Abstract
Using static bomb combustion calorimetry, the combustion energy of 1-methylhydantoin was obtained, from which the standard molar enthalpy of formation of the crystalline phase at T = 298.15 K of the compound studied was calculated. Through thermogravimetry, mass loss rates were measured as a function of temperature, from which the enthalpy of vaporization was calculated. Additionally, some properties of fusion were determined by differential scanning calorimetry, such as enthalpy and temperature. Adding the enthalpy of fusion to the enthalpy of vaporization, the enthalpy of sublimation of the compound was obtained at T = 298.15 K. By combining the enthalpy of formation of the compound in crystalline phase with its enthalpy of sublimation, the respective standard molar enthalpy of formation in the gas phase was calculated. On the other hand, the results obtained in the present work were compared with those of other derivatives of hydantoin, with which the effect of the change of some substituents in the base heterocyclic ring was evaluated.
Highlights
Heterocyclic chemistry is one of the vastest and most complex branches of organic chemistry
Some hydantoin derivatives have some applications in the agrochemical area as bactericides, fungicides, and herbicides [12,13,14,15]
Values stated in the certificate of analysis provided by the supplier. c Results obtained from differential scanning calorimetry
Summary
Heterocyclic chemistry is one of the vastest and most complex branches of organic chemistry. Heterocyclic chemical structures that contain nitrogen are very important molecules that participate, from biological processes constituting the nitrogenous bases in RNA and DNA, even in different industries such as pharmaceuticals. Hydantoins and their derivatives are five-membered cyclic ureas with substituents at different positions on the ring. Molecular thermochemistry allows us to have an approach to understand the thermodynamic stability of molecules, and rests on their chemical bonds and the interactions present in them This knowledge is important since it allows us to establish relationships between energy, structure, and reactivity in molecules.
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