204 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Chondroitin on hydrolysis with hydrochloric acid yields chondrosin. The 

 sulphuric acid and acetic acid are split off and the molecule ruptured between 

 the glycuronic acid molecules. Chondrosin is a glucosidic combination of 

 chondrosamine and glycuronic acid. 



Preparation of the Barium Salt of Chondroitin and Chondroitin 

 Sulphuric Acid. 



The nasal septa of cattle, freed from bone and other extraneous material,, 

 are ground up in a meat chopper. 5 kilo, portions are allowed to stand for 2 

 days with 10 litres of a 2 per cent, solution of potassium hydroxide. The solu- 

 tion is strained off through a cloth, the insoluble matter treated with 5 litres 

 of potash solution and washed with water. The solutions are united, acidified 

 with acetic acid and concentrated on a water-bath with excess of barium 

 carbonate to about half the volume. The clear liquid is poured off and the 

 residue filtered on a folded filter. The liquid and nitrate are acidified with 

 acetic acid and evaporated to about 2 litres with barium carbonate. The solid 

 matter, consisting of protein and barium carbonate, is separated from the clear 

 yellow liquid by centrifugalisation and dropped into 8 volumes of glacial acetic 

 acid and stirred with a mechanical stirrer. The acid potassium salt is precipi- 

 tated, filtered off, washed with glacial acetic acid, alcohol and ether. 200 

 gm. of this product, which may give a slight biuret reaction, are dissolved in 

 10 litres of water, the solution is mechanically stirred and basic lead acetate 

 added so long as a precipitate is formed. The lead salt is filtered off, washed 

 with water by grinding in a mortar, suspended in 5 litres of water, to which 

 100 gm. of barium acetate and 50 c.c. of acetic acid have been added, and 

 decomposed with hydrogen sulphide. The lead sulphide is filtered off and 

 the slightly turbid solution is precipitated by adding one-third of its volume 

 of alcohol. The barium salt thus obtained is filtered off and washed with 50 

 per cent, alcohol, 95 per cent, alcohol, absolute alcohol and ether. It forms 

 a white powder and is a mixture of the barium salt of Chondroitin and chon- 

 droitin sulphuric acid. 



Preparation of Chondrosin. 



50 gm. of the barium salt of Chondroitin sulphuric acid are dissolved in 

 150 c.c. of equal parts of concentrated hydrochloric acid and water and heated 

 for an hour on the water-bath. Barium sulphate begins to separate out at once, 

 the solution after i hour showing the maximum reduction of Fehling's solu- 

 tion. The filtered solution is evaporated in vacuo to a thick syrup, the syrup 

 is dissolved in 40 c.c. of hot water and poured into 500 c.c. of absolute 

 alcohol ; partial precipitation of chondrosin hydrochloride takes place. 2 

 volumes of absolute ether are added after 12-16 hours and the precipitate is 

 filtered off and washed with absolute ether. About 27 gm., dried over cal- 

 cium chloride for 2 days, are obtained. It may be purified by solution in 

 water and reprecipitated with alcohol and ether. It is a colourless powder^ 

 which is not hygroscopic if properly washed. 



