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Ammonium Hydroxide


Other Names:

Aqueous ammonia

Ammonia water






General Information:


Structure:



CAS Number: 1336-21-6

Molecular Weight: 35.04 g/mol

Appearance: Colorless liquid

Chemical Formula: NH4OH

Melting Point: -57.5 C (25% w/w)

Boiling Point: 37.3 C (25% w/w)

Density: 0.91 g/mL (25% w/w)


Ammonium hydroxide (NH4OH) solutions are basic, with a 1M NH3 solution having a pH of 11.63. Saturated NH4OH solutions contain 35% ammonia (by mass), however, concentrated solutions that are used in organic chemistry labs are typically 28-30% ammonia (by mass). The concentration of ammonia decreases slightly every time a bottle is opened due to evaporation of ammonia, especially if the bottle was removed from a refrigerator and allowed to warm to room temperature.




Common Uses:


Reagent in amide coupling reactions (serves as a source of NH3)





Nucleophile in SNAr reactions





Additive in the catalytic reduction of nitriles





Additive in silica gel chromatography



Procedure excerpt:
…concentrated in vacuo. The resulting crude material was purified by chromatography [330 g SiO2, 0-5% (10% NH4OH in MeOH)/(DCM)] to provide…




Additive in reverse phase chromatography



Procedure excerpt:
…heated with shaking at 90 C overnight. The crude solution was purified by reverse phase chromatography (C18, 5-95% ACN/H2O, 0.1% NH4OH) to provide…




Safety:


Mixing ammonia containing compounds (ex. NH3, NH4OH, or NH4Cl) and bleach (NaOCl) is very dangerous because it produces toxic by-pdts. People have died from mixing cleaning supplies that contain ammonia and bleach. Household cleaning products that contain ammonia are typically aqueous solutions (NH4OH).




References:


1) WO2014149164, page 213

2) WO2012149280, page 72

3) WO2016014463, page 91

4) WO2015084384, page 62

5) WO2015051043, page 127

6) Wikipedia: Ammonium hydroxide (link)

7) www.sigmaaldrich.com: Ammonium hydroxide solution (link)

8) The Chlorine Institute, Sodium Hypochlorite Incompatibility Chart (link)