Aromatic hydrocarbons, reactions Resins, formation

Solid Catalysts. Nafion-H is an active catalyst for acylation with aroyl halides and anhydrides.60,61 The reaction is carried out at the boiling point of the aromatic hydrocarbons. Yields with benzoyl chloride using 10-30% Nafion-H for benzene, toluene, and p-xylene are 14%, 85% and 82%, respectively. Attempted acylation with acetyl chloride, however, led to HC1 evolution and ketene formation. Nation resin-silica nanocomposite materials containing a dispersed form of the resin within silica exhibits significantly enhanced activity in Friedel-Crafts acylations.62,63... 

Nitrated hydroxyaromatics may enter into the atmosphere from both primary and secondary sources. The formation of nitrophenols and nitrocresols in die combustion processes of motor vehicles has been reported by Tremp et al. (1993). Others primary sources may be combustion of coal, wood, manufacture of phenol-formaldehyde resins, pharmaceuticals disinfectants, dyes and explosives (Harrison et al., 2005). Studies in our and other laboratories have shown that an additional important source of diese compounds in the atmosphere could be the gas-phase OH-radical initiated photooxidation of aromatic hydrocarbons such as benzene, toluene, phenol, cresols and dihydroxybenzenes in the presence of NOx during the daytime as well as the reaction of NO3 radicals widi these aromatics during the night time (Atkinson et al., 1992 Olariu et al., 2002). Once released or... 

Purely aromatic ketones generally do not give satisfactory results pinacols and resinous products often predominate. The reduction of ketonic compounds of high molecular weight and very slight solubility is facilitated by the addition of a solvent, such as ethanol, acetic acid or dioxan, which is miscible with aqueous hydrochloric acid. With some carbonyl compounds, notably keto acids, poor yields are obtained even in the presence of ethanol, etc., and the difficulty has been ascribed to the formation of insoluble polymolecular reduction products, which coat the surface of the zinc. The adffition of a hydrocarbon solvent, such as toluene, is beneficial because it keeps most of the material out of contact with the zinc and the reduction occurs in the aqueous layer at such high dilution that polymolecular reactions are largdy inhibited (see Section IV,143). 

It is also assumed that heterocyclic nitrogen plays an important role in thermolysis of resins and asphaltenes, by which the first reactions involve thermolysis of aromatic alkyl bonds. Secondary reactions are aromatization of naphthenic species and condensation of aromatic rings that activates the coke formation. Thus, the initial step in the coke formation from heavier fractions (resins and asphaltenes) is the formation of volatile hydrocarbons and nonvolatile heteroatom-containing systems. Products obtained are insoluble in the surrounding medium enhancing the carbonization to finally form coke (Magaril and Aksenova, 1968 ... 

Formation of Diarylmethanes and Hydrocarbon Resins. The foimation of diarylmethanes and compounds in which seA -eral aromatic nuclei are linked by methylene groups represents a further stage of formaldehyde ccaidensation than, that inAmlved in halomethylations. These substances are obtained as by-products of halomethylations and predominate Avhen the reaction is run for an excessive length of time or otherwise subjected to... 

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