Nitrobenzene, as solvent

There is usually no reaction with nitrobenzene as solvent. However, in this medium acetoxybenzylidene azlactones undergo a Fries rearrangement [Eq. (16)]. 

The next and only other major kinetic study was carried out by Jensen and Brown184, who used aluminium chloride as catalyst, nitrobenzene as solvent, benzene- and p-toluene-sulphonyl chlorides as sulphonylating agents and benzene, chlorobenzene, alkyl- and polyalkylbenzenes as aromatic substrates184. 

Brown and Young410,411 studied the benzoylation of benzene and toluene by benzoyl chloride catalysed by aluminium chloride at 25 °C in nitrobenzene as solvent. For a given concentration of reagents, the rate equation was... 

The use of ethylene dichloride as solvent was extended by Brown et al. 11 to the determination of the kinetics of benzoylation of other aromatics, using benzoyl chloride catalysed by aluminium chloride, and the data are included in Table 109 the relative reactivities are thus benzene, 1.0 toluene, 117 o-xylene, 1,393 m-xylene, 3,960 and p-xylene, 243 and these values are closely similar to those obtained with nitrobenzene as solvent. No exact comparison of the coefficients with those of Corriu et al. 16 is possible because of the different temperatures employed, but the rates appear to be comparable for the two sets of data after allowing for reasonable temperature dependencies. 

The results of reactions with and without MW irradiation are reported in Table 4.11. The reaction yields are comparable, but the reaction times of the irradiated reactions are considerably reduced. The alumina does not give acceptable results. The same reactions were carried out in nitrobenzene as solvent and under free-solvent conditions with and without MW irradiation. The results are reported in Table 4.12. In this case too, the only significant difference is the reaction time, so that the authors [41] concluded that MW-promoted reactions proceed like the thermal reactions except for a much higher reaction rate. 

The EMF and SHG responses for nitrobenzene as solvent were qualitatively identical to those for l,k2-dichloroethane [Fig, 17(b)]. The only difference between the results for the two solvents was that the SHG response to KCl of nitrobenzene membranes with ionic sites was more sensitive than for 1,2-dichloroethane membranes with ionic sites, where an increase in the SHG intensity was observed at KCl activities above 10 " M KCl. 

The heat of decomposition (238.4 kJ/mol, 3.92 kJ/g) has been calculated to give an adiabatic product temperature of 2150°C accompanied by a 24-fold pressure increase in a closed vessel [9], Dining research into the Friedel-Crafts acylation reaction of aromatic compounds (components unspecified) in nitrobenzene as solvent, it was decided to use nitromethane in place of nitrobenzene because of the lower toxicity of the former. However, because of the lower boiling point of nitromethane (101°C, against 210°C for nitrobenzene), the reactions were run in an autoclave so that the same maximum reaction temperature of 155°C could be used, but at a maximum pressure of 10 bar. The reaction mixture was heated to 150°C and maintained there for 10 minutes, when a rapidly accelerating increase in temperature was noticed, and at 160°C the lid of the autoclave was blown off as decomposition accelerated to explosion [10], Impurities present in the commercial solvent are listed, and a recommended purification procedure is described [11]. The thermal decomposition of nitromethane under supercritical conditions has been studied [12], The effects of very high pressure and of temperature on the physical properties, chemical reactivity and thermal decomposition of nitromethane have been studied, and a mechanism for the bimolecular decomposition (to ammonium formate and water) identified [13], Solid nitromethane apparently has different susceptibility to detonation according to the orientation of the crystal, a theoretical model is advanced [14], Nitromethane actually finds employment as an explosive [15],... 

Golden obtained polymeric materials with molecular weights up to 1800 from potassium />-chlorophenoxide in refluxing nitrobenzene as solvent in the presence of copper bronze as catalyst (28). 

In this reaction, nitrobenzene as solvent has an important function because it causes acylation to occur predominantly at the 6-position, whereas l-acetyl-2-methoxynaphthalene is the principal product when carbon disulfide is used. The main feature of this procedure is the particular attention given to temperature control in order to obtain reliable results. It has been observed that the ratio of 6-acetylated to 1-acetylated nerolin is dependent on the temperature, the lower temperatures favoring 1 -acetylation. Below 0° the yield of 6-acetylated product is only 3-10%. At higher temperatures the 6-acetylated product predominates, but an increased amount of tarry material is formed. 

