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mw-first-heading"><span class="mw-page-title-main">CAS Registry Number</span></h1> <div id="p-lang-btn" class="vector-dropdown mw-portlet mw-portlet-lang" > <input type="checkbox" id="p-lang-btn-checkbox" role="button" aria-haspopup="true" data-event-name="ui.dropdown-p-lang-btn" class="vector-dropdown-checkbox mw-interlanguage-selector" aria-label="Go to an article in another language. Available in 60 languages" > <label id="p-lang-btn-label" for="p-lang-btn-checkbox" class="vector-dropdown-label cdx-button cdx-button--fake-button cdx-button--fake-button--enabled cdx-button--weight-quiet cdx-button--action-progressive mw-portlet-lang-heading-60" aria-hidden="true" ><span class="vector-icon mw-ui-icon-language-progressive mw-ui-icon-wikimedia-language-progressive"></span> <span class="vector-dropdown-label-text">60 languages</span> </label> <div class="vector-dropdown-content"> <div class="vector-menu-content"> <ul class="vector-menu-content-list"> <li class="interlanguage-link interwiki-af mw-list-item"><a href="https://af.wikipedia.org/wiki/CAS-registernommer" title="CAS-registernommer – Afrikaans" lang="af" hreflang="af" data-title="CAS-registernommer" data-language-autonym="Afrikaans" data-language-local-name="Afrikaans" class="interlanguage-link-target"><span>Afrikaans</span></a></li><li class="interlanguage-link interwiki-ar mw-list-item"><a href="https://ar.wikipedia.org/wiki/%D8%B1%D9%82%D9%85_%D8%A7%D9%84%D8%AA%D8%B3%D8%AC%D9%8A%D9%84_CAS" title="رقم التسجيل CAS – Arabic" lang="ar" hreflang="ar" data-title="رقم التسجيل CAS" data-language-autonym="العربية" data-language-local-name="Arabic" class="interlanguage-link-target"><span>العربية</span></a></li><li class="interlanguage-link interwiki-ast mw-list-item"><a href="https://ast.wikipedia.org/wiki/N%C3%BAmberu_de_rexistru_CAS" title="Númberu de rexistru CAS – Asturian" lang="ast" hreflang="ast" data-title="Númberu de rexistru CAS" data-language-autonym="Asturianu" data-language-local-name="Asturian" class="interlanguage-link-target"><span>Asturianu</span></a></li><li class="interlanguage-link interwiki-az mw-list-item"><a href="https://az.wikipedia.org/wiki/CAS-da_qeydiyyat_n%C3%B6mr%C9%99si" title="CAS-da qeydiyyat nömrəsi – Azerbaijani" lang="az" hreflang="az" data-title="CAS-da qeydiyyat nömrəsi" data-language-autonym="Azərbaycanca" data-language-local-name="Azerbaijani" class="interlanguage-link-target"><span>Azərbaycanca</span></a></li><li class="interlanguage-link interwiki-bn mw-list-item"><a href="https://bn.wikipedia.org/wiki/%E0%A6%95%E0%A7%8D%E0%A6%AF%E0%A6%BE%E0%A6%B8_%E0%A6%A8%E0%A6%BF%E0%A6%AC%E0%A6%A8%E0%A7%8D%E0%A6%A7%E0%A6%A8_%E0%A6%A8%E0%A6%AE%E0%A7%8D%E0%A6%AC%E0%A6%B0" title="ক্যাস নিবন্ধন নম্বর – Bangla" lang="bn" hreflang="bn" data-title="ক্যাস নিবন্ধন নম্বর" data-language-autonym="বাংলা" data-language-local-name="Bangla" class="interlanguage-link-target"><span>বাংলা</span></a></li><li class="interlanguage-link interwiki-bg mw-list-item"><a href="https://bg.wikipedia.org/wiki/CAS_%D1%80%D0%B5%D0%B3%D0%B8%D1%81%D1%82%D1%80%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%B5%D0%BD_%D0%BD%D0%BE%D0%BC%D0%B5%D1%80" title="CAS регистрационен номер – Bulgarian" lang="bg" hreflang="bg" data-title="CAS регистрационен номер" data-language-autonym="Български" data-language-local-name="Bulgarian" class="interlanguage-link-target"><span>Български</span></a></li><li class="interlanguage-link interwiki-bs mw-list-item"><a href="https://bs.wikipedia.org/wiki/CAS_registarski_broj" title="CAS registarski broj – Bosnian" lang="bs" hreflang="bs" data-title="CAS registarski broj" data-language-autonym="Bosanski" data-language-local-name="Bosnian" class="interlanguage-link-target"><span>Bosanski</span></a></li><li class="interlanguage-link interwiki-br mw-list-item"><a href="https://br.wikipedia.org/wiki/Niverenn_CAS" title="Niverenn CAS – Breton" lang="br" hreflang="br" data-title="Niverenn CAS" data-language-autonym="Brezhoneg" data-language-local-name="Breton" class="interlanguage-link-target"><span>Brezhoneg</span></a></li><li class="interlanguage-link interwiki-ca mw-list-item"><a href="https://ca.wikipedia.org/wiki/N%C3%BAmero_CAS" title="Número CAS – Catalan" lang="ca" hreflang="ca" data-title="Número CAS" data-language-autonym="Català" data-language-local-name="Catalan" class="interlanguage-link-target"><span>Català</span></a></li><li class="interlanguage-link interwiki-cs mw-list-item"><a href="https://cs.wikipedia.org/wiki/Registra%C4%8Dn%C3%AD_%C4%8D%C3%ADslo_CAS" title="Registrační číslo CAS – Czech" lang="cs" hreflang="cs" data-title="Registrační číslo CAS" data-language-autonym="Čeština" data-language-local-name="Czech" class="interlanguage-link-target"><span>Čeština</span></a></li><li