Alkylated benzenes alkylbenzenes

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). ... 

The importance of a primary steric effect in the nitration of alkyl-benzenes has been mentioned ( 9.1.1). The idea was first introduced by Le Fevre to account for the fact that -alkyltoluenes (alkyl = Et, -Pr,68a t-Bu ) are nitrated mainly adjacent to the methyl group. Without the rate data reported for the alkylbenzenes the effect might equally well have been accounted for by hyperconjugation. 

Indeed, with the BPhT counter-anion, there are also five distal ET groups in FeCp(C5Et6) + BPh4 [79]. On the other hand, the five Et groups of FeCp (C5Et II)+ PF6 are all distal (the latter complex was specifically obtained from FeCp (CO)2Br and C6Et6, which may open the route to penta-alkylbenzenes from hexa-alkyl benzenes [80]). 

Takada and Ishimatari [20] extracted alkylbenzenes with normal C10-C14 and branched Cn-C13 alkyl chains from marine and coastal sediment and suspended matter in benzene methanol. The extract in benzene was then applied to a Florisil column for removal of copper sulphide and polar materials, and then subjected to silica gel column chromatography. Alkyl benzenes were quantified and identified using gas chromatography with flame ionization detection. The recoveries of alkyl benzenes were 81-94%. 

Linear alkylbenzene (LAB) is produced by alkylating benzene with either alkylhalides or mono-olefins, the second option being the most widely used in commercial processes. The characteristics of final LAB, namely the isomer distribution, depend on the alkylation catalyst used HF catalyst produces a LAB known a Low 2-phenyl with a 2-phenyl isomer content around 17%, while fixed bed and A1C13 processes produce a High 2-phenyl LAB, which consists of approximately 30% of this isomer. Commercial LAB is a mixture of Ci0, Cu, C12 and Ci3 homologues with all positional isomers except the terminal one... 

Mixed coupling between naphthalene and alkyl benzenes has also been demonstrated (Table 10, numbers 10-13). The relative yield of mixed coupling products increases with the basicity of the alkyl benzene with mesitylene 19%, with tetramethylbenzene 42%, and with pen-tamethylbenzene 64%. This suggests an electrophilic reaction between naphthalene cation radicals and alkylbenzenes. The mixed coupling reaction of phenan-threne with anisole has been studied kinetically [163]. 

Superacids were shown to have the ability to effect the protolytic ionization of a bonds to form carbocations even in the presence of benzene.190 The formed car-bocations then alkylate benzene to form alkylbenzenes. The alkylation reaction of benzene with Ci—C5 alkanes (methane, ethane, propane, butane, isobutane, isopentane) are accompanied by the usual acid-catalyzed side reactions (isomerization, disproportionation). Oxidative removal of hydrogen by SbF5 is the driving force of the reaction ... 

Product distribution data (Table V) obtained in the hydrocracking of coal, coal oil, anthracene and phenanthrene over a physically mixed NIS-H-zeolon catalyst indicated similarities and differences between the products of coal and coal oil on the one hand and anthracene and phenanthrene on the other hand. There were differences in the conversions which varied in the order coal> anthracene>phenanthrene coal oil. The yield of alkylbenzenes also varied in the order anthracene >phenanthrene>coal oil >coal under the conditions used. The alkylbenzenes and C -C hydrocarbon products from anthracene were similar to the products of phenanthrene. The most predominant component of alkylbenzenes was toluene and xylenes were produced in very small quantities. Methane was the most and butanes the least predominant components of the gaseous product. The products of coal and coal oil were also found to be similar. The most predominant components of alkylbenzenes and gaseous product were benzene and propane respectively. The data also indicated distinct differences between products of coal origin and pure aromatic hydrocarbons. The alkyl-benzene products of coal and coal oil contained more benzene and xylenes and less toluene, ethylbenzene and higher benzenes when compared to the products from anthracene and phenanthrene. The gaseous products of coal and coal oil contained more propane and butanes and less methane and ethane when compared to the products of anthracene and phenanthrene. The differences in the hydrocracked products were obviously due to the differences in the nature of reactants. Coal and coal oil contain hydroaromatic, naphthenic, heterocyclic and aliphatic structures, in addition to polynuclear aromatic structures. Hydrocracking under severe conditions yielded more BTX as shown in Table VI. The yields of BTX obtained from coal, coal oil, anthracene and phenanthrene were respectively 18.5, 25.5, 36.0, and 32.5 percent. Benzene was the most... 

Carbocations are perhaps the most important electrophiles capable of substituting onto aromatic rings, because this substitution forms a new carbon-carbon bond. Reactions of carbocations with aromatic compounds were first studied in 1877 by the French alkaloid chemist Charles Friedel and his American partner, James Crafts. In the presence of Lewis acid catalysts such as aluminum chloride (A1C13) or ferric chloride (FeCl3), alkyl halides were found to alkylate benzene to give alkylbenzenes. This useful reaction is called the Friedel-Crafts alkylation. 

This two-step sequence can synthesize many alkylbenzenes that are impossible to make by direct alkylation. For example, we saw earlier that n-propylbenzene cannot be made by Friedel-Crafts alkylation. Benzene reacts with n-propyl chloride and AICI3 to give isopropylbenzene, together with some diisopropylbenzene. In the acylation, however, benzene reacts with propanoyl chloride and A1C13 to give ethyl phenyl ketone (propiophenone), which is easily reduced to n-propylbenzene. 

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). 

Application The Detal process uses a solid, heterogeneous catalyst to produce linear alkylbenzene (LAB) by alkylating benzene with linear olefins made by the Pacol process. 

UOP Alkylbenzene, linear (LAB) Kerosine LAB is produced by alkylating benzene with olefins using several processes 41 1998... 

The mono- and poly-alkylated benzenes are treated using modifications of the above procedure. Monoalkylbenzenes are added to a preformed complex of acyl halides and aluminum chloride in carbon tetrachloride (Perrier modification). In this manner, the manipulation is easier, no tars are encountered, and the yields are improved (85-90%). The procedure shows no advantage, however, in the acylation of alkoxy- or chloro-aromatic compounds. The addition of benzoyl chloride to p-alkylbenzenes in the presence of aluminum chloride in cold carbon disulfide is a good procedure for making p-alkylbenzophenones (67-87%). The condensation of homologs of benzene with oxalyl chloride under similar conditions yields p,p -di alkylbenzophenones (30-55%). Polyalkylbenzenes have been acylated with acetic anhydride and aluminum chloride (2.1 1 molar ratio) in carbon disulfide in 54-80% yields. Ferric chloride catalyst has been used under similar conditions. Acetylation of p-cymene with acetyl chloride and aluminum chloride in carbon disulfide yields 2-methyl-5-isopropylaceto-phenone (55%). ... 

The activity of the catalyst shown in Figure 4.10 in the alkylation of benzene with alkenes is comparable to that of aluminium chloride, but it shows improved selectivity towards monoalkylation compared to A1C13 itself and is readily recoverable and reusable (unlike A1C13, which needs to be removed from the reaction after one use, typically by a water quench). The alkylation of alkylbenzenes, and to a lesser extent halobenzenes, can also be carried out using supported aluminum chloride (Table 4.11). 

UOP LLC, A Honeywell Co. Alkylbenzene, linear (LAB) C,(,and C,3 normal paraffins of 98-i-% purity UOP/CEPSA process uses a solid, heterogeneous catalyst to produce linear alkylbenzene (LAB) by alkylating benzene with linear olefins made by UOP Pacol, DeFine and PEP processes 33 NA... 

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