COMPARISON OF EXPERIMENTAL AND CALCULATED VALUES OF COMBUSTION HEAT OF ALKYL GLYCIDE ETHERS AS AN ELEMENT OF ENSURING CIVIL SAFETY

Abstract

The heats of combustion of four glycidol ethers - the most typical representatives of epoxy compounds, determined experimentally and calculated by methods, used in the theory of combustion - were compared. In reference books and literary sources, information on these values is given only for individual representatives and only determined experimentally. Meanwhile, since the middle of the last century, epoxy compounds have been widely used in industry and in everyday life. Having a significant percentage of carbon and hydrogen in their composition, they all belong to combustible substances. In addition, the lower representatives of this series are quite volatile (the boiling point of methyl glycidol is 110⁰C), which requires attention to ensuring civil safety during their production and use. One of the most important indicators of the fire hazard of substances is the heat of combustion. The latter can be determined quickly and without significant costs in each specific case by calculation. But, given the presence of significant strain energy in the epoxy cycle, the calculation by known methods in this case is accompanied by significant errors. To obtain reliable data, it is necessary to estimate these errors, which in this case each of the methods gives and to determine the directions of improvement of the most suitable of the methods. The calculation of the heat of combustion of methyl glycidol, ethyl glycidol, n-butyl glycidol and tert.-butyl glycidol was carried out according to the formula of D.I. Mendeleev, according to the Handrick method and according to the difference in bond energies between atoms in the initial glycidol ethers and in the products of their combustion. The calculation error by each of the methods was estimated by comparing the obtained values with the actual values of the heats of combustion, found earlier by experimental combustion of these ethers in a calorimetric bomb. It was found that the calculation of the heat of combustion of glycidol ethers according to the D.I. Mendeleev formula gives a result that is 3.0% higher than the actual value, while the calculation according to the Handrick method gives a result that is 1.7% higher than the actual value. The formal calculation according to bond energies does not take into account the intermolecular effect of atoms and groups of atoms and the intermolecular effect of molecules, and most importantly, the energy of tension in the epoxy cycle. The tension in the epoxy cycle significantly weakens both carbon-carbon and carbon-oxygen bonds. The latter results in obtaining results that are significantly (about 20%) lower than the actual ones. According to the results of the study, it is recommended to choose the calculation according to the Handrick method when estimating the heat of combustion of epoxy compounds at the moment. Despite the empirical nature of this method, it provides quite acceptable results. In the future, to use a theoretically justified method of calculation based on bond energies between atoms, it is necessary to establish the exact value of the tension in the epoxy cycle.