class="interlanguage-link interwiki-da mw-list-item"><a href="https://da.wikipedia.org/wiki/CAS-nummer" title="CAS-nummer – Danish" lang="da" hreflang="da" data-title="CAS-nummer" data-language-autonym="Dansk" data-language-local-name="Danish" class="interlanguage-link-target"><span>Dansk</span></a></li><li class="interlanguage-link interwiki-de mw-list-item"><a href="https://de.wikipedia.org/wiki/CAS-Nummer" title="CAS-Nummer – German" lang="de" hreflang="de" data-title="CAS-Nummer" data-language-autonym="Deutsch" data-language-local-name="German" class="interlanguage-link-target"><span>Deutsch</span></a></li><li class="interlanguage-link interwiki-et mw-list-item"><a href="https://et.wikipedia.org/wiki/CAS-i_registreerimisnumber" title="CAS-i registreerimisnumber – Estonian" lang="et" hreflang="et" data-title="CAS-i registreerimisnumber" data-language-autonym="Eesti" data-language-local-name="Estonian" class="interlanguage-link-target"><span>Eesti</span></a></li><li class="interlanguage-link interwiki-el mw-list-item"><a href="https://el.wikipedia.org/wiki/%CE%91%CF%81%CE%B9%CE%B8%CE%BC%CF%8C%CF%82_CAS" title="Αριθμός CAS – Greek" lang="el" hreflang="el" data-title="Αριθμός CAS" data-language-autonym="Ελληνικά" data-language-local-name="Greek" class="interlanguage-link-target"><span>Ελληνικά</span></a></li><li class="interlanguage-link interwiki-es mw-list-item"><a href="https://es.wikipedia.org/wiki/N%C3%BAmero_de_registro_CAS" title="Número de registro CAS – Spanish" lang="es" hreflang="es" data-title="Número de registro CAS" data-language-autonym="Español" data-language-local-name="Spanish" class="interlanguage-link-target"><span>Español</span></a></li><li class="interlanguage-link interwiki-eo mw-list-item"><a href="https://eo.wikipedia.org/wiki/CAS-numero" title="CAS-numero – Esperanto" lang="eo" hreflang="eo" data-title="CAS-numero" data-language-autonym="Esperanto" data-language-local-name="Esperanto" class="interlanguage-link-target"><span>Esperanto</span></a></li><li class="interlanguage-link interwiki-eu mw-list-item"><a href="https://eu.wikipedia.org/wiki/CAS_erregistro_zenbaki" title="CAS erregistro zenbaki – Basque" lang="eu" hreflang="eu" data-title="CAS erregistro zenbaki" data-language-autonym="Euskara" data-language-local-name="Basque" class="interlanguage-link-target"><span>Euskara</span></a></li><li class="interlanguage-link interwiki-fa mw-list-item"><a href="https://fa.wikipedia.org/wiki/%D8%B4%D9%85%D8%A7%D8%B1%D9%87_%D8%AB%D8%A8%D8%AA_%D8%B3%DB%8C%E2%80%8C%D8%A7%DB%8C%E2%80%8C%D8%A7%D8%B3" title="شماره ثبت سی‌ای‌اس – Persian" lang="fa" hreflang="fa" data-title="شماره ثبت سی‌ای‌اس" data-language-autonym="فارسی" data-language-local-name="Persian" class="interlanguage-link-target"><span>فارسی</span></a></li><li class="interlanguage-link interwiki-fr mw-list-item"><a href="https://fr.wikipedia.org/wiki/Num%C3%A9ro_CAS" title="Numéro CAS – French" lang="fr" hreflang="fr" data-title="Numéro CAS" data-language-autonym="Français" data-language-local-name="French" class="interlanguage-link-target"><span>Français</span></a></li><li class="interlanguage-link interwiki-gl mw-list-item"><a href="https://gl.wikipedia.org/wiki/N%C3%BAmero_CAS" title="Número CAS – Galician" lang="gl" hreflang="gl" data-title="Número CAS" data-language-autonym="Galego" data-language-local-name="Galician" class="interlanguage-link-target"><span>Galego</span></a></li><li class="interlanguage-link interwiki-ko mw-list-item"><a href="https://ko.wikipedia.org/wiki/CAS_%EB%93%B1%EB%A1%9D%EB%B2%88%ED%98%B8" title="CAS 등록번호 – Korean" lang="ko" hreflang="ko" data-title="CAS 등록번호" data-language-autonym="한국어" data-language-local-name="Korean" class="interlanguage-link-target"><span>한국어</span></a></li><li class="interlanguage-link interwiki-hi mw-list-item"><a href="https://hi.wikipedia.org/wiki/CAS_%E0%A4%B8%E0%A4%82%E0%A4%96%E0%A5%8D%E0%A4%AF%E0%A4%BE" title="CAS संख्या – Hindi" lang="hi" hreflang="hi" data-title="CAS संख्या" data-language-autonym="हिन्दी" data-language-local-name="Hindi" class="interlanguage-link-target"><span>हिन्दी</span></a></li><li class="interlanguage-link interwiki-hr mw-list-item"><a href="https://hr.wikipedia.org/wiki/CAS_registarski_broj" title="CAS registarski broj – Croatian" lang="hr" hreflang="hr" data-title="CAS registarski broj" data-language-autonym="Hrvatski" data-language-local-name="Croatian" class="interlanguage-link-target"><span>Hrvatski</span></a></li><li class="interlanguage-link interwiki-id mw-list-item"><a href="https://id.wikipedia.org/wiki/Nomor_CAS" title="Nomor CAS – Indonesian" lang="id" hreflang="id" data-title="Nomor CAS" data-language-autonym="Bahasa Indonesia" data-language-local-name="Indonesian" class="interlanguage-link-target"><span>Bahasa Indonesia</span></a></li><li