Nitrogen-containing model compounds

Nitrogen Containing Model Compounds (Aniiine C6H7N, indole C8H7N,... 

Hansson KM, Samuelsson J, TuUin C, Amand LE. Formation of HNCO, HCN, and NH3 from the pyrolysis of bark and nitrogen-containing model compounds. Combust Flame. 2004 137 265-277. 

In general, the model compounds are chosen to reflect the pyrolysis process of complex coal. The pyrolysis mechanisms of oxygen-, nitrogen-, and sulfur-containing model compounds in coal will be introduced in detail in the following sections to illustrate some important pyrolysis reactions of coal. 

The intramolecular hydrogen migration appears often in the pyrolysis mechanism of oxygen-, nitrogen-, and sulfur-containing model compounds, and plays an important role, which can be summarized as follows (a) it offers more reasonable reaction paths for the formation of products (b) it allows for reasonable interpretation of experimental results (c) it needs less activation energy (d) it explains the distribution of products. 

A large number and diverse classes of compounds have been reported to possess tyrosinase inhibitory activities to various extents from the millimo-lar to nanomolar concentration ranges. From our laboratory we have also reported a large variety of tyrosinase inhibitors and for some of them we have performed molecular modeling as well. Among them there are several alkaloids, and nitrogen-containing molecules are also present. 

The use of surface-enhanced resonance Raman spectroscopy (SERRS) as an identification tool in TLC and HPLC has been investigated in detail. The chemical structures and common names of anionic dyes employed as model compounds are depicted in Fig. 3.88. RP-HPLC separations were performed in an ODS column (100 X 3 mm i.d. particla size 5 pm). The flow rate was 0.7 ml/min and dyes were detected at 500 nm. A heated nitrogen flow (200°C, 3 bar) was employed for spraying the effluent and for evaporating the solvent. Silica and alumina TLC plates were applied as deposition substrates they were moved at a speed of 2 mm/min. Solvents A and B were ammonium acetate-acetic acid buffer (pH = 4.7) containing 25 mM tributylammonium nitrate (TBAN03) and methanol, respectively. The baseline separation of anionic dyes is illustrated in Fig. 3.89. It was established that the limits of identification of the deposited dyes were 10 - 20 ng corresponding to the injected concentrations of 5 - 10 /ig/ml. It was further stated that the combined HPLC-(TLC)-SERRS technique makes possible the safe identification of anionic dyes [150],... 

The results of model compound studies with three different types of epoxides, obtained in the presence and absence of ammonium perchlorate are shown in Figures 4, 5, and 6. The epoxide DER-332 shows a uniform rate of disappearance for the acid and epoxide species in this reaction. In the presence of ammonium perchlorate, the rate is increased, and a minimum of side reactions occur. Similar data but faster reaction rates are obtained with Epon X-801, but the consumption of epoxide species by side reactions is increased, particularly in the presence of ammonium perchlorate. On the other hand, the epoxide ERLA-0510 (Table IV), which contains a basic nitrogen, shows a reaction rate which is an order of magnitude greater than that for DER-332, accompanied by a substantial increase in side reactions. In the presence of ammonium perchlorate, the side reactions of ERLA-0510 predominate. In all probability, the side reactions of the multifunctional epoxides studied are homopolymerization. 

We decided to use as a very sensitive model reaction the hydrogenation of 1-chloro-2,4-di-nitrobenzene in order to find new and efficient dehalogenation inhibitors. For comparison, dicyandiamide was used as standard inhibitor. We concentrated our search of new modifiers on nitrogen containing compounds and found the most interesting effects with compounds of the following general structure... 

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