The chemical formula of aluminum chloride is AlCl3, which is a compound of chlorine and aluminum. Aluminum chloride has a low melting point and boiling point, and it will sublime, becoming a covalent compound. Molten aluminum chloride is not easy to conduct electricity, unlike most salts containing halogen ions (such as sodium chloride).
AlCl3 adopts a "YCl3" structure, which is the densest cubic layered structure of Al3+, while Al3+ in AlBr3 occupies the gap between adjacent tetrahedrons of the Br− densest packed frame. When melted, AlCl3 forms a volatile dimer Al2Cl6, which contains two three-center four-electron chlorine bridge bonds. At higher temperatures, the Al2Cl6 dimer dissociates to form flat triangular AlCl3, which is similar in structure to boron trifluoride (BF3).
Aluminum chloride is a colorless transparent crystal or white and slightly yellowish crystalline powder. When aluminum chloride vapor is dissolved in a non-polar solvent or in a molten state, it exists as a covalent dimer molecule (Al2Cl6). It is soluble in water and many organic solvents. The aqueous solution is acidic. In the presence of aromatic hydrocarbons, the mixture of aluminum chloride and aluminum can be used to synthesize bis(aromatic hydrocarbon) metal complexes. For example, diphenylchromium is prepared by Fischer-Hafner synthesis from specific metal halides.
Main purpose
1. Aluminum chloride is mainly used in Friedel-Crafts reactions, such as the preparation of anthraquinone from benzene and phosgene, which is used in the dyeing and finishing industry.
2. In the above reaction of benzene and its derivatives, the main product is the para-isomer. In comparison, the alkylation reaction involves more problems and is not as widely used as the acylation reaction. Regardless of the reaction, aluminum chloride and other raw materials and equipment must be moderately dry, and a small amount of water will help the reaction proceed.
Since aluminum chloride can be coordinated with the reaction product, it must be used in Friedel-Crafts reaction in the same amount as the reactant, not a "catalytic amount". The aluminum chloride after the reaction is difficult to recover, and a large amount of corrosive waste is generated. In order to meet the requirements of green chemistry, chemists began to use yttrium fluoride or dysprosium fluoride to replace aluminum chloride to reduce pollution. Aluminum chloride is also commonly used to add aldehyde groups to the benzene ring. For example, the Gartman-Koch reaction uses carbon monoxide, hydrogen chloride, aluminum chloride and cuprous chloride as catalysts.
3. Aluminum chloride has a wide range of applications in organic chemistry. It can catalyze the Ene reaction, such as the addition of 3-butene-2-one (methyl vinyl ketone) and carvone
4 . AlCl3 is also commonly used in hydrocarbon polymerization and isomerization reactions. Important examples include the industrial production of ethylbenzene. Ethylbenzene can be used to further prepare styrene, polystyrene, and dodecylbenzene as a cleaning agent. In the presence of aromatic hydrocarbons, the mixture of aluminum chloride and aluminum can be used to synthesize bis(aromatic hydrocarbon) metal complexes. For example, diphenylchromium is prepared by Fischer-Hafner synthesis from specific metal halides. Low concentration of basic aluminum chloride is often one of the ingredients of antiperspirants, and patients with hyperhidrosis will have a higher concentration (12% or higher) when using it.
5. Used as a catalyst for organic synthesis, such as petroleum cracking, synthetic dyes, synthetic rubber, synthetic detergents, medicines, perfumes, etc.;
6. Used in the manufacture of pesticides, organoaluminum compounds, phthalocyanine series organic pigment catalysts, and ethylbenzene manufacturing catalysts;
7. Used in metal smelting and lubricating oil synthesis;
8. Food grade products are used as leavening agents, sake and other anti-tarnishing agents and pectin flocculants;
9. Used as analytical reagent, preservative, and mordant.
Notes
Anhydrous aluminum chloride reacts violently with alkali, so it needs to be handled properly. Aluminum chloride containing crystal water is less problematic.
Inhalation of anhydrous aluminum chloride or contact with eyes and skin can cause irritation.
Invasion route: inhalation, ingestion, transdermal absorption.
Health Hazards
Inhalation of high concentrations of aluminum chloride can stimulate the upper respiratory tract to produce bronchitis, and it has a stimulating effect on the skin and mucous membranes. Individuals can cause bronchial asthma. When a large amount is mistakenly taken, it can cause oral erosion, gastritis, gastric bleeding and mucosal necrosis.
Chronic effects: Long-term exposure can cause headache, dizziness, loss of appetite, cough, nasal congestion, chest pain and other symptoms.
Acute toxicity: LD503730mg/kg (oral for rats); Dangerous characteristics: It reacts with water and generates heat and emits toxic corrosive gas; combustion (decomposition) products: chloride, alumina.
Security terms
After S26 accidentally comes into contact with eyes, please rinse immediately with plenty of water and seek medical advice.
S45 If an accident occurs or you feel unwell, seek medical attention immediately (show the label if possible).
S36/37/39 Wear appropriate protective clothing, gloves and goggles or masks.
Security measures
Eye protection: wear chemical safety glasses.
Protective clothing: wear work clothes (made of anti-corrosion materials).
Hand protection: wear rubber gloves.
Skin contact: Take off contaminated clothing immediately and rinse thoroughly with plenty of running water.
Ingestion by mistake: When the patient is awake, rinse his mouth immediately and drink milk or egg white. Seek medical attention immediately.
Protective measures Respiratory protection: When you may be exposed to its dust, you should wear a dust mask. Wear a gas mask when necessary.
Fire extinguishing method: dry powder, sandy soil. Water is forbidden.
Others: After work, take a shower and change clothes. Store clothes contaminated by poisons separately and wash them before use. Maintain good hygiene.
Emergency response to leakage
Isolate the contaminated area with warning signs around it. It is recommended that emergency personnel wear self-contained breathing apparatus and chemical protective clothing. Do not directly touch the leakage, do not make the leakage contact with combustible materials (wood, paper, oil, etc.), use a clean shovel to collect in a closed container and mark it, waiting for disposal. If there is a large amount of leakage, it is best not to treat it with water and remove it under the guidance of a technician.
First aid measures
Skin contact: Take off contaminated clothing immediately and rinse thoroughly with plenty of running water.
　　 Eye contact: immediately lift the eyelids, rinse with running water for 10 minutes or rinse with 2% sodium bicarbonate solution.
　　 Inhalation: quickly leave the scene to a place with fresh air. Pay attention to keep warm and keep the airway unobstructed. Give artificial respiration if necessary. Seek medical attention.
　　 Ingestion: When the patient is awake, rinse his mouth immediately and drink milk or egg white. Seek medical attention immediately.
　　Extinguishing methods: dry powder, sandy soil. Water is forbidden.