class="interlanguage-link interwiki-is mw-list-item"><a href="https://is.wikipedia.org/wiki/CAS-n%C3%BAmer" title="CAS-númer – Icelandic" lang="is" hreflang="is" data-title="CAS-númer" data-language-autonym="Íslenska" data-language-local-name="Icelandic" class="interlanguage-link-target"><span>Íslenska</span></a></li><li class="interlanguage-link interwiki-it mw-list-item"><a href="https://it.wikipedia.org/wiki/Numero_CAS" title="Numero CAS – Italian" lang="it" hreflang="it" data-title="Numero CAS" data-language-autonym="Italiano" data-language-local-name="Italian" class="interlanguage-link-target"><span>Italiano</span></a></li><li class="interlanguage-link interwiki-he mw-list-item"><a href="https://he.wikipedia.org/wiki/%D7%9E%D7%A1%D7%A4%D7%A8_CAS" title="מספר CAS – Hebrew" lang="he" hreflang="he" data-title="מספר CAS" data-language-autonym="עברית" data-language-local-name="Hebrew" class="interlanguage-link-target"><span>עברית</span></a></li><li class="interlanguage-link interwiki-lt mw-list-item"><a href="https://lt.wikipedia.org/wiki/CAS_registracijos_numeris" title="CAS registracijos numeris – Lithuanian" lang="lt" hreflang="lt" data-title="CAS registracijos numeris" data-language-autonym="Lietuvių" data-language-local-name="Lithuanian" class="interlanguage-link-target"><span>Lietuvių</span></a></li><li class="interlanguage-link interwiki-lmo mw-list-item"><a href="https://lmo.wikipedia.org/wiki/N%C3%BCmer_CAS" title="Nümer CAS – Lombard" lang="lmo" hreflang="lmo" data-title="Nümer CAS" data-language-autonym="Lombard" data-language-local-name="Lombard" class="interlanguage-link-target"><span>Lombard</span></a></li><li class="interlanguage-link interwiki-hu mw-list-item"><a href="https://hu.wikipedia.org/wiki/CAS-sz%C3%A1m" title="CAS-szám – Hungarian" lang="hu" hreflang="hu" data-title="CAS-szám" data-language-autonym="Magyar" data-language-local-name="Hungarian" class="interlanguage-link-target"><span>Magyar</span></a></li><li class="interlanguage-link interwiki-mk mw-list-item"><a href="https://mk.wikipedia.org/wiki/CAS-%D0%B1%D1%80%D0%BE%D1%98" title="CAS-број – Macedonian" lang="mk" hreflang="mk" data-title="CAS-број" data-language-autonym="Македонски" data-language-local-name="Macedonian" class="interlanguage-link-target"><span>Македонски</span></a></li><li class="interlanguage-link interwiki-ml mw-list-item"><a href="https://ml.wikipedia.org/wiki/%E0%B4%B8%E0%B4%BF.%E0%B4%8E.%E0%B4%8E%E0%B4%B8%E0%B5%8D_%E0%B4%B1%E0%B4%9C%E0%B4%BF%E0%B4%B8%E0%B5%8D%E0%B4%9F%E0%B5%8D%E0%B4%B0%E0%B4%BF_%E0%B4%A8%E0%B4%AE%E0%B5%8D%E0%B4%AA%E0%B5%BC" title="സി.എ.എസ് റജിസ്ട്രി നമ്പർ – Malayalam" lang="ml" hreflang="ml" data-title="സി.എ.എസ് റജിസ്ട്രി നമ്പർ" data-language-autonym="മലയാളം" data-language-local-name="Malayalam" class="interlanguage-link-target"><span>മലയാളം</span></a></li><li class="interlanguage-link interwiki-ms badge-Q70893996 mw-list-item" title=""><a href="https://ms.wikipedia.org/wiki/Nombor_Pendaftaran_CAS" title="Nombor Pendaftaran CAS – Malay" lang="ms" hreflang="ms" data-title="Nombor Pendaftaran CAS" data-language-autonym="Bahasa Melayu" data-language-local-name="Malay" class="interlanguage-link-target"><span>Bahasa Melayu</span></a></li><li class="interlanguage-link interwiki-nl mw-list-item"><a href="https://nl.wikipedia.org/wiki/CAS-nummer" title="CAS-nummer – Dutch" lang="nl" hreflang="nl" data-title="CAS-nummer" data-language-autonym="Nederlands" data-language-local-name="Dutch" class="interlanguage-link-target"><span>Nederlands</span></a></li><li class="interlanguage-link interwiki-ja mw-list-item"><a href="https://ja.wikipedia.org/wiki/CAS%E7%99%BB%E9%8C%B2%E7%95%AA%E5%8F%B7" title="CAS登録番号 – Japanese" lang="ja" hreflang="ja" data-title="CAS登録番号" data-language-autonym="日本語" data-language-local-name="Japanese" class="interlanguage-link-target"><span>日本語</span></a></li><li class="interlanguage-link interwiki-frr mw-list-item"><a href="https://frr.wikipedia.org/wiki/CAS-Numer" title="CAS-Numer – Northern Frisian" lang="frr" hreflang="frr" data-title="CAS-Numer" data-language-autonym="Nordfriisk" data-language-local-name="Northern Frisian" class="interlanguage-link-target"><span>Nordfriisk</span></a></li><li class="interlanguage-link interwiki-no mw-list-item"><a href="https://no.wikipedia.org/wiki/CAS-nummer" title="CAS-nummer – Norwegian Bokmål" lang="nb" hreflang="nb" data-title="CAS-nummer" data-language-autonym="Norsk bokmål" data-language-local-name="Norwegian Bokmål" class="interlanguage-link-target"><span>Norsk bokmål</span></a></li><li class="interlanguage-link interwiki-nn mw-list-item"><a href="https://nn.wikipedia.org/wiki/CAS-nummer" title="CAS-nummer – Norwegian Nynorsk" lang="nn" hreflang="nn" data-title="CAS-nummer" data-language-autonym="Norsk