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Mingcan Xu

Publications and source records attributed to Mingcan Xu.

5 recordsLinked to original sources
PubMed2006

Understanding the structural properties of a dendrimeric material directly from powder X-ray diffraction data.

Complete structure determination of an early-generation dendrimeric material has been carried out directly from powder X-ray diffraction data, using the direct-space genetic algorithm technique for structure solution followed by Rietveld refinement. This work represents the first application of modern direct-space techniques for structure determination from powder X-ray diffraction data in the case of a dendrimeric material and paves the way for the future application of this approach to enable complete structure determination of other dendrimeric materials that cannot be prepared as single crystal samples suitable for single crystal X-ray diffraction studies.

Letter↗
PubMed2006

Highly efficient one-step conversion of cyclohexane to adipic acid using single-site heterogeneous catalysts.

A solid source of 'active' oxygen (acetylperoxyborate, APB), when dissolved in aqueous solution in the presence of a single-site microporous catalyst containing redox centres (Fe(III)AlPO-31, Mn(III)AlPO-5, Fe(III)AlPO-5), converts cyclohexane with high efficiency (ca. 88%) and exceptionally high selectivity (ca. 81%) to adipic acid at 383 K; this procedure is also effective in converting styrene to styrene oxide and -pinene and (+)-limonene to their corresponding epoxides.

Journal Article↗
PubMed2005

Altering the polymorphic product distribution in a solid-state dehydration process by rapid sample rotation in a solid-state NMR probe.

There is currently considerable interest in the phenomenon of polymorphism in organic molecular solids, and a key issue in this field is to understand the experimental techniques and procedures that may be employed to obtain new polymorphic forms of a given molecule. This paper demonstrates that the polymorphic form of a material (sodium acetate) obtained by a solid-state dehydration process (starting from sodium acetate trihydrate) can be altered by carrying out the dehydration process under conditions of rapid (several kilohertz) sample rotation in a solid-state magic-angle-spinning NMR probe. This observation suggests a new opportunity to influence the outcome of solid-state dehydration/desolvation processes and, in particular, to alter the polymorphic form of the product obtained.

Journal Article↗
PubMedDate not supplied

Time-resolved observation of the decomposition process of N,N,N-Trimethylanilinium cations on zeolite H-Y by in situ stopped-flow 13C MAS NMR spectroscopy.

N,N,N-Trimethylanilinium cations were synthesized on acidic zeolite H-Y by direct reaction of N,N-dimethylaniline and methanol. Time-resolved observation of the detailed decomposition process of N,N,N-trimethylanilinium cations was achieved by in situ 13C stopped-flow (SF) MAS NMR spectroscopy at reaction temperatures of 498 K to 573 K.

Aniline Compounds↗