Factual Databases

  • Bordwell pKa Table

    An overview of PKa values (acidity in DMSO) of functional groups.

  • ChEBI

    Chemical Entities of Biological Interest (ChEBI) is a freely available dictionary of ‘small molecular entities’. It includes compounds that are either products of nature or synthetic products used to intervene in the processes of living organisms (either on purpose, as for drugs, or by accident, as for chemicals in the environment) but not molecular entities directly encoded by the genome such as nucleic acids, proteins and peptides derived from proteins by cleavage.

  • ChemBank

    ChemBank is a freely available collection of data about small molecules and resources for studying their properties, especially their effects on biology. A structure database of over 900,000 reference structures with full search capabilities is recently added.

  • Chemfinder

    Search engine especially designed for chemists. Entering either name (full, contains, starts with, ends with), molecular formula, molecular weight, CA registry number or (sub)structure, all available information is presented including physical property data and 2D chemical structures.

  • ChemIDplus

    Database containing over 380,000 chemical records, of which over 263,000 include chemical structures, searchable by name, synonym, CAS registry number, molecular formula, classification code, locator code, and structure. Locator links allow immediate searching of other databases for information about a given chemical.

  • Heterocycles Database

    This database lists the natural products with heterocyclic ring system whose structure has been determined since 1975. It contains over 31,000 compounds and can be searched by name, MW, MF, natural source, author and journal.

  • Integrated Spectral Data Base System for Organic Compounds

    Includes 6 different types of spectra: EI mass, 1H decoupled 13C NMR, 1H NMR pattern (90 and/or 400 MHz), 1H NMR parameter (300 MHz pattern generated), FT-IR, laser-Raman, and ESR.

  • Chemexper Chemical Directory

    Database containing chemical products (>200,000) with their physical characteristics. Searchable by substructure, registry number, molecular formula, chemical name as well as by physical and chemical characteristics and combinations of those data.

  • Molbank

    Stores experimental records for individual molecules. Searchable by 2D structure, substructure, author , compound name, etc.

  • NIST Webbook

    Searchable database (formula, name, CAS registry number, molecular weight, ionization energy or proton affinity) of a full array of data compiled and distributed by NIST. Of particular interest for organic chemists are the IR spectra (> 16,000 compounds) and mass spectra (> 15,000 compounds). [Guide] [FAQ]

  • PubChem

    PubChem provides information on the biological activities of small molecules. PubChem includes substance information, compound structures, and bioactivity data in three primary databases, PCSubstance, PCCompound, and PCBioAssay, respectively. Searchable by structure, chemical name or keywords as well as by bioassay description. [Help] [FAQ]

  • General

  • Data and Property Calculation Sites on the Web
  • Chemical & Physical Property Information Resources


    • Focus: online acces to chemical reference works from Chapman & Hall/CRC.
    • Source: Chapman & Hall/CRC chemical reference works
  • Reaxis (former Crossfire Beilstein)
    • Focus: chemical structures and their associated chemical and physical properties (>350), preparative methods, and literature references.
    • Coverage: > 8 million compounds, > 10 million chemical reactions and > 35 million associated chemical property and bioactivity records, (1771 - )
    • Source: about 180 organic chemistry journals
    • Guides: Fact Searching, Structure Searching, Compound Preparation.
  • The Combined Chemical Dictionary
    • Focus: diverse range of compounds (natural products, organic compounds, inorganic and organometallic compounds, pharmacological agents and analytical reagents) and their associated data
    • Coverage: about 600,000 compounds
    • Source: Dictionary of Organic Compounds (269,000 compounds), Dictionary of Natural Products (178,000 compounds), Dictionary of Inorganic and Organometallic Compounds (103,000 compounds), Dictionary of Drugs (44,000 compounds) and Dictionary of Analytical Reagents (14,000 compounds)
  • CRC Handbook of Data on Organic Compounds (HODOC II)
    • Focus: the most frequently used physical and chemical data of organic compounds
    • Coverage: about 25,000 compounds
    • Source: CRC Handbook of Data on Organic Compounds
  • Properties of Organic Compounds 6.0
    • Focus: physical property and spectral data of commonly sought organic compounds
    • Coverage: over 29,000 compounds
    • Access: CRC Chemistry Portal
  • Specinfo
    • Focus: chemical structures together with NMR, IR and/or mass spectral information
    • Coverage: more than 660,000 spectra: 152,500 compounds, > 80,000 13C-NMR spectra, > 1745 19F-NMR, > 853 15N-NMR, > 675 17O-NMR, > 1930 31P-NMR spectra, > 17,070 IR spectra > 65,900 mass spectra (1980 - )
    • Guide: STN Database summary sheet
  • SPRESIweb
    • Focus: properties of chemical structures
    • Coverage: 5,0 million structures
    • Access: Internet (intranet) or SD file