Tollens' reagent
Tollens' reagent (chemical formula ) is a chemical
Laboratory preparation
This reagent is not commercially available due to its short
. The ions convert theIn the next step, sufficient
Alternatively,
Uses
Qualitative organic analysis
Once the presence of a
The test rests on the premise that aldehydes are more readily
In a positive test, the diamine silver(I) complex oxidizes the aldehyde to a
Tollens' reagent can also be used to test for terminal alkynes (). A white precipitate of the
Both Tollens' reagent and
Staining
In
In silver mirroring
Tollens' reagent is also used to apply a silver mirror to glassware; for example the inside of an insulated vacuum flask. The underlying chemical process is called silver mirror reaction. The reducing agent is glucose (an aldehyde) for such applications. Clean glassware is required for a high quality mirror. To increase the speed of deposition, the glass surface may be pre-treated with tin(II) chloride stabilised in hydrochloric acid solution.[5]
For applications requiring the highest optical quality, such as in telescope mirrors, the use of tin(II) chloride is problematic, since it creates nanoscale roughness and reduces the reflectivity.[6][7] Methods to produce telescope mirrors include additional additives to increase adhesion and film resilience, such as in Martin's method, which includes tartaric acid and ethanol.[7]
Safety
Aged reagent can be destroyed with dilute acid to prevent the formation of the highly explosive silver nitride.[8]
See also
- Benedict's reagent
- Walden reductor (opposite use involving metallic silver)
References
- .
- ^ a b Webpath website http://library.med.utah.edu/WebPath/HISTHTML/MANUALS/FONTANA.PDF. Retrieved 4 February 2009
- ^ "Oxidation of aldehydes and ketones". chemguide.co.uk. Retrieved 31 January 2010.
- .
- ISBN 0-9518216-0-1.
- ^
N. Chitvoranund1; S. Jiemsirilers; D.P. Kashima (2013). "Effects of surface treatments on adhesion of silver film on glass substrate fabricated by electroless plating". Journal of the Australian Ceramic Society. 49: 62–69.
{{cite journal}}
: CS1 maint: numeric names: authors list (link) - ^ .
- ISBN 0-582-21866-7.
External links
- Video of experimental process involving Tollens' reagent
- Tollens' reagent on www.wiu.edu
- Univ. of Minnesota Organic Chemistry Class Demo Archived 3 March 2016 at the Wayback Machine Result Archived 3 March 2016 at the Wayback Machine