298 
Chemistry  of  the  Coca  bases. 
Am.  Jour.  Pb arm- 
June,  1889. 
By  long  continued  heating  at  this  temperature  a  point  is  reached  at 
which  the  decomposition  of  the  base  goes  on  rapidly  and  a  refreshing 
odor  is  given  off.  This  is  probably  due  to  the  formation  of  the  methyl 
ester  of  cocaic  acid. 
The  hydrochloride  undergoes  decomposition  even  more  readily  than 
the  base  itself.  Even  at  100°  C.  it  gives  off,  together  with  one 
molecule  of  water,  a  certain  amount  of  methyl  chloride  ■  if  the  salt  be 
heated  for  some  hours  to  120°  C.  the  residue  contains  only  traces  of 
chlorine.  This  decomposition  takes  place  according  to  the  following 
equation  : — 
C19H23N04HC1+H20=C18H21N04+CH3C1+H20. 
The  residue  thus  left  is  chiefly  cocamylecgonine  C18H21lSr04,  but 
owing  to  a  secondary  change  it  contains  some  cocaic  acid. 
A  similar  decomposition  takes  place  when  the  water  solution  of  the 
hydrochloride  is  boiled  for  some  time,  but  then  the  methyl  is  given 
off  chiefly  in  the  state  of  methyl  alcohol,  and  on  cooling  the  cocamyl- 
ecgonine separates  as  a  colorless  or  yellowish  oil.  When  the  solu- 
tion of  the  salt  is  mixed  with  hydrochloric  acid,  the  decomposition  is 
not  only  promoted,  but  the  cocamylecgonine  produced  is  also  split  up 
into  ecgonine  and  cocaic  acid.    C18H21N04+H20=C9H15N03-f  C9H802. 
I  have  given  the  name  of  cocaic  acid  to  the  product  thus  formed, 
because  it  is  characteristic  of  coca.  To  purify  this  acid  the  crude  pro- 
duct is  boiled  with  lime  and  water.  From  a  dilute  solution  of  the 
lime  salt  hydrochloric  acid  precipitates  the  acid  in  a  crystalline  form  ; 
by  recrystallization  from  boiling  glacial  acetic  acid  it  is  obtained  in, 
the  form  of  small  colorless  laminse  which  melt  at  266°  C.  Cocaic 
acid  is  sparingly  soluble  in  ether,  but  it  dissolves  more  readily  in  hot 
alcohol,  and  on  cooling  crystallizes  out  in  needles  The  composition 
of  cocaic  acid  is  represented  by  the  formula  C9H802.  The  lead  salt 
(C9H802)2Pb-|-H20  crystallizes  in  small  needles. 
Cocaic  acid  is  in  fact  nothing  else  than  the  substance  that  has  been 
meanwhile  described  by  Liebermann  as  ^-isatropic  acid,  but  the  melt- 
ing point  assigned  to  it  by  that  chemist  is  incorrect  and  too  high. 
In  the  residue  left  after  treating  the  crude  cocaic  acid  with  lime 
there  was  a  lime  salt  of  another  acid  that  dissolved  readily  in  ether, 
and  crystallized  from  the  ether  solution  in  long  flat  prisms.  The 
quantity  obtained  was  too  small  for  analysis. 
After  removing  this  acid,  the  hydrochloric  solution  left  on  evapora- 
tion a  residue  of  ecgonine  hydrochloride.    It  melted  at  234°-238°  C- 
