Ammonium acetate

Ammonium acetate, also known as spirit of Mindererus in aqueous solution, is a chemical compound with the formula NH4CH3CO2. It is a white, hygroscopic solid and can be derived from the reaction of ammonia and acetic acid. It is available commercially.[5]

Ammonium acetate
Names
IUPAC name
Ammonium ethanoate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.010.149
RTECS number
  • AF3675000
UNII
  • InChI=1S/C2H4O2.H3N/c1-2(3)4;/h1H3,(H,3,4);1H3 Y
    Key: USFZMSVCRYTOJT-UHFFFAOYSA-N Y
  • InChI=1/C2H4O2.H3N/c1-2(3)4;/h1H3,(H,3,4);1H3
    Key: USFZMSVCRYTOJT-UHFFFAOYAY
  • o=c([o-])C.[N+H4]
Properties
C2H7NO2
Molar mass 77.083 g·mol−1
Appearance White solid crystals, deliquescent
Odor Slightly acetic
Density 1.17 g/cm3 (20 °C)[1]
1.073 g/cm3 (25 °C)
Melting point 113 °C (235 °F; 386 K)[2]
102 g/100 mL (0 °C)
148 g/100 mL (4 °C)[1]
143 g/100 mL (20 °C)
533 g/100 mL (80 °C)
Solubility Soluble in alcohol, SO2, acetone, liquid ammonia[3]
Solubility in methanol 7.89 g/100 mL (15 °C)[4][1]
131.24 g/100 g (94.2 °C)[3]
Solubility in dimethylformamide 0.1 g/100 g[3]
Acidity (pKa) 9.9
Basicity (pKb) 33
-41.1·10−6 cm3/mol
Viscosity 21
Structure
Orthorhombic
Thermochemistry
−615 kJ/mol[3]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Irritant
GHS labelling:[4]
Warning
H303, H316, H320, H333
P281, P335
NFPA 704 (fire diamond)
Flash point 136 °C (277 °F; 409 K)[4]
Lethal dose or concentration (LD, LC):
386 mg/kg (mice, intravenous)[3]
Safety data sheet (SDS) JT Baker
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Uses

It is the main precursor to acetamide:[6]

NH4CH3CO2 → CH3C(O)NH2 + H2O

It is also used as a diuretic.[5]

Buffer

As the salt of a weak acid and a weak base, ammonium acetate is often used with acetic acid to create a buffer solution. Ammonium acetate is volatile at low pressures. Because of this, it has been used to replace cell buffers that contain non-volatile salts in preparing samples for mass spectrometry.[7] It is also popular as a buffer for mobile phases for HPLC with ELSD detection for this reason. Other volatile salts that have been used for this include ammonium formate.

When dissolving ammonium acetate in pure water, the resulting solution typically has a pH of 7, because the equal amounts of acetate and ammonium neutralize each other. However, ammonium acetate is a dual component buffer system, which buffers around pH 4.75 ± 1 (acetate) and pH 9.25 ± 1 (ammonium), but it has no significant buffer capacity at pH 7, contrary to common misconception.[8]

Other
  • a biodegradable de-icing agent.
  • a catalyst in the Knoevenagel condensation and as a source of ammonia in the Borch reaction in organic synthesis.
  • a protein precipitating reagent in dialysis to remove contaminants via diffusion.
  • a reagent in agricultural chemistry for determination of soil CEC (cation exchange capacity) and determination of available potassium in soil wherein the ammonium ion acts as a replacement cation for potassium.
  • part of calley's method for lead artifact conservation

Food additive

Ammonium acetate is also used as a food additive as an acidity regulator; INS number 264. It is approved for usage in Australia and New Zealand.[9]

Production

Ammonium acetate is produced by the neutralization of acetic acid with ammonium carbonate or by saturating glacial acetic acid with ammonia.[10] Obtaining crystalline ammonium acetate is difficult on account of its hygroscopic nature.

References
  1. Pradyot, Patnaik (2003). Handbook of Inorganic Chemicals. The McGraw-Hill Companies, Inc. ISBN 0-07-049439-8.
  2. Davidson, Arthur W.; McAllister, Walter H. (1930). "Solutions of Salts in Pure Acetic Acid. Ii. Solubilities of Acetates1". Journal of the American Chemical Society. 52 (2): 507–519. doi:10.1021/ja01365a010. ISSN 0002-7863.
  3. "Ammonium acetate".
  4. "Safety Data Sheet of Ammonium Acetate" (PDF). tedia.com. Tedia Company Inc. 2011-08-12. Retrieved 2014-06-10.
  5. Hosea Cheung; Robin S. Tanke; G. Paul Torrence. "Acetic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_045.pub2.
  6. Coleman, G. H.; Alvarado, A. M. (1923). "Acetamide". Organic Syntheses. 3: 3.; Collective Volume, vol. 1, p. 3
  7. Berman, Elena S. F.; Fortson, Susan L.; Checchi, Kyle D.; Wu, Ligang; Felton, James S.; Kuang Jen, J. Wu; Kulp, Kristen S. (2008). "Preparation of single cells for imaging/profiling mass spectrometry". J Am Soc Mass Spectrom. 19 (8): 1230–1236. doi:10.1016/j.jasms.2008.05.006. PMID 18565760.
  8. Konermann, Lars (2017). "Addressing a Common Misconception: Ammonium Acetate as Neutral pH "Buffer" for Native Electrospray Mass Spectrometry". American Society for Mass Spectrometry. 28 (9): 1827. doi:10.1007/s13361-017-1739-3. Retrieved 25 October 2022.
  9. Australia New Zealand Food Standards Code "Standard 1.2.4 - Labelling of ingredients". Retrieved 2011-10-27.
  10. Brannt, William (1914). A practical treatise on the manufacture of vinegar. Lancaster, PA: Henry Carey Baird & Co. pp. 316–317.
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