Using a ~ o m ~ u t e r b a se-An "Experiment" for the Organic Laboratories One of the problems with introducing students to the use of computer databases is cost. Used theinexpensive ONTAP files of the DIALOG system t o teach students how t o perform computer literature searches has recently been described.' This note tells about an affordable approach to a different type of computer search. Chemical Information Systems, Inc. very generously exempts nonprofit, degree-granting educational institutions from payment of the annual subscription fee to their ChemiealInformation System (CIS) and gives a discount of the first $1001 month usage. The CIS is a collection of data bases and data analysis computer programs that contains numeric, textual, and some bibliographic information in the areas of chemical and physical properties including crystallographic properties, mass, infrared, and carbon-13 nuclear magnetic resonance spectroscopy, toxicology, environment, regulations, and nucleotide sequence5 a wenlth ul material from whlch to r h r m r pmt,lems ior rtudmt atsrrhers The rumpunenLz ul the CIS iudged most suitalrle for introduci~lgour studrnti 11, computer searching wew the infrared Search Systrrn !IRSS, and the Struclure and Womenclature Search S s s r ~ miShNSS1. Vrum the infrared spectrum uf nn unknown~compound,the students in organic and forensic labs use IRSS toget a list of possible compounds. ~ a b i n narrowed g down the possibilities from six million known compounds to a short list of pwsibilities, the students can then easily confirm the identity of the unknown compound by visual comparison of its spectrum with those in alibrary of spectra or by means of other simple tests. The sample must be as pure as w i b l e , and the infrared spectrum must be of good quality-that is, wavelengths a m a t e and percent transmittances between 5 and 95. The positions of the centers of the infrared absorption hands are read from the speetnvn and tabulated in order of decreasing intensity, beginning with the strongest hand and continuing until all hands with percent transmittance less than or equal to 50 have been entered. If either O-H or C-0 stretching is absent, this fact is noted, and then the bands with percent transmittance greater than 50 hut less than or equal to 60 are listed. As much of this information as needed to reduce the list of possible compounds t o a minimum (not mare than 20 and preferably five or fewer) is input to the computer. After the computer has supplied the student with a list of Chemical Ahstract Registry numbers and systematic names of compounds with the spectral features entered, she or he uses the Structure and Nomenclature Search system to find structural formulas and synonyms, and completes the identification of the unknown. Because the compounds in IRSS were not chosen for teaching purposes, but reflect the information needs of various U S . government agencies, many of the compounds commonly used for unknowns in organic qualitative analysis because they are inexpensive and relatively inert physiologically either are not included or have only their strangest hands listed, too few for successful identification. Therefore unknowns must be chosen with
' Gaus, P. L.. Boders, C. L.. Jr., Powell, D. L., and Sufbey, D. J., J. CHEM. EOUC.,60 1048 (1983). For information about Me Chemical Information System, contact Chemical Information Systems. Inc..
7215 York Road, Baltimore. MD
21212. - - A list of compounds h a t have been successfully idemified plus a copy of me detailed procedure furnished to stvjents will be sem on request. Please enclose a stamped, self-addressed, legal envelope.
University of
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Journal of Chemical Education
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