  Ontologies order and interconnect knowledge of a certain field in a formal
and semantic way so that they are machine-parsable. They try to define allwhere
acceptable definition of concepts and objects, classify them, provide
properties as well as interconnect them with relations (e.g. "A is a special
case of B"). More precisely, Tom Gruber defines Ontologies as a "specification
of a conceptualization; [...] a description (like a formal specification of a
program) of the concepts and relationships that can exist for an agent or a
community of agents." [1] An Ontology is made of Individuals which are
organized in Classes. Both can have Attributes and Relations among themselves.
Some complex Ontologies define Restrictions, Rules and Events which change
attributes or relations. To be computer accessible they are written in certain
ontology languages, like the OBO language or the more used Common Algebraic
Specification Language. With the rising of a digitalized, interconnected and
globalized world, where common standards have to be found, ontologies are of
great interest. [2] Yet, the development of chemical ontologies is in the
beginning. Indeed, some interesting basic approaches towards chemical
ontologies can be found, but nevertheless they suffer from two main flaws.
Firstly, we found that they are mostly only fragmentary completed or are still
in an architecture state. Secondly, apparently no chemical ontology is
widespread accepted. Therefore, we herein try to describe the major
ontology-developments in the chemical related fields Ontologies about chemical
analytical methods, Ontologies about name reactions and Ontologies about
scientific units.
