Am.  Jour,  Pharm. 
Sept.,  1888. 
A  New  Base  in  Tea. 
463 
Theobromine  sublimes  at  290°  G.  without  melting.  Theophylline 
also  sublimes  at  a  temperature  above  its  melting  point. 
Theophylline  forms  definitely  crystallizable  salts  with  hydrochloric 
and  nitric  acids,  platinum  chloride  and  gold  chloride,  as  well  as  a 
crystallizable  sparingly  soluble  double  salt  with  mercuric  chloride.  In 
a  pure  state  the  base  is  not  precipitated  from  a  dilute  solution  by 
mercuric  nitrate. 
Paraxanthine  forms,  as  Salomon  showed,  a  sparingly  soluble  com- 
pound with  soda,  which  separates  in  crystals  on  adding  caustic  soda 
solution  to  a  dilute  solution  of  the  base.  Theophylline  also  forms  a 
compound  with  soda,  but  it  is  readily  soluble,  this  difference  between 
the  two  bases  being  very  marked. 
Theophylline  resembles  theobromine  in  forming  a  silver  compound" 
which  separates  in  an  amorphous  state  on  adding  silver  nitrate 
to  a  water  solution  of  the  base.  This  compound  is  soluble  in  warm 
ammonia,  and  on  cooling  the  solution  it  crystallizes  out.  The  com- 
pound thus  obtained  and  dried  at  130°  C.  contained  37'18  per  cent,  of 
silver,  corresponding  to  the  formula  C7H7N402Ag.  This  silver  com- 
pound dissolves  readily  in  nitric  acid. 
When  theophylline  is  mixed  with  chlorine  water  and  the  liquid 
evaporated,  a  scarlet-colored  residue  is  left,  which  becomes  violet  on 
addition  of  ammonia,  just  as  is  the  case  with  theobromine. 
The  great  similarity  between  the  characters  of  theophylline  and 
theobromine  suggest  that  these  substances  are  both  derivatives  of 
xanthine,  and  with  that  idea  the  introduction  of  the  methyl  group 
was  attempted.  By  heating  the  silver  compound  with  a  calculated 
proportion  of  methyl  iodide  and  some  methyl  alcohol  in  a  closed  tube 
for  twenty-four  hours  at  a  temperature  of  100°  C.  a  crystallizable 
product  was  obtained  which  showed  on  analysis  that  a  methyl  group 
had  been  taken  up,  the  composition  and  characters  agreeing  perfectly 
with  those  of  caffeine.  The  melting  point  of  the  substance  thus 
obtained  was  229°  C,  and  accordingly  from  this  experiment  it  may 
be  inferred  that  theophylline  is  a  dimethylxanthine.  The  positions 
of  the  methyl  groups  have  yet  to  be  determined  by  an  oxidation 
experiment. 
Note. — Theophylline  is  doubtless  the  same  base  which  in  1871 
was  obtained  in  small  quantity  by  Zoeller  (^Annalen,  vol.  158,  p.  185) 
from  Himalayan  tea,  and  which  Liebig  believed  to  be  identical  with 
theobromine,  mainly  because  it  yielded  a  crystallizable  silver  com- 
