Ammonium metavanadate is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula NH
4VO
3. It is a white salt, although samples are often yellow owing to impurities of V
2O
5. It is an important intermediate in the purification of vanadium.
[Günter Bauer, Volker Güther, Hans Hess, Andreas Otto, Oskar Roidl, Heinz Roller, Siegfried Sattelberger "Vanadium and Vanadium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. ]
Synthesis and structure
The compound is prepared by the addition of ammonium salts to solutions of vanadate ions, generated by dissolution of
V2O5 in basic aqueous solutions, such as hot sodium carbonate. The compound precipitates as a colourless solid. This precipitation step can be slow.
The compound adopts a polymeric structure consisting of chains of
O3sup>−, formed as corner-sharing VO
4 tetrahedra. These chains are interconnected via
hydrogen bond
In chemistry, a hydrogen bond (or H-bond) is a primarily electrostatic force of attraction between a hydrogen (H) atom which is covalently bound to a more electronegative "donor" atom or group (Dn), and another electronegative atom bearing a ...
s with
ammonium
The ammonium cation is a positively-charged polyatomic ion with the chemical formula or . It is formed by the protonation of ammonia (). Ammonium is also a general name for positively charged or protonated substituted amines and quaternary a ...
ions.
Uses
Vanadium is often purified from aqueous extracts of slags and ore by selective precipitation of ammonium metavanadate. The material is then roasted to give
vanadium pentoxide
Vanadium(V) oxide (''vanadia'') is the inorganic compound with the formula V2 O5. Commonly known as vanadium pentoxide, it is a brown/yellow solid, although when freshly precipitated from aqueous solution, its colour is deep orange. Because o ...
:
[
:2 NH4VO3 → V2O5 + 2 NH3 + H2O
]
Other
Vanadates can behave as structural mimics of phosphates, and in this way they exhibit biological activity.[Crans, D. C.; Chatterjee, P. B. "Vanadium Biochemistry" Reedijk, Jan; Poeppelmeier, Kenneth, Eds. Comprehensive Inorganic Chemistry II (2013), 3, 323-342. ]
Ammonium metavanadate is used to prepare Mandelin reagent The Mandelin reagent is used as a simple spot-test to presumptively identify alkaloids as well as other compounds. It is composed of a mixture of ammonium metavanadate and concentrated sulfuric acid. Its primary use is for the detection of ketamine ...
, a qualitative test for alkaloid
Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...
s.
References
{{Vanadium compounds
Vanadates
Ammonium compounds
Inorganic compounds