Where do I find compound properties on the Web?

As you're probably already discovered, simply typing the name of your compound into a public search engine isn't very productive. Most chemical data is stored in databases that the public engines don't index. You have to go directly to the database service to perform your search. A few of the best database sites are listed below.

Start with ChemFinder if you're looking for the basics (structures, melting points and boiling points, molecular weights, and specific gravities). The ChemFinder compound database contains over 75,000 unique substances collected from 350 sites.

Start with the NIST Chemistry Webbook for thermodynamic and spectroscopic data. (Beware: the nomenclature used isn't always what a general chemistry student might expect, e. g. the gas phase species like AlOH are indexed as "aluminum hydroxide").

Searching chemical handbooks, commercial databases, and multivolume data compilations in the library is still the most efficient way to find authoritative data. See Gary Wiggins' guide to searching for chemical and physical properties of substances for an overview of literature sources. Links to pages for the leading chemical handbooks are included in the list below.

For more esoteric data, try a search of the Journal of Chemical and Engineering Data and other ACS journals by typing your compound name or property into the box below.

Selected compound property resources

Antoine Equation (nextstep@athena.compulink.gr)

A JavaScript calculator that estimates vapor pressure for a few common materials using the Antoine equation.
http://www.compulink.gr/users/nextstep/antoine.html (4/11/99)

CRC Handbook of Chemistry and Physics (CRC Press)
This quintessential handbook contains data for about 2500 inorganic compounds and 12000 organic compounds. Relevant physical properties listed include crystal structure, color, solubility, melting points, boiling points, heats of formation, heats of vaporization, heats of fusion, entropies, heat capacities, critical pressure and temperature, vapor pressure, and optical properties. (Book/CDROM; no Web access).
http://www.crcpress.com/catalog/9720.htm (12/12/98)

CS Chemfinder (Cambridge Software)
Chemfinder is the most comprehensive resource for chemical compound data on the Web at this time. Enter the formula, name, molecular weight, or even a drawn structure fragment of a compound and this database fills in the blanks and returns structural formulas and a few other properties, along with compound-specific MSDS links. The database presently contains over 75000 compounds, although detailed data is available only for a few thousand of the most common compounds. Cambridge provides a free browser plugin that allows you to draw the molecular structure you're searching for in the browser window. If you find yourself using the database regularly, the site will require you to register (registration is free). Searches are (quite reasonably) restricted for bandwidth considerations. A commercial version of the database doesn't have these restrictions.
http://chemfinder.camsoft.com (7/25/98)

Engineering Material Properties (Apache Point Observatory)
A table of properties for common materials, including densities, heat capacities, heats of combustion, heats of vaporization, heats of fusion, thermal conductivities, thermal expansion coefficients, viscosities, and more.
http://www.apo.nmsu.edu/Telescopes/SDSS/eng.papers/19950926_ConversionFactors/19950926_MProperties.html (9/19/98)

MatWeb: The Free Online Materials Properties Database (Automation Creations, Inc.)
A growing database of properties of industrial materials, including densities and other physical properties, as well as mechanical, thermal, and electrical properties.
http://www.matweb.com/ (7/25/98)

Metal Alloy Properties Data (Principal Metals)
A comprehensive, searchable database containing material property and composition data for more than 5000 metal alloys.
http://www.principalmetals.com/properties/step1.asp (01/26/00)

NIST Atomic Spectroscopic Database (National Institute of Standards and Technology)
Energy levels, transition probabilities, and wavelengths for atomic line spectra. Ionization energies for neutral atoms are also available on a hyperlinked periodic table.
http://physics.nist.gov/PhysRefData/ASD1/choice.html?archive/data.html (7/25/98)

NIST Chemistry WebBook (National Institute of Standards and Technology)
Property and spectral data for elements, organic compounds, and small inorganic compounds can be retrieved by chemical formula, name, partial formula, CAS registry number, molecular weight, or by thermochemical properties. The database includes thermochemical data (enthalpies, entropies, heat capacities, ...) for several phases and for reactions and phase transitions, ion energetics data (ionization energies, electron affinities, ...) and spectroscopic information (IR, UV, visible, and mass spectra).
http://webbook.nist.gov/chemistry/ (7/25/98)

Properties of Gases and Liquids (R. C. Reid, J. M. Praunitz, B. E. Poling)
This handbook provides models and parameters for estimating thermodynamic properties of gases and liquids, both pure and mixtures, including enthalpies, entropies, fugacity coefficients, heat capacities, and critical points; vapor-liquid and liquid-liquid equilibria. ISBN: 0070517991, published by McGraw-Hill.
http://www.amazon.com/exec/obidos/ISBN%3D0070517991/002-3780039-4315040 (4/11/99)

Thermo Explorer (SEA++, Octavian Micro Development)
A "chemical engineering calculator" that searches a database of 600 common compounds to give boiling points, melting points, critical points, dipole moments, liquid densities, and plots of vapor pressure and heat capacity over specific temperature ranges.
http://www.seapp.com/tech.html (7/25/98)

Thermo Properties Page (Quest Consultants, Inc.)
Select a pure substance or a mixture from a list of about 300 compounds to calculate liquid and vapor densities, enthalpies, heat capacities, and compositions at an input temperature and pressure. Calculations are based on the empirical Peng-Robinson equation of state. You can calculate dew points, bubble points, enthalpy-pressure diagrams, and pressure-volume diagrams by following links on the bottom of the page.
http://www.questconsult.com/~jrm/thermot.html (11/19/99)

Vapor Pressures of Pure Substances (Bernhard Spang)
A brief introduction to the Antoine equation, used to estimate the vapor pressure of substances as a function of temperature. Includes Antoine equation parameters for selected substances.
http://chemengineer.about.com/library/weekly/aa071497.htm (4/11/99)

Author: Fred Senese senese@antoine.frostburg.edu

General Chemistry Online! Where do I find compound properties on the Web?