88 



THE SIMPLER NATURAL BASES 



d-Adrenaline has the same physical and chemical properties as 1-adrenaline and melts 

 also at 211-212, but is much less active physiologically. 



Adrenaline is a fairly strong base and can be dissolved in the theoretical quantity of a 

 mineral acid, or even in somewhat less than one equivalent (Gunn and Harrison [1908]). 

 Being a phenol, it is also soluble in caustic alkalies, but not in ammonia or sodium carbonate. 

 The chief chemical characteristic of adrenaline is the readiness with which it undergoes 

 oxidation, on account of the presence of a catechol nucleus. A large number of mild oxidis- 

 ing agents colour adrenaline solutions pink, rose red, and brown, and the same change takes 

 place on exposure to air, slowly in acid, rapidly in alkaline solution. Adrenaline is most 

 stable in solutions containing a slight excess of acid, for instance one and a half equivalents 

 of acid to one equivalent of the base. The coloration takes place much more rapidly when 

 minute traces of iron are present (Gunn and Harrison [1908]). A number of colour reac- 

 tions, depending on this oxidative change, are described below (pp. 89-91). According to Abel 

 [1902, 3] extracts of the supra-renal gland are more stable to Fehling's solution than solutions 

 of the pure active principle. Adrenaline solutions do not give precipitates with the common 

 alkaloidal reagents, but on heating with dilute acids, or by the action of concentrated hydro- 

 chloric acid in the cold, adrenaline is transformed into a substance yielding alkaloidal re- 

 actions (Abel's epinephrine). 



The salts of the optically active adrenalines are mostly amorphous and deliquescent ; the 

 borate prepared by evaporating 1-83 gr. of the base and 0*93 gr. of boric acid in 5 c.c. of 

 water is said to be more stable (D.R.P. 167317). The chief crystalline salt of adrenaline is 

 the bitartrate, employed in the resolution of the synthetic product, Pauly [1904] prepared 

 a crystalline urate. The racemic base yields, in addition, a crystalline hydrochloride, mp. 

 157 (D.R.P. 202169), and a crystalline oxalate, but the corresponding salts of both d-and 

 1-adrenaline are amorphous (Flacher [1908]). 



No crystalline derivatives of adrenaline are known. Abel and Pauly prepared benzoyl 

 derivatives of somewhat uncertain composition. Von Fiirth obtained a tri-benzenesulphonyl 

 derivative which contains the alcoholic hydroxyl of the side chain intact, for Friedmann 

 [1904, 1906] converted it into m-nitrobenzoyl-tribenzenesulphonyl-adrenaline and oxidised 

 it to tribenzenesulphonyl-adrenalone. Stolz obtained a tri-p-chlorbenzoyl derivative. 



The constitution of adrenaline was ascertained from the following 

 reactions ; 



On fusion with potash catechol and protocatechuic acid are formed ; 

 on heating with acids or caustic soda methylamine is eliminated. On 

 methylation and subsequent oxidation with permanganate veratric acid, 

 vanillin and trimethylamine were obtained. The constitution is further 

 proved by Friedmann's work (see above, p. 83) and finally of course 

 by synthesis and resolution. 



The alleged production of skatole on potash fusion is probably due 

 either {o the presence of protein impurities, or to that of a benzoyl 



