Osazone
{{Short description|Class of chemical compounds}}
Image:D-glucose-osazone-3D-balls.png of glucosazone]]
Osazone are a class of carbohydrate derivatives found in organic chemistry formed when reducing sugars are reacted with excess of phenylhydrazine at boiling temperatures.{{cite journal |last1=El Khadem |first1=Hassan S. |last2=Fatiadi |first2=Alexander J. |title=Hydrazine derivatives of carbohydrates and related compounds |journal=Advances in Carbohydrate Chemistry and Biochemistry |date=2000 |volume=55 |page=175-263 |doi=10.1016/S0065-2318(00)55006-9 |isbn=9780120072552 |url=https://www.sciencedirect.com/science/article/abs/pii/S0065231800550069 |access-date=31 March 2021 |ref=1}}{{Cite journal| doi = 10.1039/J39700002567| title = Structure of saccharide osazones| year = 1970| last1 = Mester | first1 = L.| last2 = El Khadem | first2 = H.| last3 = Horton | first3 = D.| journal = Journal of the Chemical Society C: Organic| issue = 18| pages = 2567 }}
Formation
Osazone formation was developed by Emil Fischer,{{cite journal | doi =10.1002/ange.19530650202 | title =Emil Fischer zum 100. Geburtstag | year =1953 | last1 =Helferich | first1 =B. | journal =Angewandte Chemie | volume =65 | pages =45–52 | issue =2| bibcode =1953AngCh..65...45H }} who used the reaction as a test to identify monosaccharides.
The formation of a pair of hydrazone functionalities involves both oxidation and condensation reactions.{{cite book|last1=Ramakrishnan|first1=S.|url=https://books.google.com/books?id=BVpDI7n2M9gC&pg=PA20|title=Textbook of Medical Biochemistry|date=2004|publisher=Orient Blackswan|isbn=9788125020714|language=en}} Since the reaction requires a free carbonyl group, only "reducing sugars" participate. Sucrose, which is nonreducing, does not form an osazone.
:Image:Osazone-Formation.png reacts with phenylhydrazine to give glucosazone. The same product is obtained from fructose and mannose.]]
Appearance
Osazones are highly coloured and crystalline compounds. Osazones are readily distinguished.{{Cite book|last=Gupta|first=Anil|title=Comprehensive Biochemistry for Dentistry|publisher=Springer|year=2019|isbn=978-981-13-1035-5|location=Singapore|pages=108–110|chapter=Carbohydrates}}
Historic references
- {{cite journal | year = 1908 | last1 = Fischer | first1 = Emil|title = Schmelzpunkt des Phenylhydrazins und einiger Osazone | journal = Berichte der Deutschen Chemischen Gesellschaft | volume = 41 | pages = 73–77 |doi=10.1002/cber.19080410120 | url = https://zenodo.org/record/1426269 }}
- {{cite journal | doi = 10.1002/cber.189402702249 | title = Ueber einige Osazone und Hydrazone der Zuckergruppe | year = 1894 | last1 = Fischer | first1 = Emil | journal = Berichte der Deutschen Chemischen Gesellschaft | volume = 27 | pages = 2486–2492 | issue = 2| url = https://zenodo.org/record/1425750 }}
- {{cite journal | doi = 10.1038/175220a0 | title = Mechanism of Osazone Formation | year = 1955 | last1 = Barry | first1 = VINCENT C. | last2 = Mitchell | journal = Nature | volume = 175 | pages = 220 | pmid = 13235861 | first2 = PW | issue = 4448|bibcode = 1955Natur.175..220B | doi-access = free }}