Use of QSAR methods for predicting the chemiluminescent behaviour of organic compounds upon reaction with potassium permanganate in an acid medium

In previous work, molecular connectivity computations were successfully used to predict the chemiluminescent behaviour of organic compounds upon reaction with common strong oxidants and the native fluorescence too; both of them in a liquid phase. The obtained results were used to develop new analytical procedures to the given compounds. For the first time, connectivity methods were used for a purely analytical purpose. In this work, we went deeper into the knowledge of direct chemiluminescence processes by using molecular connectivity in the form of QSAR methods to predict the chemiluminescence intensity produced by reactions between organic compounds (pharmaceuticals mainly) and potassium permanganate in a liquid phase. The choice of this oxidant was dictated by its being the most active by far in producing chemiluminescence. We used discriminant analysis to examine the results for 63 substances the emission intensity of which upon reaction with acid potassium permanganate was experimentally measured in a continuous-flow manifold. Descriptors were chosen by applying stepwise linear dicriminant analysis (LDA) to Snedecor F-values, using the smallest Mahalanobis distance, the minimum error on the test set and the lowest value of the Wilks’lambda as sorting criterion. The theoretical predictions thus obtained were checked against the experimental results for a set of 16 compounds not used in the previous theoretical computations the chemiluminescent behaviour of which was also experimentally assessed. The result was a hit rate of 87.5% in the predictions.