Aluminum trichloride catalyst

Isomerization of cyclohexane in the presence of aluminum trichloride catalyst with continuous removal of the lower boiling methylcyclopentane by distillation results in a 96% yield of the latter (54). The activity of AlCl -HCl catalyst has been determined at several temperatures. At 100°C, the molar ratio of methylcyclopentane to cyclohexane is 0.51 (55). 

In the former reaction the main product is chloro(j3-chlorovinyl)methyl-arsine. In the latter triphenylarsine is produced in low yield together with traces of the compounds (CHCl=CH) AsCl3 and the remaining phenyl-arsines are produced in approximately equal amounts. The aluminum trichloride catalyst probably also helps the redistribution reactions (see Section II, A, 6,e). Long-chain acetylene derivatives also react with chloro-arsines in the same way 3,186), but complex products are obtained from tetrolic acid and arsenic trichloride 187). Hexafluorobut-2-yne does not react with arsenic trichloride although it does so with chlorodimethylarsine on heating or ultraviolet irradiation 188). 

There are many other industrial examples such as acrylic fibers made from polyacrylonitrile (with 7% vinyl acetate). The monomer is fairly water soluble at about 5% and the polymerization occurs in the aqueous phase. However, the polymer is insoluble in water. The primary particles precipitate and agglomerate, forming larger particles that are stabilized by ionic initiator end groups. Butyl rubber (isobutylene+ < 5% isoprene) is produced by cationic polymerization with aluminum trichloride catalyst in methyl chloride at about -100 °C. The polymer precipitates as fine polymer particles from the reaction medium. 

An early liquid phase process used an aluminum trichloride catalyst at 85°- 95°C at pressures just above atmospheric. A low ethylene/benzene ratio was used to limit the formation of diethylbenzene and other polyethylbenzenes. By-products could, however, be recycled with benzene and were recovered as ethylbenzene by transalkylation. Ethylbenzene selectivity was about 94% based on benzene and higher on et lene. The catalyst that formed in solution was thought to be HAlCLt-w-C 5C2H5, which gradually deactivated and was replenished as required. Other acid catalysts such as boron trifluoride can be used in the hquid phase process, which is still widely used in older plants. 

A typical cationic polymeriza tion is conducted with highly purified monomer free of moisture and residual alcohol, both of which act as inhibitors, in a suitably dry unreactive solvent such as toluene with a Eriedel-Crafts catalyst, eg, boron triduoride, aluminum trichloride, and stannic chloride. Usually low temperatures (—40 to —70°C) are favored in order to prevent chain-transfer or sidereactions. 

Cycloadditions (253) of butenolides with isoprene afforded a 1 1 mixture of Diels-Alder regioisomers. The selectivity is increased by the use of aluminum trichloride as catalyst. Although the butenolides studied did not react with furan, even in the presence of catalysts, they reacted smoothly with cyclopentadiene. For example, reaction of (—)-angelica lactone (159a) with... 

Hubbard and Miller87 used a Lewis acid catalyzed Diels-Alder reaction between y.y-disubstituted o. /i-unsaluralcd esters and cyclopentadiene in their approach toward oligomeric cyclopentanoids. In order for the reaction to proceed, they needed to add trimethylaluminum as a desiccant prior to addition of the Lewis acid catalyst aluminum trichloride. The endo/exo selectivity of the reaction with 97, depicted in equation 29, increased from 98/99 = 75/25 to 88/12 when the reaction temperature was dropped from room temperature to —20 °C. 

Chlorine-based plasma etching of aluminum films causes serious degradation of photoresist materials. To some extent, these effects are a result of the etch product, AICI3. Aluminum trichloride is a Lewis acid used extensively as a Friedel-Crafts catalyst. Therefore, it is hardly surprising that this material reacts with and severely degrades photoresists (74). 

A somewhat similar isomerization was observed with the sultam 5-methylimino-4-phenyl-l,3,4-dithiazolidine 1-dioxide (17 i = H). On heating at 60°C in the presence of benzoyl chloride, rearrangement into the isomeric 5-phenylimino-4-methyl-l,3,4-dithiazolidine 1-dioxide (19, 1 = H) was found (Scheme IV.ll). As intermediate can be proposed the amidinium salt 18 (78JOC4951). Furthermore, NMR-controlled test tube experiments revealed that this rearrangement also occurs under influence of aluminum trichloride and methanesulfonyl chloride. Also, the 2-phenyl derivative 17 (R = CeHs) could be isomerized it required heating in acetone with m-dichlorobenzoic acid as catalyst (Scheme IV.ll). 

