Benzene alkylbenzene

Smith and coworkers have screened the solid catalysts for aromatic nitration, and found that zeolite (3 gives the best result. Simple aromatic compounds such as benzene, alkylbenzenes, halogenobenzenes, and certain disubstituted benzenes are nitrated in excellent yields with high regioselectivity under mild conditions using zeolite (3 as a catalyst and a stoichiometric quantity of nitric acid and acetic anhydride.11 For example, nitration of toluene gives a quantitative yield of mononitrotoluenes, of which 79% is 4-nitrotoluene. Nitration of fluorobenzene under the same conditions gives p-fluoronitrobenzene exclusively (Eqs. 2.1 and 2.2)... 

Besides 1-15 to 1-17, several other formylation methods are known.302 In one of these, dichloromethyl methyl ether formylates aromatic rings with Friedel-Crafts catalysts.303 ArCHClOMe is probably an intermediate. Orthoformates have also been used.304 In another method, aromatic rings are formylated with formyl fluoride HCOF and BF3.305 Unlike formyl chloride, formyl fluoride is stable enough for this purpose. This reaction was successful for benzene, alkylbenzenes, PhCl, PhBr, and naphthalene. Phenols can be regioselectively formylated in the ortho position in high yields by treatment with two equivalents of paraformaldehyde in aprotic solvents in the presence of SnCL and a tertiary amine.306 Phenols... 

It is well-recognized that phenols are completely protonated in superacidic solutions.420 This raised the possibility that protonated phenols, once formed in these media, might resist further electrophilic attack. Electrophilic hydroxylations of aromatics with hydrogen peroxide (98%) in superacidic media has been achieved by Olah and Ohnishi617 in Magic Acid, which allows clean, high-yield preparation of monohydroxylated products. Benzene, alkylbenzenes, and halobenzenes are efficiently hydroxylated at low temperatures. The obtained yields and isomer distributions are shown in Table 5.36. Subsequently, Olah et al.618 found that benzene and... 

In general circumstances, unless solvolysis is involved, the more common organic solvents, such as benzene, alkylbenzenes, methanol, acetone, chloroform, and diethyl ether, dissolve little of the true coal substance and usually extract only that material that is occluded within the coal matrix. 

Using Menke s conditions, Smith et al.[29,30] have described a method for the nitration of benzene, alkylbenzenes and halogenobenzenes using zeolites with different topologies (HBeta, HY, HZSM-5 and HMordenite) as catalysts and a stoichiometric amount of nitric acid and acetic anhydride. The reactions were carried out without solvent at temperatures between -50 °C and 20 °C. For the nitration of toluene, tridirectional zeolites HBeta and HY were the most active catalysts achieving >99 % conversion in 5 min reaction time. However, HY exhibited selectivity to the p-nitrotoluene very similar to the homogeneous phase, while with HBeta, selectivities to p-nitrotoluene higher than 70% could be achieved. HBeta zeolite exhibited excellent para-selectivity for the nitration of the different monosubstituted aromatics (Table 5.1). The catalyst can be recycled and the only by-product, acetic acid, can be separated by vacuum distillation. 

Under acidic conditions, the alkylation and dealkylation of aromatic compounds are reversible reactions involving several steps in which n- and CT-complexes are formed. However, dealkylation proceeds only under more drastic conditions compared with alkylation. Nevertheless, this is not always the case. For example, if the aromatic compound is of the DPM type, the dealkylation may proceed under mild conditions since the cations formed (Fig. 6.6.5) are resonance-stabilized. This statement is supported by the fact that DPM derivatives may be degraded even at room temperature by aluminum chloride to yield benzene, alkylbenzene, and alkyldiphenylmethane, together with some resinous substances (Tsuge and Tashiro 1962, 1965). 

Simple aromatic compounds such as benzene, alkylbenzene.s, and halobenzenes (e. g., 12) arc nitrated in quantitative yield and with high para selectivity in a solvent-frcc process by the use of a mixture of nitric acid and acetic anhydride at 0-20 C in the presence of zeolite beta... 

