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Have you ever wondered where the bright red pigment of your favourite woollen socks comes from? It's quite likely that it is derived from Amines. This is just one example of the uses of Amines.
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Jetzt kostenlos anmeldenHave you ever wondered where the bright red pigment of your favourite woollen socks comes from? It's quite likely that it is derived from Amines. This is just one example of the uses of 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:
Fig. 1 - Primary, secondary and tertiary amines
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.
Fig. 2 - A quaternary ammonium cation
Let's now briefly consider some of the characteristic properties of amines:
Check out Amines for a more detailed look into the properties of amines and the characteristics of these molecules. Head over to Amines Basicity if you want to learn more about their reactions as nucleophiles and bases.
Now that we know not only what amines are, but also about their characteristics and properties, we can look at some of their applications in daily life. After that, we'll consider their uses in industry.
Head over to Proteins Biochemistry to learn more about proteins. You can also learn more about polyamides and other polymers in Condensation Polymers.
Knowing what we use amines for is well and good, but how do we make those products in industry? It is now time to learn about two important industrial applications of amines.
The first important use of amines in industry is making 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.
Fig. 3 - A quaternary ammonium salt
Quaternary ammonium salts have a few uses: conditioners, detergents, and antimicrobial agents. They're suitable because of one particular characteristic: 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.
The second use of amines in industry is making diazonium salts and azo compounds. Diazonium salts contain an -N+≡N group, while azo compounds contain an N=N azo group. Producing azo compounds involves a multi-step synthesis:
Let's investigate those steps in more detail.
Firstly, phenylamine reacts with nitric(III) acid at low temperatures to form a diazonium salt containing the -N≡N+ group. Nitric(III) acid is extremely reactive and so must be prepared in situ. To carry out the reaction, we mix phenylamine with a chilled solution of a strong acid, such as 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:
$$HCl+NaNO_2\rightarrow HNO_2+NaCl$$
The nitric(III) acid formed then reacts with phenylamine and more hydrochloric acid to form a diazonium salt:
$$C_6H_5NH_2+NHO_2+HCl\xrightarrow{\text{< 10}^\circ \text{C}} C_6H_5N^+N\space Cl^-+2H_2O$$
Here's a diagram to help you understand the structure of the molecules involved.
Fig. 4 - Forming a diazonium salt
This reaction must be carried out below 10°C. If you heat the mixture, a different reaction takes place. Instead, you produce phenol (C6H5OH), nitrogen gas, and water:
$$C_6H_5NH_2+NHO_2+HCl\xrightarrow{\text{< 10}^\circ \text{C}} C_6H_5OH+N_2+H_2O$$
The second step of the process involves reacting the diazonium salt with another aromatic organic molecule. This is an example of a coupling reaction, forming an azo compound with the N=N azo functional group. In this reaction, the diazonium ion acts as an electrophile and substitutes into the second molecule's benzene ring.
One example is the reaction of a diazonium salt with phenol. This reaction takes place in a basic solution, typically of sodium hydroxide, and produces an azo compound with two benzene rings, one with an -OH group. These benzene rings are joined by an N=N azo bridge. It also produces an acid, which varies depending on the diazonium salt used.
Here's the equation for the reaction between a diazonium chloride salt and phenol. The structural formulae of these molecules can get a little tricky, so we've used displayed formulae to show you the reaction.
Fig. 5 - Forming an azo compound using phenol
A similar reaction takes place between diazonium salts and phenylamine. This produces another type of azo compound, but this time the second benzene ring has an -NH2 amine group instead of a phenyl group:
Fig. 6 - Forming an azo compound using phenylamine. This time, the azo product has an amine group instead of a phenyl group
To conclude this section, we'll consider the uses of azo compounds. Thanks to their two benzene rings, which are full of delocalised pi electrons, azo compounds are very stable and present with vivid colours. Azo compounds, therefore, form the basis of many dyes, including ones such as methyl orange that are used as pH indicators. They're also used in the textile industry and in tattoo inks.
This article is dedicated to the uses of amines, both in everyday life and in industry, and so you should now have an appreciation of why these molecules are so valuable. However, we'll end by summarising a few of reasons why amines are important to us. Then, we'll take a deep dive into the importance of amines in the human body.
Without amines, we probably wouldn't exist. It sounds dramatic, but it is true! This is because all amino acids are amines. Let's explore their uses and importance inside the human body.
We explore the biochemistry of amino acids in the article Amino Acids. You can also look at proteins from a chemist's point of view in Proteins Biochemistry. However, you can also head over to the biology side of StudySmarter to find out about amino acids, proteins, neurotransmitters, and hormones, from a more biological stance. These articles might help you and give you more to think about:
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.
Amines are used in cosmetics, dyes, pharmaceuticals, and plastics.
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.
Amines aren't acidic, but basic. This means that they act as proton acceptors.
Amines can form hydrogen bonds. This means that they have high melting and boiling points.
Shorter-chain amines are soluble in water.
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SIGNUP SIGNUPFlashcards in Uses of Amines15
Start learningWhat is an amine?
An ammonia derivative containing a nitrogen atom bonded to at least one R group.
Which of the following are true about amines?
Amines are polar molecules.
True or false? Some proteins are not made of amines.
False
Compare and contrast a tertiary amine with a quaternary ammonium ion.
Which of the following types of bonding are present in quaternary ammonium salts?
Covalent, dative covalent and ionic
Which of the following contain amines?
Proteins
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