Merck Index Online


Encyclopedia of chemicals, drugs, and biologicals.


The Merck Index Online is the internationally recognized encyclopedia of chemical substances, including human and veterinary drugs, biologicals and natural products. It contains more than 10,000 monographs. Compounds are selected on the basis of present or historic importance and interest.

The information provided includes chemical, common and generic names, trademarks and their associated companies, CAS Registry Numbers, molecular formulas and weights, physical and toxicity data, therapeutic and commercial uses, chemical structures and selected literature references for each substance.

The Merck Index Online consists of several databases:

  • The Compound Search database allows searching for compounds by physical properties, compound attributes, and structure. The Compound Search database can be searched with or without the ChemDraw Plug-in.
  • The Organic Name Reactions database contains a list of reactions which have come to be recognized and referred to by name within the chemistry community. The descriptions are composed of name(s) associated with the reaction, the original and/or primary contributor(s), a concise description of the transformation, a reaction scheme, key references, and cross references to other organic named reactions. 
  • The Additional Tables section lists multiple tables, including abbreviations, glossary, and a chemical terms translator in PDF format.

To use the structure editor, you will need the ChemDraw Plugin, which is available for download on the Merck site. For now, users will need to register to get the download.

Please allow other UC researchers to use this resource by logging out as soon as searches are completed.