Aluminum halide

Because reduction of unsaturated and carbonyl compounds by aluminum-based reagents obviously occupies an important part of functional transformations and could be the subject of another independent review, discussion of this issue is deliberately excluded here. 

AICI3 has also been employed in the chemistry of highly fluorinated carboca-tions [4]. For example, addition of carbon tetrachloride to tetrafluoroethylene in the presence of AICI3 produced the corresponding halogenated hydrocarbon [5]. 

Although detailed studies of the scope of this type of reaction with AICI3 as catalyst have been reported [6,7], more recent work on the use of halofluoroalkanes as alkylating agents has emphasized the activity and selectivity advantages accruing from the 

Recently, reaction of hexafluoroacetone (FIFA) with tetrafluoroethylene (TFA) catalyzed by ACF was reported as producing F-2,2-dimethyloxetane (1) in high yield (Sch. 1) [10]. 

Polytetrafluoroethylene is the only by-product formed. Trifluoroethylene and 2-chloro- and 2-bromo-l,l-difluoroethylene all react with FIFA regiospecifically to give monohydrooxetanes 2 in 91-98 % yield. The formation of only one isomer, in sharp contrast to the earlier photochemical process [11], is consistent with an electrophilic mechanism (Sch. 2). 

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CARBON - CARBONAND ARTIFICIALGRAPHITE - BAKED AND GRAPHITIZED CARBON] (Vol 4) Aluminum halides and aluminum nitrates... 

Aluminum halides and aluminumnitrate, Aluminum oxide(Alumina),... 

Aluminum Halides. AH the halogens form covalent aluminum compounds having the formula AIX. The commercially most important are the anhydrous chloride and fluoride, and aluminum chloride hexahydrate. 

The aluminum halides and aluminum nitrates have similar properties with the exception of the family of aluminum fluoride compounds which are discussed elsewhere (see Fluorine compounds, inorganic). Of the remaining members ia this aluminum haUde family, chloride derivatives are the most commercially important alurniaum brornide /7727-/3 -JJ AlBr, alumiaum iodide [7784-23-8] and alumiaum nitrate [13473-90-0] are of... 

Chlorine or bromine react with benzene in the presence of carriers, such as ferric halides, aluminum halides, or transition metal halides, to give substitution products such as chlorobenzene or bromobenzene [108-86-17, C H Br occasionally para-disubstitution products are formed. Chlorobenzene [108-90-7] ... 

The second general method is the aluminum halide-catalyzed reaction of acid halides with ethylene to give g-halo ketones which are subsequently converted to ketals. ... 

An efficient catalyst for thermal isomenzations of halofluorocarbons [6, 7, 8, 9] IS prepared by treatment of alumina with dichlorodifluoromethane at 200-300 °C [9] or aluminum chloride with chlorofluorocarbons in the presence of metals [W] or palladium on alumina [II These catalysts are far more efficient than aluminum halides themselves (equations 1 and 2)... 

As catalysts for the Fries rearrangement reaction are for example used aluminum halides, zinc chloride, titanium tetrachloride, boron trifluoride and trifluoromethanesulfonic acid7... 

Thermolysis rates are enhanced substantially by the presence of certain Lewis acids (e.g. boron and aluminum halides), and transition metal salts (e.g. Cu ", Ag1).46 There is also evidence that complexes formed between azo-compounds and Lewis acids (e.g. ethyl aluminum scsquichloridc) undergo thermolysis or photolysis to give complexed radicals which have different specificity to uncomplexed radicals.81 83... 

Boron and aluminum halides have incomplete octets and act as Lewis acids. 

E. L. Eliel, Reductions with Lithium Aluminum Hydride — Aluminum Halide Combinations, Record Chem. Progress 22, 129 (1961). 

The possibility of ion formation during the interaction between two Lewis acid molecules as shown in the scheme above is important for the initiation of cationic polymerizations in the absence of cation forming additives (e.g. HX or RX)1). When aluminum-halides A1X3 (X = Cl, Br) are concerned, the ion formation in solution could be experimentally proven163). The formation of ionic species in pure SbCl5/ SbFj system has already been pointed out. 

