CINXE.COM

<!DOCTYPE html><html data-wf-domain="www.cas.org" data-wf-page="657223094414605528acadbf" data-wf-site="650861f00f97fe8153979335" lang="en"><head><meta charset="utf-8"/><title>CAS REGISTRY | CAS</title><link rel="alternate" hrefLang="x-default" href="https://www.cas.org/cas-data/cas-registry"/><link rel="alternate" hrefLang="en" href="https://www.cas.org/cas-data/cas-registry"/><link rel="alternate" hrefLang="pt-BR" href="https://www.cas.org/pt-br/cas-data/cas-registry"/><link rel="alternate" hrefLang="ko-KR" href="https://www.cas.org/ko/cas-data/cas-registry"/><link rel="alternate" hrefLang="es-ES" href="https://www.cas.org/es-es/cas-data/cas-registry"/><link rel="alternate" hrefLang="zh-CN" href="https://www.cas.org/zh-hans/cas-data/cas-registry"/><link rel="alternate" hrefLang="ja" href="https://www.cas.org/ja/cas-data/cas-registry"/><meta content="CAS REGISTRY®, the CAS substance collection, is the premier source relied upon by scientists and regulators worldwide for accurate information on chemical substances." name="description"/><meta content="CAS REGISTRY" property="og:title"/><meta content="CAS REGISTRY®, the CAS substance collection, is the premier source relied upon by scientists and regulators worldwide for accurate information on chemical substances." property="og:description"/><meta content="CAS REGISTRY" property="twitter:title"/><meta content="CAS REGISTRY®, the CAS substance collection, is the premier source relied upon by scientists and regulators worldwide for accurate information on chemical substances." property="twitter:description"/><meta property="og:type" content="website"/><meta content="summary_large_image" name="twitter:card"/><meta content="width=device-width, initial-scale=1" name="viewport"/><link href="https://cdn.prod.website-files.com/650861f00f97fe8153979335/css/cas-org.36b92ce45.min.css" rel="stylesheet" type="text/css"/><script type="text/javascript">!function(o,c){var n=c.documentElement,t=" w-mod-";n.className+=t+"js",("ontouchstart"in o||o.DocumentTouch&&c instanceof DocumentTouch)&&(n.className+=t+"touch")}(window,document);</script><link href="https://cdn.prod.website-files.com/650861f00f97fe8153979335/6585a20f2b9c762a8e082a87_cas-favicon.png" rel="shortcut icon" type="image/x-icon"/><link href="https://cdn.prod.website-files.com/650861f00f97fe8153979335/6585a218bfa3f8e706a9b92a_cas-webclip.png" rel="apple-touch-icon"/><link href="https://www.cas.org/cas-data/cas-registry" rel="canonical"/><script> window.dataLayer = window.dataLayer ||[]; function gtag(){dataLayer.push(arguments);} gtag('consent','default',{ 'ad_storage':'denied', 'analytics_storage':'denied', 'ad_user_data':'denied', 'ad_personalization':'denied', 'personalization_storage':'denied', 'functionality_storage':'granted', 'security_storage':'granted', 'wait_for_update': 500 }); gtag("set", "ads_data_redaction", true); </script> <script src="https://cmp.osano.com/16BPzAUFV1UoQ26HU/a9d65c21-17eb-4eec-b081-a08a1ff580e7/osano.js"></script> <script async src="https://www.googletagmanager.com/gtag/js?id=G-0LKKGQYK33"></script> <script type="text/javascript" src="//cdn-4.convertexperiments.com/js/10047855-100411829.js"></script>  <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start': new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0], j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src= 'https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f); })(window,document,'script','dataLayer','GTM-5RS86Q');</script>  <style>.box-1,.box-2{height:100%;text-align:center}*{-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;-o-font-smoothing:antialiased}ul.cas-list li::marker{content:"\2014"}ul li::marker{content:"\2014"}.osano-cm-drawer-toggle .osano-cm-label{color:#102a43}a{text-decoration:none}button{background-color:unset;padding:unset;text-align:inherit}section{position:relative}:where([data-container]){position:relative;width:100%;max-width:90rem;margin-right:auto;margin-left:auto;padding-top:var(--scale--scale-128px);padding-right:var(--scale--scale-32px);padding-bottom:var(--scale--scale-128px);padding-left:var(--scale--scale-32px)}.container:tiny{overflow:hidden}.em-dash-list{list-style:none;padding-left:0;margin-left:20px}.em-dash-list li{align-items:baseline}.em-dash-list li:before{content:"\2014";color:#41b6e6;display:inline-block;width:1em;margin-right:6px}.styled-table{border-collapse:collapse;margin:25px 0;font-size:1rem;font-family:sans-serif;min-width:400px;box-shadow:0 0 15px rgba(0,0,0,.15)}.styled-table thead tr{background-color:#41b6e6;color:#fff;text-align:left}.styled-table td,.styled-table th{padding:12px 15px}.styled-table tbody tr{border-bottom:1px solid #dcdcdc}.styled-table tbody tr:nth-of-type(2n){background-color:#fff}.styled-table tbody tr:last-of-type{border-bottom:2px solid #41b6e6}.styled-table tbody tr.active-row{font-weight:700;color:#41b6e6}.grid{display:grid;grid-template-columns:1fr 1fr;gap:20px}.box,.col{padding:20px}.box-1{background:#0032a0;color:#fff}.box-2{background:#ffc72c;color:#0032a0}@media (max-width:600px){.grid{grid-template-columns:1fr}}</style> <style media="print"> /* Hide header and footer */ .site-header, .site-footer_component { display: none !important; } /* Remove default margins */ @page { margin: 0; } body { margin: 1cm; } </style><script type="application/ld+json"> { "@context": "http://schema.org", "@type": "WebPage", "name": "CAS REGISTRY | CAS", "description": "CAS REGISTRY®, the CAS substance collection, is the premier source relied upon by scientists and regulators worldwide for accurate information on chemical substances.", "url": "https://www.cas.org/cas-data/cas-registry", "publisher": { "@type": "Organization", "name": "CAS", "url": "https://www.cas.org", "contactPoint": { "@type": "ContactPoint", "telephone": "+1-614-447-3731", "email": "help@cas.org", "faxnumber": "1-614-447-3751", "availableLanguage": "English", "contactType": "customer service" }, "address": { "@type": "PostalAddress", "streetAddress": "2540 Olentangy River Road", "addressLocality": "Columbus", "addressRegion": "OH", "postalCode": "43202", "addressCountry": "USA" } "sameAs": [ "https://www.facebook.com/CAS", "https://twitter.com/CASChemistry", "https://www.linkedin.com/company/cas", "https://www.youtube.com/user/ChemAbstractsService/featured" ] } } </script><script src="https://cdn.prod.website-files.com/650861f00f97fe8153979335%2F6544eda5f000985a163a8687%2F671a4cc4f8d90a0a94a07cb1%2Ffinsweetcomponentsconfig-1.0.1.js" type="module" async="" siteId="650861f00f97fe8153979335" finsweet="components"></script></head><body><div class="w-embed w-iframe">  <noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-5RS86Q" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> </div><div class="page-wrapper"><header class="site-header"><div data-w-id="dff35351-dfb0-8d4f-486b-faee40785252" class="top-nav-wrapper"><div class="banner-component"><div>CAS STNext® Coffee