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Poster communications
Degradation Studies of Cyanex 301
Abstract : Despite the numerous studies found in the literature on CYANEX® 301, very few explain its degradation in depth. To the best of our knowledge none has explained the inconsistency between the “common knowledge” of “CYANEX® 301 degrades into CYANEX® 272” (dithiophosphinic acid degrading into the corresponding phosphinic acid) and the 31P spectrum obtained by NMR of the degradation compound. The 31P {1H} NMR analysis of a solution of CYANEX® 301 in prolonged contact with nitric acid shows a very complex spectrum, with resonances about 20 ppm downfield from what could have been expected.
The degradation product giving those multiple resonances in a pattern that could be interpreted as a triplet of triplet is actually a dimer, where two molecules of CYANEX® 301 are linked by a disulfide bridge, corresponding to the condensation of the SH groups. The explanation of the complexity of the spectrum comes from the comparison with the spectrum obtained for the degradation of a stereoisomerically-purified CYANEX® 301. This purification led to the removal of the [R;S] and [S;R] isomers from the initial mixture, and yielded a white crystalline solid proven to comprise exclusively [R;R] and [S;S] isomers by XRD analysis. It was determined that the carbon chirality induced an asymmetry of the phosphorus atoms upon condensation, leading to a wide combination of magnetically non-equivalent P-31 nuclei, which can also exhibit coupling through the S-S bond The complete explanation of the NMR spectra was established and corroborated by elemental analysis
https://hal-cea.archives-ouvertes.fr/cea-01267748
Contributor : Philippe Marc Connect in order to contact the contributor
Submitted on : Thursday, February 4, 2016 - 8:13:43 PM
Last modification on : Thursday, August 1, 2019 - 10:56:05 AM
Long-term archiving on: : Saturday, November 12, 2016 - 9:53:53 AM
Contributor : Philippe Marc Connect in order to contact the contributor
Submitted on : Thursday, February 4, 2016 - 8:13:43 PM
Last modification on : Thursday, August 1, 2019 - 10:56:05 AM
Long-term archiving on: : Saturday, November 12, 2016 - 9:53:53 AM
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