Aluminium chloride

inorganic compound

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synonym AlCl3 (AlCl3) generally refers to aluminum chloride

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Aluminum chloride is an inorganic compound, chemical formula is AlCl three Is a compound of chlorine and aluminum. The melting point and boiling point of aluminum chloride are very low, and will sublimate Covalent compound 。 Molten aluminum chloride is not easy to conduct electricity, and most salts containing halogen ions (such as sodium chloride ）Different.

AlCl three Yes "YCl three ”Structure, Al 3+ Cubic densest stacking layered structure, while AlBr three Medium Al 3+ But Br − Adjacent tetrahedral gaps of the densest stacked frame. AlCl during melting three Generate volatile dimer Al two Cl six , containing two three center four electron chlorine bridge bonds, Al at higher temperatures two Cl six The dimer dissociates to form planar triangular AlCl three , and Boron trifluoride （BF three ）Similar structure.

Aluminium chloride is a white crystalline powder. Aluminum chloride vapor or dissolved in Non-polar solvent In or at Melting state When the covalent dimer (Al two Cl six ）Form exists. Soluble in water and many organic solvents. The aqueous solution is acidic. In the presence of aromatic hydrocarbons, aluminum chloride can be mixed with aluminum to synthesize bis (aromatic) metal complexes. For example, diphenylchromium is prepared through Fischer Hafner synthesis of specific metal halides.

Chinese name: Aluminium chloride^[2]
Foreign name: aluminium chloride^[2]
Alias: Aluminum chloride ^[2]
chemical formula: AlCl₃^[2]
molecular weight: one hundred and thirty-three point three four^[2]
CAS login number: 7446-70-0^[2]
EINECS login number: 231-208-1
Melting point: 194 ℃^[2]

Boiling point: 178 ℃ (sublimation)
Water solubility: Soluble
Density: 2.44 g/cm³
Appearance: White crystalline powder
Application: metallurgical industry
Security description: S28；S45
Hazard symbol: C
Hazard description: R34
UN dangerous goods number: one thousand seven hundred and twenty-six

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▪ Risk terminology

brief introduction

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Aluminium chloride, chemical formula: AlCl three , is the chloride of aluminum. The melting point and boiling point of aluminum chloride are very low, which will sublimate to Covalent compound 。 Molten aluminum chloride is not easy to conduct electricity, and most salts containing halogen ions (such as sodium chloride ）Different.

AlCl three Yes "YCl three ”Structure, Al 3+ Cubic densest stacking layered structure, while AlBr three Medium Al 3+ But Br − Adjacent tetrahedral gaps of the densest stacked frame. AlCl during melting three Generate volatile Dimer Al two Cl six , containing two three center four electron chlorine bridge bonds, Al at higher temperatures two Cl six The dimer dissociates to form planar triangular AlCl three , and BF three Similar structure.

Aluminum chloride is colorless transparent crystal or white crystalline powder with light yellow tinge. Aluminum chloride vapor or dissolved in Non-polar solvent In or at Melting state They all exist in the form of covalent dimers. Soluble in water and many organic solvents. The aqueous solution is acidic. In the presence of aromatic hydrocarbons, aluminum chloride can be mixed with aluminum to synthesize bis (aromatic) metal complexes. For example, diphenylchromium is prepared through Fischer Hafner synthesis of specific metal halides.

physical property

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Aluminium chloride

Aluminum chloride, white crystalline powder, with strong smell of hydrochloric acid, industrial products are pale yellow. Soluble in water alcohol 、 chloroform 、 carbon tetrachloride , slightly soluble in benzene 。 Molten aluminum chloride is not easy to conduct electricity, and most salts containing halogen ions (such as sodium chloride ）Different. The aqueous solution of aluminum chloride is completely dissociated and is a good conductor.

Aluminum chloride sublimates at 178 ℃, and its vapor is an associated bimolecule. It can absorb water in the air and partially hydrolyze to release hydrogen chloride.

Aluminum chloride is colorless transparent crystal or white and slightly yellowish crystalline powder. Easily absorb water and partially hydrolyze to release Hydrogen chloride And form acid mist. Easily soluble in water and strongly hydrolyzed, the solution is acidic. It is also soluble in ethanol and ether, and gives off a lot of heat at the same time.^[1]

chemical property

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Aluminum chloride is a strong Lewis acid, which can Lewis base React to produce compounds, even with Benzophenone and Mesitylene Such weak Lewis base action. If chloride ion exists, aluminum chloride will generate tetrachloroaluminate ion (AlCl four - ）：

AlCl three (aq) + Cl - (aq) ⇌ AlCl four - (aq)

In water, aluminum chloride will be partially hydrolyzed to form hydrogen chloride gas or H three O + Ions. Its aqueous solution is the same as that of other aluminum containing substances, and contains hydrated aluminum ions sodium hydroxide Reaction can generate Aluminium hydroxide Sedimentation:

AlCl three (aq) + 3 NaOH(aq) =Al(OH) three (s) + 3NaCl(aq)
AlCl three (aq) + 3H two O =AlO two - + 3HCl + H three O +
AlCl three +4NaOH=NaAlO two +3NaCl+2H two O

Aluminum chloride is easy to deliquescence, and may explode in contact with water due to heat release during hydration. It will partially hydrolyze and release hydrogen chloride.

