Physical Properties of Amines


Amines are chemical compounds that display a distinct set of physical properties that are associated with the connectivity with the carbon atom. This product is quite similar to that of ammonia in terms of structure. There are four different kinds of amines that are formed depending on the replacement of hydrogen atoms by ammonia molecules.

What are Amines?

Amines are chemical compounds that have a distinct set of properties associated with them. Amines are molecules as well as functional groups that are found in organic chemistry, the compound possesses a lone pair of basic nitrogen atoms. Amines are officially considered to be derivatives of ammonia that have one or multiple hydrogen atoms replaced by alkyl or the aryl group. Some of the important amines are amino acids, biogenic amines, trimethylamine and aniline. Mainly, there are three different kinds of amines to be found in nature, which are classified as primary, secondary, and tertiary amines. The classifications are conducted based on the replaced amount of the hydrogen atoms from the ammonia.

Figure 1: Amine

Classification of Amines

Primarily, classifications of amines are conducted based on the replaced number of hydrogen atoms from the ammonia. The different types of amines are discussed below −

Figure 2: Classifications of amines

Fvasconcellos 20:17, 8 January 2008 (UTC). Original image by DrBob contribs)., IUPAC-amine, CC BY-SA 3.0

Primary Amine

In case one hydrogen atom of ammonia molecule is substituted by alkyl or the aryl group it is known as primary amine. Since this kind of amine retains only one substituent on the nitrogen, these are named along with the substituent as a prefix. It is also called 1° amines. This kind of amine is produced when salt is made in the first stage that is acknowledged as ammonium bromide.

It is similar to ammonium bromide however; an ethyl group substitutes a hydrogen atom that is found in the ammonium ion. Ammonia gives out hydrogen atoms from ethyl ammonium ion, producing primary amine.

Secondary Amine

Two different organic substitutes are utilised to get rid of excess hydrogen atoms in the ammonia molecule that produces an amine. The ammonia gives off the hydrogen ion from dimethyl ammonium ion that leaves secondary amine that is also termed diethylamine.

Tertiary Amines

This kind of amine is produced when a particular organic compound substitutes all the hydrogen atoms. It can either belong to an aryl group or it might belong to an aromatic group. This is prepared, as ammonia removes hydrogen ions from triethylammonium ion that leaves a tertiary amine which is termed triethylamine. Tertiary amine has three alkyl groups bound to nitrogen.

Cyclic Amines

There is another kind of amine while the nitrogen is incorporated into a structure of a ring. It thereby produces either secondary or tertiary amines.

Structure of Amines

Based on the composition of amine, every one of the $\mathrm{sp^3}$ hybridised orbitals of nitrogen overlaps with the orbits of hydrogen or the carbons. Every amine possesses an unshared pair of electrons in the fourth orbit of nitrogen.

Figure 3: Structure of amine

Kes47 (?), Primary-amine-2D-general, marked as public domain, more details on Wikimedia Commons

The angle formed by C-N-E (where E represents either Carbon or Hydrogen) is less than 109.5° because of the presence of unshared pairs of electrons. The angle of deviation gets a bit lower in cases of trimethylamine which is 108°

Physical properties of Amines

Some of the properties of amines are mentioned below −

  • Lower aliphatic amines exist in a gaseous state.

  • Primary amines contain multiple carbon atoms which are liquid at room temperature.

  • Lower aliphatic amines can form hydrogen bonds with water molecules, it makes the amines soluble in water.

  • Enhancing the size of hydrophobic alkyl rises the molar mass of amines

  • The intermolecular association is quite prominent in primary amines as compared to secondary amines. Intermolecular association is not present in tertiary amines.

  • The boiling point is highest in primary amines and lowest in tertiary amines.

Uses of Amines

Some of the uses of amines are mentioned below −

  • Amines are used in the production of azo-dyes

  • They are extensively used in the production of chemicals that protection of crops and food products.

  • Amines are also helpful in the production of pharmaceutical products. Morphine and Demerol are helpful as painkillers.

  • Amines are helpful as pest control agents.

  • Amines help in the tanning of leather

  • Methamphetamines and amphetamines are considered recreational drugs.

  • These are also found in personal care products.

  • Amines are widely found in the global market in the form of ethanol amine


Amines are quite a common substance that is widely used for various functions. The amines are made from ammonia products by substitution of hydrogen atoms with other organic compounds. Primarily, there are three distinct types of amines to be found which have their distinct set of properties associated with them. Amines are mostly found in narcotic and pharmaceutical products. Its associated property of being soluble in water along with other aspects makes it highly useful in different industries.


Q1. Is amine flammable?

Ans. In general, amines have a high boiling point, and primary amines have the highest boiling point. These products are combustible but are not extremely flammable in a room temperature.

Q2. What are the chemical properties of amine?

Ans. Amines are organic products having one of multiple nitrogen atoms, structurally theta is often dependent on them. Amines also mirror the structure of ammonia but amines also retain extra properties that are dependent on the carbon atoms.

Q3. Where are amines used?

Ans. Amines is mostly used in the narcotics and medication industry. Different kinds of drugs are produced with the help of this compound. Amines are also found in the production of chemicals for the purification of water. These products are also found in cosmetic and care products. Amines are also found in safety chemicals used for the protection of chemicals.

Updated on: 25-Apr-2023


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