Lecture Date searching in CAS STNext</div><a href="https://www.cas.org/resources/webinar/cas-stnext-coffee-lecture-date-searching-in-cas-stnext" class="banner__link w-inline-block"><div class="banner__text">Register now</div><div class="banner__icon w-embed"><svg width="18" height="18" viewBox="0 0 18 18" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M10.8698 4.28285C10.5773 4.57535 10.5773 5.04785 10.8698 5.34035L13.7798 8.25035H2.40234C1.98984 8.25035 1.65234 8.58785 1.65234 9.00035C1.65234 9.41285 1.98984 9.75035 2.40234 9.75035H13.7873L10.8773 12.6603C10.5848 12.9528 10.5848 13.4254 10.8773 13.7179C11.1698 14.0104 11.6423 14.0104 11.9348 13.7179L16.1273 9.52535C16.4198 9.23285 16.4198 8.76035 16.1273 8.46785L11.9273 4.28285C11.6423 3.99035 11.1623 3.99035 10.8698 4.28285Z" fill="currentColor"/> </svg></div></a></div><div class="courtesy_nav-component"><div data-animation="default" data-collapse="small" data-duration="400" data-easing="ease" data-easing2="ease" role="banner" class="courtesy-navbar w-nav"><div class="courtesy-navbar_container"><div class="courtesy-navbar__wrapper"><div class="courtesy-navbar__search-component"><form action="/search" typeof="WebSite" vocab="https://schema.org/" class="search w-form"><input class="search__input w-input" maxlength="256" name="query" typeof="SearchAction" placeholder="Search…" property="query-input" type="search" id="search" required=""/><input type="hidden" property="target" value="https://www.cas.org/search?query={search_term_string}"/><input type="submit" class="button button__search w-button" value="Search"/></form></div><div class="courtesy-navbar__language-wrapper"><nav role="navigation" class="courtesy-nav__menu w-nav-menu"><a href="/training" class="courtesy-nav__link w-nav-link">Training</a><a href="/contact" class="courtesy-nav__link w-nav-link">Contact</a><a href="/cas-solutions-login" class="courtesy-nav__link w-nav-link">Login</a></nav><div class="menu-button-4 w-nav-button"><div class="icon-2 w-icon-nav-menu"></div></div><div data-hover="false" data-delay="0" class="language__dropdown w-dropdown"><div class="language__dropdown--toggle w-dropdown-toggle"><div class="language__dropdown--icon w-icon-dropdown-toggle"></div><div class="language__dropdown--prompt">Choose language</div></div><nav class="language__dropdown--locales w-dropdown-list"><div class="language__dropdown--locales-wrapper w-locales-list"><div role="list" class="language__dropdown--locales-list w-locales-items"><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="en" href="/cas-data/cas-registry" aria-current="page" class="language__dropdown--locale-link w--current">English</a></div><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="pt-BR" href="/pt-br/cas-data/cas-registry" class="language__dropdown--locale-link">Portuguese</a></div><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="ko-KR" href="/ko/cas-data/cas-registry" class="language__dropdown--locale-link">Korean</a></div><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="es-ES" href="/es-es/cas-data/cas-registry" class="language__dropdown--locale-link">Spanish</a></div><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="zh-CN" href="/zh-hans/cas-data/cas-registry" class="language__dropdown--locale-link">Chinese</a></div><div role="listitem" class="language__dropdown--locale w-locales-item"><a hreflang="ja" href="/ja/cas-data/cas-registry" class="language__dropdown--locale-link">Japanese</a></div></div></div></nav></div></div></div></div></div></div></div><div data-animation="default" class="site-navbar w-nav" data-easing2="ease" fs-scrolldisable-element="smart-nav" data-easing="ease" data-collapse="medium" data-w-id="215f21f3-d3c1-74ca-22fa-c34c35e3158b" role="banner" data-duration="400"><div class="site-nav__container"><a href="https://www.cas.org" class="navbar_logo-link w-nav-brand"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/65babbec1c38d54bcc033f7c_CAS_PREF_3C_RGB_POS.svg" loading="lazy" width="126" alt="CAS Logo" class="navbar_logo"/></a><nav role="navigation" class="site-navbar_menu is-page-height-tablet w-nav-menu"><div class="mobile-search_wrapper"><form action="/search" class="mobile-search_component w-form"><input class="mobile-search_input w-input" maxlength="256" name="query" placeholder="" type="search" id="mobile-search" required=""/><input type="submit" class="mobile-search_button w-button" value="Search"/></form></div><div data-hover="false" data-delay="200" data-w-id="215f21f3-d3c1-74ca-22fa-c34c35e31596" class="navbar-main_menu-dropdown w-dropdown"><div class="navbar_dropdown-toggle w-dropdown-toggle"><div>Solutions</div><div class="dropdown-chevron w-embed"><svg width=" 100%" height=" 100%" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M2.55806 6.29544C2.46043 6.19781 2.46043 6.03952 2.55806 5.94189L3.44195 5.058C3.53958 4.96037 3.69787 4.96037 3.7955 5.058L8.00001 9.26251L12.2045 5.058C12.3021 4.96037 12.4604 4.96037 12.5581 5.058L13.4419 5.94189C13.5396 6.03952 13.5396 6.19781 13.4419 6.29544L8.17678 11.5606C8.07915 11.6582 7.92086 11.6582 7.82323 11.5606L2.55806 6.29544Z" fill="currentColor"/> </svg></div></div><nav class="navbar-main_dropdown-list navbar-column-4-width w-dropdown-list"><div class="navbar-main_dropdown-content"><div id="w-node-da5a10a2-dd85-3827-8c9d-eb3bf354b8de-f9289f4b" class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><a href="/solutions/biofinder-discovery-platform" class="nav__dropdown-platform-link">CAS BioFinder Discovery Platform</a></div><div id="w-node-da5a10a2-dd85-3827-8c9d-eb3bf354b8e2-f9289f4b" class="nav_dropdown-link-wrap"><a href="/solutions/cas-scifinder-discovery-platform" class="nav__dropdown-platform-link">CAS SciFinder Discovery Platform</a><div class="nav__link-list"><a href="/solutions/cas-scifinder-discovery-platform/cas-scifinder" class="nav__dropdown-link w-inline-block"><div>CAS SciFinder</div></a><a href="/solutions/cas-scifinder-discovery-platform/cas-formulus" class="nav__dropdown-link w-inline-block"><div>CAS Formulus</div></a><a href="/solutions/cas-scifinder-discovery-platform/cas-analytical-methods" class="nav__dropdown-link w-inline-block"><div>CAS Analytical Methods</div></a></div></div></div><div id="w-node-da5a10a2-dd85-3827-8c9d-eb3bf354b8ef-f9289f4b" class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><a href="/solutions/stn-ip-protection-suite" class="nav__dropdown-platform-link">STN IP Protection Suite</a><div class="nav__link-list"><a href="/solutions/stn-ip-protection-suite/stnext" class="nav__dropdown-link w-inline-block"><div>CAS STNext</div></a><a href="/solutions/stn-ip-protection-suite/cas-scientific-patent-explorer" class="nav__dropdown-link w-inline-block"><div>CAS Scientific Patent Explorer</div></a><a href="/solutions/stn-ip-protection-suite/patmon" class="nav__dropdown-link w-inline-block"><div>Fiz Patmon</div></a><a href="/solutions/stn-ip-protection-suite/cas-search-guard" class="nav__dropdown-link