Many organic compounds react with carboxylic acids, acyl halides, or anhydrides in the presence of certain metallic halides, metallic oxides, iodine, or inorganic acids to form carbonyl compounds. The reaction is generally applicable to aromatic hydrocarbons. Benzene, alkylbenzenes, biphenyl, fluorene, naphthalene, anthracene, acenaphthene, phenanthrene, higher aromatic ring systems, and many derivatives undergo the reaction. 

Isatins condense with benzene,alkylbenzenes, and phe-nols3 55.s42 under acidic conditions to give 192. Hydroquinone and A-methylisatin with sulfuric-acetic acid gave 193. Pyrroles and indoles 3 also condense with isatin under acidic or basic conditions. 

Normal and branched alkanes, benzene-alkylbenzenes, copaene, cadalene, phenols, sesquiterpanes, and pentacyclic triterpanes decrease in relative concentration with the maturity of the coal. 

The overall stoichiometry is shown in equation I. In some cases (benzene, alkylbenzenes) a more reactive iodine donor is required such as aluminum(III) iodide, iron(II) iodide, or copper(I) iodide. 

Gattermann-Koch reaction. Formulation of benzene, alkylbenzenes, or polycyclic aromatic hydrocarbons with carbon monoxide and hydrochloric acid in the presence of aluminum chloride at high pressure. Addition of cuprous chloride allows the reaction to proceed at atmospheric pressure. 

Olah, G.A. and Ohnishi. R. (1978) Oxyfunctionalization of hydrocarbons. 8. Electrophilic hydroxylation of benzene, alkylbenzenes, and halobenzenes with hydrogen peroxide in superadds. /. Org. Chem., 43, 865-867. 

The way in which Lewis acids oxidize aromatic compounds is not known clearly. Aromatics which are not easily oxidized, such as benzene, alkylbenzenes, naphthalene, and which give colored solutions as noted above, undoubtedly form charge-transfer complexes with the Lewis acid (see p. 175). Aromatics which are oxidized easily undergo complete electron transfer and form the cation radical, but the final state of the electron acceptor is not too-well known. A Lewis-acid anion radical has never been detected in these systems. Although the initial reaction in oxidations by antimony pentachloride has been represented as in eqn (12), it is not... 

The additions of thiols and sulphenyl chlorides to alkenylphosphonic derivatives to yield (2-alkylthioethyl)phosphonic compounds are reactions which have already been noted" Dialkyl (alkylthiomethyl)phosphonates yield a-chloro derivatives when treated with ncs in CCl/° the resultant dialkyl (l-alkylthio-l-chloromethyl)phosphonates undergo Friedel-Crafts arylation with benzene, alkylbenzenes or other activated aromatics in the presence of SnCl4 or TiCl/ yields are said to be good. 

Benzene, alkylbenzenes, and polyphenyls appear to undergo multiple exchange,... 

Alkylation. Benzene, alkylbenzenes, and halobenzenes undergo alkylation with 2,2,4-trimethylpentane in the presence of HSO3F SbFs at temperatures as low as — 30°C with good selectivity (eq 12). ... 

Aromatic compounds such as benzene, alkylbenzenes, and halobenzenes can be dlrecfly oxygenated with hydrogen... 

Benzene, alkylbenzenes and phenolic ethers react with CAN in acetonitrile to give nitration of the aromatic ring and, if of-hydrogen atoms are present, also products of side-chain substitution (Din tiirk and Ridd, 1982a, 1982b). With many substrates, for instance with toluene. 

Generally, the Vilsmeier reaction fails for benzene, alkylbenzenes and naphthalene. The reaction gives low yields in the case of phenol ethers if the para-position is already occupied and fails for highly substituted benzofurans, indicating that the presence of a sufficiently reactive (labile) hydrogen atom on the aromatic ring is necessary for successful application. However, Martinez et al. reported the formylation of 1,3,5-trimethylbenzene, naphthalene, acenaphthene, anthracene and phenanthrene in fair yield using the trifluoromethanesulphonic anhydride/dimethylformamide complex (Eq 1.29). 

The values of of different solutes (alkanes, cycloalkanes, 1-alkenes, 1-alkynes, benzene, alkylbenzenes, and alcohols) in the ionic liquids [EM1M][FAP], [EM1M][TCB], [BMlM][BOB] and [HMIM][BOB] obtained at several temperatures were listed in table 1-4. 

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