Open data for chemical substances, structures and products?

Question

I'm looking for large open data which provides chemical compounds, substances, structures and products. Database of chemical reactions, formulas and similar would be beneficial as well.

Some academia and industrial databases (not open data):

• The CambridgeSoft Available Chemicals Exchange (ChemACX) (6.8 million substances, 6.7 million structures and 10.4 million products)
• Instant JChem (millions of structures)
• CAS REGISTRY by CAS (89 million unique organic and inorganic chemical substances, very costly)
• Reaxys and Reaxys Medicinal Chemistry (a fully indexed and organized database of around 16,000 periodicals containing 500 million published experimental facts - very costly)

Links:

• New Chemical Compound Database Knows All the Reactions
• A database of drugs and their targets on SE
• Software for predicting chemical reactions on SE
• Open data for chemical substances, structures and products? on SE

Answer 1

You may try to download Structures, Sequences and Ligand free of charge from:

• Protein Data Bank (RCSB) by specifying PDB IDs which you looking for (e.g. 2bg9),
• PubChem by NCBI (BioAssays, Compounds and Substances),
• ChemSpider (free chemical structure database providing fast access to over 28 million structures, properties and associated information),
• Wikipedia (Chemical_substances) by downloading the whole database or specific category (e.g. Chemical substances, Chemical compounds, etc.) by using Special:Export into XML format.

Also check out few free chemistry softwares which could potentially contain some databases:

• Yenka Chemistry (before Crocodile Chemistry) - complete virtual laboratory which offer free home licenses for personal, non-commercial, non-academic use only.
• Gamess and Quantum ESPRESSO - Open-Source computer codes for electronic-structure calculations and materials modeling at the nanoscale

See also:

• Which Chemical Database Software Are Available?
• Program that simulates basic reactions in organic chemistry