w-inline-block"><div>CAS Search Guard</div></a></div></div></div><div id="w-node-da5a10a2-dd85-3827-8c9d-eb3bf354b900-f9289f4b" class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><a href="/solutions/cas-custom-services" class="nav__dropdown-platform-link">CAS Custom Services</a><div class="nav__link-list"><a href="/solutions/cas-custom-services/ip-services" class="nav__dropdown-link w-inline-block"><div>CAS IP Services</div></a><a href="/solutions/cas-registry-services" class="nav__dropdown-link w-inline-block"><div>CAS Registry Services</div></a></div></div></div><div id="w-node-da5a10a2-dd85-3827-8c9d-eb3bf354b90b-f9289f4b" class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><a href="/solutions/other-solutions" class="nav__dropdown-platform-link">Other CAS Solutions</a><div class="nav__link-list"><a href="/solutions/other-solutions/cas-chemical-compliance-index" class="nav__dropdown-link w-inline-block"><div>CAS Chemical Compliance Index</div></a><a href="/solutions/other-solutions/chemzent" class="nav__dropdown-link w-inline-block"><div>ChemZent</div></a><a href="/solutions/other-solutions/cas-chemical-supplier-insights" class="nav__dropdown-link w-inline-block"><div>CAS Chemical Supplier Insights</div></a></div></div></div></div><a href="/solutions" class="navbar_button-full-width w-inline-block"><div>View all solutions</div><div class="button-icon-small w-embed"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--ic" width="100%" height="100%" preserveAspectRatio="xMidYMid meet" viewBox="0 0 24 24"><path fill="currentColor" d="M6 7c0 .55.45 1 1 1h7.59l-8.88 8.88a.996.996 0 1 0 1.41 1.41L16 9.41V17c0 .55.45 1 1 1s1-.45 1-1V7c0-.55-.45-1-1-1H7c-.55 0-1 .45-1 1"></path></svg></div></a></nav></div><div data-hover="false" data-delay="200" data-w-id="6ce5613a-a398-6459-54a8-c1335306637d" class="navbar-main_menu-dropdown w-dropdown"><div class="navbar_dropdown-toggle w-dropdown-toggle"><div>Featured industries</div><div class="dropdown-chevron w-embed"><svg width=" 100%" height=" 100%" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M2.55806 6.29544C2.46043 6.19781 2.46043 6.03952 2.55806 5.94189L3.44195 5.058C3.53958 4.96037 3.69787 4.96037 3.7955 5.058L8.00001 9.26251L12.2045 5.058C12.3021 4.96037 12.4604 4.96037 12.5581 5.058L13.4419 5.94189C13.5396 6.03952 13.5396 6.19781 13.4419 6.29544L8.17678 11.5606C8.07915 11.6582 7.92086 11.6582 7.82323 11.5606L2.55806 6.29544Z" fill="currentColor"/> </svg></div></div><nav class="navbar-main_dropdown-list navbar-column-2_width navbar_industries w-dropdown-list"><div class="navbar-main_dropdown-content navbar-column-2"><div class="navbar_dropdown-link-list"><div id="w-node-_6ce5613a-a398-6459-54a8-c13353066388-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/industries/agriculture" class="nav__dropdown-link w-inline-block"><div>Agriculture</div></a><a href="/industries/batteries" class="nav__dropdown-link w-inline-block"><div>Batteries</div></a><a href="/industries/business-of-science" class="nav__dropdown-link w-inline-block"><div>Business of Science</div></a><a href="/industries/coatings-and-inks" class="nav__dropdown-link w-inline-block"><div>Coatings and Inks</div></a></div></div></div><div class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/industries/drug-discovery" class="nav__dropdown-link w-inline-block"><div>Drug Discovery</div></a><a href="/industries/electronics-and-materials" class="nav__dropdown-link w-inline-block"><div>Electronics and Materials</div></a><a href="/industries/plastics-and-polymers" class="nav__dropdown-link w-inline-block"><div>Plastics and Polymers</div></a><a href="/industries/sustainability" class="nav__dropdown-link w-inline-block"><div>Sustainability</div></a></div></div></div></div><a href="/industries" class="navbar_button-full-width w-inline-block"><div>View all industries</div><div class="button-icon-small w-embed"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--ic" width="100%" height="100%" preserveAspectRatio="xMidYMid meet" viewBox="0 0 24 24"><path fill="currentColor" d="M6 7c0 .55.45 1 1 1h7.59l-8.88 8.88a.996.996 0 1 0 1.41 1.41L16 9.41V17c0 .55.45 1 1 1s1-.45 1-1V7c0-.55-.45-1-1-1H7c-.55 0-1 .45-1 1"></path></svg></div></a></nav></div><div data-hover="false" data-delay="200" data-w-id="f8145756-c9d7-6b6d-891c-40f169ec6d18" class="navbar-main_menu-dropdown w-dropdown"><div class="navbar_dropdown-toggle w-dropdown-toggle"><div>CAS Data</div><div class="dropdown-chevron w-embed"><svg width=" 100%" height=" 100%" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M2.55806 6.29544C2.46043 6.19781 2.46043 6.03952 2.55806 5.94189L3.44195 5.058C3.53958 4.96037 3.69787 4.96037 3.7955 5.058L8.00001 9.26251L12.2045 5.058C12.3021 4.96037 12.4604 4.96037 12.5581 5.058L13.4419 5.94189C13.5396 6.03952 13.5396 6.19781 13.4419 6.29544L8.17678 11.5606C8.07915 11.6582 7.92086 11.6582 7.82323 11.5606L2.55806 6.29544Z" fill="currentColor"/> </svg></div></div><nav class="navbar-main_dropdown-list navbar-column-2_width w-dropdown-list"><div class="navbar-main_dropdown-content navbar-column-2"><div class="navbar_dropdown-link-list"><div id="w-node-f8145756-c9d7-6b6d-891c-40f169ec6d20-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/cas-data/cas-registry" aria-current="page" class="nav__dropdown-link w-inline-block w--current"><div>CAS REGISTRY®</div></a><a href="/cas-data/cas-reactions" class="nav__dropdown-link w-inline-block"><div>CAS Reactions</div></a><a href="/cas-data/cas-references" class="nav__dropdown-link w-inline-block"><div>CAS References</div></a></div></div></div><div class="navbar_dropdown-link-list"><div class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/cas-data/cas-patents" class="nav__dropdown-link w-inline-block"><div>CAS Patents</div></a><a href="/cas-data/cas-commercial-sources" class="nav__dropdown-link w-inline-block"><div>CAS Commercial Sources</div></a><a href="/cas-data/cas-formulations" class="nav__dropdown-link w-inline-block"><div>CAS Formulations</div></a><a href="/cas-data/life-sciences-data" class="nav__dropdown-link w-inline-block"><div>CAS Life Sciences</div></a></div></div></div></div><a href="/cas-data" class="navbar_button-full-width w-inline-block"><div>View all CAS Data</div><div class="button-icon-small w-embed"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--ic" width="100%" height="100%" preserveAspectRatio="xMidYMid meet" viewBox="0 0 24 24"><path fill="currentColor" d="M6 7c0 .55.45 1 1 1h7.59l-8.88 8.88a.996.996 0 1 0 1.41 1.41L16 9.41V17c0 .55.45 1 1 1s1-.45 1-1V7c0-.55-.45-1-1-1H7c-.55 0-1 .45-1 1"></path></svg></div></a></nav></div><div data-hover="false" data-delay="200" data-w-id="73ecd304-4e29-38f3-18bb-b8cd3eb6ac2b" class="navbar-main_menu-dropdown w-dropdown"><div class="navbar_dropdown-toggle w-dropdown-toggle"><div>Resources</div><div class="dropdown-chevron w-embed"><svg width=" 100%" height=" 100%" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M2.55806 