Organic compound
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An organic compound is any member of a large class of chemical compounds whose molecules contain carbon and hydrogen; therefore, carbides, carbonates, carbon oxides and elementary carbon are not organic (see below for more on the definition controversy for this word). The study of organic compounds is termed organic chemistry, and since it is a vast collection of chemicals (over half of all known chemical compounds), systems have been devised to classify organic compounds. A few of the compound classes based on the functional groups they carry are as follows:
Many organic compounds are also of prime importance in biochemistry:
- Antigens
- Polysaccharides, carbohydrates and sugars
- Enzymes
- Hormones
- Lipids and fatty acids
- Neurotransmitters
- Nucleic acids
- Proteins, peptides and amino acids
- Vitamins
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Number crunching
Browsing a large number of structures, people have tried to gain an understanding of common properties. The statistical analysis of chemical structures is called chemical informatics. The Beilstein database contains a large collection of organic compounds. A cheminformatics study involving 5.9 million substances and 6.5 million reactions showed that the organic compound universe consists of a core of around 200,000 molecules strongly connected to each other and a large periphery (3.6 million molecules) around it [1]. Core and periphery are surrounded by a group of non-connected small islands containing 1.2 million molecules, a model resembling the world wide web. More key statistics:
- The core molecules (only 3.5% of the total) are involved in 35% of all reactions giving rise to 60% of all molecules.
- The average distance between two molecules in the core is 8.4 synthetic steps and 95% of all connecting reactions are fewer than 15 steps. Any molecule in the periphery can be reached by one from the core in fewer than 3 steps.
- The relative size of the core peaked in 1880 and has since then declined.
- The core contains 70% of the top 200 industrial chemicals.
- An optimised chemical inventory of 300 chemicals for a hypothetical chemical company allows the synthesis of up to 1.2 million organic compounds and contains 10 Wittig reagents, 6 Grignard reagents, 2 DNA building blocks and 18 aromatic aldehydes.
History and nomenclature
The name "organic" is an historical name, dating back to 19th century, when it was believed that organic compounds could only be synthesised in living organisms through vis vitalis - the "life-force". The theory that organic compounds were fundamentally different from those that were "inorganic", that is, not synthesized through a life-force, was disproved with the synthesis of urea, an "organic" compound by definition of its known occurrence only in the urine of living organisms, from potassium cyanate and ammonium sulfate by Friedrich Wöhler in the Wöhler synthesis.
The dividing line between organic and inorganic is presently contested, and is historically arbitrary. Generally speaking, organic compounds are often defined as those compounds which have carbon-hydrogen bonds, and inorganic compounds, those without. This even-more specific definition has some problems, notably that (with some historical irony) it excludes urea itself as an organic, since urea has carbon and hydrogen, but no carbon-hydrogen bond. In this scheme, carbonic acid is inorganic and so is oxalic acid, whereas formic acid is organic. This definition would also leave out non-hydrogen-containing fluorocarbons like Teflon and Freon, or put them in a grey area, since they are carbon-containing and have many of the same properties of C-H compounds, due to the similarity of the C-F bond to the C-H bond.
Most pure organic compounds today are artificially produced, although a few are extracted from natural sources because they would be far too expensive to produce artificially (for example, sucrose).
See also
References
- ^ The Core and Most Useful Molecules in Organic Chemistry Kyle J. M. Bishop, Rafal Klajn, Bartosz A. Grzybowski Angewandte Chemie International Edition Volume 45, Issue 32 , Pages 5348 - 5354 2006 DOI:10.1002/anie.200600881
| Topics in organic chemistry |
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Aromaticity | Covalent bonding | Functional groups | Nomenclature | Organic compounds | Organic reactions | Organic synthesis | Publications | Spectroscopy | Stereochemistry |
| List of organic compounds |
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Organic compounds | Organic chemistry