To date Organic Chemistry is defined as the branch of chemistry that studies the structure, properties, composition, preparation, and reacti...
To date Organic Chemistry is defined as
the branch of chemistry that studies the structure, properties, composition, preparation, and reactions of compounds containing the carbon atom.
Most Organic Chemistry textbooks provide a more general definition.
Organic Chemistry is the study of carbon compounds.
A compound is a substance composed of two or more different elements bonded by a chemical bond. According to the above definitions the carbon allotropes are not organic. They are carbon-based materials but are “classified” as inorganic.
Usually, when we think about organic chemistry, we think about the carbon atom. The general assumption is that all compounds or materials that contain a carbon are organic compounds. However, that is not the case. There are compounds and molecules that contain at least one carbon but they are considered inorganic. The latter is for historical reasons and based on chemical properties. For example, if a compound possesses properties similar to inorganic compounds, it is classified as inorganic. However, there has been significant discussion of whether those carbon-containing compounds and molecules (including the carbon allotropes) should be classified as inorganic. Basically, it depends on who you ask.
Diamond, for example, is a carbon allotrope, and it is classified as an inorganic material even though it contains only carbon atoms. The main argument is that diamonds are minerals, and historically minerals are classified as inorganic.
Nevertheless, if you are an organic chemist, you are expected to understand the chemistry of those carbon-based molecules not included by definition.
References
2. L.G. Wade, J.W. Simek, Organic Chemistry, Pearson, 9th Ed. 2017
3. J.G. Smith, Organic Chemistry, McGraw-Hill, 6th Ed. 2020
4. S. Bewick, R. Parsons, T. Forsythe, S. Robinson, and J. Dupon, Chemistry - LibreTexts (March 4, 2021).
