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Computer Assisted Analysis of Infrared Spectra
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''"U. '". o"'""Y' The interpretation of infrared spectra has become an integral part of virtually """"*"'"'.'" g;~:. m* m-M rn every course dealing with the identification of organic compounds. At the very least, yz:;; the student is taught to recognize the hands characteristic of the more common fuuc- ,:c tional groups. In recent years the availability of excellent texts and low-cost spectro- ~y-w. photometers with rather high resolution has made it very tempting to pursue infrared ' & ~ : e ~ M ; : v ~ d :&:":,""!" ~ ~ : analysis in greater detail. However, if class time is spent discussing some of the finer ~ ~ ~ a ~ ~ ~ m ' ' ~ points of infrared spectroscopy, then not enough time may he available for the pre-lab practice sessions needed by the average student. Our experience indicates that without ; AnE interactive practice sessions students either do poorly on their unknowns, or they ':2:"d:E;:;::4DY".:!ZY::::8 OI1DYAE AL,pw.cc ",.- s .mw -amrn "%A" ,am A.D law spend an inordinate amount of time in analyzing the unknown spectra. "rn""TZC w,m sm "7 Am, * , a "m , , m : , ' . "R'8'ma An interactive computer program, capable of giving assistance and instantaneous evaluation of performance on practice spectra has been written in the hope that it k,;;vzx;;;:h~: ;g ~ - y ; ; ~ ; ~ ~ ~ , ~ , - ~ ~ would serve as a substitute for classroom exercises on spectral identification. The pro,*""'" ,'""',. ,. """"'* gram is written in Fortran for an IBM system with time sharing option (TSO)through a remote terminal. The student indicates the number of the spectrum he wishes to ana- ~~~~~r ~ ~ ~ g , ' ~ ~ lyze, and the sampling technique used in its preparation. A series of questions about wereemured bytbe~tudant;sllotbgeoerntd. enwere the presence of specific structural features follows, to which the student may respond "yes", "no", or "help". Asking for help results in a listing of the characteristic frequeneles of the functionality in question. An incorrect response elicits an error message, including the probable source of error. Twelve practice spectra are currently available, and it is a simple matter to add others. Full-scale copies of actual spectra from departmental instrumentation are used in an effort to make the exercise as authentic as possible. A portion of a typical student-computer dialog is shown above. A second application of the program involves assistance on actual student unknowns. In this mode of operation, the program leads the student through an analysis scheme by providing information on characteristic frequencies in e systematic manner. In both of the above applications, the program allows for the entry of the sample handling technique used in spectral preparation, and then provides reminders concerning any regions of the spectrum which are obscured by the technique. Most of the common functional groups have been incorporated into the program. However, no provision has been made far heterocyclic or polynuclear aromatic compounds. Initial results of the use of the program are encouraging in that it does seem to adequately take the place of the inclass practice sessions used in previous years. A program listing is available upon request.
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Virginia Polytechnic Institute a n d S t a t e University Blacksburg, 24061
26 / Journal of Chemical Education
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Harold M. Bell
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