APPENDIX TO CHAPTER I AMINES 127 



water and dissolved in a little boiling alcohol. After concentration 

 the alcoholic solution is poured into thirty volumes of water when the 

 benzoyl compounds crystallise. The concentrated alcoholic solution 

 of the crystals is then poured into twenty volumes of ether when 

 dibenzoyl putrescine separates and the cadaverine compound remains 

 dissolved. Another method is due to Loewy and Neuberg [1904]. 

 After filtering off the cystine the bases in the urine are precipitated 

 with phosphotungstic acid and after regeneration are treated in 

 alkaline solution with phenylisocyanate. The precipitated com- 

 pounds of the diamines are very little soluble in most organic solvents, 

 and are boiled out with alcohol, dried and dissolved in warm pyridine. 

 On adding dry acetone the putrescine compound crystallises at once, 

 the cadaverine compound only on standing. 



Properties and Compounds of Putrescine. 



The base is obtained synthetically by reduction of ethylene di- 

 cyanide (succino-nitrile), but more conveniently by reduction of 

 succindialdoxime (Willstatter and Heubner [1907]). 



Putrescine is a liquid of semen-like odour; m.p. 27-28; b.p. 158- 

 160; slightly volatile with steam; very soluble in water, miscible 

 with alcohol, very little soluble in ether. 



The dihydrochloride, C 4 H 12 N 2 . 2HC1, crystallises in leaflets and 

 needles and is insoluble in absolute alcohol. On destructive distilla- 

 tion it yields pyrrolidine (rigid proof of the constitution) (Ackermann 



[1907, I])- 



The platinichloride, C 4 H 12 N 2 . H 2 PtCl 6 , needles or six-sided plates, 

 is sparingly soluble in water (Brieger [1885, 2, p. 26]). 



The aurichloride, C 4 H 12 N 2 . 2HAnCl 4 . 2H 2 O, is less soluble than 

 the cadaverine salt (Brieger [1886, I, p. 51]). 



The mercur i chloride is readily soluble in water, but not in alcohol. 



The dipicrate, C 4 H 12 N 2 . 2C 6 H 8 O 7 N 3 , silky needles, hardly soluble 

 in cold water, decomposes at 250. 



The dipicrolonate, C 4 H 12 N 2 . 2C 10 H 8 O 5 N 4 , dissolves in 13,157 parts 

 of cold and 65 3 parts of boiling water, and in 17,857 parts of cold and 

 954 parts of boiling alcohol ; decomposes at 263 (Otori [1904, 3]). 



The dibenzoyl derivative, C 4 H 8 (NHCOC 6 H 5 ) 2 , crystallises in long 

 needles ; m.p. 178 ; almost insoluble in ether ; sparingly in cold, readily 

 in hot alcohol. 



The phenylisocyanate, C 4 H 8 (NH . CO. NH . C 6 H 6 ) 2 , forms sheaves 

 of needles from pyridine acetone ; m.p. 240 (corr.). Insoluble in water 

 and most organic solvents ; hardly soluble in boiling alcohol. 



