title: Chemical and thermochemical aspects of the ozonolysis of ethyl oleate: decomposition enthalpy of ethyl oleate ozonide.
abstract: Neat ethyl oleate was ozonized in a bubble reactor and the progress of the ozonolysis was followed by infrared (FT-IR) spectroscopy and by the differential scanning calorimetry (DSC). The ozonolysis was conducted till a molar ratio O3/C=C≈1 when the exothermal reaction spontaneously went to completion. A specific thermochemical calculation on ethyl oleate ozonation has been made to determine the theoretical heat of the ozonization reaction using the group increment approach. A linear relationship was found both in the integrated absorptivity of the ozonide infrared band at 1110 cm(-1) and the ozonolysis time as well as the thermal decomposition enthalpy of the ozonides and peroxides formed as a result of the ozonation. The DSC decomposition temperature of ozonated ethyl oleate occurs with an exothermal peak at about 150-155 °C with a decomposition enthalpy of 243.0 kJ/mol at molar ratio O3/C=C≈1. It is shown that the decomposition enthalpy of ozonized ethyl oleate is a constant value (≈243 kJ/mol) at any stage of the O3/C=C once an adequate normalization of the decomposition enthalpy for the amount of the adsorbed ozone is taken into consideration. The decomposition enthalpy of ozonized ethyl oleate was also calculated using a simplified thermochemical model, obtaining a result in reasonable agreement with the experimental value.
authors: Actinium Chemical Research srl, Via Casilina 1626A, 00133 Rome, Italy. Electronic address: franco.cataldo@fastwebnet.it.
authors: Franco
authors: F
authors: Cataldo
mesh_terms: D002152:Calorimetry, Differential Scanning; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009829:Oleic Acids / Q000737:chemistry*; D010126:Ozone / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics
chemical_list: C503429:1,2,4-trioxane; D006571:Heterocyclic Compounds; D009829:Oleic Acids; D010126:Ozone; C033180:ethyl oleate
keywords: DSC; Decomposition enthalpy; Ethyl oleate; FT-IR spectroscopy; Ozone; Thermochemistry