Hydrocarbons, aromatic, alkylation

Figure 5.3-8 Loop reactor as used in aromatic hydrocarbon alkylation experiments.

The petroleum-based oils contain hundreds to thousands of hydrocarbon compounds, including a substantial fraction of nitrogen- and sulfur-containing compounds. The hydrocarbons are mainly mixtures of snaight- and branched-chain hydrocarbons (alkanes), cycloalkanes, and aromatic hydrocarbons. Polynuclear aromatic hydrocarbons, alkyl polynuclear aromatic hydrocarbons, and metals are important components of motor oils and crankcase oils, with the used oils... 

Non-chlorinated Lewis acids, such as scandium triflate, were found to be good catalysts for Friedel-Crafts alkylation reactions (167). Although no aromatic hydrocarbon alkylation occurred in CH2CI2, [BMIMJPFg, Sc(OTf)3 catalyzed the alkylation of benzene with high yields of the monoalkylated product. The lower acidity of the ionic liquid led to fewer byproducts and therefore higher yields. The products were separated by simple decantation and the catalyst was reused. 

BP Chemicals studied the use of chloroaluminates as acidic catalysts and solvents for aromatic hydrocarbon alkylation [41]. At present, the existing AICI3 technology (based on red oil catalyst) is still used industrially, but continues to suffer from poor catalyst separation and recycling [42]. The aim of the work was to evaluate the AlCl3-based ionic liquids, with the emphasis placed on the development of a clean... 

Polycyclic aromatic hydrocarbons Alkylated aromatic hydrocarbons Chlorinated aromatic compounds Chlorobenzenes Polychlorinated biphenyls Polychlorinated dibenzo[l,4]dioxins Chlorinated guaiacols and catechols Nitrogen-containing aromatic compounds Azaarenes and aromatic nitriles Oxygenated aromatic compounds 2,4-Dipentyl phenol Polycyclic quinones and ketones Aliphatic carboxylic acids Cs and C, dicarboxylic acids... 

ILs can also be anchored to the support through the imidazoHum cation. The cation is first grafted on the support. The Lewis acid is added in a second step. As an example, IL has been anchored by reaction of a chloroaluminate ofa 1-triethoxy-silyl derivative of 3-methylimidazolium on the wall of silica MCM-41. Another approach is to anchor the cation on the support using a sol-gel method. The potential of these supported ILs has been investigated for aromatic hydrocarbon alkylation reactions (see below). 

At temperatures lower than those usually employed in catalytic cracking other polymolecular reactions become predominant namely, polymerization, and, in the presence of aromatic hydrocarbons, alkylation. These conversions can also be interpreted in terms of the conventionally assumed carbonium-ion mechanism. 

Solvents Aromatic Hydrocarbons Alkyl Nitrites Anesthetics... 

The Friedel-Crafts Reaction, in which an aromatic hydrocarbon reacts with an alkyl halide under the influence of aluminium chloride ... 

Friedel and Crafts reaction. alkyl halide condenses with an aromatic hydrocarbon in the presence of anhydrous aluminium chloride to yield, in the first instance, a hydrocarbon in accordance with the following scheme —... 

RCH=CHjj -H H3SO4 — RCHlCHjlOSOaOH Polyalkylated aromatic hydrocarbons and alkyl phenyl ethers are sulphonated ... 

Another type of soHd supetacid is based on perfluorinated resin sulfonic acid such as the acid form of Du Font s Nafion resin, a copolymer of a perfluorinated epoxide and vinylsulfonic acid or soHd, high molecular weight petfluotoalkanesulfonic acids such as petfluotodecanesulfonic acid, CF2(CF2)qS02H. Such sohd catalysts have been found efficient in many alkylations of aromatic hydrocarbons (225) and other Friedel-Crafts reactions (226). 

The first resins to be produced on a commercial scale were the coumarone—indene or coal-tar resins (1) production in the United States was started before 1920. These resins were dominant until the development of petroleum resins, which were estabHshed as important raw materials by the mid-1940s. Continued development of petroleum-based resins has led to a wide variety of aHphatic, cyclodiene, and aromatic hydrocarbon-based resins. The principal components of petroleum resins are based on piperylenes, dicyclopentadiene (DCPD), styrene, indene, and their respective alkylated derivatives. 

PMMA is not affected by most inorganic solutions, mineral oils, animal oils, low concentrations of alcohols paraffins, olefins, amines, alkyl monohahdes and ahphatic hydrocarbons and higher esters, ie, >10 carbon atoms. However, PMMA is attacked by lower esters, eg, ethyl acetate, isopropyl acetate aromatic hydrocarbons, eg, benzene, toluene, xylene phenols, eg, cresol, carboHc acid aryl hahdes, eg, chlorobenzene, bromobenzene ahphatic acids, eg, butyric acid, acetic acid alkyl polyhaHdes, eg, ethylene dichloride, methylene chloride high concentrations of alcohols, eg, methanol, ethanol 2-propanol and high concentrations of alkahes and oxidizing agents. 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

Coal tar is the condensation product obtained by cooling to approximately ambient temperature, the gas evolved in the destmctive distillation of coal. It is a black viscous Hquid denser than water and composed primarily of a complex mixture of condensed ring aromatic hydrocarbons. It may contain phenoHc compounds, aromatic nitrogen bases and their alkyl derivatives, and paraffinic and olefinic hydrocarbons. Coal-tar pitch is the residue from the distillation of coal tar. It is a black soHd having a softening point of 30—180°C (86—359°F). 

Low temperature tars contain 30—35 wt % non aromatic hydrocarbons, ca 30% of caustic-extractable phenols in the distillate oils, and 40—50% of aromatic hydrocarbons. The latter usually contain one or more alkyl substituent groups. On atmospheric distillation, coke-oven tars yield 55—60% pitch, whereas CVR tars give 40—50% pitch. The pitch yield from low temperature tars is in the 26—30% range. 

Sodium (metal). Used as a fine wire or as chips, for more completely drying ethers, saturated hydrocarbons and aromatic hydrocarbons which have been partially dried (for example with calcium chloride or magnesium sulfate). Unsuitable for acids, alcohols, alkyl halides, aldehydes, ketones, amines and esters. Reacts violently if water is present and can cause a fire with highly flammable liquids. 

Aromatic ethers and furans undergo alkoxylation by addition upon electrolysis in an alcohol containing a suitable electrolyte.Other compounds such as aromatic hydrocarbons, alkenes, A -alkyl amides, and ethers lead to alkoxylated products by substitution. Two mechanisms for these electrochemical alkoxylations are currently discussed. The first one consists of direct oxidation of the substrate to give the radical cation which reacts with the alcohol, followed by reoxidation of the intermediate radical and either alcoholysis or elimination of a proton to the final product. In the second mechanism the primary step is the oxidation of the alcoholate to give an alkoxyl radical which then reacts with the substrate, the consequent steps then being the same as above. The formation of quinone acetals in particular seems to proceed via the second mechanism. ... 

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