nynorsk" data-language-local-name="Norwegian Nynorsk" class="interlanguage-link-target"><span>Norsk nynorsk</span></a></li><li class="interlanguage-link interwiki-oc mw-list-item"><a href="https://oc.wikipedia.org/wiki/Num%C3%A8ro_CAS" title="Numèro CAS – Occitan" lang="oc" hreflang="oc" data-title="Numèro CAS" data-language-autonym="Occitan" data-language-local-name="Occitan" class="interlanguage-link-target"><span>Occitan</span></a></li><li class="interlanguage-link interwiki-nds mw-list-item"><a href="https://nds.wikipedia.org/wiki/CAS-Tall" title="CAS-Tall – Low German" lang="nds" hreflang="nds" data-title="CAS-Tall" data-language-autonym="Plattdüütsch" data-language-local-name="Low German" class="interlanguage-link-target"><span>Plattdüütsch</span></a></li><li class="interlanguage-link interwiki-pl mw-list-item"><a href="https://pl.wikipedia.org/wiki/Numer_CAS" title="Numer CAS – Polish" lang="pl" hreflang="pl" data-title="Numer CAS" data-language-autonym="Polski" data-language-local-name="Polish" class="interlanguage-link-target"><span>Polski</span></a></li><li class="interlanguage-link interwiki-pt mw-list-item"><a href="https://pt.wikipedia.org/wiki/N%C3%BAmero_CAS" title="Número CAS – Portuguese" lang="pt" hreflang="pt" data-title="Número CAS" data-language-autonym="Português" data-language-local-name="Portuguese" class="interlanguage-link-target"><span>Português</span></a></li><li class="interlanguage-link interwiki-ro mw-list-item"><a href="https://ro.wikipedia.org/wiki/Num%C4%83r_registru_CAS" title="Număr registru CAS – Romanian" lang="ro" hreflang="ro" data-title="Număr registru CAS" data-language-autonym="Română" data-language-local-name="Romanian" class="interlanguage-link-target"><span>Română</span></a></li><li class="interlanguage-link interwiki-ru mw-list-item"><a href="https://ru.wikipedia.org/wiki/%D0%A0%D0%B5%D0%B3%D0%B8%D1%81%D1%82%D1%80%D0%B0%D1%86%D0%B8%D0%BE%D0%BD%D0%BD%D1%8B%D0%B9_%D0%BD%D0%BE%D0%BC%D0%B5%D1%80_CAS" title="Регистрационный номер CAS – Russian" lang="ru" hreflang="ru" data-title="Регистрационный номер CAS" data-language-autonym="Русский" data-language-local-name="Russian" class="interlanguage-link-target"><span>Русский</span></a></li><li class="interlanguage-link interwiki-simple mw-list-item"><a href="https://simple.wikipedia.org/wiki/CAS_registry_number" title="CAS registry number – Simple English" lang="en-simple" hreflang="en-simple" data-title="CAS registry number" data-language-autonym="Simple English" data-language-local-name="Simple English" class="interlanguage-link-target"><span>Simple English</span></a></li><li class="interlanguage-link interwiki-sk mw-list-item"><a href="https://sk.wikipedia.org/wiki/Registra%C4%8Dn%C3%A9_%C4%8D%C3%ADslo_CAS" title="Registračné číslo CAS – Slovak" lang="sk" hreflang="sk" data-title="Registračné číslo CAS" data-language-autonym="Slovenčina" data-language-local-name="Slovak" class="interlanguage-link-target"><span>Slovenčina</span></a></li><li class="interlanguage-link interwiki-sl mw-list-item"><a href="https://sl.wikipedia.org/wiki/%C5%A0tevilka_CAS" title="Številka CAS – Slovenian" lang="sl" hreflang="sl" data-title="Številka CAS" data-language-autonym="Slovenščina" data-language-local-name="Slovenian" class="interlanguage-link-target"><span>Slovenščina</span></a></li><li class="interlanguage-link interwiki-sr mw-list-item"><a href="https://sr.wikipedia.org/wiki/%D0%A6%D0%90%D0%A1_%D1%80%D0%B5%D0%B3%D0%B8%D1%81%D1%82%D0%B0%D1%80%D1%81%D0%BA%D0%B8_%D0%B1%D1%80%D0%BE%D1%98" title="ЦАС регистарски број – Serbian" lang="sr" hreflang="sr" data-title="ЦАС регистарски број" data-language-autonym="Српски / srpski" data-language-local-name="Serbian" class="interlanguage-link-target"><span>Српски / srpski</span></a></li><li class="interlanguage-link interwiki-sh mw-list-item"><a href="https://sh.wikipedia.org/wiki/CAS_registarski_broj" title="CAS registarski broj – Serbo-Croatian" lang="sh" hreflang="sh" data-title="CAS registarski broj" data-language-autonym="Srpskohrvatski / српскохрватски" data-language-local-name="Serbo-Croatian" class="interlanguage-link-target"><span>Srpskohrvatski / српскохрватски</span></a></li><li class="interlanguage-link interwiki-fi mw-list-item"><a href="https://fi.wikipedia.org/wiki/CAS-numero" title="CAS-numero – Finnish" lang="fi" hreflang="fi" data-title="CAS-numero" data-language-autonym="Suomi" data-language-local-name="Finnish" class="interlanguage-link-target"><span>Suomi</span></a></li><li class="interlanguage-link interwiki-sv mw-list-item"><a href="https://sv.wikipedia.org/wiki/CAS-nummer" title="CAS-nummer – Swedish" lang="sv" hreflang="sv" data-title="CAS-nummer" data-language-autonym="Svenska" data-language-local-name="Swedish" class="interlanguage-link-target"><span>Svenska</span></a></li><li