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

Ammonium acetate skeletal formula
Ball-and-stick model of ammonium acetate
Crystalline of ammonium acetate
Names
IUPAC name Ammonium ethanoate
Identifiers
CAS Number	631-61-8 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:62947 N
ChemSpider	11925 Y
ECHA InfoCard	100.010.149
EC Number	211-162-9
PubChem CID	517165
RTECS number	AF3675000
UNII	RRE756S6Q2 Y
UN number	3077
CompTox Dashboard (EPA)	DTXSID5023873
InChI 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
SMILES O=C([O-])C.[N+H4]
Properties
Chemical formula	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]
Solubility in water	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
Magnetic susceptibility (χ)	−41.1·10−6 cm3/mol
Viscosity	21
Structure
Crystal 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]
Pictograms
Signal word	Warning
Hazard statements	H303, H316, H320, H333
Precautionary statements	P281, P335
NFPA 704 (fire diamond)	[4] 1 1 1
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). N verify (what is YN ?) Infobox references

History

The synonym Spirit of Mindererus is named after R. Minderer, a physician from Augsburg.^[6]

Uses

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.