32  Nicotin  and  Nicotinic  Acid.  . 
Ethyl  chlorocarbonate  acts  violently  on  pyridene,  but  does  not  fornn> 
ethyl  nicotinate  ;  the  only  products  are  ethyl  chloride,  ethyl  carbonate, 
and  pyridene  hydrochloride.  Neither  is  ethyl  nicotinate  formed  by 
acting  with  ethyl  iodide  on  silver  nicotinate.  When  the  compound  oi 
nicotinic  chloride  with  hydrochloric  acid  (see  below)  is  treated  with 
absolute  alcohol,  a  violent  action  occurs,  and  the  product  evaporated  in 
a  desiccator  deposits  crystals  of  nicotinic  acid  hydrochloride.  The 
mother  liquor  from  these  crystals  gives  with  caustic  soda  an  oily  liquid, 
probably  containing  the  ether,  Vv'hich  no  doubt  existed  in  combination 
with  dydrochloric  acid. 
If  nicotinic  acid,  or  better,  potassium  nicotinate,  is  treated  with  phos  - 
phorus pentachloride,  energetic  action  ensues,  and  a  volatile  crystalline 
compound  sublimes,  the  analysis  of  which  corresponds  approximately  with 
the  formula  C^H^N.COCl. HCI.  This  chloride  is  insoluble  in  ether, 
chloroform,  benzin,  and  petroleum-ether.  When  heated  with  water  it  is 
reconverted  into  nicotinic  acid  ;  but  no  amide  could  be  formed  from  it 
by  the  action  of  ammojiia. 
When  the  double  chloride  of  zinc  and  nicotin,  CjoHj^Na-lHCl-}- 
ZnCi2-l-4H^O,  is  distilled  with  soda-  lime,  a  large  quantity  of  gas  is 
given  off,  containing  ammonia,  methylamin,  free  hydrogen  and  traces 
of  hydrocarbons.  The  liquid  distillate  consists  principally  of  nicotin, 
but  contains  also  a  considerable  quantity  of  pyrrol,  which  was  sepa- 
rated by  fractional  distillation,  and  analyzed  as  the  cadmium  double  salt. 
By  carefully  adding  water  to  the  fraction  245 — 270°,  containing  much 
nicotin,  an  oily  liquid  was  separated,  which,  when  dissolved  in  hydro- 
chloric acid  and  fractionally  precipitated  by  platinic  chloride  gave  a 
carmine-red  easily  decomposable  double  salt,  (Cj^3HjiN.HC])2.PtCl^. 
The  free  base  is  a  yellowish  liquid  of  extremely  penetrating  and  repul- 
sive odor,  boiling  between  250  and  270^^.  The  smallest  quantity  of  it, 
dissolved  in  hydrochloric  acid,  gives  an  intensely  red  solution  when 
boiled  with  platinic  chloride.  It  is  probably  formed  from  nicotin  by  the 
direct  separation  of  ammonia,  C\qHj_jN2  —  NHg^Ci^HiiN. — Jour^ 
Chem.  Soc.^  Oct.,  1879,  I'^'O'ti  Liebig's  Annalen. 