class="interlanguage-link interwiki-tl mw-list-item"><a href="https://tl.wikipedia.org/wiki/Bilang_Pangrehistro_ng_CAS" title="Bilang Pangrehistro ng CAS – Tagalog" lang="tl" hreflang="tl" data-title="Bilang Pangrehistro ng CAS" data-language-autonym="Tagalog" data-language-local-name="Tagalog" class="interlanguage-link-target"><span>Tagalog</span></a></li><li class="interlanguage-link interwiki-ta mw-list-item"><a href="https://ta.wikipedia.org/wiki/%E0%AE%9A%E0%AE%BF%E0%AE%8F%E0%AE%8E%E0%AE%9A%E0%AF%81_%E0%AE%8E%E0%AE%A3%E0%AF%8D" title="சிஏஎசு எண் – Tamil" lang="ta" hreflang="ta" data-title="சிஏஎசு எண்" data-language-autonym="தமிழ்" data-language-local-name="Tamil" 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src="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Cascommonchemistry2022.png/220px-Cascommonchemistry2022.png" decoding="async" width="220" height="203" class="mw-file-element" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/2/27/Cascommonchemistry2022.png/330px-Cascommonchemistry2022.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/2/27/Cascommonchemistry2022.png/440px-Cascommonchemistry2022.png 2x" data-file-width="500" data-file-height="461" /></a><figcaption>Screenshot of the CAS Common Chemistry database with information about <a href="/wiki/Caffeine" title="Caffeine">caffeine</a> (<a rel="nofollow" class="external text" href="https://commonchemistry.cas.org/detail?cas_rn=58-08-2">58-08-2</a>).</figcaption></figure> <p>A <b>CAS Registry Number</b><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> (also referred to as <b>CAS RN</b><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> or informally <b>CAS Number</b>) is a <a href="/wiki/Unique_identifier" title="Unique identifier">unique identification number</a>, assigned by the <a href="/wiki/Chemical_Abstracts_Service" title="Chemical Abstracts Service">Chemical Abstracts Service</a> (CAS) in the US to every <a href="/wiki/Chemical_substance" title="Chemical substance">chemical substance</a> described in the open scientific literature, in order to index the substance in the <b>CAS Registry</b>. This registry includes all substances described since 1957, plus some substances from as far back as the early 1800s;<sup id="cite_ref-CAScontent_3-0" class="reference"><a href="#cite_note-CAScontent-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> it is a <a href="/wiki/Chemical_database" title="Chemical database">chemical database</a> that includes <a href="/wiki/Organic_compounds" class="mw-redirect" title="Organic compounds">organic</a> and <a href="/wiki/Inorganic_compounds" class="mw-redirect" title="Inorganic compounds">inorganic</a> compounds, <a href="/wiki/Mineral" title="Mineral">minerals</a>, <a href="/wiki/Isotope" title="Isotope">isotopes</a>, <a href="/wiki/Alloys" class="mw-redirect" title="Alloys">alloys</a>, mixtures, and nonstructurable materials (UVCBs, substances of <b>u</b>nknown or <b>v</b>ariable composition, <b>c</b>omplex reaction products, or <b>b</b>iological origin).<sup id="cite_ref-crc_4-0" class="reference"><a href="#cite_note-crc-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> CAS RNs are generally <a href="/wiki/Serial_number" title="Serial number">serial numbers</a> (with a <a href="/wiki/Check_digit" title="Check digit">check digit</a>), so they do not contain any information about the structures themselves the way <a href="/wiki/Simplified_molecular-input_line-entry_system" class="mw-redirect" title="Simplified molecular-input line-entry system">SMILES</a> and <a href="/wiki/International_Chemical_Identifier" title="International Chemical Identifier">InChI</a> strings do. </p><p>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,<sup id="cite_ref-CAScontent_3-1" class="reference"><a href="#cite_note-CAScontent-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> plus additional information about each substance. It is updated with around 15,000 additional new substances daily.<sup id="cite_ref-5" class="reference"><a href="#cite_note-5"><span class="cite-bracket">[</span>5<span class="cite-bracket">]</span></a></sup> A collection of almost 500 thousand CAS registry numbers are made available under a <a href="/wiki/CC_BY-NC" class="mw-redirect" title="CC BY-NC">CC BY-NC</a> license at ACS Commons Chemistry.