- Mechanism of 1,4,5,8-naphthalene tetracarboxylic acid dianhydride hydrolysis and formation in aqueous solution
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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.
- Barros,Cuccovia,Farah,Masini,Chaimovich,Politi
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- Catalytic oxidation of acenaphthene and its derivatives in acetic acid
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The chemistry of formation of products of acenaphthene oxidation in the presence of the catalyst containing both manganese and cobalt bromides under batch conditions is discussed. The main reaction products are acenaphthene quinone, acenaphthenol-9, trans-acenaphthylene glycol, naphthalide, and naphthalic anhydride. The sequence of reactions leading to the final products is established. It is shown that the main oxidation product in the presence of the manganese-based catalyst is naphthalic anhydride, and the main product in the presence of the cobalt-based catalyst is acenaphthene quinone. The process and engineering techniques providing for the high overall and fractional yields of the desired products are discussed.
- Bukharkina, Tatiana V.,Grechishkina, Olga S.,Digurov, Nikolai G.,Kon'kov, Ivan I.
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- Synthesis and application of a MOF-derived Ni@C catalyst by the guidance from an: In situ hot stage in TEM
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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.
- Xu, Dan,Pan, Ying,Chen, Mingyi,Pan, Qinying,Zhu, Liangkui,Xue, Ming,Zhang, Daliang,Fang, Qianrong,Qiu, Shilun
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- Hydrothermal Generation of Conjugated Polymers Using the Example of Pyrrone Polymers and Polybenzimidazoles
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Various polyimides and polyamides have recently been prepared via hydrothermal synthesis in nothing but H2O under high-pressure and high-temperature conditions. However, none of the prepared polymers feature a truly conjugated polymer backbone. Here, we report on an expansion of the synthetic scope of this straightforward and inherently environmentally friendly polymerization technique to the generation of conjugated polymers. Selected representatives of two different polymer classes, pyrrone polymers and polybenzimidazoles, were generated hydrothermally. We present a mechanistic discussion of the polymer formation process as well as an electrochemical characterization of the most promising product.
- Gl?cklhofer, Florian,Mezzavilla, Stefano,Taublaender, M. Josef,Thiele, Sophia,Unterlass, Miriam M.
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supporting information
p. 15050 - 15060
(2020/05/18)
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- Industrialized preparation method of 1,4,5,8-naphthalene tetracarboxylic acid
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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.
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Paragraph 0018; 0021; 0022
(2017/05/05)
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- Process for the preparation of naphthalene-1,4,5,8-tetracarboxylic acid
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Naphthalene-1,4,5,8-tetracarboxylic acid and typical derivative(s) thereof is (are) prepared by oxidation of periacenaphthindenones of the formula STR1 where R is H or lower alkyl, in a lower aliphatic carboxylic acid with nitric acid, optionally using also oxygen, in the presence of oxidation catalysts at temperatures above about 100° C; the reaction product being worked up in known manner. Naphthalene-1,4,5,8-tetracarboxylic acid is an important preliminary product for the manufacture of dyestuffs.
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- Process for preparing naphtholyene arylimidazol-peri-dicarboxylic acid imides
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Process for preparing naphthoylene-arylimidazo-peri-dicarboxylic acid-imide-compounds of the formula SPC1 Wherein R1 is hydrogen, hydroxy or amino, phenyl, alkyl having 1 to 8 carbon atoms, hydroxyalkyl, alkoxyalkyl, amino-alkyl, mono- or dialkylaminoalkyl, hydroxyalkoxyalkyl, alkoxyalkoxyalkyl, carbalkoxyalkyl, carboxylalkyl or phenyl-alkyl having each 1 to 6, preferably 1 to 4 carbon atoms in the alkyl or alkoxy portion and R is hydrogen or halogen, alkyl, alkoxy, carbalkoxy having each 1 to 4 carbon atoms, nitro, cyano, carbonamido, mono- or dialkylcarbonamido or sulfonamido, mono- or dialkylsulfonamido and n represents the integers 1 to 3, in which process naphthalimide-4,5-dicarboxylic acids of the general formula SPC2 Or the anhydride thereof are condensed in an aqueous medium with a diamine of the general formula SPC3 At temperatures of from 80° to 160°C. R1, R and n having the above meanings.
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