Aluminum chloride, complexes with benzene

Secondary alkyl halides react by a similar mechanism involving attack on benzene by a secondary carbocation Methyl and ethyl halides do not form carbocations when treated with aluminum chloride but do alkylate benzene under Friedel-Crafts conditions The aluminum chloride complexes of methyl and ethyl halides contain highly polarized carbon-halogen bonds and these complexes are the electrophilic species that react with benzene... 

Aluminum chloride coordinates with 1-chloropropane to give a Lewis acid/Lewis base complex, which can be attacked by benzene to yield propylbenzene or can undergo an intramolecular hydride shift to produce isopropyl cation. Isopropylbenzene arises by reaction of isopropyl cation with... 

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). 

As for PdsCltt, adducts with benzene, CS2, CHC13, and Br are known. On heating with A1Q3, Pt6Cl12 gives a purple vapor of an aluminum chloride complex. 

The aluminum chloride complexes of methyl and ethyl halides contain highly polarized carbon-halogen bonds, and these complexes are the electrophilic species that react with benzene. 

In practice, the catalyst system is in the form of a so-called "red" complex, which is not perfectly soluble in aromatic hydrocarbons, and which contains 25 to 30 weight per cent of promoted aluminum chloride, combined with 45 to 50 per cent of benzene/ethyl-benzene and about 25 per cent of higher molecular weight hydrocarbon compounds. Because it is heavier the catalyst settles at the bottom of the reactor. Since the complex is also corrosive, the reactor must be provided with a refractory lining or the reactor walls vitrified. 

In the concerted process, the benzene ring reacts with the alkyl halide-aluminum chloride complex to form the alkylated benzene. In this mechanism, there is no carbocation rearrangement because there is no free carbocation stage. In the two step process, however, there is a free carbocation stage. The alkyl halide complexes with the aluminum chloride. This complex breaks down to form the free carbocation, which can then undergo rearrangement to form a more stable species. The benzene ring can then react with the carbocation to form the alkylated benzene. Therefore, reactions (a), (b) and (c) must have followed the two step mechanism that is, the c-arbocation mechanism. 

Dry benzene (260 mL) was added to the pseudoacid chloride followed by 56 g (0.42 mol) of aluminum chloride. The mixture was heated at reflux until the evolution of hydrogen chloride ceased. After being cooled, the aluminum chloride complex was destroyed with 6 N hydrochloric acid. The benzene layer was extracted with 5% sodium bicarbonate and dried over sodium sulfate. The benzene was removed under vacuum, and the residue was recrystallized from acetone/water to give 32 g (13% based on tetracarboxylic dianhydride) of bis(3,3-diphenyl-6-phthalidyl) ketone, m.p. 238-39 C. 

A sample of 4-nitrophthalic anhydride (64 g, 0.33 mol) was added to 500 mL of dry benzene, followed by the slow addition with stirring of 107 g (0.80 mol) of aluminum chloride. The mixture was then heated at reflux until the evolution of hydrogen chloride ceased, then cooled. The aluminum complex was destroyed by the addition of 500 g of ice and 200 mL of 12 M HCl. The benzene was extracted with water and with saturated NaCl and dried over sodium sulfate. The benzene was then removed, and the crude benzoylbenzoic acids were placed in a Soxhlet and extracted with methanol for 24 hrs. The extract was allowed to cool and after filtration gave 2-benzoyl-4-nitrobenzoic acid. Yield 10%, m.p. 158-160 C (lit. 163-5 C). The other isomer, 2-benzoyl-5-nitrobenzoic acid, was isolated by reducing the filtrate to one-third its volume and cooling. The yield was 50.0 g (55.6%) m.p. 207-211 C (lit. S 212 °C). A solution of 50.0 g (0.18 mol) of 2-benzoyl-5-nitrobenzoic acid and 50 mL of thionyl chloride was heated at reflux for 3 hrs. After the excess thionyl chloride was removed under vacuum, 500 mL of dry benzene was added to the pseudoacid chloride. Aluminum chloride (46.0 g, 0.40 mol) was slowly added and the mixture was heated at reflux until the evolution of hydrogen chloride ceased. After the aluminum chloride complex was destroyed... 

