Benzenes and Nitrobenzene

In the USA, 150,000 t benzene were used in 1976 for the production of chlorobenzene [27]. It is assumed in western Europe that 500,000 t benzene will have been used in 1979 as initial product for chloro- and nitrobenzene [3]. Based on these figures, the annual world production of chlorinated benzenes can be estimated at 600,000-800,000 t. Direct chlorination of benzene with chlorine gas is effected on a continuous basis in the presence of catalysts, such as aluminium, mercury, iron, sulphur chlorides or molybdenum chloride [32, 36, 43], following which the mixture is separated and purified by washing, chemical treatment and distillation operations. Chlorobenzene is used mainly for the production of phenol, chloronit-robenzenes, DDT, and as a solvent, o-dichlorobenzene is a solvent, whereas p-dichlorobenzene is used as an intermediate or (in addition to naphthalene) as a mothproofing agent [292]. 

Chlorinated benzenes may also result from volatile aromatics in water during the disinfection process with chlorine (see later sections). 

In the USA, 340,000 t benzene were used for the production of nitrobenzene in 1976. Consumption of benzene for aniline production in the USA was 208,000 t in 1975, and is estimated at 281,000 t in 1980 [3]. In western Europe, it is assumed that 500,000 t benzene will be used in 1979 as the initial product for chloro- and nitrobenzene [3]. On the basis of these figures, it can be deduced that the annual world production of nitrobenzene is in the order of 800,000 to 1 million t. Nitrobenzene is generally obtained on a continuous basis by the reaction of benzene with a mixture of sulphuric acid and nitric acid [36], and it is used in particular as the initial product for intermediates - particularly aniline - and as a solvent. 

The losses of chlorinated benzenes and nitrobenzene in the chemical industry are probably low - also because of the low vapour pressure - and will total less than 20,000 t. Losses from its use as a solvent could be higher, perhaps in the order of 50,000-100,000 t worldwide. The quantities of chlorinated aromatics formed during the chlorine disinfection of waters are difficult to assess, but are probably low. 

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The object of these studies has been the determination of the degree of association in thiazole and its alkyl derivatives. Various solvents have been used cyclohexane (154), carbon tetrachloride (155, 156), benzene and nitrobenzene (157). 

Solvent Treatment. Solvent processes can be divided into two main categories, solvent extraction and solvent dewaxing. The solvent used in the extraction processes include propane and cresyHc acid, 2,2 -dichlorodiethyl ether, phenol (qv), furfural, sulfur dioxide, benzene, and nitrobenzene. In the dewaxing process (28), the principal solvents are benzene, methyl ethyl ketone, methyl isobutyl ketone, propane, petroleum naphtha, ethylene dichloride, methylene chloride, sulfur dioxide, and iV-methylpyrroHdinone. 

For instance, it has been observed that the addition of additives such as cyclohexane, benzene, and nitrobenzene to water/AOT/isoctane systems considerably increases the maximum amount of solubilized water [48]. The same effect has been observed in the presence of finite amounts of cytochrome c [49]. 

The oxidation of benzene to phenol and 1,4-dihydroxybenzene (Figure 2.11a) (Hyman et al. 1985), both side chain and ring oxidation of ethyl benzene, and ring-hydroxylation of halogenated benzenes and nitrobenzene (Keener and Arp 1994). 

Even though some nitroaromatic compounds are purposefully spread in the environment as pesticides, the majority of their environmental releases are accidental. For example, in the United States alone, 5.1 tons of nitrobenzene were released in soil in 2002 [65]. The greatest known industrial releases have occurred in China in 2005, an explosion at a chemical factory resulted in the accidental release of 100 tons of benzene and nitrobenzene to the Songhua River [66]. 

TABLE 3. Enthalpies of formation of polynitrobenzenes (including benzene and nitrobenzene)0... 

Kralj, F. and Sincic, D. Mutual solubilities of phenol, salicyaldehyde, phenol-salicyaldehyde mixture, and water with and without the presence of sodium chloride and sodium chloride plus sodium sulfate, J. Chem. Eng. Data, 25 (4) 335-338,1980. Kramer, C.R. and Henze, U. Partitioning properties of benzene derivatives. 1. Temperature dependence of the partitioning of monosubstituted benzenes and nitrobenzenes in the n-octanol/water system, Z. Phys. Chem., 271(3) 503-513,1990. Krasnoshchekova, R.Ya. and Gubergrits, M. Solubility of paraffin hydrocarbons in fresh and salt water, Neftekhlmlya, 13(6) 885-888, 1973. 

We now turn to the two aryl hydroxylamines, Af-phenylhydroxylamine and its o-nitro derivative. As liquids, the former compound has an enthalpy of formation that is ca 20 kJmoH more positive than that of the latter. For comparison, we find the enthalpies of the corresponding hquid species without the NHOH group, Le. benzene and nitrobenzene, differ by 36.5 kJmol . Alternatively said, equation 4 is endothermic by 16.1 kJmol . 

The above-mentioned radical acceptors are not the only effective protective agents against radiation. Studies performed with benzene and nitrobenzene in natural rubber and styrene butadiene rubber (SBR) with N-phenyl-p-naphtylamine demonstrated radiation protection of the respective compounds. 

From the reaction (equation 19) of anilines and naphthylamines, [VC14L2] were obtained,414,424 and with diamines (14)-(16), compounds VCUL result. They are hygroscopic, insoluble in CHCI3, CCI4, benzene and nitrobenzene and slightly soluble in acetone and dioxane. 

Coleman, Newman, and Garrett have kinetically investigated the decomposition of benzoyl azide in benzene and nitrobenzene solution with halides as Lewis adds.1 7 They grouped the halides into three classes based on the kinetic equation involved ... 