6.29544C2.46043 6.19781 2.46043 6.03952 2.55806 5.94189L3.44195 5.058C3.53958 4.96037 3.69787 4.96037 3.7955 5.058L8.00001 9.26251L12.2045 5.058C12.3021 4.96037 12.4604 4.96037 12.5581 5.058L13.4419 5.94189C13.5396 6.03952 13.5396 6.19781 13.4419 6.29544L8.17678 11.5606C8.07915 11.6582 7.92086 11.6582 7.82323 11.5606L2.55806 6.29544Z" fill="currentColor"/> </svg></div></div><nav class="navbar-main_dropdown-list navbar-column-2_width navbar_resources w-dropdown-list"><div class="navbar-main_dropdown-content navbar-column-2 navbar_resources"><div class="navbar_dropdown-link-list"><div id="w-node-_2f9fe6c6-c578-de26-c4e8-58c417e8eb54-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/resources/cas-insights" class="nav__dropdown-link w-inline-block"><div>CAS Insights</div></a><a href="/cas-events" class="nav__dropdown-link w-inline-block"><div>Events</div></a><a href="/cas-webinars" class="nav__dropdown-link w-inline-block"><div>Webinars</div></a><a href="/resources/white-papers" class="nav__dropdown-link w-inline-block"><div>White papers</div></a></div></div></div><div class="navbar_dropdown-link-list"><div id="w-node-_2f9fe6c6-c578-de26-c4e8-58c417e8eb63-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/resources/case-studies" class="nav__dropdown-link w-inline-block"><div>Case Studies</div></a><a href="https://commonchemistry.cas.org/" class="nav__dropdown-link w-inline-block"><div>CAS Common Chemistry</div></a><a href="/resources/chemical-safety-library" class="nav__dropdown-link w-inline-block"><div>CAS Chemical Safety Library</div></a><a href="https://cassi.cas.org/" class="nav__dropdown-link w-inline-block"><div>CAS Source Index (CASSI)</div></a></div></div></div></div><a href="/resources" class="navbar_button-full-width w-inline-block"><div>View all resources</div><div class="button-icon-small w-embed"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--ic" width="100%" height="100%" preserveAspectRatio="xMidYMid meet" viewBox="0 0 24 24"><path fill="currentColor" d="M6 7c0 .55.45 1 1 1h7.59l-8.88 8.88a.996.996 0 1 0 1.41 1.41L16 9.41V17c0 .55.45 1 1 1s1-.45 1-1V7c0-.55-.45-1-1-1H7c-.55 0-1 .45-1 1"></path></svg></div></a></nav></div><div data-hover="false" data-delay="200" data-w-id="7cad82f7-9dad-9ea8-65e5-8a505736f212" class="navbar-main_menu-dropdown w-dropdown"><div class="navbar_dropdown-toggle w-dropdown-toggle"><div>About</div><div class="dropdown-chevron w-embed"><svg width=" 100%" height=" 100%" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M2.55806 6.29544C2.46043 6.19781 2.46043 6.03952 2.55806 5.94189L3.44195 5.058C3.53958 4.96037 3.69787 4.96037 3.7955 5.058L8.00001 9.26251L12.2045 5.058C12.3021 4.96037 12.4604 4.96037 12.5581 5.058L13.4419 5.94189C13.5396 6.03952 13.5396 6.19781 13.4419 6.29544L8.17678 11.5606C8.07915 11.6582 7.92086 11.6582 7.82323 11.5606L2.55806 6.29544Z" fill="currentColor"/> </svg></div></div><nav class="navbar-main_dropdown-list navbar-column-2_width navbar_about w-dropdown-list"><div class="navbar-main_dropdown-content navbar-column-2"><div class="navbar_dropdown-link-list"><div id="w-node-_257986f8-6154-22b2-c35d-1ceffe0d3de8-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/about-us" class="nav__dropdown-link w-inline-block"><div>About CAS</div></a><a href="/about/cas-history" class="nav__dropdown-link w-inline-block"><div>CAS Story</div></a><a href="/careers" class="nav__dropdown-link w-inline-block"><div>Careers</div></a><a href="/about/futureleaders" class="nav__dropdown-link w-inline-block"><div>Future Leaders</div></a></div></div></div><div class="navbar_dropdown-link-list"><div id="w-node-_257986f8-6154-22b2-c35d-1ceffe0d3df4-f9289f4b" class="nav_dropdown-link-wrap"><div class="nav__link-list"><a href="/cas-innovation-incubator" class="nav__dropdown-link w-inline-block"><div>CAS Innovation Incubator</div></a><a href="/about/faqs" class="nav__dropdown-link w-inline-block"><div>FAQs</div></a><a href="/press-releases" class="nav__dropdown-link w-inline-block"><div>Press Releases</div></a></div></div></div></div></nav></div><div class="mobile-utility-nav_wrapper"><a href="/training">Training</a><a href="/cas-solutions-login">Log in</a><a href="/contact">Contact</a></div><div class="mobile-locales_wrapper w-locales-list"><div data-hover="false" data-delay="0" class="mobile-locales_dropdown w-dropdown"><div class="mobile-locales_dropdown-toggle w-dropdown-toggle"><div class="w-icon-dropdown-toggle"></div><div>English</div></div><nav class="mobile-locales_dropdown-list w-dropdown-list"><div role="list" class="locales-list w-locales-items"><div role="listitem" class="locale_link w-locales-item"><a hreflang="en" href="/cas-data/cas-registry" aria-current="page" class="locale_link w--current">English</a></div><div role="listitem" class="locale_link w-locales-item"><a hreflang="pt-BR" href="/pt-br/cas-data/cas-registry" class="locale_link">Portuguese</a></div><div role="listitem" class="locale_link w-locales-item"><a hreflang="ko-KR" href="/ko/cas-data/cas-registry" class="locale_link">Korean</a></div><div role="listitem" class="locale_link w-locales-item"><a hreflang="es-ES" href="/es-es/cas-data/cas-registry" class="locale_link">Spanish</a></div><div role="listitem" class="locale_link w-locales-item"><a hreflang="zh-CN" href="/zh-hans/cas-data/cas-registry" class="locale_link">Chinese</a></div><div role="listitem" class="locale_link w-locales-item"><a hreflang="ja" href="/ja/cas-data/cas-registry" class="locale_link">Japanese</a></div></div></nav></div></div></nav><div class="navbar12_menu-button w-nav-button"><div class="menu-icon1"><div class="menu-icon1_line-top"></div><div class="menu-icon1_line-middle"><div class="menu-icon_line-middle-inner"></div></div><div class="menu-icon1_line-bottom"></div></div></div></div></div></header><main itemtype="https://schema.org/Organization" role="main" itemscope="" class="main-wrapper"><section class="promo-hero__wrapper"><div class="promo-hero__container"><div class="promo-hero__inner"><div id="w-node-_869f332c-648c-0d92-8b2f-48693bd2b5c4-28acadbf" class="promo-hero__body"><h1 id="w-node-_869f332c-648c-0d92-8b2f-48693bd2b5c5-28acadbf" class="promo-hero__title">CAS REGISTRY®</h1><p id="w-node-_869f332c-648c-0d92-8b2f-48693bd2b5c7-28acadbf" class="promo-hero__content">CAS REGISTRY, the CAS substance collection, is the premier source relied upon by scientists, manufacturers, regulators, and data scientists worldwide for accurate information on chemical substances.