46  Action  of  Hydrochloric  Acid  on  Caffeine.        {Am' ^'lisT^' 
ACTION  OF  HYDROCHLORIC  ACID  ON  CAFFEINE. 
By  E.  Schmidt. 
It  was  thought  possible  that  theobromine  might  be  formed  by  this 
reaction  with  elimination  of  a  methyl-group.  No  reaction,  however, 
takes  place  below  about  240°,  the  caffeine  then  decomposing,  with  for- 
mation of  carbonic  anhydride,  ammonium  chloride,  methylamine 
hydrochloride,  sarcosine  hydrochloride,  and  traces  of  formic  acid, 
C8H10N4O2  +  6H20  =  2C02+  2MeNH2+  NH3  +  CH202  +  C3H7N02. 
The  reaction  is  effected  in  sealed  tubes,  the  temperature  being  main- 
tained at  240 — 250°  for  6 — 12  hours  ;  above  260°  the  product  becomes 
partially  carbonized.  The  caffeine  employed  was  the  pure  product  obtained 
from  tea.  The  methylamine  hydrochloride  is  separated  and  purified 
by  means  of  its  platinochloride,  which  crystallizes  partly  in  lustrous 
yellow  plates  and  partly  in  orange-red  rosette-like  groups.  The  sarco- 
sine was  identified  by  means  of  its  copper  salt  (C3H6N02)2Cu,  2H20, 
sarcosine  obtained  Jby  the  action  of  barium  hydroxide  on  caffeine 
yielding  a  perfectly  similar  salt.  These  results  show  that  caffeine  yields 
the  same  products  by  the  action  either  of  hydrochloric  acid  or  of 
barium  hydroxide,  except  that  in  the  former  case  the  intermediate  pro- 
duct, caffeidine,  is  not  produced.  Theobromine  is  decomposed  by 
hydrochloric  acid,  with  formation  of  the  same  products  as  in  the  case 
of  caffeine,  but  the  proportion  of  ammonia  to  methylamine  is  in  this 
case  two  molecules  of  the  former  to  one  of  the  latter,  showing  that  the 
additional  methyl-group  in  the  caffeine  must  be  united  with  a  nitrogen 
atom.  The  fact  that  only  one  of  the  four  nitrogen  atoms  in  caffeine 
can  be  eliminated  as  ammonia  is  in  accordance  with  the  formula  given 
by  Fischer  (Annalen,  215,  314),  and  Medicus  (ibid.,  175,  250),  but  is 
^ot  explained  by  Strecker's  formula  (ibid.,  118,  171). 
\  The  author  has  also  very  carefully  compared  artificial  caffeine  as 
prepared  by  Strecker  (loc.  cit.)  with  natural  caffeine  obtained  from  tea. 
His  results  confirm  those  previously  obtained  by  Strecker,  a  compari- 
son of  the  following  salts  proving  that  artificial  and  natural  caffeine 
are  identical.  The  hydrochloride,  C8H10N4O2,  HC1,  2H20,  forms  color- 
less monoclinic  crystals,  which  give  off  hydrochloric  acid  and  water  by 
exposure  to  air,  leaving  pure  caffeine,  the  same  change  taking  place 
rapidly  at  100°,  or  by  the  action  of  water  or  alcohol.  The  platino- 
chloride, (C8H10N4O2)2,  H2PtCl6,  crystallizes  in  small  rosette-like  groups 