<sup id="cite_ref-6" class="reference"><a href="#cite_note-6"><span class="cite-bracket">[</span>6<span class="cite-bracket">]</span></a></sup> </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="History_and_use">History and use</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=1" title="Edit section: History and use"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>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 discovered. Well-known chemicals may additionally be known via multiple generic, historical, commercial, and/or <a href="/wiki/Black_market" title="Black market">(black)-market</a> names, and even <a href="/wiki/Chemical_nomenclature" title="Chemical nomenclature">systematic nomenclature</a> based on structure alone was not universally useful. An algorithm was developed to translate the <a href="/wiki/Structural_formula" title="Structural formula">structural formula</a> 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.<sup id="cite_ref-7" class="reference"><a href="#cite_note-7"><span class="cite-bracket">[</span>7<span class="cite-bracket">]</span></a></sup> </p><p>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 databases today allow searching by CAS Registry Number, and it is used as a global standard.<sup id="cite_ref-8" class="reference"><a href="#cite_note-8"><span class="cite-bracket">[</span>8<span class="cite-bracket">]</span></a></sup> </p> <div class="mw-heading mw-heading2"><h2 id="Format">Format</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=2" title="Edit section: Format"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>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. </p><p>A CAS RN is separated by hyphens into three parts, the first consisting from two up to seven digits,<sup id="cite_ref-9" class="reference"><a href="#cite_note-9"><span class="cite-bracket">[</span>9<span class="cite-bracket">]</span></a></sup> the second consisting of two digits, and the third consisting of a single digit serving as a <a href="/wiki/Check_digit" title="Check digit">check digit</a>. This format gives CAS a maximum capacity of 1,000,000,000 unique numbers. </p><p>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 <a href="/wiki/Modular_arithmetic" title="Modular arithmetic">modulo</a> 10. For example, the CAS number of <a href="/wiki/Water" title="Water">water</a> 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. </p> <div class="mw-heading mw-heading2"><h2 id="Granularity">Granularity</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=3" title="Edit section: Granularity"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Stereoisomer" class="mw-redirect" title="Stereoisomer">Stereoisomers</a> and <a href="/wiki/Racemic_mixture" title="Racemic mixture">racemic mixtures</a> are assigned discrete CAS Registry Numbers: <span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">L</span></span>-<a href="/wiki/Epinephrine" class="mw-redirect" title="Epinephrine">epinephrine</a> has 51-43-4, <span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">D</span></span>-epinephrine has 150-05-0, and racemic <span class="smallcaps"><span style="font-variant: small-caps; text-transform: lowercase;">DL</span></span>-epinephrine has 329-65-7</li> <li>Different <a href="/wiki/Phase_(matter)" title="Phase (matter)">phases</a> do not receive different CAS RNs (liquid water and ice both have 7732-18-5), but different crystal structures do (<a href="/wiki/Carbon" title="Carbon">carbon</a> in general is 7440-44-0, <a href="/wiki/Graphite" title="Graphite">graphite</a> is 7782-42-5 and <a href="/wiki/Diamond" title="Diamond">diamond</a> is 7782-40-3)</li> <li>Commonly encountered mixtures of known or unknown composition may receive a CAS RN; examples are <a href="/wiki/Leishman_stain" title="Leishman stain">Leishman stain</a> (12627-53-1) and <a href="/wiki/Mustard_oil" title="Mustard oil">mustard oil</a> (8007-40-7).</li> <li>Some <a href="/wiki/Chemical_elements" class="mw-redirect" title="Chemical elements">chemical elements</a> are discerned by their oxidation state, e.g. the element <a href="/wiki/Chromium" title="Chromium">chromium</a> has 7440-47-3, the trivalent Cr(III) has 16065-83-1 and the <a href="/wiki/Hexavalent_chromium" title="Hexavalent chromium">hexavalent Cr(VI) species</a> have 18540-29-9.</li> <li>Occasionally whole classes of molecules receive a single CAS RN: the class of enzymes known as <a href="/wiki/Alcohol_dehydrogenase" title="Alcohol dehydrogenase">alcohol dehydrogenases</a> has 9031-72-5.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Search_engines">Search engines</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=4" title="Edit section: Search engines"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li>CHEMINDEX Search via <a href="/wiki/Canadian_Centre_for_Occupational_Health_and_Safety" title="Canadian Centre for Occupational Health and Safety">Canadian Centre for Occupational Health and Safety</a><sup id="cite_ref-cis_10-0" class="reference"><a href="#cite_note-cis-10"><span class="cite-bracket">[</span>10<span class="cite-bracket">]</span></a></sup></li> <li>ChemIDplus Advanced via <a href="/wiki/United_States_National_Library_of_Medicine" title="United States National Library