A CAS Registry Number,also referred to as CASRN or CAS Number, is a unique numerical identifier assigned by the Chemical Abstracts Service (CAS) to every chemical substance described in the open scientific literature (currently including all substances described from 1957 through the present, plus some substances from the early or mid 1900s), including organic and inorganic compounds, minerals, isotopes, alloys and nonstructurable materials (UVCBs, substances of unknown or variable composition, complex reaction products, or biological origin).
The registry maintained by CAS is an authoritative collection of disclosed chemical substance information. It currently identifies more than 158 million unique organic and inorganic substances and 67 million protein and DNA sequences,plus additional information about each substance. It is updated with around 15,000 additional new substances daily.
This section does not cite any sources . (June 2017) (Learn how and when to remove this template message)
Historically, chemicals have been identified by a wide variety of synonyms. Frequently these are arcane and constructed according to regional naming conventions relating to chemical formulae, structures or origins. Well-known chemicals may additionally be known via multiple generic, historical, commercial, and/or (black)-market names.
CAS Registry Numbers (CASRN) are simple and regular, convenient for database searches. They offer a reliable, common and international link to every specific substance across the various nomenclatures and disciplines used by branches of science, industry, and regulatory bodies. Almost all molecule databases today allow searching by CAS Registry Number.
On the other hand, CASRNs are not related to chemistry, are proprietary and unrelated to any previous systems, and do not readily form phonetic analogs or synonyms.
A CAS Registry Number has no inherent meaning but is assigned in sequential, increasing order when the substance is identified by CAS scientists for inclusion in the CAS REGISTRY database.
A CASRN is separated by hyphens into three parts, the first consisting from two up to seven digits,the second consisting of two digits, and the third consisting of a single digit serving as a check digit. This current format gives CAS a maximum capacity of 1,000,000,000 unique identifiers.
The check digit is found by taking the last digit times 1, the preceding digit times 2, the preceding digit times 3 etc., adding all these up and computing the sum modulo 10. For example, the CAS number of water is 7732-18-5: the checksum 5 is calculated as (8×1 + 1×2 + 2×3 + 3×4 + 7×5 + 7×6) = 105; 105 mod 10 = 5.
| Wikidata has the property: |
To find the CAS number of a compound given its name, formula or structure, the following free resources can be used:
UN numbers are four-digit numbers that identify hazardous materials, and articles in the framework of international transport. Some hazardous substances have their own UN numbers, while sometimes groups of chemicals or products with similar properties receive a common UN number. A chemical in its solid state may receive a different UN number than the liquid phase if their hazardous properties differ significantly; substances with different levels of purity may also receive different UN numbers.
The Merck Index is an encyclopedia of chemicals, drugs and biologicals with over 10,000 monograph on single substances or groups of related compounds published online by the Royal Society of Chemistry.
A chemical database is a database specifically designed to store chemical information. This information is about chemical and crystal structures, spectra, reactions and syntheses, and thermophysical data.
Chemical Abstracts Service (CAS) is a division of the American Chemical Society. It is a source of chemical information. CAS is located in Columbus, Ohio, United States.
This article discusses some common molecular file formats, including usage and converting between them.
The IUPAC International Chemical Identifier is a textual identifier for chemical substances, designed to provide a standard way to encode molecular information and to facilitate the search for such information in databases and on the web. Initially developed by IUPAC and NIST from 2000 to 2005, the format and algorithms are non-proprietary.
The Beilstein database is the largest database in the field of organic chemistry, in which compounds are uniquely identified by their Beilstein Registry Number. The database covers the scientific literature from 1771 to the present and contains experimentally validated information on millions of chemical reactions and substances from original scientific publications. The electronic database was created from Beilstein's Handbook of Organic Chemistry, founded by Friedrich Konrad Beilstein in 1881, but has appeared online under a number of different names, including Crossfire Beilstein. Since 2009, the content has been maintained and distributed by Elsevier Information Systems in Frankfurt under the product name "Reaxys".
PubChem is a database of chemical molecules and their activities against biological assays. The system is maintained by the National Center for Biotechnology Information (NCBI), a component of the National Library of Medicine, which is part of the United States National Institutes of Health (NIH). PubChem can be accessed for free through a web user interface. Millions of compound structures and descriptive datasets can be freely downloaded via FTP. PubChem contains substance descriptions and small molecules with fewer than 1000 atoms and 1000 bonds. More than 80 database vendors contribute to the growing PubChem database.
The European Community number is a unique seven-digit identifier that was assigned to substances for regulatory purposes within the European Union by the European Commission. The EC Inventory comprises three individual inventories, EINECS, ELINCS and the NLP list.
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances, chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.
ChemSpider is a database of chemicals. ChemSpider is owned by the Royal Society of Chemistry.
Dichlorodiphenyldichloroethane (DDD) is an organochlorine insecticide that is slightly irritating to the skin. DDD is a metabolite of DDT. DDD is colorless and crystalline; it is closely related chemically and is similar in properties to DDT, but it is considered to be less toxic to animals than DDT. The molecular formula for DDD is (ClC6H4)2CHCHCl2 or C14H10Cl4, whereas the formula for DDT is (ClC6H4)2CHCCl3 or C14H9Cl5.
A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. Two atoms of the same element bonded in a molecule do not form a chemical compound, since this would require two different elements.
2-Fluoroethanol is the chemical compound with the formula CH2FCH2OH and the simplest fluorohydrin. This colorless liquid is one of the simplest stable fluorinated alcohols. It was developed for use as a rodenticide, insecticide, and acaricide. Owing to its easy oxidation to fluoroacetic acid, fluoroethanol is highly toxic (LD50 = 10 mg/kg). The related difluoro- and trifluoroethanols are far less dangerous.
The Hazardous Substances Data Bank (HSDB) is a toxicology database on the U.S. National Library of Medicine's (NLM) Toxicology Data Network (TOXNET). It focuses on the toxicology of potentially hazardous chemicals, and includes information on human exposure, industrial hygiene, emergency handling procedures, environmental fate, regulatory requirements, and related areas. All data are referenced and derived from a core set of books, government documents, technical reports, and selected primary journal literature. All entries are peer-reviewed by a Scientific Review Panel (SRP), members of which represent a spectrum of professions and interests. Current Chairs of the SRP are Dr. Marcel J. Cassavant, MD, Toxicology Group, and Dr. Roland Everett Langford, PhD, Environmental Fate Group.
IUPAC Polymer Nomenclature are standardized naming conventions for polymers set by the International Union of Pure and Applied Chemistry (IUPAC) and described in their publication "Compendium of Polymer Terminology and Nomenclature", which is also known as the "Purple Book". Both the IUPAC and Chemical Abstracts Service (CAS) make similar naming recommendations for the naming of polymers.
The CompTox Chemicals Dashboard is a freely accessible online database created and maintained by the U.S. Environmental Protection Agency (EPA). The database provides access to multiple types of data including physicochemical properties, environmental fate and transport, exposure, usage, in vivo toxicity, and in vitro bioassay. EPA and other scientists use the data and models contained within the dashboard to help identify chemicals that require further testing and reduce the use of animals in chemical testing. The Dashboard is also used to provide public access to information from EPA Action Plans, e.g. around perfluorinated alkylated substances.,
Poly(ethyl methacrylate) (PEMA) is a hydrophobic synthetic acrylate polymer. It has properties similar to the more common PMMA, however it produces less heat during polymerization, has a lower modulus of elasticity and an overall softer texture. It may be vulcanized using lead oxide as a catalyst and it can be softened using ethanol.