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rom structure to number: How does the magic behind CAS registry numbers work
The identification of chemicals plays a vital role in the scientific community, and the CAS Registry Number (CAS RN) is one of the core elements. These unique identification numbers identify all chemical substances in the chemical literature. Since 1957, the Chemical Abstracts Service (CAS) has assigned a unique number to each chemical substance described, allowing the scientific community to easily find and use these chemicals in a huge database. .
"The CAS Registry Number is a reliable, common international link that facilitates the use of a specific substance in all branches of science, industry and regulatory agencies."
The format of the CAS registry number consists of three parts, separated by hyphens. The first part consists of two to seven digits, the second part consists of two digits, and the third part is a check digit. This structure enables CAS to generate up to 1 billion unique numbers. However, these numbers themselves do not contain any information about the molecular structure; unlike SMILES or InChI strings, CAS registry numbers are more like index identifiers.
History and Use of CAS Registry Numbers
During the early stages of index development for chemicals, identifying whether a substance was newly discovered was a challenge because of the various synonyms that existed. Common chemical substances often have multiple commercial names or historical names, which makes information retrieval difficult. For this reason, CAS developed an algorithm that can convert chemical structures into a table that is easy for computers to search, which laid the foundation for CAS's registration system. In 1965, the CAS chemical registration system was officially launched and has become an important tool in scientific literature.
"Historically, chemicals have had a variety of synonyms, and the CAS registry number solves this problem and provides a standardized solution."
Different numbering methods
CAS personally assigns registration numbers by making careful distinctions between different categories of substances. For example, stereoisomers and racemic mixtures are each assigned separate CAS registry numbers. Specifically, L-epinephrine has a registration number of 51-43-4, while D-epinephrine has a registration number of 150-05-0, and specifically DL-epinephrine has a registration number of 329-65-7. In addition, substances in the same phase, such as liquid water and ice, share the same registration number 7732-18-5, while different crystal structures can have different numbers.
"This sophisticated numbering system allows the scientific community to accurately identify and reference various chemicals."
Search Engines and Resources
As technology advances, many resources are available to help scientists and researchers find the appropriate CAS registry number. For example, CHEMINDEX of the Canadian Centre for Occupational Health and Safety, ChemIDplus of NLM and Common Chemistry in the Australian Chemical Substances List, etc., these resources provide a convenient way to query chemical information.
Challenges Ahead
In the context of globalization and networking, the CAS registration number is becoming increasingly indispensable as an international standard. However, as new chemicals continue to be discovered and described, how to effectively manage and index these substances remains a major challenge for CAS. The additional updates of approximately 15,000 new substances every day undoubtedly significantly increase this workload.
"In the future, with the advancement of technology, the use of CAS registration numbers will become more widespread and continue to lead changes in the field of chemistry."
In short, CAS registry number is not only a tool for identifying chemical substances, but also an important bridge for communication and management in the chemical community. However, as chemical research continues to develop and change, can we find more effective ways to manage and communicate information?
