The common compound tetramethylammonium chloride, used to disinfect water, is also an amine. Amines are the precursor to many dyes and tanning agents. Head over to Proteins Biochemistry to learn more. You can also learn more about polyamides and other polymers in Condensation Polymers.

Uses of amines in industry

Knowing what we use amines for is well and good, but how do we make those products? It is now time to learn about two important industrial applications of amines.

Quaternary ammonium saltsAzo compounds

Quaternary ammonium salts

Earlier, we learned that a quaternary ammonium ion consists of a nitrogen atom bonded to four organic hydrocarbon R groups. It has a permanent positive charge, which means that it can bond ionically to negatively-charged ions, forming a quaternary ammonium salt.

‍

Quaternary ammonium salts have a few uses: conditioners, detergents, and antimicrobial agents. They're suitable because of their charge. In conditioners and fabric softeners, the positive charge of the ammonium ion is attracted to the negative charge of wet clothes or hair, and the ammonium ions form a layer on the surface. This helps keep the hair or fabric smooth and glossy. In detergents and antimicrobial agents, the positive charge of the ammonium ion is attracted to the negative charge of bacterial cell walls. This disrupts the wall and damages the cell.

Azo compounds

In industry, amines are commonly used to produce diazonium salts and azo compounds. Diazonium salts contain an -N+≡N group, while azo compounds contain an N=N azo group. The production of azo compounds involves a multi-step synthesis process.

To start, phenylamine (C6H5NH2) is mixed with nitric(III) acid (HNO2) at low temperatures to form a diazonium salt containing the -N≡N+ group. Nitric(III) acid is highly reactive and must be prepared in situ. To carry out the reaction, we mix phenylamine with a chilled solution of a strong acid, like hydrochloric acid (HCl), and then add sodium nitrite (NaNO2). The hydrochloric acid and sodium nitrite first react to form nitric(III) acid and sodium chloride. The nitric(III) acid formed then reacts with phenylamine and more hydrochloric acid to form a diazonium salt.

One example of using a diazonium salt is to react it with phenol to produce an azo compound with two benzene rings, one with an -OH group. This reaction takes place in a basic solution, typically of sodium hydroxide, and also produces an acid, which varies depending on the diazonium salt used. The structural formulae of these molecules can get complicated, so we've used displayed formulae to show you the reaction.

Overall, amines play an important role in the production of many compounds used in industry. To learn more about the fascinating world of amines and their properties, check out our comprehensive guide on Amines.

In addition to their role in the production of diazonium salts, amines also have many practical uses in various fields. Azo compounds, which are made from diazonium salts, are very stable and contain two benzene rings full of delocalized pi electrons. This makes them highly useful in the production of dyes, including those used in the textile industry, as well as pH indicators like methyl orange. They are also used in the production of tattoo inks.

Overall, amines are incredibly versatile molecules with a wide range of applications in various industries. From pharmaceuticals to dyes, their unique properties make them indispensable in many fields. To learn more about amines and their uses, check out our comprehensive guide on Amines.

Uses of Amines

What are some examples of amines? 

Examples of amines include methylamine and phenylamine. However, we also find amines in daily life. For example, all proteins are made from amines known as amino acids, whilst many drugs such as morphine are also amines.

What are amines used for? 

Amines are used in cosmetics, dyes, pharmaceuticals, and plastics.

What is the importance of amines? 

Amines play important roles in many drugs, cosmetics, detergents, plastics, and antimicrobials. They also make up all proteins, which are found in every cell in our body.

Are amines acidic? 

Amines aren't acidic, but basic. This means that they act as proton acceptors.

What are the physical properties of amines? 

Amines can form hydrogen bonds. This means that they have high melting and boiling points.Shorter-chain amines are soluble in water.

‍