</p><a href="/contact" class="button w-button">Contact us</a></div></div></div></section><nav aria-label="Breadcrumb" class="section__breadcrumbs"><div class="container-breadcrumbs"><ol typeof="BreadcrumbList" vocab="https://schema.org/" role="list" class="breadcrumbs w-list-unstyled"><li typeof="ListItem" property="itemListElement" class="breadcrumbs__list-item"><a href="/?r=0" typeof="WebPage" property="item" class="breadcrumbs__item-link w-inline-block"><div property="name" class="breadcrumbs__list-item--text">Home</div></a><meta property="position" content="1"/><div class="breadcrumbs__separator w-embed"><svg width="32" height="32" viewBox="0 0 32 32" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M20 8L11 23.5885" stroke="currentColor" stroke-width="1.5"/> </svg></div></li><li typeof="ListItem" property="itemListElement" class="breadcrumbs__list-item"><a href="/cas-data" typeof="WebPage" property="item" class="breadcrumbs__item-link w-inline-block"><div property="name" class="breadcrumbs__list-item--text">CAS Data</div></a><meta property="position" content="2"/><div class="breadcrumbs__separator w-embed"><svg width="32" height="32" viewBox="0 0 32 32" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M20 8L11 23.5885" stroke="currentColor" stroke-width="1.5"/> </svg></div></li><li typeof="ListItem" property="itemListElement" class="breadcrumbs__list-item"><div property="name" class="breadcrumbs__list-item--text">CAS Registry®</div><meta property="position" content="3"/></li></ol></div></nav><section class="section"><div class="container"><div class="grid-layout grid-layout--2-column"><div><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/65afdecee777985ebbc748fc_cas-registry.webp" loading="lazy" sizes="(max-width: 767px) 100vw, (max-width: 1439px) 50vw, 720px" srcset="https://cdn.prod.website-files.com/650861f00f97fe8153979335/65afdecee777985ebbc748fc_cas-registry-p-500.webp 500w, https://cdn.prod.website-files.com/650861f00f97fe8153979335/65afdecee777985ebbc748fc_cas-registry-p-800.webp 800w, https://cdn.prod.website-files.com/650861f00f97fe8153979335/65afdecee777985ebbc748fc_cas-registry-p-1080.webp 1080w, https://cdn.prod.website-files.com/650861f00f97fe8153979335/65afdecee777985ebbc748fc_cas-registry.webp 1200w" alt=""/></div><div id="w-node-_73c16c7d-e4f0-062e-6d92-e0ec318bf2df-28acadbf" class="grid-layout__text"><h2>What is a CAS Registry Number®?</h2><div class="w-richtext"><p>Chemical compounds are described in many different ways including molecular formulas, chemical structures, generic, systematic, common, and trade names. This lack of clarity can cause frustration, delays, and even safety concerns.</p><p>A CAS Registry Number is a unique and unambiguous identifier for a specific substance that allows clear communication and, with the help of CAS scientists, links together all available data and research about that substance. Governmental agencies rely on CAS Registry Numbers for substance identification in regulatory applications because they are unique, easy validated, and internationally recognized.</p></div></div></div></div></section><section class="section section-features"><div class="container"><div class="section__header"><h2 class="section__feature-title">Features</h2></div><div class="w-layout-grid grid-column-3"><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd86f65a8514c026cd8bc_CAS_Icons_Final_RGB_Patents.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>Authoritative source for accurate chemical names, structures, and CAS Registry Numbers®.</p></div></div></div><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd879a4fa47615abba4cc_CAS_Icons_Final_RGB_Substance.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>219 million organic substances, alloys, coordination compounds, minerals, mixtures, polymers, and salts disclosed in publications since the early 1800s.</p></div></div></div><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd854521a8c00a67217f1_CAS_Icons_Final_RGB_Biosequences.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>~75 million protein and nucleic acid sequences.</p></div></div></div><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd85dd5abc43d0c0f9fc4_CAS_Icons_Final_RGB_Data%20Standardization.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>Enriched with ~8 billion experimental and predicted property data points and spectra.</p></div></div></div><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd873cf601b34f30e521e_CAS_Icons_Final_RGB_Proven%20Reliability.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>Updated daily with thousands of new substances to alert you to the most recent discoveries.</p></div></div></div><div class="card__feature"><div class="card__feature--left-border"></div><div class="card__feature--content"><div class="card__feature-icon-wrapper"><img src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/662fd85a0af5c3573e1384ec_CAS_Icons_Final_RGB_Content.svg" loading="lazy" width="92" height="92" alt="" class="card__feature-icon"/></div><div class="rich-text_features w-richtext"><p>Linked to relevant publications, reactions, chemical suppliers, formulations, and more, as part of the CAS Content Collection™.</p></div></div></div></div></div></section><section aria-labelledby="faq-heading" itemscope="" itemtype="https://schema.org/FAQPage" class="section faq-section"><div class="container"><div class="faq-header-wrapper"><div class="faq-heading"><div class="faq-heading-subhead">FAQs</div><h2 id="faq-heading" class="faq-heading-title">CAS REGISTRY and CAS Registry Number</h2></div><div class="faq-heading--cta-wrapper"><p>Still have a question in mind?<br/>Contact us directly!</p><a href="/contact" class="button w-button">Contact us</a></div></div><div class="w-layout-grid faq-layout"><div class="faq-wrap"><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">What is CAS REGISTRY?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p><a href="https://www.cas.org/cas-data/cas-registry">CAS REGISTRY</a> is the most authoritative collection of disclosed chemical substance information.</p><p>CAS REGISTRY covers substances identified from the scientific literature from 1957 to the present, with additional substances going back to the early 1900s.</p><p>CAS REGISTRY is updated daily with thousands of new substances.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">What is a CAS Registry Number (CAS RN)?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>Each CAS Registry Number (CAS RN) identifier:</p><ul role="list"><li>Is a unique numeric identifier.</li><li>Designates only one substance.</li><li>Has no chemical significance.</li><li>Is a link to a wealth of information about a specific chemical substance.</li></ul></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">What does a CAS Registry Number look like?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>A CAS Registry Number is a numeric identifier that can contain up to 10 digits, divided by hyphens into three parts.</p><p>The right-most digit is a <a href="https://www.cas.org/support/documentation/chemical-substances/checkdig">check digit</a> used to verify the validity and uniqueness of the entire number.</p><p>For example, 58-08-2 is the CAS Registry Number for caffeine.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">How does CAS assign Registry Numbers?