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CAS Registry
Numbers (CAS RN) 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
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The CAS Registry is an authoritative collection of disclosed chemical substance information. It identifies more than 204 million unique organic and inorganic substances and 69 million protein and DNA sequences, plus additional information about each substance. It is updated with around 15,000
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Historically, chemicals have been identified by a wide variety of synonyms. One of the biggest challenges in the early development of substance indexing, a task undertaken by the
Chemical Abstracts Service, was in identifying if a substance in literature was new or if it had been previously
569:
Jacobs, Andrea; Williams, Dustin; Hickey, Katherine; Patrick, Nathan; Williams, Antony J.; Chalk, Stuart; McEwen, Leah; Willighagen, Egon; Walker, Martin; Bolton, Evan; Sinclair, Gabriel; Sanford, Adam (13 June 2022).
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Jacobs, Andrea; Williams, Dustin; Hickey, Katherine; Patrick, Nathan; Williams, Antony J.; Chalk, Stuart; McEwen, Leah; Willighagen, Egon; Walker, Martin; Bolton, Evan; Sinclair, Gabriel; Sanford, Adam (13 May 2022).
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of a chemical into a computer-searchable table, which provided a basis for the service that listed each chemical with its CAS Registry Number, the CAS Chemical
Registry System, which became operational in 1965.
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A CAS RN 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
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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.
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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
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65:. This registry includes all substances described since 1957, plus some substances from as far back as the early 1800s; it is a
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additional new substances daily. A collection of almost 500 thousand CAS registry numbers are made available under a
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do not receive different CAS RNs (liquid water and ice both have 7732-18-5), but different crystal structures do (
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discovered. Well-known chemicals may additionally be known via multiple generic, historical, commercial, and/or
717:"CAS Common Chemistry in 2021: Expanding Access to Trusted Chemical Information for the Scientific Community"
572:"CAS Common Chemistry in 2021: Expanding Access to Trusted Chemical Information for the Scientific Community"
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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.
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Commonly encountered mixtures of known or unknown composition may receive a CAS RN; examples are
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based on structure alone was not universally useful. An algorithm was developed to translate the
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Occasionally whole classes of molecules receive a single CAS RN: the class of enzymes known as
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databases today allow searching by CAS Registry Number, and it is used as a global standard.
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519:"CAS Common Chemistry expands collection of publicly available chemical information"
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described in the open scientific literature, in order to index the substance in the
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113:), so they do not contain any information about the structures themselves the way
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170:. This format gives CAS a maximum capacity of 1,000,000,000 unique numbers.
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Screenshot of the CAS Common
Chemistry database with information about
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National
Induscctrial Chemicals Notification and Assessment Scheme.
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National
Industrial Chemicals Notification and Assessment Scheme.
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Common
Chemistry via Australian Inventory of Chemical Substances
89:, mixtures, and nonstructurable materials (UVCBs, substances of
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801:"ESIS : European chemical Substances Information System"
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NIOSH Pocket Guide to
Chemical Hazards, index of CAS numbers
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has 7440-47-3, the trivalent Cr(III) has 16065-83-1 and the
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Search Tool of
Australian Inventory of Chemical Substances
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are discerned by their oxidation state, e.g. the element
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or structure, the following free resources can be used:
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To find the CAS number of a compound given its name,
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469:
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https://www.cas.org/content/chemical-substances/faqs
853:"HSNO Chemical Classification Information Database"
640:Canadian Centre for Occupational Health and Safety
283:Canadian Centre for Occupational Health and Safety
357:International Union of Pure and Applied Chemistry
975:
297:European chemical Substances Information System
421:"CAS Registry Number Verified Partner Program"
964:ChemSub Online (Multilingual chemical names)
721:Journal of Chemical Information and Modeling
576:Journal of Chemical Information and Modeling
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197:are assigned discrete CAS Registry Numbers:
799:European Commission Joint research Centre.