The reaction of sulfur dichloride with benzonitrile in the presence of a Lewis acid catalyst yields 3,5-diphenyl-l,2,4-thiadiazole (39), along with the 3-o-chlorophenyl (278) and 3-p-chlorophenyl (279) analogues in a total yield of 80%. The proposed mechanism proceeds via a complex between benzonitrile, Lewis acid for example, aluminum trichloride, and sulfur dichloride to give an intermediate (280) which then adds a second molecule of nitrile (Scheme 62) <83BCJ180>. 

A 1 2 mixture of l-methyl-3-ethylimidazolium chloride and aluminum trichloride, an ionic liquid that melts below room temperature, has been recommended recently as solvent and catalyst for Friedel-Crafts alkylation and acylation reactions of aromatics (Boon et al., 1986), and as solvent for UV/Vis- and IR-spectroscopic investigations of transition metal halide complexes (Appleby et al., 1986). The corresponding 1-methyl-3-ethylimidazolium tetrachloroborate (as well as -butylpyridinium tetrachlo-roborate) represent new molten salt solvent systems, stable and liquid at room temperature (Williams et al., 1986). 

Interestingly, in these cases, the use of aluminum trichloride as a Lewis acid catalyst promoted regiospecificity and only the l,l-dicyclopropyl-2-mcthylenecyclobutanes were obtained (see Section 1.3.4.2.). Furthermore, the catalyzed cycloadditions proceeded under milder conditions (room temperature vs. 200 °C for noncatalyzed cycloadditions). In the same study, the cycloaddition of 1,1-dimethylallene (14) with tetracyanoethene proceeded regiospecifically giving 3-(l-methylethylidene)cyclobutane-l,l,2,2-tetracarbonitrile (15) in 71% yield.11,12... 

Aluminum trichloride and boron trifluoride as additives have a similar effect on the fluorination of (trichloromethyl)benzene by antimony(III) fluoride. With the additives, the reaction starts even at O C but no exchange is observed in the absence of the catalysts.12 The relative exchange reactivity order of the antimony halides is as follows antimony(III) fluoride < anti-mony(III) fluoride + antimony/V) chloride < antimony(V) dichlorotrifluoride, antimony/V) di-bromotrifluoride < antimony/V) fluoride.3... 

Other catalysts used in fluorinations with antimony(III) fluoride are boron trifluoride and aluminum trichloride. The reaction of (trichloromethyl)benzene with antimony(III) fluoride and catalytic amounts of aluminum trichloride at 0 X gives mainly (dichlorofluoromethyl)ben-zene and a little (chlorodifluoromethyl)benzene. With greater amounts of aluminum trichloride, the major product is (chlorodifluoromethyl)benzene, bp 142 C.81... 

The importance of aluminum trichloride (and AlBr3 which is more soluble in hydrocarbons) as a catalyst, particularly for Friedel-Crafts alkylation and acylation of aromatic compounds,... 

The acetylation of carbazole by acetic anhydride in the presence of boron trifluoride produces the 9-acetyl derivative. Further acetylation requires more vigorous conditions, using aluminum trichloride as a catalyst, and yields 2,9-diacetylcarbazole, which, upon base-catalyzed hydrolysis, produces 2-acetylcarbazole (80T3017). Acetylation of 1-phenyl-isoindole under mild conditions in the presence of pyridine yields l-acetyl-3-phenylisoin-dole, whereas the presence of an ester group at the 1-position deactivates the ring sufficiently to prevent acylation (81AHC(29)34l). 

Ashikari, Kanemitsu, Yanagisawa, Nakagawa, Okomoto, Ko-bayashi and Nishioko (59) have studied the copolymerization of propylene and styrene. They found decreasing styrene content and conversion of the copolymer by increasing aluminum to titanium ratios with triisobutyl aluminum and titanium trichloride catalysts. The trialkylaluminum titanium tetrachloride catalyst had relatively low steric control on the polymerization while trialkylaluminum-titanium trichloride had higher steric control. The ionicity which is required for atactic polymerization is more cationic for styrene than for propylene which is more cationic than that for ethylene. Some of the catalyst systems for these three monomers are shown on the ionicity chart in Fig. 9. 

Aluminum trichloride is the most commonly used catalyst, although aluminum tribromide is more efficient.1 For the rearrangement of l-broino-2-chloro-1,L2-lrifluoroethane (3) to 2-bromo-2-chloro-l,l,l-trifhioroethane (4). none of the following Lewis acids are effective iron(III) chloride. iron(III) bromide, antimony(III) chloride, antimony(V) chloride. tin(IV) chloride, titanium(IV) chloride, zinc(II) chloride, and boron trifluoride-diethyl ether complex.1" ... 