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>A CAS Registry Number is assigned to a substance when it enters the CAS REGISTRY database. Numbers are assigned in sequential order to unique, new substances identified by CAS scientists for inclusion in the database.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">What kinds of compounds does the CAS REGISTRY contain?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>CAS REGISTRY contains a wide variety of substances, including the world's largest collection of:</p><ul role="list"><li>Organic and inorganic compounds.</li><li>Metals and alloys.</li><li>Minerals.</li><li>Coordination compounds and organometallics.</li><li>Elements, isotopes, and nuclear particles.</li><li>Proteins and nucleic acids.</li><li>Polymers.</li><li>Non-structurable materials and those of unknown or variable composition and biologics (UVCBs).</li></ul></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">Why have CAS Registry Numbers become the world standard?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>Since CAS Registry Numbers are not dependent upon any system of chemical nomenclature, they can:</p><ul role="list"><li>Provide a reliable common link between the various nomenclature used to describe substances.</li><li>Serve as an international resource for chemical substance identifiers used by scientists, industry, and regulatory bodies.</li></ul></div></div></nav></div></div><div class="faq-wrap"><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">Why do regulatory agencies rely on CAS Registry Numbers?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>Chemical compounds can be described in many different ways, such as molecular formulas, structure diagrams, systematic names, proprietary trade names, etc.</p><p>A CAS Registry Number, however, is unique and specific to only one substance regardless of how many other ways the substance can be described.</p><p>Governmental agencies have found CAS Registry Numbers ideal for keeping track of substances because they are:</p><ul role="list"><li>Unique.</li><li>Validated quickly and reliably.</li><li>Internationally recognized.</li></ul></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">Where can I find CAS REGISTRY Numbers?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>Find CAS Registry Numbers in:</p><p>In <a href="https://www.cas.org/solutions/cas-scifinder-discovery-platform/cas-scifinder-n">CAS SciFinder</a>® and <a href="https://www.cas.org/solutions/stn-ip-protection-suite/stnext">CAS STNext</a><sup>®</sup> databases, CAS publications, and other sources such as:</p><ul role="list"><li>Governmental regulatory agency commercial chemical inventories.</li><li><a href="https://www.cas.org/support/documentation/chemical-substances/info-exchange">Selected Elsevier databases.</a></li><li>Handbooks, guides, and technical reports.</li><li>Other printed reference works.</li><li>Chemical catalogs.</li></ul></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">Why do some substances in CAS REGISTRY have zero references? How can I learn more about these substances?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>Records in CAS REGISTRY represent substances indexed for the CAS databases (CAS References, CAS Reactions, CAS Chemical Supplier Insights, CAS Markush) and other databases in products such as CAS SciFinder and STN. Substances that come from sources other than literature or patent publications may not contain any references. CAS indexes these substances to support registration policies, chemical libraries, chemical catalogs, web sources, reaction databases, and data collections not represented in STN.</p><p>To learn more about a substance in REGISTRY that does not have any literature or patent references consult the <a href="https://www.cas.org/support/documentation/chemical-substances/zerorefs">Source of Registration (SR) and Class Identifier (CI) fields in CAS STNext</a>.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">How can I obtain or request assignment of a CAS Registry Number?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>The CAS <a href="https://www.cas.org/solutions/cas-custom-services/cas-registry-services/inventory-expert-services">Inventory Expert Service</a> and <a href="https://www.cas.org/solutions/cas-custom-services/knowledge-management/chemist-consultation">Nomenclature and Registration</a> service offer you several options for confirming and assigning CAS Registry Numbers and obtaining CA Index Names. Note that there is a fee associated with these services.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">Why is it important to come to CAS for Registry Numbers?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>While printed publications may contain outdated information, the CAS REGISTRY database is updated daily providing your best source for the latest CAS Registry Number information.</p><p>CAS is the source and final authority for CAS Registry Numbers. Other resources may have associated an incorrect CAS Registry Number with a compound, and use of that incorrect CAS Registry Number in searches could lead you to irrelevant or inappropriate information.</p></div></div></nav></div><div data-hover="false" data-delay="0" aria-labelledby="question1-heading" itemprop="mainEntity" itemscope="" itemtype="https://schema.org/Question" class="faq-item w-dropdown"><div class="faq-item__toggle w-dropdown-toggle"><div class="faq-item-title"><h3 itemprop="name" class="faq-title-content">What is the CAS RN Verified Partner Program?</h3><div class="faq-item__icon-wrap"><div class="faq-item__icon w-embed"><svg width="16" height="16" viewBox="0 0 16 16" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M8 10L5 7H11L8 10Z" fill="currentColor"/> </svg></div></div></div></div><nav class="faq-item__content w-dropdown-list"><div itemscope="https://schema.org/Answer" itemprop="acceptedAnswer" class="faq-tab"><div itemprop="text" class="w-richtext"><p>A CAS Registry Number license is required anytime an organization will “publish” CAS Registry Numbers to the public or use them to support features of a platform that is publicly or commercially available. See the <a href="https://www.cas.org/support/documentation/chemical-substances/cas-rn-verified-partner-program">CAS Registry Number Verified Partner Program</a> for more information.