Chemical substance In organic chemistry, there can be more than one chemical compound with the same composition and molecular weight. Generally, these are called isomers. Isomers usually have substantially different chemical properties, and often may be isolated without spontaneously interconverting. A common example is glucose vs. fructose. The former is an aldehyde, the latter is a ketone. Their interconversion requires either enzymatic or acid-base catalysis. However, tautomers are an exception: the isomerization occurs spontaneously in ordinary conditions, such that a pure substance cannot be isolated into its tautomers, even if these can be identified spectroscopically or even isolated in special conditions. A
GESTIS Substance Database GESTIS Substance Database GESTIS Substance Database is a freely accessible online information system on chemical compounds. It is maintained by the Institut für Arbeitsschutz der Deutschen Gesetzlichen Unfallversicherung (IFA, Institute for Occupational Safety and Health of the German Social Accident Insurance). Information on occupational medicine and first aid is compiled by Henning Heberer and his team (TOXICHEM, Leuna). The database contains information for the safe handling of hazardous substances and other chemical substances at work: The available information relates to about 9,400 substances. Data are updated immediately after publication of new official regulations or after the issue of new scientific