Aluminium chlorohydrate

Basic aluminium chloride Other names Aluminium hydroxychloride Aluminium chlorhydroxide Aluminium chlorohydrol Polyaluminium chloride Identifiers CAS number [1327-41-9] EC number 215-477-2 ATC code M05BX02 Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Aluminium chloride dihydroxide IUPAC name aluminium chloride dihydroxide Identifiers InChI InChI=1/Al.ClH.2H2O/h;1H;2*1H2/q+3;;;/p-3 InChIKey YCLAMANSVUJYPT-DFZHHIFOAH Standard InChI InChI=1S/Al.ClH.2H2O/h;1H;2*1H2/q+3;;;/p-3 Standard InChIKey YCLAMANSVUJYPT-UHFFFAOYSA-K CAS number [10284-64-7] EC number 233-632-2 ChemSpider 8373134 Properties Chemical formula AlCl(OH)2 Molar mass 96.449 g/mol Hazards Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Aluminium dichloride hydroxide IUPAC name aluminium dichloride hydroxide Identifiers InChI InChI=1/Al.2ClH.H2O/h;2*1H;1H2/q+3;;;/p-3 InChIKey IDOSCGGXFAKNLS-DFZHHIFOAS Standard InChI InChI=InChI=1S/Al.2ClH.H2O/h;2*1H;1H2/q+3;;;/p-3 Standard InChIKey IDOSCGGXFAKNLS-UHFFFAOYSA-K CAS number [14215-15-7] EC number 238-071-7 ChemSpider 8466237 Properties Chemical formula AlCl2(OH) Molar mass 114.89 g/mol Hazards Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Dialuminium chloride pentahydroxide IUPAC name dialuminium chloride pentahydroxide Identifiers InChI InChI=1/2Al.ClH.5H2O/h;;1H;5*1H2/q2*+3;;;;;;/p-6 InChIKey ZGRQKCWNBYXGOB-CYFPFDDLAZ Standard InChI InChI=1S/2Al.ClH.5H2O/h;;1H;5*1H2/q2*+3;;;;;;/p-6 Standard InChIKey ZGRQKCWNBYXGOB-UHFFFAOYSA-H CAS number [12042-91-0] EC number 234-933-1 ChemSpider 8329776 Properties Chemical formula Al2Cl(OH)5 Molar mass 174.45 g/mol Hazards Material safety data sheet (MSDS) External MSDS Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Aluminium chlorohydrate or basic aluminium chloride is a group of salts having the general formula Al_nCl_(3n-m)(OH)_m. It is used in deodorants and antiperspirants and as a flocculant in water purification.

In water purification, where it is usually called polyaluminium chloride, this compound is preferred in some cases because the pH value can be varied according to the exact values chosen for the subscripts n and m in the pattern formula. Although many variations are used, an especially important combination is Al₁₂Cl₁₂(OH)₂₄. The actual pH correlates to the formula m/(3n).

Structure

Aluminium chlorohydrate is best described as an inorganic polymer and as such is difficult to structurally characterise. However, techniques such as gel permeation chromatography, X-ray crystallography and ²⁷Al-NMR have been used in research by various groups including that of Nazar and Laden to show that the material is based on Al₁₃ units with a Keggin ion structure and that this base unit then undergoes complex transformations to form larger poly-aluminium complexes.

Synthesis

Aluminium chlorohydrate can be commercially manufactured by reacting aluminium with hydrochloric acid. A number of aluminium-containing raw materials can be used, including aluminium metal, alumina trihydrate, aluminium chloride, aluminium sulfate and combinations of these. The products can contain by-product salts, such as sodium/calcium/magnesium chloride or sulfate.

Because of the potential explosive hazard of mixing aluminium metal with hydrochloric acid, the most common industrial practice is to prepare a solution of aluminium chlorohydrate (ACH) by reacting aluminium hydroxide with hydrochloric acid. The ACH product is reacted with aluminium ingots at 100 °C using steam in an open mixing tank. The Al to ACH ratio and the time of reaction allowed determines the polymer form of the PAC n:m ratio.

Safety

The variation most commonly used in deodorants and antiperspirants is Al₂Cl(OH)₅. There is no scientific evidence supporting widespread rumors that aluminium salts in deodorants can cause Alzheimer's disease or breast cancer. Amongst others, research published in the Journal of the National Cancer Institute found no evidence whatsoever that these compounds increase the risk of breast cancer. However, aluminium is a neurotoxin that alters the function of the blood-brain barrier, and it is one of the few abundant elements that appears to have no beneficial function to living cells.

External links

• D09AA08, M05BX02
• NIOSH Pocket Guide to Chemical Hazards 0024
• IPCS Environmental Health Criteria 194: Aluminium