Aluminium sulfacetate

Aluminium sulfacetate is a mixture of aluminium salts dissoloved in water with formula Al
2
SO
4
(CH
3
CO
2
)
4
.[1][2]

UsesEdit

It is an evenly balanced mixture of aluminium sulfate and aluminium acetate. It can be used as a mordant, which is a substance used to set dyes on fabrics[3] that typically contains a polyvalent metal ion like aluminium or iron,[4] In mixtures with basic aluminium diacetate or aluminium sulfacetate, aluminium triacetate has been used as a mordant with alizarin dye.[1] In 1899, Albert Ganswindt recommended that the use of impure sulfacetates that are empyreumatic liquids "should be abandoned" in favour of pure preparations.[5] Empyreuma is an obsolete chemical and medical term referring to "the smell and taste associated with burning vegetable and animal matter",[6] and likely results in this case from the use of pyroligneous acid (wood acid) or wood acid lime in the preparation of the mordant.[5]

PreparationEdit

A common approach to preparing aluminium sulfacetate is by reaction of aluminium sulfate with lead(II) acetate. The relative amount of each reagent controls the composition of the resulting mixture.[1] When the stoichiometric ratio of lead acetate to aluminium sulfate exceeds 3:1, the process is theoretically driven to completion and aluminium triacetate is the sole product. With less lead acetate, a mixture of aluminium triacetate and aluminium sulfacetate results that becomes increasingly rich in the latter as the reagent mole ratio approaches 2:1. This approach is used to form various mixtures for mordant applications:[1]

Al
2
(SO
4
)
3
  +   3 Pb(CH
3
CO
2
)
2
  →   2 Al(CH
3
CO
2
)
3
  +   3 PbSO
4

Basic aluminium sulfacetates can also be prepared, Al
2
SO
4
(CH
3
CO
2
)
4 - n
(OH)
n
, with hydroxide anions replacing some acetate ions. The extreme cases are aluminium sulfacetate itself (n = 0) and the double salt of aluminium sulfate and aluminium hydroxide (n = 4 case, Al
2
SO
4
(OH)
4
). Aluminium sulfacetate is made from the hydrates of aluminium sulfate and lead acetate:[2]

Al
2
(SO
4
)
3
•18H
2
O
  +   2 Pb(CH
3
CO
2
)
2
•3H
2
O
  →   Al
2
SO
4
(CH
3
CO
2
)
4
  +   2 PbSO
4
  +   24 H
2
O

The n = 1 and n = 2 cases, both of which are basic aluminium sulfacetates, are prepared using sodium bicarbonate along with the regents:[2]

2 Al
2
(SO
4
)
3
•18H
2
O
  +   3 Pb(CH
3
CO
2
)
2
•3H
2
O
  +   2 NaHCO
3
  →   Al
2
SO
4
(CH
3
CO
2
)
3
OH
  +   3 PbSO
4
  +   Na
2
SO
4
  +   2 CO
2
  +   45 H
2
O
Al
2
(SO
4
)
3
•18H
2
O
  +   Pb(CH
3
CO
2
)
2
•3H
2
O
  +   2 NaHCO
3
  →   Al
2
SO
4
(CH
3
CO
2
)
2
(OH)
2
  +   PbSO
4
  +   Na
2
SO
4
  +   2 CO
2
  +   21 H
2
O

The n = 3 case, also a basic aluminium sulfacetate, is prepared using acetic acid instead of lead acetate, along with sodium bicarbonate:[2]

Al
2
(SO
4
)
3
•18H
2
O
  +   CH
3
COOH
  +   4 NaHCO
3
  →   Al
2
SO
4
(CH
3
CO
2
)(OH)
3
  +   2 Na
2
SO
4
  +   CO
2
  +   19 H
2
O

ReferencesEdit

  1. ^ a b c d von Georgievics, Georg (2013). The Chemical Technology of Textile Fibres – Their Origin, Structure, Preparation, Washing, Bleaching, Dyeing, Printing and Dressing. Read Books. ISBN 9781447486121.
  2. ^ a b c d Hummel, J. J.; Knecht, Edmund (1888). Die Färberei und Bleicherei der Gespinnstfasern (in German). Springer-Verlag. pp. 116–118. ISBN 9783642912061.
  3. ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version:  (2006–) "Mordant". doi:10.1351/goldbook.M04029
  4. ^ Llewellyn, Bryan D. (May 2005). "Stain Theory – How mordants work". Archived from the original on 14 August 2007.
  5. ^ a b Ganswindt, Albert (1889). Handbuch der Färberei und der damit verwandten vorbereitenden und vollendenden Gewerbe (in German). p. 270.
  6. ^ "Definition of empyreuma". Collins Dictionary. 2016. Retrieved 23 November 2016.