A  m.  Jour.  Pliarm.) 
January,  1900.  j 
Constitution  of  the  Alkaloids. 
17 
In  1879  Ladenburg  heated  on  a  water-bath  the  salt  tropine  tropate 
with  dilute  hydrochloric  acid,  and  thus  artificially  produced  the  op- 
posite reaction  to  that  just  given,  and  the  result  was  the  elimina- 
tion of  a  molecule  of  water,  and  the  formation  of  atropine,  which 
possessed  all  the  physical  and  physiological  properties  of  the  natural 
alkaloid.  Faith  in  synthesis  was  established.  For  establishing  this 
faith  Ladenburg  has  this  year,  as  we  have  just  heard,  been  decorated 
by  the  British  Society  with  the  Hanbury  Medal,  the  highest  gift 
pharmacy  can  bestow  upon  scientific  sages.  By  varying  the  acid, 
Ladenburg  made  a  whole  line  of  so-called  tropeines,  i.  e.,  he  used  val- 
erianic, acetic,  butyric,  salicylic,  benzoic,  etc.,  acids  and  obtained 
valeryl-tropeine,  acetyl-tropsine,  etc.  Some  of  these  were  also  found 
to  possess  mydriatic  properties.  The  constitution  ot  tropine  was. 
worked  out  by  Ladenburg  and  Merling,  and  found  to  be  as  follows: 
CH2 
/\ 
H2C  CH 
I  I 
H2C      C       —  CH2.CH2OH 
X/ 
N 
I 
CH3 
i.  e.,  a  tri-hydro-pyridyl-ethyl  alcohol  or  derivative  of  pyridine.  The 
constitution  of  tropic  acid  has  also  been  determined  by  the  same 
author  and  found  to  be 
and  this  has  been  confirmed  by  synthesis.    This  gives  us  the  consti  - 
tution complete  of  atropine: 
CH2 
H2C       CH  CfiH5 
H2C       C    —  CH2  —  CH2  —  O  —  CO  —  CH 
N/ 
N.CH3  CH2  — OH 
To  have  traced  all  the  steps  by  which  these  authors  found  the 
constitution  of  tropine  and  tropic  acid  would  have  taken  too  much 
time,  and  I  do  not  think  it  would  have  been  interesting  to  all  of 
you.  While  all  three  of  the  belladonna  alkaloids  have  mydriatic 
pioperties,  they  are  all  different  chemically.  Atropine  melts  at 
1 15-5°,  and  hyoscyamine,  its  isomer,  at  1 08-5°,  but  up  to  to-day  the 
difference  in  chemical  constitution  between  the  two  is  unknown,  as. 
hyoscyamine  changes  into  atropine  even  when  it  is  melted.  They 
are  probably  stereo-isomers. 
