Ammonium persulfate

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Ammonium persulfate
Structural formulas of two ammonium cations and one peroxydisulfate anion
Ball-and-stick models of two ammonium cations and one peroxydisulfate anion
Solid sample of ammonium persulfate, as a white powder
Identifiers
CAS number 7727-54-0 YesY
ChemSpider 56400 YesY
UNII 22QF6L357F YesY
EC number 231-786-5
UN number 1444
RTECS number SE0350000
Jmol-3D images Image 1
Image 2
Properties
Molecular formula (NH4)2S2O8
Molar mass 228.18 g/mol
Appearance white to yellowish crystals
Density 1.98 g/cm3
Melting point 120 °C (393 K) decomp.
Solubility in water 80 g/100 mL (25 °C)
Hazards
MSDS External MSDS
EU Index 016-060-00-6
EU classification Oxidant (O)
Harmful (Xn)
Irritant (Xi)
R-phrases R8, R22, R36/37/38, R42/43
S-phrases (S2), S22, S24, S26, S37
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
LD50 689 mg/kg, oral (rat)
Related compounds
Other anions Ammonium thiosulfate
Ammonium sulfite
Ammonium sulfate
Other cations Sodium persulfate
Potassium persulfate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Ammonium persulfate (APS) is the inorganic compound with the formula (NH4)2S2O8. It is a colourless (white) salt that is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used in polymer chemistry, as an etchant, and as a cleaning and bleaching agent.

The dissolution of the salt in water is endothermic.

Preparation[edit]

Ammonium persulfate is prepared by electrolysis of a cold concentrated solution ammonium sulfate in sulfuric acid at a high current density.[1] The method was first described by H. Marshall.[2]

Uses[edit]

As an oxidizer and a source of radicals, APS finds many commercial applications.

Salts of peroxydisulfate are mainly used as radical initiators in the polymerization of certain alkenes. Commercially important polymers prepared using persulfates include styrene-butadiene rubber and polytetrafluoroethylene. In solution, the dianion dissociates to give radicals:[3]

[O3SO-OSO3]2- \overrightarrow{\leftarrow} 2 [.SO4]-

The sulfate radical adds to the alkene to give a sulfate ester radical. It is also used along with tetramethylethylenediamine to catalyze the polymerization of acrylamide in making a polyacrylamide gel.

Illustrative of its powerful oxidizing properties, it is used to etch copper on printed circuit boards as an alternative to ferric chloride solution.[4] This property was discovered many years ago. In 1908, John William Turrentine used a dilute ammonium persulfate solution to etch copper. Turrentine weighed copper spirals before placing the copper spirals into the ammonium persulfate solution for an hour. After an hour, the spirals were weighed again and the amount of copper dissolved by ammonium persulfate was recorded. This experiment was extended to other metals such as nickel, cadium, and iron, all of which yielded similar results. [5] The oxidation equation is thus: 1/2 S2O8 (aq)2- + e- -> SO4 (aq)2-.

Ammonium persulfate is the main component of Nochromix, a laboratory cleaning agent. On dissolving in sulfuric acid, it is used to clean laboratory glassware as a metal-free alternative to chromic acid baths.[6] It is also a standard ingredient in western blot gels and hair bleach.

Persulfates are used as oxidants in organic chemistry.[7]

Safety[edit]

Airborne dust may be irritating to eye, nose, throat, lung and skin upon contact. Exposure to high levels of dust may cause difficulty in breathing.[8]

It has been noted that persulfate salts are a major cause of asthmatic effects in women.[9] Furthermore, it has been suggested that exposure to ammonium persulfate can cause asthmatic effects in hair dressers and receptionists working in the hair dressing industry. These asthmatic effects are proposed to be caused by the oxidation of cysteine residues, as well as methionine residues.[10]

References[edit]

  1. ^ F. Feher, "Potassium Peroxydisulfate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 390.
  2. ^ Hugh Marshall (1891). "LXXIV. Contributions from the Chemical Laboratory of the University of Edinburgh. No. V. The persulphates". J. Chem. Soc., Trans. 59: 771. doi:10.1039/CT8915900771. 
  3. ^ Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort (2005), "Peroxo Compounds, Inorganic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_177.pub2 
  4. ^ "Ammonium Persulphate: Copper Etchant". MG Chemicals. 
  5. ^ Turrentine, J. W. (1908). "Action of Ammonium Persulphate on Metals.". Journal of Physical Chemistry 11: 623–631. doi:10.1021/j150089a004. 
  6. ^ "Nochromix". Sigma-Aldrich. Retrieved 2008-03-01. [dead link]
  7. ^ Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp. 193–197 (1995).
  8. ^ [1] FMC Corporation, MSDS sheet dated: 06/26/2009
  9. ^ De Vooght, V.; Jesus Cruz, M.; Haenen, S.; Wijnhoven, K.; Munoz, X.; Cruz, M.; Munoz, X.; Morell, F.; Nemery, B (2010). "Ammonium persulfate can initiate an asthmatic response in mice.". Thorax 65: 252–257. doi:10.1136/thx.2009.121293. 
  10. ^ Pignatti, P.; Frossi, B.; Pala, G.; Negri, S.; Oman, H.; Perfetti, L.; Pucillo, C.; Imbriani, M.; Moscato, G. (2013). "Oxidative activity of ammonium persulfate salt on mast cells and basophils: implication in hairdressers' asthma.". Int. Arch. Allergy Immunol. 160: 409–419. doi:10.1159/000343020. 

External links[edit]