A hydrogen that will not sit stillAcetic acid’s acidic hydrogen is mobile: it belongs to both carboxyl oxygens rather than to either. Write the whole /h layer, immobile run first.A variable exercise. What you write is compared with what the InChI engine generates for the same structure, with 3 hints if you want them.Convert a structure to its InChI and InChIKey and back, convert a whole CSV, XLSX or SDF file, learn how the identifier is derived, and practise writing its layers. The InChI engine is WebAssembly running in your browser, so the tool needs JavaScript — and nothing you open ever leaves your machine.

Convert — a structure in, an InChI out

Batch — a whole CSV, XLSX or SDF file

Tutorial — how an InChI is derived

Exercises — write the layers yourself

Cheatsheet — every layer in a table

Tests — the IUPAC regression corpora

Download — take the engine away

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