of Medicine">United States National Library of Medicine</a><sup id="cite_ref-adv_11-0" class="reference"><a href="#cite_note-adv-11"><span class="cite-bracket">[</span>11<span class="cite-bracket">]</span></a></sup></li> <li>Common Chemistry<sup id="cite_ref-ss_12-0" class="reference"><a href="#cite_note-ss-12"><span class="cite-bracket">[</span>12<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-13" class="reference"><a href="#cite_note-13"><span class="cite-bracket">[</span>13<span class="cite-bracket">]</span></a></sup> via Australian Inventory of Chemical Substances<sup id="cite_ref-adhg_14-0" class="reference"><a href="#cite_note-adhg-14"><span class="cite-bracket">[</span>14<span class="cite-bracket">]</span></a></sup></li> <li><a href="/wiki/European_chemical_Substances_Information_System" title="European chemical Substances Information System">European chemical Substances Information System</a><sup id="cite_ref-eecs_15-0" class="reference"><a href="#cite_note-eecs-15"><span class="cite-bracket">[</span>15<span class="cite-bracket">]</span></a></sup> via the website of <a href="/wiki/Royal_Society_of_Chemistry" title="Royal Society of Chemistry">Royal Society of Chemistry</a><sup id="cite_ref-fcrn_16-0" class="reference"><a href="#cite_note-fcrn-16"><span class="cite-bracket">[</span>16<span class="cite-bracket">]</span></a></sup></li> <li>HSNO Chemical Classification Information Database via <a href="/wiki/Environmental_Risk_Management_Authority" title="Environmental Risk Management Authority">Environmental Risk Management Authority</a><sup id="cite_ref-hcci_17-0" class="reference"><a href="#cite_note-hcci-17"><span class="cite-bracket">[</span>17<span class="cite-bracket">]</span></a></sup></li> <li>Search Tool of Australian Inventory of Chemical Substances<sup id="cite_ref-ast_18-0" class="reference"><a href="#cite_note-ast-18"><span class="cite-bracket">[</span>18<span class="cite-bracket">]</span></a></sup></li> <li>USEPA CompTox Chemicals Dashboard<sup id="cite_ref-19" class="reference"><a href="#cite_note-19"><span class="cite-bracket">[</span>19<span class="cite-bracket">]</span></a></sup></li></ul> <div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=5" title="Edit section: See also"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a href="/wiki/Academic_publishing" title="Academic publishing">Academic publishing</a></li> <li><a href="/wiki/Beilstein_Registry_Number" title="Beilstein Registry Number">Beilstein Registry Number</a></li> <li><a href="/wiki/Chemical_file_format" title="Chemical file format">Chemical file format</a></li> <li><a href="/wiki/Dictionary_of_chemical_formulas" class="mw-redirect" title="Dictionary of chemical formulas">Dictionary of chemical formulas</a></li> <li><a href="/wiki/European_Community_number" title="European Community number">EC#</a> (EINECS and ELINCS, European Community)</li> <li><a href="/wiki/Enzyme_Commission_number" title="Enzyme Commission number">EC number</a> (Enzyme Commission)</li> <li><a href="/wiki/International_Union_of_Pure_and_Applied_Chemistry" title="International Union of Pure and Applied Chemistry">International Union of Pure and Applied Chemistry</a></li> <li><a href="/wiki/List_of_CAS_numbers_by_chemical_compound" title="List of CAS numbers by chemical compound">List of CAS numbers by chemical compound</a></li> <li><a href="/wiki/Chemical_file_format#MDL_number" title="Chemical file format">MDL number</a></li> <li><a href="/wiki/PubChem" title="PubChem">PubChem</a></li> <li><a href="/wiki/Registration_authority" title="Registration authority">Registration authority</a></li> <li><a href="/wiki/UN_number" title="UN number">UN number</a></li></ul> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=CAS_Registry_Number&action=edit&section=6" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output 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a{background:url("//upload.wikimedia.org/wikipedia/commons/d/d6/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/a/aa/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/4/4c/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}</style><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.cas.org/support/documentation/chemical-substances/cas-rn-verified-partner-program">"CAS Registry Number Verified Partner Program"</a>. 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Retrieved <span class="nowrap">10 August</span> 2020</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.cas.org&rft.atitle=CAS+Content%3A+Substances&rft_id=https%3A%2F%2Fwww.cas.org%2Fabout%2Fcas-content&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACAS+Registry+Number" class="Z3988"></span></span> </li> <li id="cite_note-crc-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-crc_4-0">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFAmerican_Chemical_Society" class="citation web cs1"><a href="/wiki/American_Chemical_Society" title="American Chemical Society">American Chemical Society</a>. <a rel="nofollow" class="external text" href="https://web.archive.org/web/20080725010848/http://www.cas.org/expertise/cascontent/registry/regsys.html#q2#q2">"CAS Registry and CASRNs"</a>. 