160  Researches  on  the  Cinchona  Alkaloids,  {^""A^prii'fssi™'' 
EESEARCHES  ON  THE  CONSTITUTION  OF  THE  CIN- 
CHONA ALKALOIDS. 
By  O.  Hesse. 
Continued  from  page  112, 
III.  Action  of  Acetic  Anhydrid  upon  the  Apo-bases. — The  conver- 
sion of  the  original  cinchona  alkaloids  into  the  previously  mentioned 
apo-bases  could  possibly  depend  upon  the  hydroxyl  groups  contained 
in  the  former  suffering  a  change  of  position ;  on  the  other  hand^  it  was 
not  to  be  expected  that  in  the  quinia  and  quinidia  derivatives  two 
acetyl  groups  would  be  substituted  for  hydrogen.  The  conversion  of 
the  apo-bases  in  question  into  the  acetic  ethers  Avas  easily  accomplished ; 
the  pure  bases,  dried  at  100°C.,  were  dissolved  in  a  sufficient  quantity 
of  acetic  anhydrid  ;  this  solution  was  allowed  to  stand  for  some  hours 
at  60  to  80°,  and  then  evaporated  at  the  same  temperature  after  the 
addition  of  a  little  w^ater.  The  amorphous  residue  obtained  was 
taken  up  with  cold  water,  the  compound  ether  precipitated  by  ammo- 
nia, and  extracted  by  shaking  with  ether.  After  w^asliing  the"  etheriai 
solution  with  water,  and  treating  with  animal  charcoal,  it  w^as  allowed 
to  evaporate  slowly,  when  the  compound  ethers  were  left  in  the  form 
of  slightly  yellowish  residues  which  permit  of  being  well  dried  at  100°C.^ 
becoming  brittle  on  cooling,  and  with  the  exception  of  the  diapocin- 
chonia  ether  furnish  white  powders.  All  dissolve  readily  in  ether^ 
chloroform  and  alcohol,  possess  a  bitter  taste  and  slightly  alkaline 
reaction ;  are  very  sparingly  soluble  in  water,  but  readily  in  dilute 
hydrochloric  acid,  from  which  solution  they  are  precipitated  by  ammo- 
nia or  caustic  soda  in  an  amorphous,  resinous  form. 
With  dilute  sulphuric  acid  the  apoquinia  and  apoquinidia  ethers 
produce  solutions  having  a  blue  fluorescence,  which  is  not  shown  by 
the  compound  ethers  of  the  other  apo-bases.  The  alcoholic  solutions 
of  the  first  two  compound  ethers  give  upon  the  addition  of  chlorine 
and  ammonia  an  intense  dark  green  coloration,  while  the  other  com- 
pound ethers  do  not  possess  this  property.  These  distinctions  are 
dependent  upon  the  fact  that  in  apoquinia  and  apoquinidia  two  atom& 
of  hydrogen  were  exchanged  for  acetyl,  and  bodies  formed  which  in 
respect  to  their  constitution  resemble  the  acetic  ethers  of  the  original 
bases,  quinia  and  quinidia,  only  that  instead  of  the  methoxyl  group 
they  contain  an  acetoxyl  group.  If  these  bodies  be  boiled  with  an 
alcoholic  solution  they  are  decomposed  according  to  the  equation  : 
