What are organic compounds?

The organic compounds are those from living organisms and containing carbon and hydrogen atoms bonded together in the form of open chain or closed cycles.

In addition to carbon and hydrogen, organic compounds can also contain other elements such as oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), fluorine (F), chlorine (Cl), bromine (Br) or iodine (I). All of these are called heteroatoms.

Life would not be possible without organic compounds, which is why all living things contain them. There are thousands of these substances and we can find them everywhere, starting with our own bodies.

Characteristics of organic compounds

They are based on the chemistry of carbon

Carbon forms the basis of all organic compounds. In these compounds, the carbon atoms can bond with each other or with other elements. Each carbon atom always forms 4 bonds in total, between single, double and triple bonds.

There are three main types of chemical bonds which are the covalent bond, the ionic bond and the metallic bond. Organic compounds are characterized by having only covalent bonds between all their atoms.

They are combustible

Charcoal is a fuel that is obtained from the organic compounds present in wood.

Because they contain so many carbon atoms, organic compounds are combustible. This means that they can be burned through a combustion reaction with oxygen in the air.

The combustion reactions of organic compounds are exothermic reactions that release a lot of heat. All living beings take advantage of all this energy to carry out all the reactions that keep us alive.

They possess isomerism

Many organic compounds have the same molecular formula, but they are completely different compounds. This property is called isomerism, and it is characteristic of organic compounds.

For example, both methyl ether and ethanol have the molecular formula C 2 H 6 O, but the former is a gas while the latter is a liquid.

Another characteristic of organic compounds is that they can form gigantic molecules by repeating a group of atoms over and over again in a long chain. These compounds are called polymers and a typical example of them is plastics.


Another property that characterizes organic compounds is their solubility. Many of them, particularly the polar organic compounds, are soluble in water. Other compounds do not dissolve in water, but they do dissolve in organic solvents such as cyclohexane.

Types of organic compounds

Organic compounds have properties and characteristics that make them very different from inorganic compounds (those that do not come from living things, such as minerals).

Many of these characteristics allow them to be classified in different ways, which gives rise to different types of organic compounds. The most important classification criteria are:

  • According to its origin.
  • According to its structure and composition.
  • According to the functional group.
  • According to its polarity.

The types of organic compounds classified according to each of these criteria are described below:

Types of organic compounds according to their origin

Depending on where they come from, organic compounds can be:

  • Natural organic compounds : they are those that are found in nature and that come directly from living beings. Cellulose is a good example, as it is the most abundant natural organic compound on earth.
  • Synthetic organic compounds : they refer to those organic compounds that are synthesized by chemists in a laboratory or chemical plant. All the plastics that we use every day are synthetic, and so are many medicines.

Types of organic compounds according to their structure and composition

According to the atoms that make them up and the way in which these atoms are linked together, organic compounds can be:

  • Aliphatic hydrocarbons : formed only by carbon and hydrogen and where the carbons form open chains, either linear or branched. They include alkanes, alkenes, and alkynes.
  • Aromatic hydrocarbons : the compounds that belong to this family, also called arenes, contain unsaturated rings (which may still have more hydrogens) that have great molecular stability. This property is called aromaticity and is characteristic of benzene and all its derivatives.
  • Heterocyclic compounds : they are cyclic compounds in which one or more carbon atoms are replaced by a hetero atom that can be oxygen, nitrogen, sulfur or phosphorus. Examples of heterocycles are pyridine and furan.
  • Organometallic compounds :  s on a special class of compounds that are halfway between organic and inorganic be. They are characterized by containing an organic part with a heteroatom (O, N, S or P) covalently linked to a metal such as copper (Cu), iron (Fe) or another.

