Gusty reaction
The Böeseken reaction , also known as the Böseken reaction , is an analytical method in organic chemistry named after its discoverer, the Dutch chemist Jacob Böeseken (1868 - 1949). It is used to detect cis -1,2-diols.
application
Boric acid [B (OH) 3 ] is a very weak and only monobasic acid (pK s = 9.00), which does not react as a proton donor, but as a Lewis acid. By reaction with cis -1,2-diols such as, for example, α-D-xylopyranose (or mannitol or glycerol ), the acid strength by four to five orders of magnitude can (pK s increased = 3,80 to 5:15). This is due to a shift of the equilibrium to the right side towards a boric acid ester as a result of an esterification :
This reaction is used for the alkalimetric titration of boric acid. B (OH) 3 reacts only with cis -1,2-diols (for example with α-D-xylopyranose ) to form the corresponding acidic boric acid ester . There is no reaction with trans -1,2-diols (e.g. β-D-xylopyranose):
The Böeseken reaction thus allows the cis : trans ratio to be determined from the change in acidity in an isomer mixture of cis isomers and trans isomers . The use of this analysis method in carbohydrate chemistry is particularly well known. So the sugar-boric acid esters in the so-called. "Sugar analyzer" with ion exchange columns can be separated chromatographically because of their different acid strengths . Some monosaccharides can also be determined quantitatively, e.g. B. D-glucose in the serum and urine of diabetics .
Individual evidence
- ↑ a b c Eberhard Breitmaier, Günther Jung, Organische Chemie, 7th edition, Thieme, Stuttgart, 2012, page 883, ISBN 978-3-13-541507-9 , doi : 10.1055 / b-002-44908
- ^ A b F. Albert Cotton, Geoffrey Wilkinson: Inorganische Chemie, VEB Deutscher Verlag der Wissenschaften, Berlin, 1988, 2nd edition, pp. 244–245.
- ↑ Jakob Böeseken, Advances in carbohydrate chemistry , 4 (1949), pp. 189-210.