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Use of anhydrous aluminum trichloride

News 25/09/2022 363

1. This product is mainly used as a catalyst for organic synthesis and polymer synthesis. It is widely used in synthetic resin, synthetic rubber, petroleum cracking, synthetic dyes, synthetic detergents, medicines, spices, pesticides, etc. This product is also used for the refining of organic compounds and metals for aluminum production and the treatment of lubricating oil.
2. It is used as a catalyst for organic synthesis, such as petroleum cracking, synthetic dyes, synthetic rubber, synthetic detergents, medicines, spices, etc. It is used as catalyst for manufacturing pesticides, organic aluminum compounds, phthalocyanine organic pigments, and ethyl benzene. It is also used for metal smelting and lubricating oil synthesis. Food grade products are used as anti discoloring agents such as leavening agents, sake and flocculants of pectin.
3. Anhydrous aluminum chloride can be used as an additive for aluminum and alloy etching, as well as aluminum salt addition for solvent aluminizing.
4. Aluminum trichloride is a classical Lewis acid, which can effectively combine with heteroatoms with strong electronegativity in the substrate, such as chlorine atom, carbonyl oxygen, etc., so as to play the role of activating the substrate [1]. The most classical reaction is Friedel Crafts alkylation and acylation between chlorinated alkanes or acyl chlorides and aromatic hydrocarbons (Formula 1) [1].
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6. Friedel Crafts reaction can also be extended to non aromatic systems, such as olefins or alkynes. Representative examples are the intramolecular cyclization reaction of 1,5-cyclooctadiene induced by aluminum trichloride with acyl chloride (Formula 2) [2], and α,β- Unsaturated acyl chloride reacts with alkynes under the activation of aluminum trichloride, and further generates cyclopentenone derivatives (Formula 3) under the action of reducing agent zinc [3]. In addition, aluminum trichloride can also activate aromatic rings α- C-H bond of methyl group, so as to realize Friedel Crafts reaction on sp3 carbon. For example, 3-methyl substituted indole undergoes acylation reaction under the action of aluminum chloride to obtain 3-indole ketone compound (Formula 4) [4].
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8. The Friedel Crafts reaction involving trimethylsilane derivatives can not only improve the regioselectivity of the reaction, but also expand the scope of application of the substrate. Because the trimethylsilyl substituent is larger and easier to leave than ordinary hydrogen atoms, it can effectively stabilize β- Carbene ion（ β- Effect), so that the regioselectivity of the reaction can be completely controlled (Formula 5) [5]. In addition, diketene compound (Formula 6) [6] can be obtained by acylation of propargyl silane induced by aluminum trichloride.
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10. Friedel Crafts reaction can not only extend the substrate to non aromatic systems, but also extend the substrate activated by aluminum trichloride to other electrophilic reagents of non halogenated hydrocarbons or acyl chlorides. For example, the aryl azide compound obtains a polycyclic aromatic compound (Formula 7) [7] under the action of aluminum trichloride. For allyl sulfones, aluminum trichloride can effectively interact with sulfones to activate allyl sp3 carbon atoms, and then conduct electrophilic substitution reaction with aromatic rings to obtain intramolecular ring closing products (Formula 8) [8]. In addition, aluminum trichloride can also activate elemental sulfur, and then react with diphenyl ether to obtain a polycyclic compound (Formula 9) [9].
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13. Aluminum trichloride can also effectively interact with nitrogen atoms, so it can activate some nitrogen-containing substrates, thereby promoting Friedel Crafts reaction. For example, it interacts with the nitrogen atom of 2-chloropyridine with electron withdrawing substituent (Formula 10) [10] or with the nitrogen atom on the heteroaromatic ring (Formula 11) [11] to activate the adjacent carbon atom, thereby generating electrophilic substitution reaction with the aromatic ring or heteroaromatic ring. Aluminum trichloride can also react with carbonyl oxygen in N - (N, N-diphenylamine) phthalimide to obtain diphenylammonium cationic intermediate through electron transfer, and then produce carbazole compound (Formula 12) through intramolecular ring formation reaction [12].
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15. As Lewis acid, aluminum trichloride can also catalyze Diels Alder reaction, for example, phenylimine and diene can get nitrogen heterocyclic compound (Formula 13) under the action of AlCl3 [13]. In addition, aluminum trichloride is also used to catalyze [2+2] cycloaddition reactions, such as intramolecular alkyne cyclization (Formula 14) [14].
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17. It is used as catalyst in organic synthesis, preparation of aluminum organic compounds and refining of metals. [33]