</p></div></div></nav></div></div></div></div></section><section class="section background_blue-grey"><div class="container"><div class="section__header"><h2>Latest from CAS Insights™</h2></div><div class="insights-cms-items_wrapper w-dyn-list"><div role="list" class="grid-column-3 w-dyn-items"><div role="listitem" class="insights-cms-items_list-item w-dyn-item"><div typeof="Article" vocab="" id="w-node-a20cb0dd-b9df-6a0b-dbc5-c6732757fde8-2757fde8" class="card"><img class="card__image" src="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/673fab2932993c772c187705_1920x1080-webinar-replay-revised.jpg" width="1024" height="576" alt="" sizes="(max-width: 1439px) 33vw, 480px" property="image" loading="lazy" srcset="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/673fab2932993c772c187705_1920x1080-webinar-replay-revised-p-500.jpg 500w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/673fab2932993c772c187705_1920x1080-webinar-replay-revised-p-800.jpg 800w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/673fab2932993c772c187705_1920x1080-webinar-replay-revised.jpg 1920w"/><div property="articleSection" fs-cmsfilter-field="resource" class="card__eyebrow">Emerging Science</div><div class="card__body"><div class="card__webinar-block"></div><a itemprop="url" href="/resources/cas-insights/aging-hallmarks-webinar" class="card__title-link w-inline-block"><h2 property="headline" class="card__title">Webinar: Healthy longevity, aging hallmarks, and innovative strategies </h2></a><div itemprop="description" class="card__summary-text-field">Experts from CAS, Harvard Medical School, Procter & Gamble, and Cedars-Sinai Medical Center discuss health aging research.</div><div class="card__date-meta-block"><time property=""datePublished"" datetime="">November 22, 2024</time><span>|</span><span>Article</span></div><div class="card__feature-solution--wrapper"></div></div><div class="button-wrapper button-wrapper-full-width"><a href="/resources/cas-insights/aging-hallmarks-webinar" class="button is-small w-button">Read article</a></div></div></div><div role="listitem" class="insights-cms-items_list-item w-dyn-item"><div typeof="Article" vocab="" id="w-node-a20cb0dd-b9df-6a0b-dbc5-c6732757fde8-2757fde8" class="card"><img class="card__image" src="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image.jpeg" width="1024" height="576" alt="" sizes="(max-width: 1439px) 33vw, 480px" property="image" loading="lazy" srcset="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image-p-500.jpeg 500w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image-p-800.jpeg 800w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image-p-1080.jpeg 1080w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image-p-1600.jpeg 1600w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67337bcf758d0232da7378dd_GettyImages-2147604586_CAS-Insights-Hero-Image.jpeg 1920w"/><div property="articleSection" fs-cmsfilter-field="resource" class="card__eyebrow">Drug Discovery</div><div class="card__body"><div class="card__webinar-block"></div><a itemprop="url" href="/resources/cas-insights/protac-drug-development" class="card__title-link w-inline-block"><h2 property="headline" class="card__title">PROTACs are revolutionizing small molecule drug development</h2></a><div itemprop="description" class="card__summary-text-field">PROTACs are driving small molecule drug development to treat cancer, neurodegenerative diseases and more</div><div class="card__date-meta-block"><time property=""datePublished"" datetime="">November 15, 2024</time><span>|</span><span>Article</span></div><div class="card__feature-solution--wrapper"></div></div><div class="button-wrapper button-wrapper-full-width"><a href="/resources/cas-insights/protac-drug-development" class="button is-small w-button">Read article</a></div></div></div><div role="listitem" class="insights-cms-items_list-item w-dyn-item"><div typeof="Article" vocab="" id="w-node-a20cb0dd-b9df-6a0b-dbc5-c6732757fde8-2757fde8" class="card"><img class="card__image" src="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67225783c5eef75a33a07197_SVCGENENGSOC102248-CS-AI-in-Pharma-Article-1920x1080-Hero-revised.jpg" width="1024" height="576" alt="" sizes="(max-width: 1439px) 33vw, 480px" property="image" loading="lazy" srcset="https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67225783c5eef75a33a07197_SVCGENENGSOC102248-CS-AI-in-Pharma-Article-1920x1080-Hero-revised-p-500.jpg 500w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67225783c5eef75a33a07197_SVCGENENGSOC102248-CS-AI-in-Pharma-Article-1920x1080-Hero-revised-p-800.jpg 800w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67225783c5eef75a33a07197_SVCGENENGSOC102248-CS-AI-in-Pharma-Article-1920x1080-Hero-revised-p-1080.jpg 1080w, https://cdn.prod.website-files.com/650867962272bf8f15c1034b/67225783c5eef75a33a07197_SVCGENENGSOC102248-CS-AI-in-Pharma-Article-1920x1080-Hero-revised.jpg 1920w"/><div property="articleSection" fs-cmsfilter-field="resource" class="card__eyebrow">Digital R&D</div><div class="card__body"><div class="card__webinar-block"></div><a itemprop="url" href="/resources/cas-insights/ai-in-pharma-data-strategies-fuel-successful-drug-repurposing" class="card__title-link w-inline-block"><h2 property="headline" class="card__title">AI in Pharma: Data strategies fuel successful drug repurposing</h2></a><div itemprop="description" class="card__summary-text-field">Discover how artificial intelligence in pharma can enhance drug repurposing by leveraging dark data, ensuring data diversity, and improving data quality. </div><div class="card__date-meta-block"><time property=""datePublished"" datetime="">November 7, 2024</time><span>|</span><span>Article</span></div><div class="card__feature-solution--wrapper"></div></div><div class="button-wrapper button-wrapper-full-width"><a href="/resources/cas-insights/ai-in-pharma-data-strategies-fuel-successful-drug-repurposing" class="button is-small w-button">Read article</a></div></div></div></div></div><div class="button-wrapper cas-insights-button-wrapper"><a href="/resources/cas-insights" class="button is-small w-button">View all CAS Insights</a></div></div></section></main><footer class="site-footer_component"><section class="section"><div class="container"><div class="grid-column-5"><div class="site-footer_link-list"><div class="margin-bottom margin-xsmall"><div class="site-footer_heading">Solutions</div></div><a href="/solutions/biofinder-discovery-platform" class="site-footer_link">CAS BioFinder Discovery Platform™</a><a href="/solutions/cas-scifinder-discovery-platform" class="site-footer_link">CAS SciFinder Discovery Platform™</a><a href="/solutions/stn-ip-protection-suite" class="site-footer_link">STN IP Protection Suite™</a><a href="/solutions/cas-custom-services" class="site-footer_link">CAS Custom Services</a><a href="/solutions/other-solutions" class="site-footer_link">Other Solutions</a></div><div class="site-footer_link-list"><div class="margin-bottom margin-xsmall"><div class="site-footer_heading">Resources</div></div><a href="/resources/cas-insights" class="site-footer_link">CAS Insights</a><a href="/cas-events" class="site-footer_link">Events</a><a href="/cas-webinars" class="site-footer_link">Webinars</a><a href="/resources/white-papers" class="site-footer_link">White papers</a><a href="/resources/case-studies" class="site-footer_link">Case studies</a><a href="https://commonchemistry.cas.org/" class="site-footer_link">CAS Common Chemistry</a><a