344. Aluminum Hydroxydiacetate

Nomenclature

CAS number: 142-03-0
Bis(aceto-κO)hydroxyaluminum; hydroxybis(acetato)aluminum; basic aluminum acetate; aluminum diacetate; aluminum subacetate; aluminum hydroxyacetate; Lenicet.
C4H7AlO5; mol wt 162.08.
C 29.64%, H 4.35%, Al 16.65%, O 49.36%.
Al(OH)(CH3CO2)2.

Description and references

Prepd from aluminum hydroxide and acetic acid or from sodium acetate and aluminum chloride hexahydrate: Hood, Ihde, J. Am. Chem. Soc. 72, 2094 (1950). Other methods of prepn: Gmelins, Aluminum (8th ed.) 35B, p 296 (1934). Also prepd in aq solution, see Aluminum Subacetate Solution.

Properties

White curdy precipitate or white amorphous powder. Material that has been oven-dried at 110° is practically insoluble in water. Freshly prepared material forms numerous hydrates and is quite sol in water. Greatest soly is obtained by formation in solution. The pharmacist's stock soln (see Aluminum Subacetate Solution) contains about 8% Al(OH)(CH3CO2)2, while commercial solns used for waterproofing, contain 22 to 25% Al(OH)(CH3CO2)2. When heated, the salt loses acetic acid, and aluminum to oxygen bonding occurs, resulting in a very insol compd of disputed nature, see Gmelin's, loc. cit. and Thomas, Pap. Trade J. 100, 36 (1935). Aq solns are generally acid to litmus; gradually become turbid and gelatinous. Sometimes a more basic salt precipitates out and settles to the bottom of the container. Increasing the pH to a marked degree will clear up an old soln due to formation of sodium acetate and sodium aluminate. Urea and thiourea have been suggested as stabilizers for aq solns.

Use

Manuf color lakes; mordant in dyeing; in waterproofing and fireproofing fabrics (solns for these purposes are known as red liquor or mordant rouge because they were originally used for preparing red color lakes); in antiperspirant formulations; as disinfectant by embalmers. Dusting powder.