RXNO Ontology
The RXNO Ontology is a formal ontology of chemical named reactions.
It was originally developed at the Royal Society of Chemistry and is associated with the Open Biomedical Ontologies Foundry. The RXNO ontology unifies several previous attempts to systematize chemical reactions including the Merck Index and the hierarchy of Carey, Laffan, Thomson and Williams.
Major Reaction Categories
The twelve top-level reaction categories proposed by Carey, Laffan, Thompson and Williams are given in the table below, together with their RXNO ontology identifiers and the equivalent wikipedia categories where applicable.| Index | Reaction Category | RXNO ID | Wikipedia Category |
| 1 | Heteroatom alkylation and arylation | :Category:Carbon-heteroatom bond forming reactions | |
| 2 | Acylation and related processes | ||
| 3 | Carbon-Carbon bond formation | RXNO:0000002 | :Category:Carbon-carbon bond forming reactions |
| 4 | Heterocycle forming reactions | RXNO:0000349 | :Category:Heterocycle forming reactions |
| 5 | Protection reactions | RXNO:0000078 | |
| 6 | Deprotection reactions | RXNO:0000203 | |
| 7 | Reductions | :Category:Organic reduction reactions | |
| 8 | Oxidations | :Category:Organic oxidation reactions | |
| 9 | Functional group interconversion | RXNO:0000011 | :Category:Substitution reactions |
| 10 | Functional group addition | ||
| 11 | Resolution reactions | ||
| 12 | Miscellaneous | :Category:Organic reactions |