For Hammett correlations for rate constants of substituted benzenes reacting with hydroxyl radicals under experimental conditions of pH 9, the elementary hydroxyl radical rate constants (l/m sec 108) containing toluene, dimethoxy-benzene, benzene, and nitrobenzene correlate with aresonance as follows ... 

Compounds Hydrocarbons, molecules of the form AB3 and ABg, organic compounds containing hetroatoms (N, O, F), nitrogen and oxygen hetrocycles, flurinat-ed benzenes and nitrobenzenes... 

Kramer, C.R., Henze, U. (1990) Partitioning properties of benzene derivatives. I. Temperature dependence of the partitioning of monosubstituted benzenes and nitrobenzenes in the ra-octanol/water system. Z. Phys. Chem. (Leipzig) 271(3), 503-513. 

The effect of finely divided material on the freezing points of water, benzene, and nitrobenzene. J. Am. Chem. Soc., 43 1011-1018. 

On November 13, 2005, a series of explosion occurred within an hour at Petrochemical Plant in Jilin City, Jilin Province, China. The explosions killed five people, injured about seventy people, and caused the evacuation of over 10,000 residents. About 100 tones of benzene and nitrobenzene were discharged into the Songhua River, and a toxic slick drifted down the Songhua River and the Amur River over subsequent weeks ended up flowing into the Strait of Tartary, after going through the Chinese and Russian teritories. 

The kinetics of butadiene polymerized by bis(7T-allyl nickel trifluoro-acetate) has been studied by Teyssie et al. [173]. Equilibrium constants for the formation of the complex (with aromatic compounds which give the equibinary polymer), calculated from cryoscopic measurements or polymer micro-structure, are 6—7 and 26—35 respectively for benzene and nitrobenzene. The higher concentration of active centres compared with... 

This original Pinner method shown in Equation (1) is still widely used. Solvents such as ether, dioxane, dichloromethane, chloroform, benzene, and nitrobenzene are often used as diluents and as an aid to crystallization of the imidate salt. Methanol and ethanol are the most widely used alcohols in the Pinner reaction, but other alcohols have also been employed and have given satisfactory results. However, the use of substituted nitriles in the Pinner synthesis has some limitations, and some nitriles cannot be converted into corresponding imidates but form amides instead. Fortunately, it has been found that those nitriles which give poor yields under the acidic conditions of the Pinner synthesis give good yields under base-catalyzed conditions (Equation (2)) reported first by Nef, etc.146,147 The base-catalyzed and acid-catalyzed processes therefore complement each other. 

Solubility of nitrobenzene.—Describe the odor of nitrobenzene. Determine whether nitrobenzene is soluble in alcohol, ether, benzene, dilute hydrochloric acid, and a solution of sodium hydroxide. Mix about 2 cc. of nitrobenzene with 5 cc. of concentrated sulphuric acid and pour the mixture into water. How could you most readily separate into its constituents a mixture of benzene and nitrobenzene ... 

Electrophilic aromatic substitution is a situation in which it is useful to discuss TS structure in terms of a reaction intermediate. The ortho, para, and meta directing effects of aromatic substituents were among the first structure-reactivity relationships to be developed in organic chemistry. Certain functional groups activate aromatic rings toward substitution and direct the entering electrophile to the ortho and para positions, whereas others are deactivating and lead to substitution in the meta position. The bromination of methoxybenzene (anisole), benzene, and nitrobenzene can serve as examples for discussion. 

Fig. 3.13. Relative energies of intermediates for bromination of methoxybenzene, benzene, and nitrobenzene indicating the effect of substituents on energy of intermediates.

Take a minute to compare the electrostatic potential maps for anisole, benzene, and nitrobenzene. Notice that an electron-donating substituent (OCH3) makes the ring more red (more negative), whereas an electron-withdrawing substituent (NO2) makes the ring less red (less negative). 

The mechanism of the catalytic hydroxylation of aromatic hydrocarbons by hydrogen peroxide has been reviewed (ref.8). The hydroxylation of benzene or toluene by peroxydiphosphate (ref.9) and peroxydisulphate, (more comnronly termed persulphate) (ref. 10) in aqueous (0.05-1.OM) acid in the presence of Cu(ll) has been found to be similar. Phenol (15.6%), diphenyl (5.2%), and 2-and 4-nitrophenols (11.7% and 5.6% respectively) resulted from a mixture of benzene and nitrobenzene in water at 80 C with peroxydisulphate. 

The emulsion from the reactor was collected in a glass flask immersed in an ice bath here it separated by decanting into acid and hydrocarbon phases. The total acidity of the latter phase was measured by titrating a methanolic solution of it with standard sodium hydroxide to a methyl red endpoint. Part of the hydrocarbon phase was water washed, and it was then analyzed by gas chromatography using a Perkin Elmer Model 154 Vapor Fractometer for benzene and nitrobenzene. Certain by-products were also detected when and if they formed. 

The distributions of benzene and nitrobenzene between phases are shown in Figure 4 as a function of the organic phase... 

Figure 4. Effect of organic-phase composition on distribution of benzene and nitrobenzene between phases at 33°C (acid phase was 20 mole % sulfuric add)...

We must calculate the time required for 96% conversion. The rate information of Biggs and White [M. Biggs and R.R. White, Amer. Inst. Chem. Eng. JL, 2, 321 91956)] can be used, and one may assume that the volume of benzene and nitrobenzene are additive. Note that the equation in the title of Figure 11 of that reference is in error. (Optional question What does one do with the reaction mixture at the end—both to recover product and minimize environmental problems )... 

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