Other toluene derivatives

A further important derivative of toluene is 4-tert-butyltoluene, which is obtained by the alkylation of toluene with isobutene. 4-tert-Butyltoluene is the starting material in the production of 4-tert-butylbenzoic acid, which is used as a corrosion inhibitor and modifier for alkyd resins. 

Mild oxidation of 4-tert-butyltoluene produces 4-tert-butylbenzaldehyde, which finds application as a perfumery component. 

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Aromatic alcohols are called phenols. The simplest phenol, also called phenol, forms when a hydroxyl group replaces a hydrogen atom in the benzene ring. Phenol (carbolic acid) was used as an antiseptic in the 1800s. Today other phenol derivatives are used in antiseptic mouthwashes and in cleaning disinfectants such as Lysol. Phenols are easily oxidized, and this makes them ideal substances to use as antioxidants. By adding phenols such as BHT (butylated hydroxy toluene) and BHA (butylated hydroxy anisole) to food, the phenols oxidize rather than the food. 

Lhder these terms are known organic compds contg either two —N02, two —ONOa or two —NO groups. As a rule, they are described in this Encyclopedia under corresponding parent compds. For example, Dinitrobenzenes are described under Benzene and Dinitro-toluenes are under Toluene. If a parent compd has no other nitrated derivatives besides di-(such as mono-,, tri-, tetra-, etc — nitro- or... 

Feng and others (1986) have performed quantum chemical calculations of aromatic nitration. The results they obtained were in good accord with the ionization potentials of N02 and benzene and its derivatives. The radical pair recombination mechanism is favored for nitration whenever the ionization potential of the aromatic is much less than that of N02. According to the calculations, nitration of toluene and xylene with NO) most probably proceeds according to the ion radical mechanism. Nitration of nitrobenzene and other benzene derivatives with electroacceptor substituents can proceed through the classical polar mechanism only. As for benzene itself, both mechanisms (ion radical and polar) are possible. 

Most V6-barriers determined involve methyl groups, and V6 is invariably found to be small in corroborations with the findings above. Typical values are V6 = —24.400 0.024 J/mol for CH3N0272 V6 = -57.61 J/mol for CH3BF273), and V6 = -58.37 0.08 J/mol for CH3C6H567). For other p-toluene derivatives V6 is typically about -60 J/mol44. ... 

Nitrobenzene, 2,4-dinitro-toluene and other benzene derivatives along with phenol, phenyl propanol and thiourea Spherisorb ODS-2, 3 pm Acetonitrile-4 mM Tris, pH 9.2 (60 40) or gradient elution to 80 20 435 mm x 50 pm i.d. 158 mm effective length 78... 

Other hydrocarbons, derivatives of benzene, can be obtained by replacing the hydrogen atoms by methyl groups or similar groups. Coal tar and petroleum contain substances of this sort, such as toluene, and the three xylenes, These formulas are usually written... 

The meta compound is prepared by other methods (p. 532) in which by starting with a toluene derivative, in which the ortho and para positions are occupied, sulphonation affects the meta position. The ortho and para substituents are then removed. Sulphonic acids of xylene, mesitylene and cymene are also known. 

On a smaller scale m-xylene is oxidized to isophthalic acid. In the field of fine chemicals, different toluene derivatives and other alkyl-substituted aromatic systems are oxidized to a variety of substituted aromatic acids, which constitute important feedstocks to polymers, plastics, fibers, foils, or intermediates for pharmaceuticals and agrochemicals. 

In 1884, Friedel and Crafts reported that the alkylation of benzene or toluene with dichloromethane in the presence of AlCb avoided the corresponding diarylmethanes, besides other products derived from further alkylation and other transformations. pr ucts from the reaction with benzene are shown... 

