Catalytic nitrations

These three steps all produce significant amounts of waste. First, as discussed earlier, the nitration process results in the production of spent sulfuric acid. In the past the company had been able to sell much of this material to the coke and steel industries but declining demand meant that the acid now required disposing of, at additional cost. At the time green catalytic nitration technology was becoming available with clay, zeolite and lanthanide catalysts all providing possible alternatives to the use of sulfuric acid (see below). Improved selectivity to the desired para-isomer is an added benefit of some of these catalytic systems. However on the... 

These two concepts have been proved on a laboratory scale, mainly for hydrogenation reactions but can be transposed to many gas-liquid catalyzed reactions. Interesting potential applications have been mentioned, such as asphaltene hydrocracking or nitrate and nitrites removal from drinking water by catalytic nitrate reduction. However, the characteristics of ceramic... 

Priisse U, Hahnlein M, Daum J, and Vorlop CD. Improving the catalytic nitrate reduction. Catal Today 2000 55 79-90. 

For the time being, most of the processes of catalytic nitrate removal have been carried out in a batch mode. In the early 1990s Sell performed pilot studies in continuous... 

Sell M., Bischoff M. and Bonse D. 1992. Catalytic nitrate reduction in drinking water. Results and experiences from pilot plant trials, Vom Wasser, 79, 129-144. 

Hahnlein M., Priisse U., Daum J., Morawsky V., Kroger M., Schroder M., Schnabel M. and Vorlop K.-D. 1998. Preparation of microscopic catalysts and colloids for catalytic nitrate and nitrite reduction and their use in hallow fibre dialiser loop reactor. Stud. Surf. Sci. Catal., 118, 99-107. 

One of the most successful approaches for altering the regioselectirity of aromatic nitration involves nitration via metallation fl35]. This was discovered as a catalytic nitration which at the same time also provides unusual isomer distribution. The most important metallative nitration reactions involve metallation with mercury, palladium, and thallium salts. 

The first report of catalytic nitration via mercuration was a patent issued to Wolffenstein and Boeters (136] at the beginning of the century. They reported a procedure for the synthesis of dinitrophenol and picric add via oxynitration of benzene with mercuric nitrate and 50-55% nitric acid. The mechanism of oxynitration was delineated by Wesiheimer ei al. (137]. 

Zaraisky. A.P. Kachurin. O.I. Velichko, L.I. Shur. V.B. Tikhonova. LA. Furin. G.G. Phase transfer catalysis in reactions of electrophilic substitution. VIII. Phase transfer catalytic nitration of arenes with sodium nitrite in an acidic medium. Zh. Org. Khim. 1999, 35. 1063-1067. 

Based on this work a sensitive and stable electrochemical biosensor for nitrate was constructed using plant NR and the highest potential mediator AQ at a glassy carbon electrode. Amperometry was used to monitor the catalytic nitrate reduction current at the electrode in a homogeneously stirred 50 mM Bis-Tris buffer solution at an applied potential of -400 mV vs. NHE. An initial steady-state current response was observed in the presence of 10 pM nitrate and subsequent nitrate additions at intervals of 100 s led to a step in the current with a steady state reached within ca. 30 s. The steady-state current increased linearly with nitrate concentration from 10 to 70 pM and the detection limit was found to be 0.76 nM (S/N = 3). The practical application of the biosensor was demonstrated by the determination of nitrate... 

Coelho et al have reported the eatalytic voltammetry of NapAB from Cupri-avidus necator In the absence of mediators, no nitrate reductase electrocatalysis was found but a catalytic cathodic wave was observed upon addition of H2O2 (peroxidase activity). When MV was used as a mediator a catalytic nitrate reduetion eurrent was observed. 

Shi, M. Cui, S. Yin, W. Highly efficient catalytic nitration of phenolic compounds by nitric acid with a recoverable and reusable Zr or Hf oxychloride complex and KSE. Eur. J. Org. Chem. 2005,... 

Chaplin, B.P., Roundy, E Guy, K.A., Shaply, J.R. and Werth, C.J. (2006) Effects of natural water ions and humid add on catalytic nitrate reduction kinetics using an alumina supported Pd-Cu catalyst Environmental Science Technology, 40, 3075 1. 

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