CHEMISTRY OF THE PTOMAINES. 209 



pyridine bases. It absorbs carbonic acid energetically from 

 the air, without losing thereby the repulsive odor. The 

 boiling-point of the free base, as ordinarily obtained, is 

 about 135°. It is not decomposed by distillation with 

 potassium hydrate, and is rather difficultly volatile with 

 steam. With acids it forms beautiful crystalline salts. 

 Putresfine unites with water, like ethylenediamine, to form 

 a hydrate, and this water can only be removed by distilla- 

 tion with metallic sodium. The perfectly anhydrous base 

 boils at 15f)°-157°, and then solidifies to plates (Brieger), 

 which melt at 24° (Udranszky and Baujiann). The 

 synthetic base boils at 158°-160°, and melts at 23°- 

 24° (Ladenburg). Like cadaverine it is difficultly solu- 

 ble in ether. 



The constitution of putrescine has been determined by 

 Udranszky and Baumann (1888). They showed that 

 the dibenzoyl compound of putrescine was identical with 

 that of the synthetic tetramethylenediamine and of the 

 I)asu which they found in the urine of cystinuria. 



Putrescine, therefore, is tetramethylenediamine, a homo- 

 logue of cadaverine, and its rational formula is : 



NH2.CH2.CH2.CH2 CH^.NH^. 



The same authors (Zeitschr. f. Physiol. Chem. 13, 591) 

 point out that diamines may possibly Ofcur in putrefaction 

 as the result of oxidation of monamiiies. Thus, jjutreseine 

 might arise from metliylamine according to the equation : 



CH,.CH,.NH, CIL— CPL— NH, 



CH,.CH,.]SrH, 



+ 0=1 + H,0. 



GIL— CH,— NH, 



In a similar manner cadaverine might form from ethyl 

 and propylamine. 



Putrescine can be prepared synthetically, according to 

 Ladenburg's method, by converting ethylene bromide into 

 the cyanide and then reducing this by means of sodium 

 in absolute alcohol. 



On heating the concentrated aqueous solution of the 

 hydrochloride with potassium nitrite there is produced an 



