15问答网 > 化学：AlCl3是什么？有哪些性质？AlO2-（离子）有哪些性质？

化学：AlCl3是什么？有哪些性质？AlO2-（离子）有哪些性质？

2025-02-15 21:11:35

推荐回答（4个）

回答1：

AlCl3的空间结构如下：

Al2Cl6。期中两个Cl作为桥。

Aluminium chloride (AlCl3) is a compound of aluminium and chlorine. The solid has a low melting and boiling point, and is covalently bonded. It sublimes at 178 °C. Molten AlCl3 conducts electricity poorly,[2] unlike more ionic halides such as sodium chloride. It exists in the solid state as a six-coordinate layer lattice.

AlCl3 adopts the "YCl3" structure, featuring Al3+ cubic close packed layered structure.[3] In contrast, AlBr3 has a more molecular structure, with the Al3+ centers occupying adjacent tetrahedral holes of the close-packed framework of Br− ions. Upon melting AlCl3 gives the dimer Al2Cl6, which can vaporise. At higher temperatures this Al2Cl6 dimer dissociates into trigonal planar AlCl3, which is structurally analogous to BF3.

Aluminium chloride is highly deliquescent, and can explode upon abrupt contact with water because of the high heat of hydration. Aqueous solutions of AlCl3 are ionic and thus conduct electricity well. Such solutions are found to be acidic, indicative of partial hydrolysis of the Al3+ ion. The reactions can be described (simplified) as:

[Al(H2O)6]3+ + H2O ⇌ [Al(OH)(H2O)5]2+ + H3O+

AlCl3 is probably the most commonly used Lewis acid and also one of the most powerful. It finds widespread application in the chemical industry as the classic catalyst for Friedel-Crafts reactions, both acylations and alkylations. It also finds use in polymerization and isomerization reactions of hydrocarbons. Aluminium also forms a lower chloride, aluminium(I) chloride (AlCl), but this is very unstable and only known in the vapor phase.[2]

Aluminium chloride is a powerful Lewis acid, capable of forming stable Lewis acid-base adducts with even weak Lewis bases such as benzophenone or mesitylene.[4] Not surprisingly it forms AlCl4− in the presence of chloride ions.

In water, partial hydrolysis forms HCl gas or H3O+, as described in the overview above. Aqueous solutions behave similarly to other aluminium salts containing hydrated Al3+ ions, giving a gelatinous precipitate of aluminium hydroxide upon reaction with the correct quantity of aqueous sodium hydroxide:

AlCl3(aq) + 3 NaOH(aq) → Al(OH)3(s) + 3NaCl(aq)