The Lewis acid mediated addition of allylic tin reagents to nitroalkenes has been reported. The condensation reaction of tributyl[(Z)-2-butenyl]tin(IV) with (E)-(2-nitroethenyl)benzene or (L)-l-nitropropene catalyzed by titanium(IV) chloride proceeded with modest anti diastereoselectivity. Poorer diastereoselection resulted when diethyl ether aluminum trichloride complex was employed as the Lewis acid 18. 

Note that ethylbenzene is a derivative of two basic organic chemicals, ethylene and benzene. A vapor-phase method with boron trifluoride, phosphoric acid, or alumina-silica as catalysts has given away to a liquid-phase reaction with aluminum chloride at 90°C and atmospheric pressure. A new Mobil-Badger zeolite catalyst at 420°C and 175-300 psi in the gas phase may be the method of choice for future plants to avoid corrosion problems. The mechanism of the reaction involves complexation of the... 

Diphenylacetic acid has been obtained by the reduction of benzilic acid with hydriodic acid and red phosphorus 1 by the treatment of phenylbromoacetic acid with benzene and zinc dust,2 or with benzene and aluminum chloride 3 by the hydrolysis of diphenylacetonitrile 4 by heating a-diphenyldichloroethyl-ene with alcoholic sodium ethylate 5 by heating benzilic acid 6 from diphenylmethane, mercury diethyl, sodium and carbon dioxide 7 by the oxidation of a,a,5,S-tetraphenyl- 8-butine 8 by the decomposition of some complex derivatives obtained from diphenylketene 9 by the hydrolysis of diphenyl-5,5-hydan-toin 10 by the treatment of diphenylbromoacetic acid with copper 11 by the oxidation of dichlorodiphenylcrotonic acid.12... 

I lu flask is surrounded by an ice-calcium chloride cooling nii, lure, and the aluminum chloride is added in small portions bom the Krlenmeyer flask at such a rate that the temperature is niainlaincd between —5° and 0°. After the addition is complete, I lie mi.xiure is. stirred for an additional 30 minutes, and the temperature is then allowed to rise slowly to 10°. The red complex wliidi forms is collected with suction on a sintered-glass funnel and washed thoroughly with dry benzene (Note 2). The complex is added in small portions Iiy means of a spatula with stirring to a 600 ml. beaker nearly filled with a mixture of ice and con-eeidrated hydrochloric acid. I he mixture is then allowed to enine to room temperiitlire, and the crude ketone is collected on a sui t ion filter. 

Jensen et al.16 also studied the decomposition of 5-ethoxythiatriazole in dibutyl phthalate solution in the presence of trichloroacetic acid, tripentylamine, 4-benzylpyridine, anhydrous aluminum chloride, or trinitrobenzene, but practically no effect on the reaction rate was observed. However, later experiments have shown that the decomposition can indeed by enhanced catalytically by Lewis acids under conditions where the catalyst is not sequestered by complex formation with the solvent.19 Thus the addition of aluminum chloride to 5-phenylthiatriazole in benzene causes a brisk evolution of nitrogen at room temperature, and if instead boron tribromide is added, a rather violent reaction sets in. However, when esters or ethers are used as... 

The most common solvents are benzene and carbon disulfide. Others such as petroleum ether and sj/m-tetrachloroethane also have been employed successfully. Nitrobenzene has served as a unique solvent in conjunction with aluminum chloride, since a complex is formed reducing the activity of the catalyst. 

Thus, the direct synthesis of phenylchlorosilanes produces a complex mixture, which, apart from phenyltrichlorosilane, diphenyldichlorosilane, phenyldichlorosilane and triphenylchlorosilane, also contains silicon tetrachloride, trichlorosilane, benzene, solid products (diphenyl and carbon) and a gaseous product (hydrogen). It also forms high-boiling polyolefines, which are part of tank residue and can deposit on contact mass, reducing its activity. It should be kept in mind that the production of phenylchlorosilanes requires silicon with a minimal impurity of aluminum, because the aluminum chloride formed contributes to the detachment of the phenyl group from phenylchlorosilanes at higher temperature. The harmful effect of aluminum chloride is counteracted by the addition of metal salts to contact mass, which form a nonvolatile and nonreactive complex with aluminum chloride. 

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