The compounds AlYX are best prepared by direct reaction between the respective aluminum halide and chalcogenide in a sealed ampoule at 350°C. The reaction is complete after 2 weeks. In the case of the iodides, a mixture of A1 and I2 (molar ratio 3 10) is used instead of AII3. Other preparative methods, such as the reaction of an aluminum halide with Zn or Cd chalcogenide, or with the chalcogen itself, are applicable to the bromide and chloride only, and give poor yields (15-20%) (158, 159, 266, 327, 328). 

The diazaphosphane or aminoiminophosphane ligands with a NPN framework are another subclass of cyclophosphazenes. These compounds with both phosphorus in oxidation state (111) [104-110] and (V) [111-112] have been employed in the synthesis of four membered heterocycles and coordination chemistry with group 13 derivatives. Several complexes of trivalent phosphorus derivatives with both aluminum halide and alkyls are known as illustrated for 48 in Scheme 21 [113-119]. The structure determination of 48 confirms the formation of a four membered metallacycle [116, 117],... 

To optimize the alkylation conditions, ferrocene was reacted with allyldimethyl-chlorosilane (2) in the presence of various Lewis acids such as aluminum halides and Group lO metal chlorides. Saturated hydrocarbons and polychloromethanes such as hexane and methylene chloride or chloroform were used as solvents because of the stability of the compounds in the Lewis acid catalyzed Friedel-Crafts reactions. The results obtained from various reaction conditions are summarized in Table IV. 

But first the synthesis had to come John was interested in reduced metal halides, particularly for the post-transition metals cadmium, galHum, and bismuth (his Ph.D. dissertation was on anhydrous aluminum halides and mixed halide intermediates, a good start for what was to come ). However, he was not yet actively interested in rare-earth metals and their remarkable solubility in their halides. But these elements lured him one floor below where Adrian Daane headed the metallurgy section of Spedding s empire. He knew how to produce rare-earth metals with high purity and in sufficient quantity and also how to handle tantalum containers. What if one gave it a tr/ and reduced some rare-earth metal halides (John insists that this term is used correctly) from their respective metals at high temperatures under appropriate conditions. 

The reaction is formulated as an electrophilic attack by the aluminum halide, followed by hydride abstraction and transmetallation. A vinyl cation intermediate can account for both the regiochemistry and the stereochemistry. 

The linear dependence of the pitting potential on ionic radius is likely a reflection of the similarly linear relationship between the latter and the free energy of formation of aluminum halides.108 It is reasonable to assume that the energy of adsorption of a halide on the oxide is also related to the latter. Hence, one could postulate that the potential at which active dissolution takes place is the potential at which the energy of adsorption overcomes the energy of coulombic repulsion so that the anions get adsorbed. 

Aluminum(III) complexes are amongst the most common Lewis acids. In particular, aluminum halide species (e.g., A1C13, AlBr3) are commercially available and are widely used for various reactions. Other types of Lewis acid such as aluminum alkoxides, alkylaluminum halides, and trialkylaluminum species are also used for many kinds of Lewis-acid-mediated reactions. 

Hogeveen and co-workers <82JOC1909 83JOC4275> also reported the synthesis of tricyclic sulfinamides by the reaction of cyclobutadiene aluminum halide o complexes (65 or 66) with 53 at low temperature. Treatment of 65 or 66 with 53 at -60 °C resulted in the formation of 67 or 68 in 52% and 55% yields, respectively (Scheme 18). 

This is similar to the behavior of aluminum halides discussed earlier in this chapter, and it illustrates the fact that dehydration of a hydrated solid cannot be used as a way to prepare anhydrous halide compounds in some instances. 

Other organometallic compounds of aluminum include the alkyl hydrides, R2A1H. Molecular association of these compounds leads to cyclic tetramers. When the dimeric and trimeric compounds are dissolved in a basic aprotic solvent, the aggregates separate as a result of formation of bonds between A1 and the unshared pair of electrons on the solvent molecule. Toward Lewis bases such as trimeth-ylamine, aluminum alkyls are strong Lewis acids (as are aluminum halides). 

Osborn s discovery (14) that aluminum halides bimTto oxo ligands in tungsten oxo neopentyl complexes, and that these complexes decompose to give systems which will efficiently metathesize olefins, raised more questions concerning the role of the Lewis acid. A subsequent communication (20) answered some of the questions the aluminum halide removes We oxo ligand and replaces it with two halides to yield neopentylidene complexes (equation 8). 

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