Identifiers
The numbers that tie a material to its records.
Chemical identifiers let a material be matched unambiguously to its records. This page explains the identifiers used for Phenibut.
The identifiers
- CAS (free base)1078-21-3
- CAS (hydrochloride)3060-41-1
- PubChem CID14113 (Phenibut)
- Molecular formula (base)C10H13NO2
- Molecular formula (HCl)C10H14ClNO2
What each identifier is
CAS Registry Number — a unique numeric identifier assigned by the Chemical Abstracts Service; the free base and the hydrochloride salt carry different CAS numbers because they are distinct substances. PubChem CID — the compound identifier in the NIH PubChem database. InChI / InChIKey — structure-derived identifiers; for the canonical strings consult the PubChem record directly rather than relying on a transcription.
Using identifiers in documentation
Record the correct CAS for the exact form (base vs salt) you are documenting. See the complete chemical reference and free base vs hydrochloride.
Assigned identifiers and derived identifiers
The identifiers above fall into two groups that behave quite differently, and knowing which is which tells you what each one can be trusted to do. A CAS Registry Number and a PubChem CID are assigned: a register chose the value, it encodes nothing about the structure, and the only way to learn what it refers to is to look it up in the register that issued it. Its authority is the register’s. An InChI or InChIKey is derived: it is computed from the structure itself by a published algorithm, so the same structure produces the same string wherever it is generated, and anyone holding the structure can regenerate it and compare. Its authority is the algorithm’s.
The practical consequence is about verification. A derived identifier can be checked against a structure you already hold, with no database access at all, which is why it travels well between systems that share nothing else. An assigned identifier cannot be checked in that sense; it can only be resolved. A record that carries both is therefore checkable in two independent ways, and that redundancy is the reason to record both rather than choosing between them. How each is built is covered separately, for CAS registry numbers and for InChI and InChIKey.
Record the namespace along with the number
A bare number is not an identifier. On its own, a string of digits does not say which register issued it, and the register is part of the value rather than context that can be reconstructed later. A field holding only the digits is a field whose meaning depends on someone remembering what was intended, which is exactly the kind of assumption that does not survive a change of personnel or a migration between systems.
The fix costs nothing at the time and is unrecoverable afterwards: write the register name next to the value, so that a record says which register a number belongs to rather than leaving a reader to guess between a registry number, a database identifier and a supplier reference. The same discipline applies to lot and batch codes, where the identical failure mode is described under lot traceability.
Cross-checking a record against itself
Because these identifiers describe the same material from different directions, a self-consistent record can be checked without leaving the page. The molecular formula recorded should agree with the form that the registry number designates, and the free base and the hydrochloride do not share a formula: they differ by the elements of hydrogen chloride, which is also why they hold separate registry entries. A name should resolve in the register to the entry the number points at, and where a compound carries many names, our nomenclature page covers which refer to the same substance. The structure the formula implies should be the structure the record intends, which is the subject of the molecular structure page.
Where two sources disagree, the disagreement is itself the finding and should be recorded as one. The resolution is to go to the authoritative register rather than to adopt whichever value is more convenient or appears more often, and a documented note that two sources conflicted is far more useful to a later reader than a silently chosen winner.
Where identifier values should come from
Identifiers belong in a record as they appear in the authoritative database entry, retrieved directly. Transcription is where digits are dropped and transposed, and a value copied from a secondary page has passed through at least one opportunity for that to happen without leaving a trace. The values listed on this page are given for orientation; where an identifier is going into a record that has to hold up, take it from the issuing register itself. That is also why no canonical structure-derived string is reproduced here at all.
It is worth noting when a value was retrieved, because register content is maintained rather than fixed: entries are corrected, names are added, and cross-references change. A record that says where an identifier came from and when it was taken can be re-checked later; one that carries only the digits cannot be audited at all, only trusted.
For Research Use Only. Not for human or animal consumption. Nothing here is medical advice, a health claim, or usage guidance. No statement has been evaluated by the U.S. FDA. See our Disclaimer.