272 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



Adrenaline is a derivative of catechol and is the active principle 

 of the adrenal gland from which it is prepared as 

 well as by synthesis. 



The natural substance is laevorotatory : the syn- 

 thetical is inactive ; the dextrorotatory form has only 

 a very slight pharmacological action in comparison 

 CH 2 .NH(CH 3 ). with the laevorotatory or natural form. 

 Preparation. 



Abel's method is probably the most convenient one for preparing adrena- 

 line. To minced suprarenal glands in a series of flasks is added with 

 thorough shaking an equal weight of 3*5 per cent, trichloracetic acid in 

 alcohol. After 12 hours the mass is filtered. The filtrate is concentrated 

 to about one-fiftieth and again filtered. Concentrated ammonia is added to 

 the filtrate until the liquid just smells perceptibly of ammonia. Adrenaline is 

 precipitated, filtered off, washed with water, alcohol and ether. A yield of 

 about -2 per cent, is obtained. A further T per cent, can be obtained by 

 extracting the mass again with trichloracetic acid. It is recrystallised by 

 solution in alcohol containing oxalic acid and precipitation by ammonia. 



Properties. 



Adrenaline is a colourless crystalline solid melting at 211-212. Itis not 

 easily soluble in cold water, but more readily in hot water and is not soluble 

 in most organic solvents. 



It is a strong base and dissolves in mineral acids ; as a phenol it dissolves 

 in caustic alkalies, but not in carbonates or ammonia. Its aqueous solutions 

 are not stable, but turn pink in the air. 



Reactions. 



(1) Ferric chloride in neutral or faintly acid solution gives a green colora- 

 tion which on the careful addition of very dilute alkali changes to violet, red- 

 violet and red. 



(2) Oxidising agents and air produce a pink colour : potassium persulphate 

 added up to - i per cent, to the solution of adrenaline gives a colour at a 

 dilution of i in 5,000,000 (Ewins). 



(3) Adrenaline gives an intense blue colour with Folin's phosphotungstic 

 acid reagent for uric acid (see p. 557). One part in 3,000,000 parts of water 

 gives a reaction with this reagent. 



A full account of adrenaline is given in Barger's " Simpler Natural Bases ". 



Estimation. 



The estimation of adrenaline in the suprarenal gland is most easily 

 effected by means of the colour reaction with phosphotungstic acid as shown 

 by Folin, Cannon and Denis in 1913. 



The weighed gland is ground up in a mortar with sand and 'iN hydro- 

 chloric acid and rinsed into a conical flask. 15 c.c. of ! iN acid and 45 c.c. 

 of water are used for every 2 gm. of gland. The solution is raised to boiling ; 

 there is no coagulation, but on adding 5 c.c. of 10 per cent, sodium acetate 

 solution for .every 15 c.c. hydrochloric acid and again heating to boiling, 

 coagulation of the protein occurs. The mixture except the sand is transferred 

 to a 100 c.c. measuring flask and diluted to the mark. The solution is 

 filtered or centrifuged. 5 c.c. of the filtrate are pipetted into a 100 c.c. 



