Documents disponibles écrits par cet auteur

Identification and quantitation of volatile organic compounds from oxidation of linseed oil / Juita in Industrial & engineering chemistry research, Vol. 51 N° 16 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5645-5652 Titre : Identification and quantitation of volatile organic compounds from oxidation of linseed oil Type de document : texte imprimé Auteurs : Juita, Auteur ; Bogdan Z. Dlugogorski, Auteur ; Eric M. Kennedy, Auteur Année de publication : 2012 Article en page(s) : pp. 5645-5652 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation  Volatile  organic  compound Résumé : Solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) served to identify and quantitate the volatile organic compounds (VOCs) formed in the degradative oxidation of linseed oil. SPME involved experiments under nitrogen and oxygen atmosphere, two oil types (raw and boiled), and two different methods of sampling the head space to differentiate between the oxidation products and the oil impurities. Further experiments entailed the oxidation of neat linoleic and linolenic acids to assist with the development of a detailed reaction mechanism. The majority of the detected product species originated from the oxidation of linolenic compounds, which dominate the composition of linseed oil, while 2-propenal, pentanal, hexanal, 2,4-decadienal, and hexanoic acid, among others, were released from linoleic compounds. The concentration of hexanal (7-26), 2-pentenal (25-39), 1-penten-3-ol (3.1-4.8), trans,trans-2,4-heptadienal (33-50), trans,trans-2,4-decadienal (0.7-0.8), 3,5-octadien-2-one (2.5-6.2; relative area), ethanoic acid (137-195), and hexanoic acid (18-29) increased with the progress of oxidation; the numbers in the parentheses indicate initial and final concentration (ppm) of the species in the oil in 6 h experiments. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834476 [article] Identification and quantitation of volatile organic compounds from oxidation of linseed oil [texte imprimé] / Juita, Auteur ; Bogdan Z. Dlugogorski, Auteur ; Eric M. Kennedy, Auteur . - 2012 . - pp. 5645-5652. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5645-5652 Mots-clés : Oxidation  Volatile  organic  compound Résumé : Solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) served to identify and quantitate the volatile organic compounds (VOCs) formed in the degradative oxidation of linseed oil. SPME involved experiments under nitrogen and oxygen atmosphere, two oil types (raw and boiled), and two different methods of sampling the head space to differentiate between the oxidation products and the oil impurities. Further experiments entailed the oxidation of neat linoleic and linolenic acids to assist with the development of a detailed reaction mechanism. The majority of the detected product species originated from the oxidation of linolenic compounds, which dominate the composition of linseed oil, while 2-propenal, pentanal, hexanal, 2,4-decadienal, and hexanoic acid, among others, were released from linoleic compounds. The concentration of hexanal (7-26), 2-pentenal (25-39), 1-penten-3-ol (3.1-4.8), trans,trans-2,4-heptadienal (33-50), trans,trans-2,4-decadienal (0.7-0.8), 3,5-octadien-2-one (2.5-6.2; relative area), ethanoic acid (137-195), and hexanoic acid (18-29) increased with the progress of oxidation; the numbers in the parentheses indicate initial and final concentration (ppm) of the species in the oil in 6 h experiments. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834476

Mechanism of formation of volatile organic compounds from oxidation of linseed oil / Juita in Industrial & engineering chemistry research, Vol. 51 N° 16 (Avril 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5653-5661 Titre : Mechanism of formation of volatile organic compounds from oxidation of linseed oil Type de document : texte imprimé Auteurs : Juita, Auteur ; Bogdan Z. Dlugogorski, Auteur ; Eric M. Kennedy, Auteur Année de publication : 2012 Article en page(s) : pp. 5653-5661 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Oxidation  Volatile  organic  compound Résumé : The pathways of volatile organic compound (VOC) formation have been investigated through a computational study, employing the Gaussian 03 suite of programs. We optimized geometries and zero-point vibrational energies (ZPVEs) at the B3LYP/6-31G(d) level of theory and improved electronic energies by conducting single-point energy calculations using the large 6-311++G(3df,3pd) basis set. To describe the predominant mechanism of the linseed oil oxidation, the following sequence is proposed: hydrogen abstraction of unsaturated fatty compounds as the initiation reaction followed by the reaction of allylic-type radicals with molecular oxygen to form peroxyl radicals and finally intramolecular rearrangement through four- and five-membered rings. Quantum calculations identified low-energy pathways following cyclization resulting in the formation of major products observed, especially aldehydes and ketones. The overall energy changes taking place through the four- and five-membered rings were found to be 78 and 93 kJ mol-1 exothermic, respectively. Metal catalysts decompose hydroperoxides based on the Fenton-like mechanism into alkoxyl and peroxyl radicals. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834477 [article] Mechanism of formation of volatile organic compounds from oxidation of linseed oil [texte imprimé] / Juita, Auteur ; Bogdan Z. Dlugogorski, Auteur ; Eric M. Kennedy, Auteur . - 2012 . - pp. 5653-5661. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 16 (Avril 2012) . - pp. 5653-5661 Mots-clés : Oxidation  Volatile  organic  compound Résumé : The pathways of volatile organic compound (VOC) formation have been investigated through a computational study, employing the Gaussian 03 suite of programs. We optimized geometries and zero-point vibrational energies (ZPVEs) at the B3LYP/6-31G(d) level of theory and improved electronic energies by conducting single-point energy calculations using the large 6-311++G(3df,3pd) basis set. To describe the predominant mechanism of the linseed oil oxidation, the following sequence is proposed: hydrogen abstraction of unsaturated fatty compounds as the initiation reaction followed by the reaction of allylic-type radicals with molecular oxygen to form peroxyl radicals and finally intramolecular rearrangement through four- and five-membered rings. Quantum calculations identified low-energy pathways following cyclization resulting in the formation of major products observed, especially aldehydes and ketones. The overall energy changes taking place through the four- and five-membered rings were found to be 78 and 93 kJ mol-1 exothermic, respectively. Metal catalysts decompose hydroperoxides based on the Fenton-like mechanism into alkoxyl and peroxyl radicals. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25834477