Types of organic compounds according to the functional group

The part of an organic molecule where chemical reactions usually occur is a small group of atoms called a functional group. There are several different functional groups that allow organic compounds to be classified into:

  • Alkanes : only contain carbon and hydrogen linked only by single bonds. For example, butane.
  • Alkenes : they are hydrocarbons that contain a carbon-carbon double bond. For example, butene.
  • Alkynes : they are hydrocarbons that contain a carbon-carbon triple bond. For example, ethyne, also known as acetylene.
  • Alkyl halides : organic compounds that contain a halogen (F, Cl, Br or I) bonded to an aliphatic carbon. For example, chloromethane.
  • Alcohols : Alcohols are polar organic compounds that contain a hydroxyl group (-OH) attached to an aliphatic carbon.
  • Phenols : these compounds also contain a hydroxyl group (-OH), but in this case attached to an aromatic carbon.
  • Ethers : they are easily recognized, since they are two carbon chains linked together by an oxygen atom. For example, methyl ether.
  • Amines : they are organic compounds derived from ammonia (NH 3 ). They contain one or more aliphatic carbon chains (alkyl groups) linked to a nitrogen atom by means of single bonds.
  • Aldehydes : oxygenated organic compounds that contain a carbonyl group (C = O) attached to a hydrogen at one of its terminal carbons. In general they have characteristic odors, such as cinnamaldehyde that gives the smell of cinnamon.
  • Ketones : are oxygenated organic compounds that contain a carbonyl group (C = O) attached to two carbon chains.
  • Carboxylic acids : also called organic acids, they are weak acids that contain a carboxyl group (-COOH) in one of its terminal carbons.
  • Esters : come from the union of a carboxylic acid with an alcohol. In this case, the hydrogen in the carboxyl group is replaced by an alkyl group.
  • Amides : come from the union of a carboxylic acid with an amine. In this case, the OH of the carboxyl group is replaced by a nitrogen linked to two hydrogens, one hydrogen and one alkyl or two alkyls.

Types of organic compounds according to their polarity

We can also classify organic compounds into polar and non-polar:

  • Polar organic compounds : these compounds have polar covalent bonds with atoms like nitrogen and oxygen that make the entire molecule polar. Most of these compounds are soluble in water.
  • Nonpolar organic compounds : s on those that do not have polar bonds or the polarities of their bonds cancel each other. These compounds are not soluble in water.

Differences between organic compounds and inorganic compounds

The following table summarizes the differences between organic and inorganic compounds:

Organic compounds

Inorganic compounds


They come from living beings or their remains.

They do not come from living things.


Formed almost exclusively by C, N, O, S, P, F, Cl, Br and I.

They can be made up of any element on the periodic table.

Types of links:

They form both polar and non-polar covalent bonds.

They can form all types of chemical bonds, including polar, apolar, ionic, or metallic covalent bonds.


Most present isomerism.

Only some show isomerism.


They are combustible.

Most are not combustible.

Examples of organic compounds

1. Methane (CH 4 )

2. Ethyl acetate (C 4 H 8 O 2 )

3. Benzene (C 6 H 6 )

4. Ethyl Alcohol (C 2 H 6 O)

5. Acetone (C 3 H 6 O)

6. Formaldehyde (CH 2 O)

7. Hemoglobin (a protein)

8. Polyethylene (one of the most common plastics)

9. Glucose (C 6 H 12 O 6 )

10. Naphthalene (C 10 H 8 )

11. Butane (C 4 H 10 )

12. Acetic acid or vinegar (C 2 H 4 O 2 )

13. Neopentane (C 5 H 12 )

14. Cyclohexane (C 6 H 12 )

15. Pyridine (C 5 H 5 N)

16. Guanine (C 5 H 5 N 5 O)

17. Fructose (C 6 H 12 O 6 )

18. Ethyl ether (C 4 H 10 O)

19. Methanol (CH 4 O)

20. Chloroform (CHCl 3 )

21. Phenol (C 6 H 6 O)

22. Acetylene (C 2 H 2 )

23. Triphenylphosphine ((C 6 H 6 ) 3 P)

24. Trans-butenedioic acid (C 4 H 4 O 4 )

25. Aspartic acid (an amino acid) (C 4 H 7 NO 4 )

26. Furan (C 4 H 4 O)

27. Cinnamaldehyde (aroma of cinnamon) (C 9 H 8 O)

28. Vanillin (C 8 H 8 O 3 )

29. Sodium acetate (C 2 H 3 O 2 Na)

30. P-Xylene (C 8 H 10 )

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