ALUMINUM CHLORIDE (ALCL3): STRUCTURE, PROPERTIES, USES - CHEMISTRY - 2025

The aluminum chloride or aluminum trichloride (AlCl ₃) is a binary salt formed by aluminum and chlorine. Sometimes it appears as a yellow powder due to the presence of impurities due to the presence of iron (III) chloride.

It is obtained by combining its elements. Aluminum, which has three electrons in its last energy level (family IIIA), tends to give them away due to its metallic nature. Chlorine with seven electrons in its last energy level (VIIA family), tends to gain them to complete its octet.

The bond formed between aluminum and chlorine in aluminum trichloride is considered to be covalent, even though it is the bond between a metal and a nonmetal.

There are two classes of aluminum chloride:

• Anhydrous aluminum chloride. AlCl _3.
• Aluminum chloride hexahydrate. AlCl ₃. 6H ₂ O. This compound can be found in solid form or in solution.

Chemical structure

Anhydrous aluminum trichloride is a molecule with a planar trigonal geometry, with an angle of 120 ° corresponding to an sp ² atomic hybridization.

However, the molecule is organized in the form of dimers, in which a chlorine atom donates a pair of electrons to form bonds. These are known as coordinate covalent bonds.

This is the way in which the dimer organization of aluminum trichloride is deduced.

This organization allows the compound to form into networks of dimer layers. When water is poured onto solid aluminum trichloride they do not dissociate as expected from ionic compounds, but undergo vigorous hydrolysis.

On the contrary, in dilute aqueous solution are the ⁺³ coordinate ions and chloride. These structures are very similar to those of diborane.

In this way we have the formula Al ₂ Cl ₆

If the difference in the electronegativity of the atoms that form the bonds in this compound is measured, the following can be observed:

For aluminum Al the electronegativity value is 1.61 C and that of chlorine is 3.16 C. The difference in electronegativity is 1.55 C.

According to the rules of bond theory, for a compound to be ionic it must have a difference in the electronegativity of the atoms that make up the bond of a value greater than or equal to 1.7 C.

In the case of the Al-Cl bond, the difference in electronegativity is 1.55 C, which gives aluminum trichloride a covalent bond arrangement. This slight value can be attributed to the coordinated covalent bonds that the molecule presents.

Properties

Physical

Appearance: white solid, sometimes yellow in color due to impurities caused by ferric chloride

Density: 2.48 g / mL

Molar mass: 133.34 g / mol

Sublimation: sublimates at 178 ° C, so its melting and boiling points are very low.

Conduction: conducts electricity poorly.

Solubility: it is not soluble in water because it is a Lewis acid. It is soluble in organic solvents such as benzene, carbon tetrachloride, and chloroform.

Chemical

In water, aluminum trichloride is hydrolyzed forming HCl and the hydronium ion and aluminum hydroxide:

It is used in Friedel-Crafts reactions as a catalyst (a substance that can be recovered at the end of the reaction, because it is only there to speed up, slow down or start a reaction).

It is a corrosive substance.

In decomposition when it reacts violently with water it produces aluminum oxide and dangerous gases such as hydrogen chloride.

Applications

• Antiperspirant.
• Friedel-Crafts acylation and alkylation catalyst.

Risks: possible effects

• It is a corrosive substance, it causes skin burns and serious eye damage.
• Reacts violently with water.
• It is dangerous for the environment.
• Very toxic for aquatic organisms.

recommendations

Avoid exposure to the product without the necessary safety measures. You must use safety glasses, gloves, appropriate clothing, covered shoes.

In case of inhalation. Inhalation of the dust can irritate the respiratory tract due to the corrosive nature of the substance. Symptoms include a sore throat, cough, and shortness of breath. Symptoms of pulmonary edema can be delayed and severe cases can be fatal. Move the victim to an airy place free of contaminants. Give artificial respiration if necessary. If he is short of breath, give him oxygen. Call the doctor.

In case of contact with the skin. AlCl ₃ is corrosive. May cause irritation or burns with redness and pain. Wash immediately after contact with plenty of water, for at least 20 minutes. Do not neutralize or add substances other than water. Take off contaminated clothing and wash before reuse. consult a doctor immediately in case of injury.

In contact with the eyes. AlCl ₃ is corrosive. It causes severe pain, blurred vision, and tissue damage. Immediately flush eyes with water for at least 20 minutes, and keep eyelids open to ensure all eye and eyelid tissues are rinsed. Flushing your eyes in seconds is essential for maximum effectiveness. If you have contact lenses, remove them after the first 5 minutes and then continue rinsing your eyes. Seek medical advice. It can cause serious damage to the cornea, conjunctiva or other parts of the eye.

In case of ingestion. AlCl ₃ is corrosive. Combustion can cause pain in the mouth and esophagus and burns of the mucous membranes. It can cause gastrointestinal upset with abdominal pain, nausea, vomiting, and diarrhea. DO NOT INDUCE VOMITING. Rinse mouth, and give water to drink. Never give anything orally to an unconscious person. Call the doctor. If vomiting occurs spontaneously, turn victim to side to reduce risk of aspiration.

People with existing skin disorders or eye problems or impaired respiratory function may be more susceptible to the effects of the substance.

The packaging and storage of the AlCl ₃ compound must be done in ventilated, clean and dry places.

References

1. Chemical book, (2017), Aluminum chloride. Recovered from chemicalbook.com
2. cosmos online, cosmos.com.mx
3. Sharpe, AG, (1993), Organic Chemistry, Spain, Editorial Reverté, SA
4. F., (2017), Aluminum Chloride AlCl ₃, El Insignia. Taken from blog.elinsignia.com.
5. TriHealth, (2018), Aluminum Trichloride, last update, March 4, 2018, Retrieved from trihealth.adam.com.
6. RxWiki, (sf), Aluminum Chloride, Recovered from, rxwiki.com.