Aluminium trifluoride

The aluminium ion, charge -I- 3. ionic radius 0.045 nm, found in aluminium trifluoride, undergoes a similar reaction when a soluble aluminium salt is placed in water at room temperature. Initially the aluminium ion is surrounded by six water molecules and the complex ion has the predicted octahedral symmetry (see Table 2.5 ) ... 

Antimony trichloride vapour in contact with powdered aluminium causes the ignition of aluminium. Note that the aluminium/alkaline chlorates interaction is catalysed by aluminium trifluoride, is it due to a specific role played by fluoride ion ... 

While the electrolyte is essentiatly molten cryolite, certain additions are made and a typical electrolysis medium also contains excess aluminium trifluoride... 

In laboratory situations, metastable aluminium trifluoride phases having structures that are more open than the close-packed a-AIFa show some promise as acid catalysts. Other types of functionalized oxides, which have acidic properties and therefore potential catalytic value, include sulfated oxides (for a recent laboratory application in organo-fluorine chemistry see reference 3) and fluorinated clays." ... 

Rather surprisingly, Bu Cl undergoes dehydrochlorination at room temperature in the presence of either Sp4-fluorinated 7-alumina or p-aluminium trifluoride." As a result, this species, together with HCl, have been used as probes of surface acidity. The events that are possible at a fluorinated surface following its exposure to Bu Cl vapour at room temperature are shown in Pigure 4.9. 

The focus in this section is on derivatives of the metastable (3 phase of aluminium trifluoride, which has the hexagonal tungsten bronze structure with AlFg octahedra linked... 

In the second part (Section 5.3), the strong potential of these techniques for the study of functionalized Al-based inorganic fluorides, synthesized for their possible application as catalysts (fluorinated alumina and zeolites, high surface area aluminium trifluorides and nanostructured aluminium fluoride hydrates and hydroxyfluorides), is shown. The compounds used as model for the assignment of the V and Al NMR lines in these materials are also presented. 

Both boron and aluminium chlorides can be prepared by the direct combination of the elements. Boron trichloride can also be prepared by passing chlorine gas over a strongly heated mixture of boron trioxide and carbon. Like boron trifluoride, this is a covalent compound and a gas at ordinary temperature and pressure (boiling point 285 K). It reacts vigorously with water, the mechanism probably involving initial co-ordination of a water molecule (p, 152). and hydrochloric acid is obtained ... 

It forms an ion BCI4 only under special circumstances, and never in aqueous solutions (cf. BF3). Like the trifluoride, it is an electron pair acceptor, but the adducts formed tend to decompose more readily. Unlike the corresponding aluminium chloride, boron trichloride exists only as the monomer. 

Antimony trifluoride [7783-56-4] M 178.8, m 292 . Crystd from MeOH to remove oxide and oxyfluoride, then sublimed under vacuum in an aluminium cup on to a water-cooled copper condenser [Woolf J Chem Soc 279 1955]. 

Olivier and Berger335, who measured the first-order rate coefficients for the aluminium chloride-catalysed reaction of 4-nitroben2yl chloride with excess aromatic (solvent) at 30 °C and obtained the rate coefficients (lO5/ ) PhCI, 1.40 PhH, 7.50 PhMe, 17.5. These results demonstrated the electrophilic nature of the reaction and also the unselective nature of the electrophile which has been confirmed many times since. That the electrophile in these reactions is not the simple and intuitively expected free carbonium ion was indicated by the observation by Calloway that the reactivity of alkyl halides was in the order RF > RC1 > RBr > RI, which is the reverse of that for acylation by acyl halides336. The low selectivity (and high steric hindrance) of the reaction was further demonstrated by Condon337 who measured the relative rates at 40 °C, by the competition method, of isopropylation of toluene and isopropylbenzene with propene catalyzed by boron trifluoride etherate (or aluminium chloride) these were as follows PhMe, 2.09 (1.10) PhEt, 1.73 (1.81) Ph-iPr, (1.69) Ph-tBu, 1.23 (1.40). The isomer distribution in the reactions337,338 yielded partial rate factors of 2.37 /mMe, 1.80 /pMe, 4.72 /, 0.35 / , 2.2 / Pr, 2.55337 339. 

The role of Lewis acids in the formation of oxazoles from diazocarbonyl compounds and nitriles has primarily been studied independently by two groups. Doyle et al. first reported the use of aluminium(III) chloride as a catalyst for the decomposition of diazoketones.<78TL2247> In a more detailed study, a range of Lewis acids was screened for catalytic activity, using diazoacetophenone la and acetonitrile as the test reaction.<80JOC3657> Of the catalysts employed, boron trifluoride etherate was found to be the catalyst of choice, due to the low yield of the 1-halogenated side-product 17 (X = Cl or F) compared to 2-methyI-5-phenyloxazole 18. Unfortunately, it was found that in the case of boron trifluoride etherate, the nitrile had to be used in a ten-fold excess, however the use of antimony(V) fluoride allowed the use of the nitrile in only a three fold excess (Table 1). 

As mentioned several times Lewis acids are highly valuable catalysts but the most commonly used ones such as aluminium chloride and boron trifluoride are highly water sensitive and are not usually recovered at the end of a reaction, leading to a significant source of waste. In recent years there has been much research interest in lanthanide triflates (trifluoro-methanesulfonates) as water stable, recyclable Lewis acid catalysts. This unusual water stability opens up the possibility for either carrying out reactions in water or using water to extract and recover the catalyst from the reaction medium. 

Contact with aluminium chloride, boron trifluoride, sulfuric acid etc., may cause violently exothermic polymerisation. Organometallic products of contact of the chloride with aluminium, magnesium, zinc (or galvanised metal) may produce similar results. 

Acrylic acid, Initiator, Water, 1148 Aluminium chloride, Water, 0062 Barium peroxide, Propane, 0216 1,3-Benzodithiolium perchlorate, 2677 1,1 -Bis(fluorooxy)tetrafluoroethane, 0641 Borane-tetrahydrofuran, 0138 Boron tribromide, Water, 0122 Bromine, Aluminium, Dichloromethane, 0261 Bromine, Tungsten, Tungsten trioxide, 0261 f 1,3-Butadiene, 1480 Calcium oxide, Water, 3937 Chlorine trifluoride, Refractory materials, 3981 Chromium trioxide, Acetic acid, 4242 Copper(II) oxide, Boron, 4281 Diazoacetonitrile, 0675 Dihydroxymaleic acid, 1447 Ethyl azide, 0872... 

The transitory existence of alkylcarbonium ions in alkyl halide-Lewis acid halide systems has been inferred from a variety of observations, sueh as vapour-pressure depressions of OHsCl and C2H5CI in the presence of gallium chloride (Brown et al., 1950), the electric conductivities of aluminium chloride in ethyl chloride (Wertyporoch and Firla, 1933) and of alkyl fluorides in boron trifluoride (Olah et al., 1957), as well as the... 

Preparation of Boron Trichloride by Reacting Aluminium Trichloride with Boron Trifluoride. Perform the experiment in a fume cupboard Assemble an apparatus as shown in Fig. 112. 

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