Much work has been done to develop catalyst systems that optimize yield and reduce side reactions. The reaction has an induction period, which depends on the temperature and the amount of catalyst.8 An early patent from Bayer claims that a nearly quantitative yield can be achieved in the conversion of l,2-dibromo-1-chloro-l.2.2-trifluoroethane(5) into 1,1-di-bromo-l-chloro-2,2.2-trifluoroethane (6) when aluminum tribromide is used in 2-broino-2-chloro-1,1,1-trifluoroethane (4) as solvent.12 A Japanese patent26 describes the activation of aluminum trichloride or alumina by pretreatinent with l,L2-trichloro-l,2,2-trifluoroethane (1) (see discussion of compound 19, vide infra). A later patent claims that aluminum trichloride and tribromide can also be activated by complexing with 1,1-dichloro- (CF3CFC12) and 1,1-dibromo-1,2,2,2-tetrafluoroethane (CF3CFBr2), respectively 2 an example of the latter is shown in the formation of bromofluoroalkane 10. 

Intramolecular migration of fluorine and chlorine atoms is described in Section 5. The rearrangement of fluorine and chlorine atoms likewise can occur intermolecularly between a number of chlorofluorocarbon molecules. This disproportionation (dismutation) takes place catalyti-cally or thermally. With aluminum trichloride as a catalyst, for example, enrichment of the fluorine atoms takes place in one molecule 1 and enrichment of the chlorine atoms in the other 2. 

Aluminum trifluoride is in most widespread use as a catalyst for the disproportionation of chlorofluorocarbons. The preparation of an active aluminum trifluoride catalyst is dependent on the initial compound (aluminum trichloride or aluminum oxide), the hydrogen fluoride or chlorofluorocarbon activation component, and the reaction phase (gas or liquid).10... 

Preparation of an Aluminum Trifluoride Catalyst from Aluminum Trichloride and Hydrogen Fluoride in the Liquid Phase 1 -12... 

Conversion in the liquid phase has the disadvantage that the carbon tetrachloride formed during the disproportionation of trichlorofluoromethane forms a complex compound with the aluminum trichloride possessing no catalytic effect, so that only a relatively small amount of trichlorofluoromethane can be converted with a predetermined amount of aluminum trichloride. The continuous gas-phase method in a tubular reactor is more practicable the temperature at which it takes place must be high enough to prevent any products from condensing on the catalyst. It is also possible to perform the disproportionation process continuously in the liquid phase in a tubular reactor, under pressure and at an increased temperature. In this case aluminum trichloride must first be activated by pretreatment (partial fluorination), since the partial fluorination of aluminum trichloride greatly reduces the tendency for complex compounds to form with the chlorinated hydrocarbon when this itself has formed. 

The catalysts used successfully in the liquid phase in the order of their efficiency are anti-niony(V) chloride, aluminum tribromide, aluminum trichloride, and iron(Ill) chloride. Zinc(ll) chloride, tin(ll) chloride, boron trifluoride diethyl ether complex, and aluminum trifluoridc do not catalyze the dismutation. 

Several supports were studied, including so-called poly-alumazane, which is prepared by subsequent treatment of silanol rich silica with aluminum trichloride and ammonia. With the resulting support palladium catalysts with very high dispersion were obtained. 

The addition of hydrazoic acid to numerous acyclic and cyclic alkenes also proceeds well in the presence of titanium tetrachloride or aluminum trichloride.262 Dichloromethane or chloroform are ideal solvents for these catalysts. The addition is regiospecific and tolerates the presence of primary and secondary alcohols, as well as esters (equation 184). 

Historically, the first cracking catalyst used was aluminum trichloride. With the development of heterogeneous solids and supported catalysts, the use of AICI3 was soon superseded, since its activity was mainly due to the ability to bring about acid-catalyzed cleavage reactions. 

Acidic chloroaluminate ionic liquids were used as reaction media for Friedel-Crafts reactions as early as 1976 [34], Systematic investigations into Friedel-Crafts alkylations of benzene with the same acidic systems followed in 1986 by Wilkes et al. [35]. The alkylation of benzene with alkenes in acidic imidazolium chloroaluminate melts was disclosed in a patent by BP Chemicals in 1994 [36]. Here, as advantages over the reaction with aluminum trichloride in organic solvents, claims are made regarding the easy isolation of the product, the practically total reusability of the liquid catalyst and the better selectivity to the desired products. 

---