Nowadays, pyridinium salts are an important source of raw materials whose applications are found in chemical and industrial industry. By introducing other types of anions or by modifying their structures, their properties can be easily modified. After synthesis of a series of these compounds, a study of their structures has been started. Using Hammett substituent constants, the direct polar conjugation effect on nitrogen group of nucleus were studied. The spectroscopic characteristics determined show that the vibrations of the carbonyl group ν (c=o) are well correlated with the constants of the Hammett substituent as well as the integral intensities B8. Considering the perchlorate ion, the largest integral intensity is found with the perchlorate N- methoxycarbonyloxy-4-methyloxypyridinium with a value of 20,1.10-3 L.mol-1cm-2. The smallest value concerns the perchlorate N- methoxycarbonyloxypyridinium (15, 6.10-3 L.mol-1cm-2). The ν_(c=o) variables vary in the opposite direction and are 1826 cm-1 and 1831 cm-1, respectively. With these two characteristic quantities and the Hammett substituent parameters, the best correlation is found by using σ_R^+. The displacement of the electronic density of the radical on the nitrogen group occurs. Thus, methoxy, phenyloxy and aryloxy carbonyls groups polarize the pyridinium system group and create the conditions for the manifestation of direct polar conjugation effects.

"Chukutu" is a drink very popular with Togolese and consumed throughout the territory. It is a drink obtained by alcoholic fermentation of the sweet must of sorghum. The scientific investigations for the control of its production began timidly. In all the countries where this beer is prepared and consumed, the tasting quality differs from one producer to another and often each prepared drink is unique. No standardization is proposed in the various existing studies. The main objective of this study is the promotion of this beer by the search for a simple method of quality control accessible to producers. This involves determining the shortcomings in the production and marketing process and researching the physico-chemical characteristics and the alcoholic degrees of the different formulations of this beer using a simple and practical method, the densimetry. Beforehand, a descriptive and analytical transversal study on the knowledge, attitudes and practices of the actors (producers and consumers) of the local beer was made. A random sampling method surveyed 20 producers and 200 consumers in four districts of Greater Lomé (Adéwi, Cacaveli, Démakpoè and Fiovi). Then, an evaluation of the physico-chemical characteristics was made using the densimetry method. The alcohol levels and specific densities of the different types of this drink were evaluated. The influence of the cooking temperature of the sweet must was also studied. The results obtained show that the inspections of the competent authorities remain insufficient. A cooking temperature of 83 °C gives a beer much appreciated by consumers. The alcohol content is not constant and varies from 8.03% for tchoukoutou to 5.50% for tchapalo. In conclusion, the flexible and easy-to-explain densimetry is a method for controlling the quality of local beer. It must be recommended to producers.