Aluminium, lead chloride

Reactions of solid metals with liquid metals (e.g. dissolution of aluminium in mercury) Dissolution of metal in their fused halides (e.g. lead in lead chloride). 

Another way to obtain, under suitable conditions, stable dispersions of sur-factant-stabihzed nanoparticles consists in the direct suspension of some materials in w/o microemulsions. The formation of stable dispersions of rutile (size 80-450 mn) and carbon black (200-500 nm) in AOT// -xylene and of rutile, lead chloride, aluminium, antimony in solutions of calcium soaps in benzene has been reported [219,220],... 

Coupling between tetrachloromethane and aldehydes to form a trichloromethyl derivative is also effected with this aluminium, lead bromide reagent. At elevated temperatures, the first formed product is reduced further with the elimination of chloride and hydroxyl ions, forming a dichoroalkene [188]. 

The dissolving aluminium, lead bromide system has been combined with a Lewis acid in tetrahydrofuran to effect the combination of an allyl bromide with an acetal or an a-acetoxyamide, Altuninium chloride is employed as the Lewis acid to... 

A number of key industrial processes in oil refinery, petrochemistry and chemistry are acid catalysed. The industrial use of cheap and strong acids, such as aluminium(III) chloride or sulfuric acid, in typical workup protocols involves complete catalyst hydrolysis for product isolation. This results in high levels of corrosive waste water, which has to be treated in sophisticated downstream processes due to the presence of organic product residues. For obvious reasons, product isolation involving hydrolysis leads to a complete loss of the catalyst acidity in these conventional technologies. 

Varying mole fractions of aluminium(ni) chloride in the acidic ionic liquid lead to different ionic liquid acidities. The effect of ionic liquid acidity on the yield and selectivity was tested... 

Hydrochloric acid is a strong monobasic acid, dissolving metals to form salt and evolving hydrogen. The reaction may be slow if the chloride formed is insoluble (for example lead and silver are attacked very slowly). The rate of attack on a metal also depends on concentration thus aluminium is attacked most rapidly by 9 M hydrochloric acid, while with other metals such as zinc or iron, more dilute acid is best. 

Hydroxyalkylthiazoles are also obtained by cyclization or from alkoxyalkyl-thiazoles by hydrolysis (36, 44, 45, 52, 55-57) and by lithium aluminium hydride reduction of the esters of thiazolecarboxylic acids (58-60) or of the thiazoleacetic adds. The Cannizzaro reaction of 4-thiazolealdehyde gives 4-(hydroxymethyl)-thiazole (53). The main reactions of hydroxyalkyl thiazoles are the synthesis of halogenated derivatives by the action of hydrobroraic acid (55, 61-63), thionyl chloride (44, 45, 63-66), phosphoryl chloride (52, 62, 67), phosphorus penta-chloride (58), tribromide (38, 68), esterification (58, 68-71), and elimination that leads to the alkenylthiazoles (49, 72). 

Aluminium anodes comprise essentially three generic types Al-Zn-In, Al-Zn-Hg and Al-Zn-Sn. Since Al-Zn-Sn alloys have largely been superseded, they will not be discussed further. Indium and mercury are added to aluminium to act as activators, i.e. to overcome the natural passivation of aluminium. Despite this, aluminium anodes are not suitable for low chloride environments which would lead to passivation. These anodes are therefore not used for land-based applications (although examples of use in environments such as swamps do exist). Similarly their use in low chloride aqueous environments such as estuaries must be viewed with caution. 

Care should be exercised with some metals, notably aluminium, that solvent with free chloride is not used, as this could lead to pitting of the metal surface. 

Aluminium B a 5 o B B < I Antimony a < Barium B a 1 3 Bismuth I Boron Cadmium 1 Caesium Calcium 1 Cerium Chloride, Chlorine [ Chromium X) o o C o a Gallium I Germanium Gold 1 Hafnium Hydrogen sulphide B a 5 a B a 5 a o 1 Lanthanons Lead f Lithium 1 Magnesium f Manganese Mercury Molybdenum... 

This mechanism is consistent with all the observations except the variation in rate with initial aluminium chloride concentration. With very reactive aromatics the ionisation step (80) is rate-determining, leading to second-order kinetics, but with less reactive aromatics the ionisation is fast compared with the subsequent reaction of the ionised complex with the aromatic (81), so that this latter then becomes rate-determining. 

The above results show consistency with the known properties of the catalysts except for aluminium chloride, the tendency of which to dimerize would lead one... 

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. 

Olah et al. (1999) have been able to realize selective cyclisation of o-benzoyl benzoic acid to anthraquinone using dichlorobenzene as a solvent and Nafion-H as a catalyst. This may lead to avoidance of the Friedel-Crafts reaction using a stoichiometric amount of aluminium chloride and resulting in a lot of wa,ste. Many other examples of similar reactions have been reported. 

When nitrobenzene is in the presence of aluminium chloride at a temperature greater than 90 C the mixture obtained is thermally unstable. Its decomposition is explosive pressure rises considerably and in a very short period of time. The following reaction that leads to the formation of very unstable compounds has been identified ... 

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