- A Study of the Thermal Racemisation of (-)-3,3-Diphenyl-2-(t-butyl)oxaziridine and (-)-1-Chloro-2,2-diphenylaziridine in Several Nematic Solvents using a Microscopic Technique
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The thermal racemisation of (-)-3,3-diphenyl-2-(t-butyl)oxaziridine and (-)-1-chloro-2,2-diphenylaziridine in nematic liquid-crystal (LC) solvents has been followed directly on a thermostatic microscopic stage by measuring the variations in time of the diameters of the Grandjean-Cano disclination circles, which are associated with the induced cholesteric structure.With respect to isotropic solvents, the nematic phases exert relevant influences on the process, affecting both the activation enthalpy and entropy.Although the two variations partially compensate, the first-order rate constants are smaller in the nematic solvents.
- Spada, Gian Piero,Tampieri, Anna,Gottarelli, Giovanni,Moretti, Irene,Torre, Giovanni
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p. 513 - 516
(2007/10/02)
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- DYNAMIC STEREOCHEMISTRY OF IMINES AND DERIVATIVES. PART 18. PHOTOSYNTHESIS AND PHOTORACEMIZATION OF OPTICALLY ACTIVE OXAZIRIDINES
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Optically active oxaziridines have been synthesized with a maximum optical yield of 31percent by photoisomerization (λ > 300 nm) of achiral aldo- and keto-nitrones in the presence of the chiral solvent (+)-(S) or (-)-(R)-2,2,2-trifluoro-1-phenylethanol.Ph
- Boyd, Derek R.,Campbell, Rose M.,Coulter, Peter B.,Grimshaw, James,Neill, David C.,Jennings, W. Brian
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p. 849 - 856
(2007/10/02)
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