Computer Assisted Instruction in Organic Synthesis Student success in organic synthesis requires mastery of many individual reactions and a Logical sequence of their use. Computers have been employed to provide student drill in organic synthesis;' however, most of the methods require rather elaborate programs and make large demands upon the computer core size and time required. Clark et d zhave devised a simpler technique which entails the construction of a reagent matrix. They use general path tracing methods to predict the possible products of multistep reactions. We have modified this procedure and applied the logic of sueeessive one-step reactions to multistep sequences without the necessity for path tracing techniques. We have successfully used two Basic programs, each occupying less than 10 K computer core, in a time-sharing environment. Students can practice with a series of interconversions involving aliphatic and aromatic compounds. The key to both programs is the establishment of a reagent matrix. Syntheses are viewed as being composed of a number of consecutive single steps. Each functional group is assigned a eode so that the transformation between two groups i and j is represented as the ij-th element in the reagent matrix. The numerical value of that element is the code number of the reagent needed to effect the change of i to j. The student enters the eode numbers of the reactant and product and obtains the required reagent, if one is available for a direct, one-step conversion. In addition to the reagents ALKYLATB." The and reaction conditions. s ~ e e i aremarks l are minted. such as "DIRECTS 0 AND P" or "CANNOT ~~. direction of addition to alkenes and drrection of elimination are indrcated to the student, and for poss~hlecomplications, such as rearrangements, or fur less common reactions he is directed to the textbook. The student may invert the pruredure by asking for all possible stnrting materials (i.e.. functional erouosl for a soeeific product in s one-step reaction. Once the reactants are before him, the student can again enterthe &tant and product code numhers to obtain the reagent. By use of this two step process it is simple to construct the reaction path for an elaborate synthesis. For example, if a problem requires the synthesis of a substituted henzoie acid, the student may ohtain a list of functional groups which may he converted in one step to the carboxyl group: Cl, Br, I, R (alkyl), R-C=O, CN. If he chooses a halide, he learns that the requisite Grignard reagent cannot he used if certain other groups are present, and that C O A directs electrophilic substitution to the meta position. The problem now is the synthesis of the halobenzene. If the student knows this reaction, the computer confirms his choice: if he does not know the reaction, the computer supplies it to him. The programs may be modified easily to include other reactions. A copy of each program will he supplied on request to M. F. ~
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Rodewald, L. B., Culp, G. H., and Lagowski, J. J., J. CHEM. EDUC. 47,134 (1970); Smith, S. G., J. CHEM. EDUC., 48,727 (1971). Clark, H. A,, Marshall, J. C., and Isenhour, T. L., J. CHEM. EDUC., 50,645 (1973). Howard University Washington, D.C. ZOO59
Martin Feldman Marvin Bishop
Volume 53. Number 2, February 1976 / 91
