SciFinder is a product that contains multiple databases. Each of the search types below (which can be seen in the structure editor) represents a different database:
See below the different databases that coincide with Substances, Reactions, References, and Suppliers and the information contained within.
Last updated 9/5/2025
CAS Registry is the database for substance records. It currently includes:
Each substance is identified with a unique CAS Registry Number, commonly referred to as an RN or CAS RN. Each Registry Number follows a standard format that includes up to 10 digits separated into three groups by hyphens. The first part of the number, starting from the left, has 2 to 7 digits, the second part has 2 digits, and the final part consists of a single check digits. Examples are 58-08-2, 112514-54-2, or 2252485-99-5.
CAS is the sole authority for CAS Registry Numbers and cannot control their use by third parties. You should always use SciFinder (or another CAS product) to verify the accuracy of an RN mentioned elsewhere.
Last updated on 6/5/2025 with information from https://www.cas.org/cas-data/cas-registry and https://www.cas.org/training/documentation/chemical-substances/checkdig
At the bottom of a substance record, you can open the Additional Detail accordion to see both the Source of Registration and Substance Class(es):
The Source of Registration details how the substance was registered by CAS:
CA: Substance was registered because of appearance in literature that was indexed by CAS
CAS Client Services: The CAS Registry Services team created the RN based on client request. Essentially, some entity requested and paid for the substance to be registered. This information is strictly confidential, CAS will not share who requested a Client Services registration.
Chemical Catalog/Chemical Library: Substance was registered based on its appearance in a chemical catalog or library. The particular supplier will be listed if this is the source.
Other Sources: If a substance was registered from a data collection that CAS ingested, the source will be the name of the data collection. Examples include GVK Bio, Molecular Modeling Database (National Center for Biotechnology Information), and more.
The Substance Class characterizes what kind of substance the registration is. A detailed list of substance classes is found in the SciFinder Help pages. Examples include coordination compound, polymer, nucleic acid sequence, and more.
Last updated 6/25/2025
CAS MARPAT is the Markush database curated by CAS. It contains Markush structure records for patent documents covered in CAplus from 1988- present, including Russian patents published after 01/10/2000 and Korean patents from 2008-present.
In addition, MARPAT includes:
MARPAT covers only claimed Markush. The exceptions to claimed Markush are the following substance classes: alloys, metal oxides, inorganic salts, intermetallics, and polymers.
Last updated 6/5/205 with information from HELP CONTENT message from MARPAT in CAS STNext provided by CAS Customer Center.
In SciFinder, regulatory information is included in the Registry record of a substance if data exists for the substance in the CAS regulatory database, CHEMLIST.
CHEMLIST identifies chemical substances from more than 100 inventories and regulatory lists from around the world. The database began with national chemical inventories such as TSCA, EINECS, and ENCS. Today, it includes international lists such as HPVs, pollutant release inventories, priority chemicals, and dangerous chemicals with transportation restrictions.
You cannot search by regulatory information in SciFinder, though it is included in the Registry record display in SciFinder. If your institution/company has access to the SciFinder Discovery Platform that includes Chemical Compliance Index, this product is used to search regulatory information.
Last updated 6/5/205 with information from HELP CONTENT message from CHEMLIST in CAS STNext provided by CAS Customer Center.
When reference searching in SciFinder, you are searching two databases; CAplus and MEDLINE. See MEDLINE tab for more details about this database.
CAS covers patents from 109 patent authorities around the world. You can view the authorities and their years of coverage, as well the kind codes for the countries covered by CAS.
CAS journal indexing policy is to register chemical substances when they are related to the important aspects of the article and when there is sufficient information in the document to determine the full structure of the substance. Information from figures, text, and tables is utilized to determine suitability for indexing.
CAS patent indexing policy is to register chemical substances related to the embodiment of the patent from the claims and the examples, which comprise the essential legal content. Chemical substances are registered from other areas of the patent when there is evidence for their use or preparation.
Last updated 6/5/2025 with information from CAS Customer Center
The ONLY guaranteed indexing timeline for references in CAplus is for patents from the nine major patent offices:
Bibliographic information is available in CAplus within 2 days of patent issuance, with full indexing (substances) available within 27 days of patent issuance. This information is found on the CAS website.
**Please note that the timeframe above may be different in SciFinder. In CAS' other product, STNext, daily updates occur. SciFinder updates a few times a week so there may be prolonged wait for content to appear.**
Last updated 5/14/2025
MEDLINE is produced by the National Library of Medicine and covers worldwide literature on biomedicals topics from 1946-present. There are over 5,300 journals indexed in MEDLINE, along with records for citations covered in Index Medicus (TM), Index to Dental Literature, International Nursing Index, the HealthSTAR database, and more.
Like CAplus uses the CAS Lexicon to index its literature (see the Using the CAS Lexicon tab under Reference Searching), the equivalent to this system in MEDLINE is the Medical Subject Headings, also known as the MeSH thesaurus. Find out more about MeSH here: https://www.nlm.nih.gov/mesh/meshhome.html
MEDLINE contains some document types that do not exist in CAplus, including Clinical Trials, Commentaries, Biographies, Letters, and more. You will see these listed under the Document Type filter when looking at a Reference Results page.
Last updated 7/9/2025
CASREACT is the reaction database that currently contains more than 150 million single and multi-step reactions. SciFinder also includes product only reactions.
CASREACT covers synthetic organic research, including organometallics, total syntheses of natural products, and biotransformation reactions. Reactions are indexed from both patent and journal references.
Last updated 6/5/2025
CHEMCATS is the supplier database, a catalog file containing information about commercially available chemicals and their worldwide suppliers. Millions of chemical product listings are included in this database.
The information in CHEMCATS is supplier provided on an as-is basis. Suppliers pay to participate in CAS Chemical Supplier Insights, which allows them to list their materials in SciFinder. CAS does not sell chemical themselves, they simply list information of those who do. CAS/ACS is not liable for any materials that are bought through these suppliers.
Last updated 6/5/2025
Under the Additional Details section of a substance record, you can see if a Registry Number has any deleted RNs associated with it. A Deleted RN results when an RN is originally assigned to a substance but is later changed to another RN.
For example, a Registry Number (the Deleted Registry Number) is assigned to a trade-named substance or a natural product for which no structural information is available at the time of registration. Later it is discovered to be the same substance as that associated with another Registry Number (the Replacing Registry Number). The structure of a natural product may be elucidated and found to correspond to a structure already in the file or two trade names may be found to be equivalent designations for the same material. Because each unique substance only has one Registry Number, all the substance information for the original registration is transferred to the record for the replacing number.
It is not completely deleted in the sense that it will still be associated with the Replacing Registry Number. If you search for a Deleted RN, the replacing one will be returned. Take for example RN 71701-02-5. This Registry Number was deleted and replaced with 58-08-2. If you search for 71701-02-5 in SciFinder, 58-08-2 will be returned:
Last updated 6/25/2025 with information from the CAS Customer Center
CAS ingests data from a variety of sources including patent and non-patent literature, chemical catalogs, databases, client registrations, and more. For this reason, you are likely to encounter registered substances that have no literature associated with them.
This can be confusing if you see that the source of registration is CA. How can something be registered from CA and yet not have any references in CA? This is usually due to indexing policy, where the RN is a component of a multicomponent registration. The multicomponent registration will have the references linked, while the components will not have the reference linked.
Examples with no references:
CA: 3085296-19-8 and 3085296-21-2
Chemical library: 2871505-21-2
Chemical catalog: 2983315-58-6
Other Sources: 1223097-77-5
Last updated 6/25/2025 with information from this webpage
