I 
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'^""No'^iris^ss*""'}  Constitution  of  the  Alkaloids.  551 
and  splits  apart  into  piperic  acid,  CigHjoO^,  and  piperidine,  CgHjiN. 
This  latter  base  has  been  shown  to  be  a  hydrogen  addition  product  of 
pyridine,  C5H5N.  When  heated  with  concentrated  sulphuric  acid,  it  is 
oxidised  to  pyridine.  Piperidine  hydrochlorate,  also,  when  heated 
with  excess  of  bromine  to  180°C,  yields  dibrompyridine. 
SinapinCj  the  alkaloid  which  exists  as  sulphocyanate  in  white  mus- 
tard seed,  yields  under  the  same  reaction  as  that  applied  to  atropine 
and  piperine,  quite  different  results.  When  boiled  with  baryta  water, 
sinapine  decomposes  into  sinapic  acid,  CnH^gOg,  and  choline, 
C5H15NO2,  the  latter  a  well-known  constituent  of  the  bile,  and  pro- 
duced also  in  the  decomposition  of  the  lecithin  of  the  brain  and  yolk 
of  egg. 
Cocaine,  the  alkaloid  of  coca  leaves,  is  decomposed  by  heating 
with  hydrochloric  acid  into  methyl  alcohol,  benzoic  acid  and  a  crystal- 
line base  ecgonine,  C9H15NO3. 
Caffeine  and  theobromine  have  also  quite  different  relations.  Caffeine, 
it  will  be  remembered,  is  the  methyl  ester  of  theobromine,  and  can  be 
prepared  from  it.  When  caffeine  is  carefully  oxidised  with  chlorine, 
it  yields  dimethyl-alloxan  and  methyl-urea.  Both  theobromine  and 
caffeine  are  decomposed  by  heating  to  240°  C  in  sealed  tubes  with 
hydrochloric  acid,  identical  products  being  obtained.  These  products 
are  carbon  dioxide,  formic  acid,  ammonia,  methylamine,  and  sarcosine, 
the  last  three  being  of  course  in  combination  with  the  excess  of  hydro- 
chloric acid.  The  artificial  preparation  of  theobromine  and  caffeine 
from  xanthine,  and  guanine  also  shows  clearly  their  relations. 
If,  having  completed  our  survey  of  what  has  been  done  in  the  way 
of  decomposing  the  alkaloids  by  the  different  classes  of  reagents,  we 
review  the  field,  it  will  be  seen  that  with  all  the  alkaloids  mentioned, 
except  the  last  four,  a  more  or  less  immediate  connection  with  the  pyri- 
dine and  quinoline  bases  has  been  indicated.  The  conviction  accord- 
ingly forces  itself  upon  us  that,  if  we  want  to  attack  the  problem  of 
building  up  any  of  these  important  alkaloids  artificially,  we  must  turn 
to  these  bases  as  our  starting  point. 
As  already  stated,  both  series  occur  in  coal-tar  and  the  pyridine 
series  also  more  abundantly  in  bone-oil.  Pyridine,  picoline,  lutidine, 
and  collidine,  the  first  four  members  of  the  pyridine  series,  have,  more- 
over, all  been  formed  synthetically,  although  the  processes  are  not  such 
as  would  yield  the  products  as  cheaply  as  they  can  be  gotten  from 
DippeFs  oil.    Quinoline,  the  first  member  of  the  higher  series,  had 
