Ammonium acetate
Chemical compound From Wikipedia, the free encyclopedia
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]
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| Names | |
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| IUPAC name
Ammonium ethanoate | |
| Identifiers | |
3D model (JSmol) |
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.010.149 |
| EC Number |
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PubChem CID |
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| RTECS number |
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| UNII | |
| UN number | 3077 |
CompTox Dashboard (EPA) |
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| Properties | |
| C2H7NO2 | |
| Molar mass | 77.083 g·mol−1 |
| Appearance | White solid crystals, deliquescent |
| Odor | Slightly acetic acid like |
| 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 | |
Std enthalpy of formation (ΔfH⦵298) |
−615 kJ/mol[3] |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
Irritant |
| GHS labelling:[4] | |
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| 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): | |
LD50 (median dose) |
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).
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History
The synonym Spirit of Mindererus is named after R. Minderer, a physician from Augsburg.[6]
Uses
Summarize
Perspective
It is the main precursor to acetamide:[7]
- 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.[8] It is also popular as a buffer for mobile phases for HPLC with ELSD and CAD-based 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.[9]
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.[10]
Production
Ammonium acetate is produced by the neutralization of acetic acid with ammonium carbonate or by saturating glacial acetic acid with ammonia.[11] Obtaining crystalline ammonium acetate is difficult on account of its hygroscopic nature.
References
External links
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