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Retrieved <span class="nowrap">25 July</span> 2009</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.genre=unknown&rft.btitle=CAS+Registry+and+CASRNs&rft.au=American+Chemical+Society&rft_id=http%3A%2F%2Fwww.cas.org%2Fexpertise%2Fcascontent%2Fregistry%2Fregsys.html%23q2&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACAS+Registry+Number" class="Z3988"></span></span> </li> <li id="cite_note-5"><span class="mw-cite-backlink"><b><a href="#cite_ref-5">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation web cs1"><a rel="nofollow" class="external text" href="https://www.cas.org/cas-data/cas-registry">"CAS REGISTRY"</a>. <i>www.cas.org</i>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=unknown&rft.jtitle=www.cas.org&rft.atitle=CAS+REGISTRY&rft_id=https%3A%2F%2Fwww.cas.org%2Fcas-data%2Fcas-registry&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACAS+Registry+Number" class="Z3988"></span></span> </li> <li id="cite_note-6"><span class="mw-cite-backlink"><b><a href="#cite_ref-6">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite class="citation news cs1"><a rel="nofollow" class="external text" href="https://www.cas.org/resources/press-releases/common-chemistry">"CAS Common Chemistry expands collection of publicly available chemical information"</a>. <i>CAS</i><span class="reference-accessdate">. Retrieved <span class="nowrap">17 March</span> 2021</span>.</cite><span title="ctx_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.genre=article&rft.jtitle=CAS&rft.atitle=CAS+Common+Chemistry+expands+collection+of+publicly+available+chemical+information&rft_id=https%3A%2F%2Fwww.cas.org%2Fresources%2Fpress-releases%2Fcommon-chemistry&rfr_id=info%3Asid%2Fen.wikipedia.org%3ACAS+Registry+Number" class="Z3988"></span></span> </li> <li id="cite_note-7"><span class="mw-cite-backlink"><b><a href="#cite_ref-7">^</a></b></span> <span class="reference-text"><link rel="mw-deduplicated-inline-style" href="mw-data:TemplateStyles:r1238218222"><cite id="CITEREFShively2007" class="citation web cs1">Shively, Eric (11 June 2007). <a rel="nofollow" class="external text" href="https://cen.acs.org/articles/85/i24/CAS-Surveys-First-100-Years.html">"CAS Surveys Its First 100 Years"</a>. <i>Chemical & Engineering News</i><span class="reference-accessdate">. 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href="https://query.wikidata.org/embed.html#SELECT%20%3FWikidata_item_%20%3FWikidata_item_Label%20%3Fvalue%20%3FvalueLabel%20%3FEnglish_Wikipedia_article%20%23Show%20data%20in%20this%20order%0A%7B%0A%09%3FWikidata_item_%20wdt%3AP231%20%3Fvalue%20.%20%23Collecting%20all%20items%20which%20have%20P231%20data%2C%20from%20whole%20Wikidata%20item%20pages%0A%09OPTIONAL%20%7B%3FEnglish_Wikipedia_article%20schema%3Aabout%20%3FWikidata_item_%3B%20schema%3AisPartOf%20%3Chttps%3A%2F%2Fen.wikipedia.org%2F%3E%20.%7D%20%23If%20collected%20item%20has%20link%20to%20English%20Wikipedia%2C%20show%20that%0A%09SERVICE%20wikibase%3Alabel%20%7B%20bd%3AserviceParam%20wikibase%3Alanguage%20%22en%22%20%20%7D%20%23Show%20label%20in%20this%20language.%20%22en%22%20is%20English.%20%20%20%0A%7D%0ALIMIT%201000">uses</a></span>)</li></ul></div></div> </div> <ul><li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20080725010848/http://www.cas.org/expertise/cascontent/registry/regsys.html">CAS registry description</a>, by Chemical Abstracts Service</li></ul> <p>To find the CAS number of a compound given its name, <a href="/wiki/Chemical_formula" title="Chemical formula">formula</a> or structure, the following free resources can be used: </p> <ul><li><a rel="nofollow" class="external text" href="https://commonchemistry.cas.org/">CAS Common Chemistry</a></li> <li><a rel="nofollow" class="external text" href="http://webbook.nist.gov/chemistry/">NIST Chemistry WebBook</a></li> <li><a rel="nofollow" class="external text" href="https://cactus.nci.nih.gov/chemical/structure">NCI/CADD Chemical Identifier Resolver</a></li> <li><a rel="nofollow" class="external text" href="http://chemsub.online.fr/">ChemSub Online (Multilingual chemical names)</a></li> <li><a rel="nofollow" class="external text" href="https://www.cdc.gov/niosh/npg/npgdcas.html">NIOSH Pocket Guide to Chemical Hazards, index of CAS numbers</a></li></ul>    </div><noscript><img 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