665:United States National Library of Medicine
289:United States National Library of Medicine
740:
603:
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105:iological origin). CAS RNs are generally
362:List of CAS numbers by chemical compound
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849:Environmental Risk Management Authority
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347:(EINECS and ELINCS, European Community)
307:Environmental Risk Management Authority
213:-epinephrine has 150-05-0, and racemic
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959:NCI/CADD Chemical Identifier Resolver
774:"AICS Detailed Help / Guidance Notes"
906:"CompTox Chemicals Dashboard | Home"
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819:
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871:
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177:10. For example, the CAS number of
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826:Library & Information Centre.
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129:license at ACS Commons Chemistry.
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545:"CAS Surveys Its First 100 Years"
314:USEPA CompTox Chemicals Dashboard
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936:, by Chemical Abstracts Service
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828:"Finding a CAS Registry Number"
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549:Chemical & Engineering News
410:, by Chemical Abstracts Service
340:Dictionary of chemical formulas
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543:Shively, Eric (11 June 2007).
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1:
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101:omplex reaction products, or
51:unique identification number
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10:
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984:Chemical numbering schemes
301:Royal Society of Chemistry
55:Chemical Abstracts Service
989:American Chemical Society
690:American Chemical Society
475:"CAS Registry and CASRNs"
471:American Chemical Society
446:"CAS Content: Substances"
330:Beilstein Registry Number
262:hexavalent Cr(VI) species
230:in general is 7440-44-0,
219:-epinephrine has 329-65-7
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57:(CAS) in the US to every
934:CAS registry description
733:10.1021/acs.jcim.2c00268
588:10.1021/acs.jcim.2c00268
401:CAS registry description
287:ChemIDplus Advanced via
144:systematic nomenclature
954:NIST Chemistry WebBook
377:Registration authority
269:alcohol dehydrogenases
34:
669:"ChemIDplus Advanced"
281:CHEMINDEX Search via
97:ariable composition,
41:(also referred to as
24:
949:CAS Common Chemistry
335:Chemical file format
353:(Enzyme Commission)
325:Academic publishing
299:via the website of
39:CAS Registry Number
16:Chemical identifier
994:Unique identifiers
880:"AICS Search Tool"
694:"Substance Search"
644:"CHEMINDEX Search"
406:2008-07-25 at the
148:structural formula
59:chemical substance
53:, assigned by the
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807:on 1 January 2014
727:(11): 2737–2743.
582:(11): 2737–2743.
254:chemical elements
245:(12627-53-1) and
234:is 7782-42-5 and
67:chemical database
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882:. Archived from
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501:"CAS REGISTRY"
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140:(black)-market
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107:serial numbers
69:that includes
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63:CAS Registry
62:
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505:www.cas.org
450:www.cas.org
247:mustard oil
205:epinephrine
185:Granularity
168:check digit
111:check digit
77:compounds,
978:Categories
915:14 October
388:References
367:MDL number
222:Different
93:nknown or
47:CAS Number
759:248778162
596:1549-9596
455:10 August
382:UN number
351:EC number
75:inorganic
751:35559614
614:35559614
554:16 April
528:17 March
427:4 August
404:Archived
319:See also
258:chromium
232:graphite
127:CC BY-NC
109:(with a
83:isotopes
79:minerals
27:caffeine
942:formula
890:11 July
863:14 July
833:11 July
811:11 July
742:9199008
674:28 June
649:13 July
605:9199008
485:25 July
372:PubChem
236:diamond
71:organic
49:) is a
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784:8 July
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228:carbon
224:phases
175:modulo
159:Format
115:SMILES
87:alloys
43:CAS RN
755:S2CID
423:. CAS
252:Some
179:water
119:InChI
917:2021
892:2009
865:2009
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813:2009
786:2009
747:PMID
701:2009
676:2021
651:2009
610:PMID
592:ISSN
556:2024
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487:2009
457:2020
429:2021
193:and
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737:PMC
729:doi
600:PMC
584:doi
523:CAS
345:EC#
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
