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Cyclic imide dioximes / Sung Ok Kang in Industrial & engineering chemistry research, Vol. 51 N° 19 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 19 (Mai 2012) . - pp. 6619-6624 Titre : Cyclic imide dioximes : Formation and hydrolytic stability Type de document : texte imprimé Auteurs : Sung Ok Kang, Auteur ; Sinisa Vukovic, Auteur ; Radu Custelcean, Auteur Année de publication : 2012 Article en page(s) : pp. 6619-6624 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Stability Résumé : Poly(acrylamidoximes) play an important role in the uranium extraction from seawater. The present work reports solution studies of simple analogues to address the formation and stability of two binding sites present in these polymers, open-chain amidoximes and cyclic imide dioximes, including: (1) conditions that maximize the formation of the cyclic form, (2) the existence of a base-induced conversion from open-chain to cyclic form, and (3) degadation under acid and base conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25900214 [article] Cyclic imide dioximes : Formation and hydrolytic stability [texte imprimé] / Sung Ok Kang, Auteur ; Sinisa Vukovic, Auteur ; Radu Custelcean, Auteur . - 2012 . - pp. 6619-6624. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 19 (Mai 2012) . - pp. 6619-6624 Mots-clés : Stability Résumé : Poly(acrylamidoximes) play an important role in the uranium extraction from seawater. The present work reports solution studies of simple analogues to address the formation and stability of two binding sites present in these polymers, open-chain amidoximes and cyclic imide dioximes, including: (1) conditions that maximize the formation of the cyclic form, (2) the existence of a base-induced conversion from open-chain to cyclic form, and (3) degadation under acid and base conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25900214

Degradation of CYANEX 301 in contact with nitric acid media / Philippe Marc in Industrial & engineering chemistry research, Vol. 51 N° 40 (Octobre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13238–13244 Titre : Degradation of CYANEX 301 in contact with nitric acid media Type de document : texte imprimé Auteurs : Philippe Marc, Auteur ; Radu Custelcean, Auteur ; Gary S. Groenewold, Auteur Année de publication : 2012 Article en page(s) : pp. 13238–13244 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Nitric  acid Résumé : The nature of the degradation product obtained upon contacting CYANEX 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) with nitric acid has been elucidated and found to be a disulfide derivative. The first step to the degradation of CYANEX 301 in toluene has been studied using 31P{1H} NMR after being contacted with nitric acid media. The spectrum of the degradation product exhibits a complex multiplet around δP = 80 ppm. A succession of purifications of CYANEX 301 has resulted in single crystals of the acidic form and the corresponding ammonium salt. Unlike the original CYANEX 301, which consists of a complex diastereomeric mixture displaying all possible combinations of chiral orientations at the 2-methyl positions, the purified crystals were shown by single-crystal X-ray diffraction to be racemates, containing 50:50 mixtures of the [R;R] and [S;S] diastereomers. The comparison between the 31P {1H} NMR spectra of the degradation products resulting from the diastereomerically pure CYANEX 301 and the original diastereomeric mixture has elucidated the influence of the isomeric composition on the multiplicity of the 31P {1H} NMR peak. These NMR data indicate the initial degradation leads to a disulfide-bridged condensation product displaying multiple resonances due to phosphorus–phosphorus coupling, which is caused by the inequivalence of the two P atoms as a result of their different chirality. A total of nine different NMR resonances, six of which display phosphorus–phosphorus coupling, could be assigned, and the identity of the peaks corresponding to phosphorus atoms coupled to each other was confirmed by 31P {1H} homodecoupled NMR analysis. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300757r [article] Degradation of CYANEX 301 in contact with nitric acid media [texte imprimé] / Philippe Marc, Auteur ; Radu Custelcean, Auteur ; Gary S. Groenewold, Auteur . - 2012 . - pp. 13238–13244. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 40 (Octobre 2012) . - pp. 13238–13244 Mots-clés : Nitric  acid Résumé : The nature of the degradation product obtained upon contacting CYANEX 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) with nitric acid has been elucidated and found to be a disulfide derivative. The first step to the degradation of CYANEX 301 in toluene has been studied using 31P{1H} NMR after being contacted with nitric acid media. The spectrum of the degradation product exhibits a complex multiplet around δP = 80 ppm. A succession of purifications of CYANEX 301 has resulted in single crystals of the acidic form and the corresponding ammonium salt. Unlike the original CYANEX 301, which consists of a complex diastereomeric mixture displaying all possible combinations of chiral orientations at the 2-methyl positions, the purified crystals were shown by single-crystal X-ray diffraction to be racemates, containing 50:50 mixtures of the [R;R] and [S;S] diastereomers. The comparison between the 31P {1H} NMR spectra of the degradation products resulting from the diastereomerically pure CYANEX 301 and the original diastereomeric mixture has elucidated the influence of the isomeric composition on the multiplicity of the 31P {1H} NMR peak. These NMR data indicate the initial degradation leads to a disulfide-bridged condensation product displaying multiple resonances due to phosphorus–phosphorus coupling, which is caused by the inequivalence of the two P atoms as a result of their different chirality. A total of nine different NMR resonances, six of which display phosphorus–phosphorus coupling, could be assigned, and the identity of the peaks corresponding to phosphorus atoms coupled to each other was confirmed by 31P {1H} homodecoupled NMR analysis. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300757r