Fries rearrangement—that is, the transformation of phenolic esters to isomeric hydroxyphenyl ketones—is related to Friedel-Crafts acylations.392,393 Olah et al.394 have found a convenient way to perform the Fries rearrangement of a variety of substituted phenolic esters in the presence of Nafion-H in nitrobenzene as solvent [Eq. (5.153)]. A catalytic amount of Nafion-H is satisfactory, and the catalyst can be recycled. In contrast, Nafion-silica nanocomposites, in general, exhibit low activities in the Fries rearrangement of phenyl acetate to yield isomeric hydroxyacetophe-nones.239,395 In a recent study, BF3-H20 was found to be highly efficient under mild conditions (80°C, 1 h) to transform phenolic esters of aliphatic and aromatic carboxylic acids to ketones (71-99% yields).396 In most cases the para-hydroxyphenyl isomers are formed with high (up to 94%) selectivity. 

Table 2.2 Composition (wt%) of the reaction mixture (RM) and of the organic compounds adsorbed within the zeolite micropores (AM) after contact of a 2-MN and 1-AMN mixture for 4 min at 393 K with the zeolite in nitrobenzene as solvent...

In 1962, Bonner (14) at DuPont was the first one who reported the synthesis of wholly aromatic poly(ether ketone ketone)s (PEKK) by Friedel-Crafts acylation. Isophthaloyl chloride was condensed with diphenyl ether using nitrobenzene as solvent and aluminum trichloride as a catalyst. 

Messmer and Sziman measured the coupling rates of p-methoxybenzene-diazonium tetrafluoroborate with N,N-dimethylaniline, m-toluidine and 1- and 2-naphthylamine in nitrobenzene as solvent. Except for reactions with m-toluidine, the reaction rates were reduced significantly if a deuterium ion had to be displaced instead of a proton. The kinetic isotope effect varied from k /kp = 1.5 for 2,4,6-dj-... 

A detailed analytical study of fhe acfivity of some solid acid catalysts, including mesoporous silica-supported Nation, in the acylation of anisole with AAN allows the conclusion that catalyst deactivation is caused by the primary ketone product and/or multiple acetylated products in the micropores of Nation catalyst aggregates. i Experiments were performed with a commercially available silica-supported Nation catalyst in a continuous-mode slurry operation by using carbon-dioxide-expanded liquids (nitromethane or nitrobenzene) as solvents. At 90°C, 80% AAN conversion is observed with a TOS of 2 h, but the catalyst rapidly deactivates, and 27% conversion is evaluated after 6 h TOS with a TON value of about 400. The catalyst can, however, be completely regenerated upon nitric acid treatment. These results confirm that silica-supported Nation catalysts are promising alternatives for the traditional aluminum chloride homogeneous Lewis acid catalyst. 

StiUe coupling. A synthesis of (Zl-cinnamyl alcohols can exploit this coupling using stannoxane derivatives.- The coupling is favored by nitrobenzene as solvent, dramatic improvement of yields observed in some cases. 

Figure 5. Mooney-Rivlin plots of stress-strain data(lO) for two tetrol-based polyurethane networks from system 5 of Figures 2 and 4, prepared at various dilutions in nitrobenzene as solvent. Networks swollen in nitrobenzene at 4QOC...

Trichloro-2-thienyllithium prepared from tetrachlorothiophene by lithium-chlorine exchange (Bu"Li) reacted with aldehydes and ketones to generate carbinols. Treatment of the (2-hydroxymethyl) trichlorothiophene (406) with catalytic TsOH in refluxing benzene gave the electrophilic substitution product (407). Replacement of benzene with nitrobenzene as solvent led to... 

Polymeric salts of the poly(3,4-cycloalkylthiophene)s were obtained by electropolymerization in a divided compartment cell at 25°C in acetonitrile or nitrobenzene as solvent. The monomer and electrolyte concentrations were 0.01 and 0.1 mol/1, respectively. The optimum current density under galvanostatic conditions was found to be 2 mA/cm. Chemical polymerizations were performed using iron trichloride in acetonitrile or chloroform as oxidizing agent. 

The electropolymerization of alkylthiophene is carried out mostly in a one-compartment cell, using platinum as working electrodes and nitrobenzene as solvent. Lower temperatures, preferentially between 5-15 °C and current densities ranging 1-2mA/ cm are applied in galvanostatic conditions [74]. Dihydroisothiophene and aromatic bridged thiophene see [75]. 

The total synthesis of hikizimycin has been reported, which involves the use of nitrobenzene as solvent in an improved Vorbruggen reaction. ... 

Also obtained (by-product) by Fries rearrangement of o-tolyl acetate with aluminium chloride, ferric chloride or titanium tetrachloride in nitrobenzene as solvent between 20° and 60° (3-5%) [2143,2598-2600],... 

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