128-97-2Relevant articles and documents
Mechanism of 1,4,5,8-naphthalene tetracarboxylic acid dianhydride hydrolysis and formation in aqueous solution
Barros,Cuccovia,Farah,Masini,Chaimovich,Politi
, p. 71 - 82 (2006)
The study of highly conjugated, carbonyl-containing molecules such as 1,4,5,8-naphthalene tetracarboxylic dianhydride, III, is of interest since reactivity differences and transmission of electronic effects through the conjugated framework can be evidenced. The kinetics of hydrolysis of III in aqueous solution were determined from 5 M acid to pH 10. In basic solution hydrolysis of III yields, sequentially, 1,4,5,8-naphthalene diacid monoanhydride, II, and 1,4,5,8-naphthalene tetracarboxylic acid, I. The second order rate constant for alkaline hydrolysis is 200 fold higher for the first ring opening. The water-catalyzed hydrolysis of III yields a pH-dependent mixture of ionic forms of I and II. The rate constant for water-catalyzed hydrolysis of III is 25 fold higher than that for II. In concentrated acid the rates for reaching equilibrium (I, II and III) increase and III is the major product. The pKas of I (3.24, 5.13 and 6.25) and II (3.05, 5.90) were determined by potentiometric, fluorescence and UV spectroscopy titrations and by quantitative fit of the kinetic and equilibrium data. The apparent, pH-dependent, equilibrium constants, KEqII, for anhydride formation between I and II were obtained from the UV spectra. The quantitative fit of kinetic and equilibrium data are consistent with the assumption that anhydride formation only proceeds with the fully protonated species for both I and II and permitted the estimation of the equilibrium constants for anhydride formation, KEqII. The value of KEqII (I II) between pH 1 and 6 was ca. 5. Geometry optimization calculations in the gas phase of the reactions of III in alkaline, neutral and acid conditions, at the DFT level of theory, gave electronic distributions that were qualitatively consistent with the experimental results. The Royal Society of Chemistry 2006.
Synthesis and application of a MOF-derived Ni@C catalyst by the guidance from an: In situ hot stage in TEM
Xu, Dan,Pan, Ying,Chen, Mingyi,Pan, Qinying,Zhu, Liangkui,Xue, Ming,Zhang, Daliang,Fang, Qianrong,Qiu, Shilun
, p. 26377 - 26383 (2017)
Metal-organic frameworks (MOFs) as a class of crystalline porous solids have attracted considerable attention due to their promising potential performance. MOFs have been recently proved to be ideal sacrificial templates for fabricating their respective derivatives by changing the thermal conditions. However, uncertainties still remain, and the direct observation of transition from MOF to metal nanoparticles (NPs) dispersed in carbon matrix is an important and crucial task for the development of MOF-derived materials. Here, transmission electron microscopy (TEM) combined with in situ hot stage technique was applied to directly observe the transition from MOF to metal NPs. Through in situ TEM experiment, the nanocrystals of Ni-ntca precursor (ntca = 1,4,5,8-naphthalenetetra carboxylic acid) are pyrolyzed under the temperature of 400, 500, or 600 °C to synthesize abundant Ni-NPs embedded in hierarchically porous carbon composites. Furthermore, the as-prepared samples show high catalytic activity and stability for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with NaBH4 in aqueous conditions. More importantly, Ni@C-600, which has nickel contents of 72.8%, shorten the reduction time to 3.5 min with high conversion of nearly 100%. When the catalyst is applied to recycle after being separated from the reaction by an extern magnet, it still keeps high conversion of 92% after 8 cycles, addressing the high stability of the composites. It is believed that these results will further facilitate the exploration of the technique of the TEM combined with in situ hot stage as a powerful tool in the carbonization of MOFs to obtain MOF-derived materials with different applications.
Industrialized preparation method of 1,4,5,8-naphthalene tetracarboxylic acid
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Paragraph 0018; 0021; 0022, (2017/05/05)
The invention provides an industrialized preparation method of 1,4,5,8-naphthalene tetracarboxylic acid. According to the method, 1,4,5,8-naphthalene tetracarboxylic acid is prepared by taking cheap and easily-obtained naphthalene as a starting raw material through a Friedel-Crafts acylation reaction and a Baeyer-Villiger oxidation-hydrolysis one-pot reaction, wherein the yield of the Friedel-Crafts acylation reaction is 87%, the yield of the Baeyer-Villiger oxidation-hydrolysis one-pot reaction is 91%, and the total yield of the reactions is 79%. The method is emphasized from the chemical point and has the advantages of being short in step, simple in reaction, high in yield, simple and feasible in purification method, easy and convenient to operate and the like.