1.3.6- Trinitrobenzene, reaction with phenyl

Crude enzyme was assayed in a final volume of 0.1 mL using 25 mM DKP, 25 mM potassium phosphate buffer, pH 8.0, and 1.25 mM EGTA. Reactions were started with enzyme and incubated for 30 minutes at 30°C. The reaction product, a-AP, was quantitated by HPLC after reaction with phenyl isothiocyanate (PITC). Another spectrophotometric assay used throughout the purification was carried out by measuring a-AP with trinitrobenzene sulfonate (TNBS) after incubation at pH 8.0 and 50°C using the above substrate and buffer concentrations. One unit of enzyme activity is defined as 1 pmol a-AP produced/min at pH 8.0 and 50°C using an 6416 of... 

The use of ionic liquids as solvents for nucleophilic substitutions has been reviewed. The high solubility of triamino-trinitrobenzene in fluoride-containing ionic liquids has been the subject of molecular dynamics simulations, and is likely to be due to the formation of a Zundel complex, where a proton is shared between an amino group and a fluoride ion. The solvent effects on the rate of reaction of phenyl isocyanate with alcohols have been described by multiparameter linear equations with increased solvent polarity favouring reaction. ... 

Rate and equilibrium constants have been reported for the reactions of butylamine, pyrrolidine, and piperidine with trinitrobenzene, ethyl 2,4,6-trinitrophenyl ether, and phenyl 2,4,6-trinitrophenyl ether in acetonitrile, hi these reactions, leading to cr-adduct formation and/or nucleophilic substitution, proton transfer may be rate limiting. Comparisons with data obtained in DMSO show that, while equilibrium constants for adduct formation are lower in acetonitrile, rate constants for proton transfer are higher. This probably reflects the stronger hydrogen bonding between DMSO and NH+ protons in ammonium ions and in zwitterions.113 Reaction of 1,3,5-trinitrobenzene with indole-3-carboxylate ions in methanol has been shown to yield the re-complex (26), which is the likely precursor of nitrogen- and carbon-bonded cr-adducts expected from the reaction.114 There is evidence for the intermediacy of adducts similar to (27) from the reaction of methyl 3,5-dinitrobenzoate with l,8-diazabicyclo[5.4.0]undec-8-ene (DBU) cyclization eventually yields 2-aminoindole derivatives.115... 

We have noted that both 5 2 and SnAr reactions may occur through SET processes. There is good evidence that the SnAc reaction may involve such a pathway also. Figure 8.55 shows species identified by Bacaloglu and coworkers in a fast kinetic spectroscopy study of the reaction of hydroxide ion with l-chloro-2,4,6-trinitrobenzene (picryl chloride, 71). D ending on reaction conditions, these workers could see transients ascribed to the n complex (72), an intermediate produced by single electron transfer (73), and one or more cr complexes (74, 75). In addition, evidence was obtained for the reversible formation of a phenyl carbanion (76) and a dianion (77) that probably do not lead directly to the substitution product (78). Further support for the role of SET processes in SNAr reactions comes from the detection of radical intermediates by EPR spectrometry and by correlations of reactivity with the oxidation potentials of the nucleophiles in some studies. ... 

Inhibitors are compounds, which inhibit the polymerization process during the initiation and growth of the chain. Typical inhibitors include hydroquinone, pyrocatechol and its derivatives, aromatic p-phenylenedi-amine amines, N-phenyl-2-naphthylamine, and also trinitrobenzene, picric acid, copper salts, and others. The reaction of free radical with a monomer molecule depends on the reactivity of double bonds of Ihe latter. 

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