330 
Pyridine  and  Quinoline  Bases. 
f  Am.Jowr.  Pharm, 
1      June,  1883. 
the  hydrogen  of  the  hydroxide  takes  the  place  of  the  iodine  in  the  base. 
Thus  with  the  iodide  of  methyl-pyridylammonium  this  reaction  takes 
place, 
CsHsN.OHgl+KOH^O+KI+CsHsNCHaH. 
Methy]  pyiidyl  am-  Dibydro-picoline. 
moniurn  iodide. 
As  these  hydro-bases  can  be  readily  transformed  into  the  bases  themselves^ 
the  reaction  of  Hofmann  becomes  the  more  valuable,  because  it  enables  us 
to  pass  directly  from  any  member  of  the  series  to  the  next  higher. 
According  to  Wiscbnegradsky  the  {pyridine  bases  exist  in  the  state  of 
hydrides  in  the  {ilkaloids.  From  the  labors  of  Konigs'  and  of  Schotten,'^ 
we  knoA^  that  piperidine  is  the  hexahydropyridine,  and  more  recently 
Oeechner  de  Koninck'^  has  found  tetrahydroquinoline  in  the  crude  quino- 
line obtained  by  distilling  cinchonine  with  sodium  hydroxide.  The  re- 
searches of  Cahours  and  Etard  have  shown  that  nicotine  is  a  tetrahydroiso- 
dipyridine,  while  further  evidence  in  favor  of  this  idea  is  to  be  found  in 
the  work  of  Weidel  and  Russo.*  Starting  with  pyridine,  C5H5N,  treating 
with  metallic  sodium,  they  obtained  dipyridyl  CioHgNa.  Treated  with 
nascent  hj^drogen,  dipyridyl  takes  up  six  atoms,  and  there  is  formed  isoni- 
cotine,  CioHj^N.^. 
A  number  of  substitution  products  of  pyridine  are  known.  Hofmann, 
Anderson,  and  Ciamician  and  Dennstedt  have  described  chlorine  and  bro- 
mine derivatives.  O.  Fischer^  obtained  pyridine-sulphonic  acid  by  heating 
pyridine  with  an  excess  of  concentrated  sulphuric  acid,  and  from  this,  by 
means  of  well-known  reactions,  he  prepared  the  cyanide  and  the  cor- 
responding acid. 
Quinoline  Series,  C^.Ji^^-iiN - — By  distilling  quinine,  cinchonine  or  strych- 
nine with  potassium  hydroxide,  Gerhardt^  obtained  a  substance  having 
the  properties  of  an  energetic  base,  which  he  called  quinoline.  Two  years 
previous,  in  1843,  Runge  had  discovered  leucoline,  a  base  of  the  same 
composition  occurring  in  coal  tar.  Hofmann^  tinding  that  leucoline  and 
quinoline  gave  the  same  crystalline  precipitate  with  chromic  acid,  con- 
cluded that  the  two  bases  were  identical.  The  study  of  these  compounds 
was  undertaken  in  1860  by  C.  G.  Williams,  and  he  succeeded  in  isolating 
the  parallel  series  of  homologous  bases,  as  follows: 
Quinoline,  C9H.jN  Leucoline. 
Lepidine,  C10H9N  Iridoline. 
Dispoline,  CuHuN  Cryptidine. 
Tetrahiroline,  C12H13IS". 
By  the  decomposition  of  the  alkaloids  with  caustic  potassa,  bases  of  the 
first  series  are  exclusively  formed,  while  the  members  of  the  second  series 
1  Ibid,  xii,  2341, 
2  Ibid,  XV,  421. 
3  Annaies  de  Clumie  et  de  Phj^sique  (5),  xxvii,  433. 
Monatshefte  liir  Chemie,  iii,850. 
5  Berichte  der  deutschen  chernischeii  Gesellschaft,  xv,  62. 
6  Anriiilen  der  Chemie,  xlii,  310,  and  xliv,  279. 
'  Ibid.  liii,427. 