The solution is acidic, which is caused by partial hydrolysis of aluminum ions.

[Al(H two O) six ] 3+ + H two O ⇌ [Al(OH)(H two O) five ] 2+ + H three O +

Main purpose

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1. Aluminum chloride is mainly used in Friedel Crafts reaction In, for example, with benzene and phosgene Prepare for raw materials anthraquinone , used in dyeing and finishing industry. In the generalized Friedel Crafts reaction, the reaction formula of acyl chloride or haloalkane and aromatic substances is:

Friedel Crafts reaction

2. When benzene and its derivatives undergo the above reaction, the main product is the para isomer. In comparison, alkylation involves many problems, and is not as widely used as acylation. No matter what kind of reaction, aluminum chloride and other raw materials and instruments must be moderately dry, and a small amount of water is conducive to the reaction.

Since aluminum chloride can coordinate with reaction products, its amount must be the same as that of reactants when applied to Friedel Crafts reaction, rather than "catalytic amount". The aluminum chloride after reaction is difficult to recover and will produce a large amount of corrosive waste. In order to meet the requirements of green chemistry, chemists began to use yttrium fluoride or dysprosium fluoride instead of aluminum chloride to reduce pollution.

Aluminum chloride is also commonly used to add aldehyde groups to the benzene ring. For example, carbon monoxide, hydrogen chloride, aluminum chloride and cuprous chloride are used as catalysts in the Gatman Koch reaction.

three 、 Aluminum chloride is widely used in organic chemistry. It can catalyze Ene reaction, such as the addition of 3-butene-2-one (methyl vinyl ketone) and carvone:

Ene reaction

4、AlCl three It is also commonly used in hydrocarbon polymerization and isomerization. Important examples include the industrial production of ethylbenzene. Ethylbenzene can be used to further prepare styrene, polystyrene and dodecylbenzene as a detergent.

In the presence of aromatic hydrocarbons, aluminum chloride can be mixed with aluminum to synthesize bis (aromatic) metal complexes. For example, diphenylchromium is prepared through Fischer Hafner synthesis of specific metal halides.

Low concentration of basic aluminum chloride is often one of the components of antiperspirants, and the concentration of hyperhidrosis patients will be higher (12% or higher) when using it.

5. Used as catalyst for organic synthesis, such as petroleum cracking, synthetic dyes, synthetic rubber, synthetic detergent, medicine, spices, etc.

6. It is used as a catalyst for manufacturing pesticides, organic aluminum compounds, phthalocyanine organic pigments, and ethyl benzene.

7. Used for metal smelting and lubricating oil synthesis.

8. Food grade products are used as anti tarnish agents such as bulking agents, sake, and flocculants of pectin.

9. Used as analytical reagent, preservative, mordant.

Leakage emergency treatment

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Isolate the leakage contaminated area, set warning signs around it, and suggest that emergency personnel wear self-contained breathing apparatus and chemical protective clothing. Do not contact the leakage directly, and do not make the leakage contact with combustible materials (wood, paper, oil, etc.). Collect the leakage with a clean shovel in a closed container for marking and waiting for treatment. If there is a large amount of leakage, it is better not to treat it with water and remove it under the guidance of technicians.

Protective measures

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Eye protection: wear chemical safety goggles.

Protective clothing: wear work clothes (made of anti-corrosion materials).

Hand protection: wear rubber gloves.

Others: After work, take a shower and change clothes. Store the clothes contaminated by poisons separately and reuse them after washing. Keep good hygiene habits.

First aid measures

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Skin contact: Take off contaminated clothes immediately, and wash thoroughly with plenty of flowing water.

Eye contact: immediately lift the eyelid and wash it with flowing water for 10 minutes or with 2% sodium bicarbonate solution.

Inhalation: quickly leave the site to a place with fresh air. Keep warm and keep respiratory tract unobstructed. Perform artificial respiration when necessary. Get medical attention.

Ingestion: Rinse the mouth immediately when the patient is awake, and drink milk or egg white. Get medical attention immediately.

security information

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Safety terminology

S28：After contact with skin, wash immediately with plenty of ... (to be specified by the manufacturer).

After skin contact, immediately use a large amount of (designated by the manufacturer).

S45：In case of accident or if you feel unwell, seek medical advice immediately (show the lable where possible).

In case of an accident or feeling unwell, seek medical advice immediately (show the label if possible).

Risk terminology

R34：Causes burns.

Causes burns.

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