href="https://cassi.cas.org/" class="site-footer_link">CAS Source Index (CASSI)</a></div><div class="site-footer_link-list"><div class="margin-bottom margin-xsmall"><div class="site-footer_heading">CAS Data</div></div><a href="/cas-data/cas-registry" aria-current="page" class="site-footer_link w--current">CAS REGISTRY®</a><a href="/cas-data/cas-reactions" class="site-footer_link">CAS Reactions</a><a href="/cas-data/cas-references" class="site-footer_link">CAS References</a><a href="/cas-data/cas-patents" class="site-footer_link">CAS Patents</a><a href="/cas-data/cas-commercial-sources" class="site-footer_link">CAS Commercial Sources</a><a href="/cas-data/cas-formulations" class="site-footer_link">CAS Formulations</a></div><div class="site-footer_link-list"><div class="margin-bottom margin-xsmall"><div class="site-footer_heading">About CAS</div></div><a href="/about-us" class="site-footer_link">Our story</a><a href="/careers" class="site-footer_link">Careers</a><a href="/about/futureleaders" class="site-footer_link">CAS Future Leaders</a><a href="/cas-innovation-incubator" class="site-footer_link">CAS Innovation Incubator</a><a href="/press-releases" class="site-footer_link">Press Releases</a></div><div class="site-footer_right-wrapper"><div class="margin-bottom margin-xsmall"><div class="site-footer_heading">CAS Customer Center</div></div><div class="margin-bottom margin-xsmall is-small-mobile"><div class="text-size-small"><a href="mailto:help@cas.org" class="site-footer_link">help@cas.org</a></div><div class="text-size-small"><a href="tel:+1-800-753-4227" class="site-footer_link">800.753.4227 (North America)</a></div><div class="text-size-small"><a href="tel:+1-614-447-3731" class="site-footer_link">614.447.3731 (Worldwide)</a></div><div class="text-size-small"><a href="https://goo.gl/maps/y7K2gChT9TDv61SQ6" class="site-footer_link">2540 Olentangy River Road<br/>Columbus, Ohio 43202 U.S.A</a></div></div><a href="/contact" class="button is-small w-button">Contact us</a></div></div><div class="site-footer_divider"></div><div class="footer_bottom-wrapper"><div class="w-layout-grid footer_legal-list"><div id="w-node-_9015492a-b7f3-be43-cf28-dfe12f081ccc-2f081c75" class="footer10_credit-text">Copyright © 2024 American Chemical Society</div><a href="/legal" class="site-footer_legal-link">Legal</a><a href="/legal/privacy" class="site-footer_legal-link">Privacy</a><a href="https://solutions.cas.org/Manage-Preferences" class="site-footer_legal-link">Email preferences</a><a href="https://www.acs.org/accessibility-statement.html" class="site-footer_legal-link">Accessibility</a><a id="w-node-a2b696ea-1601-ffae-3b03-3766d928fd0d-2f081c75" class="site-footer_legal-link" href="#">Cookie preferences</a></div><div class="w-layout-grid footer_social-list"><a href="https://www.facebook.com/CAS" target="_blank" class="site-footer_social-link w-inline-block"><div class="icon-embed-xsmall w-embed"><svg width="100%" height="100%" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M22 12.0611C22 6.50451 17.5229 2 12 2C6.47715 2 2 6.50451 2 12.0611C2 17.0828 5.65684 21.2452 10.4375 22V14.9694H7.89844V12.0611H10.4375V9.84452C10.4375 7.32296 11.9305 5.93012 14.2146 5.93012C15.3088 5.93012 16.4531 6.12663 16.4531 6.12663V8.60261H15.1922C13.95 8.60261 13.5625 9.37822 13.5625 10.1739V12.0611H16.3359L15.8926 14.9694H13.5625V22C18.3432 21.2452 22 17.083 22 12.0611Z" fill="CurrentColor"/> </svg></div></a><a href="https://www.twitter.com/CASChemistry" target="_blank" class="site-footer_social-link w-inline-block"><div class="icon-embed-xsmall w-embed"><svg width="100%" height="100%" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"> <path d="M17.1761 4H19.9362L13.9061 10.7774L21 20H15.4456L11.0951 14.4066L6.11723 20H3.35544L9.80517 12.7508L3 4H8.69545L12.6279 9.11262L17.1761 4ZM16.2073 18.3754H17.7368L7.86441 5.53928H6.2232L16.2073 18.3754Z" fill="CurrentColor"/> </svg></div></a><a href="https://www.linkedin.com/company/cas" target="_blank" class="site-footer_social-link w-inline-block"><div class="icon-embed-xsmall w-embed"><svg width="100%" height="100%" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M4.5 3C3.67157 3 3 3.67157 3 4.5V19.5C3 20.3284 3.67157 21 4.5 21H19.5C20.3284 21 21 20.3284 21 19.5V4.5C21 3.67157 20.3284 3 19.5 3H4.5ZM8.52076 7.00272C8.52639 7.95897 7.81061 8.54819 6.96123 8.54397C6.16107 8.53975 5.46357 7.90272 5.46779 7.00413C5.47201 6.15897 6.13998 5.47975 7.00764 5.49944C7.88795 5.51913 8.52639 6.1646 8.52076 7.00272ZM12.2797 9.76176H9.75971H9.7583V18.3216H12.4217V18.1219C12.4217 17.742 12.4214 17.362 12.4211 16.9819V16.9818V16.9816V16.9815V16.9812C12.4203 15.9674 12.4194 14.9532 12.4246 13.9397C12.426 13.6936 12.4372 13.4377 12.5005 13.2028C12.7381 12.3253 13.5271 11.7586 14.4074 11.8979C14.9727 11.9864 15.3467 12.3141 15.5042 12.8471C15.6013 13.1803 15.6449 13.5389 15.6491 13.8863C15.6605 14.9339 15.6589 15.9815 15.6573 17.0292V17.0294C15.6567 17.3992 15.6561 17.769 15.6561 18.1388V18.3202H18.328V18.1149C18.328 17.6629 18.3278 17.211 18.3275 16.7591V16.759V16.7588C18.327 15.6293 18.3264 14.5001 18.3294 13.3702C18.3308 12.8597 18.276 12.3563 18.1508 11.8627C17.9638 11.1286 17.5771 10.5211 16.9485 10.0824C16.5027 9.77019 16.0133 9.5691 15.4663 9.5466C15.404 9.54401 15.3412 9.54062 15.2781 9.53721L15.2781 9.53721L15.2781 9.53721C14.9984 9.52209 14.7141 9.50673 14.4467 9.56066C13.6817 9.71394 13.0096 10.0641 12.5019 10.6814C12.4429 10.7522 12.3852 10.8241 12.2991 10.9314L12.2991 10.9315L12.2797 10.9557V9.76176ZM5.68164 18.3244H8.33242V9.76733H5.68164V18.3244Z" fill="CurrentColor"/> </svg></div></a><a href="https://www.youtube.com/user/ChemAbstractsService/featured" target="_blank" class="site-footer_social-link w-inline-block"><div class="icon-embed-xsmall w-embed"><svg width="100%" height="100%" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg"> <path fill-rule="evenodd" clip-rule="evenodd" d="M20.5686 4.77345C21.5163 5.02692 22.2555 5.76903 22.5118 6.71673C23.1821 9.42042 23.1385 14.5321 22.5259 17.278C22.2724 18.2257 21.5303 18.965 20.5826 19.2213C17.9071 19.8831 5.92356 19.8015 3.40294 19.2213C2.45524 18.9678 1.71595 18.2257 1.45966 17.278C0.827391 14.7011 0.871044 9.25144 1.44558 6.73081C1.69905 5.78311 2.44116 5.04382 3.38886 4.78753C6.96561 4.0412 19.2956 4.282 20.5686 4.77345ZM9.86682 8.70227L15.6122 11.9974L9.86682 15.2925V8.70227Z" fill="CurrentColor"/> </svg></div></a></div></div></div></section></footer></div><script src="https://d3e54v103j8qbb.cloudfront.net/js/jquery-3.5.1.min.dc5e7f18c8.js?site=650861f00f97fe8153979335" type="text/javascript" integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0=" crossorigin="anonymous"></script><script src="https://cdn.prod.website-files.com/650861f00f97fe8153979335/js/cas-org.53dc1f8b9.js" type="text/javascript"></script><script type="text/javascript" src="/_Incapsula_Resource?SWJIYLWA=719d34d31c8e3a6e6fffd425f7e032f3&ns=1&cb=609613790" async></script></body></html>