Energies of combustion and enthalpies of formation of 5-methyl-5-phenylhydantoin and 5,5-diphenylhydantoin

• Published in: Journal of thermal analysis and calorimetry Vol. 123; no. 3; pp. 2391 - 2396
• Main Authors: Ledo, J. Manuel, Camarillo, E. Adriana, Flores, Henoc, Ramos, Fernando, Rojas, Aarón
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2016
• Subjects: Analytical Chemistry; Calorimetry; Chemistry; Chemistry and Materials Science; Combustion; Crystal structure; Enthalpy; Equivalence; Formations; Inorganic Chemistry; Measurement Science and Instrumentation; Physical Chemistry; Polymer Sciences; Scanning; Sublimation enthalpy estimated; 5,5-Diphenylhydantoin; 5-Methyl-5-phenylhydantoin; Molar enthalpy of formation; Molar energy of combustion
• ISSN: 1388-6150; 1588-2926; 1572-8943
• DOI: 10.1007/s10973-015-5036-8

The standard molar energies of combustion Δ c U ° (cr, 298.15 K) of 5-methyl-5-phenylhydantoin and 5,5-diphenylhydantoin were obtained by static-bomb combustion calorimetry. The calorimeter was re-calibrated in order to determine the energy equivalent, and the valued obtained was ε (calor) = (10,150.8 ± 1.2) J K −1 . The heat capacities and purities of the compounds studied in present work were determined using a differential scanning calorimeter. The molar combustion energies obtained for 5-methyl-5-phenylhydantoin and 5,5-diphenylhydantoin were: −(4984.61 ± 0.87) and −(7391.36 ± 1.34) kJ mol −1 , respectively. From these combustion energy values, the standard molar enthalpies of formation (Δ f H °) in the crystalline phase at T  = 298.15 K were obtained as: −(378.40 ± 1.58) and −(223.80 ± 2.38) kJ mol −1 , respectively. Additionally, and with comparative proposes, the enthalpies of formation in the gas phase were determined using the experimental data and predicted values of the enthalpies of sublimation by using standard methods described in specialized literature.