Other nitro-derivatives of hydrocarhons and of phenols are used in explosive mixtures. Among the former are dinitro-benzene, chlor-dinitro-benzene, dinitro-toluene, di- or tri-nitro-den-vatives of mesitylene, pseudocumene, and xylene, dinitro-naphthalene. Trinitro-naphthalene and tetra-nitro-naphthalene have also been proposed. Of the nitro-phenols, perhaps the most important is tri-nitro-cresol, known as Cresilite in France, where it is added to Melinite. Other nitro-derivatives of the aromatic series will be mentioned in the section on detonators. 

Fission of the 1,4-biradical affords acetophenone in competition with cycliz-ation. The products are obtained as racemic diastereoisomers. The other ether derivatives (41, n = 2) are also reactive and undergo formation of 1,5-biradicals on irradiation. The selectivity of the reactions was investigated in the presence of chiral hosts. The best yields were obtained for the series (41, R = H, n = 2) using the host molecule (44) in toluene at — 45°C. This gave a 70% yield of products... 

Norrish Type I cleavage of benzylketones occurs very readily to yield benzyl and acyl radicals. In competition with other processes, these can couple by attack of the acyl radical upon the aromatic nucleus of the benzyl radical to give as a product an acyl toluene derivative. Turro has examined the photochemical properties of the 2-phenylalkanones (326) in solution and complexed with cyclodextrins. In solution the major fate of the Type I biradicals formed is intr2unolecular recombination by attack of the acyl radical at the para position of the benzyl radical to generate (327). However, complexatlon of (326) within the cyclodextrin cavity inhibits formation of (327) and promotes disproportionation of the blradicals to give (328). Turro has also examined the photochemistry of dlbenzylketone Included in zeolites.Recombination of the Type I radicals in this case can produce a mixture of (2-methyl-phenyl) benzylketone and (4-methylphenyl)benzylketone decarbonylation of the acyl radical competes and leads to the isolation of 1,2-dlphenylethane. It is found that the relative yields of the products... 

In 1982, Van, Zhang, Jiang and Hu41 (VZJH) reported the heats of combustion and formation of benzenesulphonamide and two of its methyl (i.e. toluene) derivatives, x-RC6H4S02NH2 R = H, 24a x-R = 2 and 4-Me, 67a and 67b, respectively. These findings are presented in Table 11. The results are internally consistent. The relative isomer stabilities of 67a and 67b is qualitatively and quantitatively consistent with that of other substituted benzenes [e.g. <5AHf(s, 37b, 37d) = 0.8 kcal mol-1]. In addition, that either of the isomeric toluenesulphonamides, 67a and 67b, is some 9 kcal mol-1 lower than that of... 

As a general observation, it is important to note that reaction between alkoxides and other metal derivatives, such as acetates, can be strongly dependent on the solvent and/or the addition order of the reactants [84]. Thus, no reaction is observed between anhydrous Pb(OAc)2 and Nb(OEt)s in THE at room temperature, but the acetate dissolves readily in toluene at room temperature in the presence of the niobium alkoxide with formation of a Pb-Nb species [80]. Another general feature is that in heterometallic acetatoalkoxides obtained by this route, the metal introduced as an alkoxide appears predominant. More condensed species are obtained if the reaction is achieved at higher temperatures [93] ... 

The quest for microorganisms capable of performing the desired biotransformation of indene led to the isolation of several strains of the genus Rhodococcus from soil samples contaminated with aromatic compounds that are able to oxidize indene to 1,2-indandiols of different chirality, and various other oxygenated derivatives [8]. Induction studies indicated that several oxygenases were present and differentially induced by naphthalene, toluene, and indene. The stereospecific nature of the enzymes expressed in Rhodococcus as well as their abihty to tolerate indene as a substrate makes these microorganisms promising candidates for development as an industrial-scale biocatalyst for the production of (21 )-indandiol. 

Another example where hydrogen bonding is a dominant supramolecular interaction is in the bis-urea motif, as found for example in 2,4-bis(2-ethylhexylureido)toluene (EHUT) (Figure 34.7). This molecule, as weU as other bis-ureido-toluene derivatives, has been studied in great detail by BouteiUer and coworkers [26, 27]. 

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