ADRENALINE (EPINEPHRIN, ADRENINE) 87 



In order to utilise the d-adrenaline, obtained as a by-product in 

 the resolution of the racemic base (according to Flacher [1908] 

 and D.R.P. 222451), the dextro-variety may be racemised by means 

 of acids (according to D.R.P. 220355). For example, 1*5 grm. 

 d-adrenaline is dissolved in 13-5 c.c. normal hydrochloric acid (= 1*65 

 mol.) and after adding I 5 c.c. of water the solution is heated to 80-90 

 for two to three hours, after which the solution is optically inactive 

 and the crystalline hydrochloride of the racemic base can be isolated 

 by means of alcoholic hydrogen chloride. When the natural base was 

 kept for six weeks at 20-30 with the same concentration of hydro- 

 chloric acid, 75 per cent, had been racemised. By repeated resolution 

 and racemisation of the d-base, the whole of the synthetic adrenaline 

 is finally obtained in the 1-form. 



For an account of the patents relating to the synthesis of adrena- 

 line reference may be made to Friedlander's " Fortschritte der Teerfar- 

 benfabrikation," 1905-7, VIII, 1181-90, and 1907-10, IX, 1024-33; 

 or to the " Chemisches Zentralblatt ". 



Adrenaline Substitutes. 



Numerous bases, more or less closely related to adrenaline, have 

 been synthesised and some of these also resemble adrenaline in 

 physiological action. Only three of them, however, have been recom- 

 mended as substitutes for the natural active principle, namely 



3 : 4 dihydroxy-phenylethanolamine (OH) 2 C 6 H 3 . CH(OH) . CH 2 . NH 2 ("arterenol ") 

 w-ethylamino-3 : 4-dihydroxy-acetophenone (OH) 2 . C 6 H 3 . CO . CH 2 . NH . C 2 H 5 



(" homorenon ") 

 3 : 4-dihydroxy-phenylethyl-methylamine (OH 2 ) C 6 H 3 . CH a . CH 2 . NH . CH 3 (" epinine ") 



Of these, arterenol is according to Schultz [1909, I] about as active 

 on the blood pressure as natural 1-adrenaline (and therefore more 

 active than the racemic base). Homorenon and epinine are much 

 less active, the former base having according to Schultz only about 

 one-eightieth of the pressor action of 1-adrenaline. 



Physical and Chemical Properties of Adrenaline. Salts and 

 Derivatives. Constitution. 



Adrenaline, when pure, crystallises in colourless sphaerocrystals consisting of super- 

 posed lamellae ; crystals suitable for crystallographic measurement have not been obtained. 

 It melts at 211-212 (uncorr.) with decomposition. According to Bertrand the solubility in 

 water at 20 is 0-0268 per cent. The base is somewhat more soluble in boiling water, but 

 less in alcohol ; it is practically insoluble in most organic solvents but dissolves in glacial 

 acetic acid, in warm ethyl oxalate (Abel) and in benzaldehyde. In the latter solvent 

 Barger and Ewins [1906] found at 90 the molecular weight 170. 



Adrenaline is lasvo-rotatory. The'more trustworthy determinations in solution in dilute 

 mineral acids are tabulated below : 



