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Screenshot of the CAS Common Chemistry database with information about caffeine ().. A CAS Registry Number [1] (also referred to as CAS RN [2] or informally CAS Number) is a unique identification number, assigned by the Chemical Abstracts Service (CAS) in the US to every chemical substance described in the open scientific literature, in order to index the substance in the CAS Registry.
According to CAS, his visionary view of CAS' potential "led to expansion, modernization, and the forging of international alliances with other information organizations." [15] CAS was an early leader in the use of computer technology to organize and disseminate information. [16] The CAS Chemical Registry System was introduced in 1965.
This is a list of CAS numbers by chemical formulas and chemical compounds, indexed by formula.The CAS number is a unique number applied to a specific chemical by the Chemical Abstracts Service (CAS).This list complements alternative listings to be found at list of inorganic compounds and glossary of chemical formulae
To be more specific, the name may need to represent the three-dimensional arrangement of the atoms. This requires adding more rules to the standard IUPAC system (the Chemical Abstracts Service system (CAS system) is the one used most commonly in this context), at the expense of having names which are longer and less familiar.
According to ASHRAE standard 34, the R-number of a chemical refrigerant is assigned systematically according to its molecular structure and has between two and four digits. If there are carbon-carbon multiple bonds, there are four digits in all: the number of these bonds is the first digit and the number of carbon atoms minus one (C-1) is next ...
This is the only sublayer that must occur in every InChI. Numbers used throughout the InChI are given in the formula's element order excluding hydrogen atoms. For example, "/C10H16N5O13P3" implies that atoms numbered 1–10 are carbons, 11–15 are nitrogens, 16–28 are oxygens, and 29–31 are phosphorus. [11] Atom connections (prefix: "c ...
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The old IUPAC system was frequently used in Europe, while the CAS is most common in America. The new IUPAC scheme was developed to replace both systems as they confusingly used the same names to mean different things. The new system simply numbers the groups increasingly from left to right on the standard periodic table.