Data methodology
Expanded A–Z directory · 11 October 2026
The A–Z index covers 201,301 distinct non-obsolete ChEBI 2-star and 3-star records from release 256, retrieved on 11 October 2026. Entries require a formula, structure or checksum-valid CAS cross-reference. It matches preferred names and EXACT or RELATED source synonyms, retaining alphabetic prefixes and ignoring leading punctuation and numbers. Alternative source names may include abbreviations, trade names and non-English names. One row represents one ChEBI ID; letter totals overlap. Missing CAS numbers and property values are shown explicitly. The detailed CAS profiles below retain their earlier release data and editorial corrections.
PubCAS connects chemical identity records with source material and useful calculations. Every published substance has a source CAS cross-reference, a passed CAS checksum, a formula and a reported mass.
Identity and selection
The initial 1,000 records are selected from ChEBI release 255, prioritising common laboratory chemicals, elements, inorganic materials and source-rich entries. Only ChEBI three-star entries are used. ChEBI cross-references are evidence from that source, not independent verification by CAS.
Cross-source matching
PubChem molecular data are attached only when the returned InChIKey matches the ChEBI InChIKey exactly. When several PubChem records share that key, the lowest matching CID is used as the navigation reference. Source differences are retained. An InChIKey match cannot establish product grade, particle size, formulation or supplier equivalence.
Properties and conditions
ChEBI-reported mass and formula are shown separately from PubChem computed descriptors. No melting point, density, toxicity threshold, UN number or customs code is inferred from a CAS number. Missing data do not establish absence of a hazard.
Calculations and structure drawings
Mass-to-moles tools use n = m/M. Theoretical element mass fractions use a parseable source formula and atomic masses from the PubChem periodic table. Isotopically modified records are excluded from standard-weight mass fractions. Structure depictions are produced from source SMILES using RDKit; they are connectivity representations, not crystal structures or product images.
Safety information
NITE classification excerpts retain the jurisdiction, source ID and classification year. The selected year is the latest available year in the retrieved source compilation for that CAS. Classification details may depend on form or concentration. NIOSH references are occupational safety guides. Neither replaces the SDS issued for a specific commercial product.
Official links and web searches
Links labelled as records use retrieved record identifiers or source index mappings. Lookups and searches are labelled separately. Country-specific web searches use an exact CAS query restricted to the stated official domain. Search results are not treated as verified records.
Updates and corrections
This is the first release, checked 27 September 2026. Source publication dates and classification years are retained rather than replaced with the site’s publication date. Corrections can be submitted from each record; unresolved questions should be checked at the primary source.
Export and attribution
Record JSON, comparison CSV and search exports include source information. ChEBI-derived content is reused under CC BY 4.0. Retain source-specific terms when reusing exports.
Reviewed presentation corrections · 2 October 2026
Raw source snapshots are preserved. Explicit corrections retain the original values in record exports and explain the evidence on the record page. Graphite uses a carbon-atom molar mass from CIAAW rather than the incompatible imported mass. Isotope labels omitted by generalized formulas are restored from the source identity and structure. Source retrieval dates remain 27 September 2026; an editorial revision is not a new source retrieval.