Am.  Jour.  Pharm.  ) 
May,  1921.  $ 
Thalleioquin  Reaction. 
335 
atoms  of  bromine  per  mol.  of  quinine;  (3)  as  a  qualitative  reaction, 
by  making  a  few  preliminary  trials  it  can  be  made  very  sensitive-  the 
limit  being  1 :  250,000  in  a  depth  of  liquid  2%.  inches  (of  course,  the 
greater  the  depth  the  greater  will  be  its  sensibility)  ;  for  quantitative 
work,  with  so  many  variables,  no  credence  of  even  approximate  ac- 
curacy can  be  assigned  to  the  reaction,  except  under  very  strict  con- 
ditions and  in  very  dilute  solutions,  as  shown. 
Bromine  Absorption  in  Aqueous  Solution. — Attempts  were  made 
to  determine  the  bromine  absorption  of  quinine  in  aqueous  solution 
for  5,  10,  and  20  minutes'  action  with  2.5,  5  and  11.5  tons  of  bromine 
per  mol.  of  quinine,  using  quinine  at  1  :  1000  and  bromine  water  at 
one-tenth  saturation,  the  excess  of  bromine  being  titrated  with  thio- 
sulphate  after  addition  of  potassium  iodide.  The  results  obtained 
showed  that  although  4  atoms  of  bromine  appears  -to  be  the  maxi- 
mum quantity  absorbed,  and  this  is  constant  for  five  minutes,  yet 
any  excess  over  2  atoms  is  only  loosely  held  and  appears  to  be  slowly 
given  up  again. 
The  earlier  workers  (Andre,  Brandes,  etc.)  did  not  find  chlorine 
in  their  product;  Commanducci,6  by  varying  the  time  of  action  of 
chlorine,  obtained  two  new  red  products  even  in  alkaline  solution — a 
statement  at  variance  with  the  present  author's  bromine  results.  Corn- 
stock  and  Koenigs,7  by  extracting  their  quinine  dibromide  with  water 
and  separating  by  means  of  ammonia,  did  not  obtain  any  thalleioquin 
reaction.  Buraczewski  and  Dziurzynski,8  on  treating  their  quinine 
pentabromide  with  water  not  above  400  C,  filtering  and  adding  am- 
monia to  the  filtrate,  obtained  a  white  flocculent  precipitate  which 
soon  became  emerald-green  and  contained  bromine,  and  they  state 
that  it  is  probably  identical  with  the  substance  formed  in  the  thalleio- 
quin reaction.  Christensen,9  by  progressive  chlorination  of  quinine, 
obtained  (1)  quinine  hydroxy  chloride  and  di chloride,  in  which  the 
vinyl  group  is  saturated  and  which  give  the  thalleioquin  reaction 
when  chlorine  followed  by  ammonia  is  added  to  the  slightly  acid  solu- 
tion; (2)  with  4  j  atoms  of  chlorine  an  unstable  base,  5-chloro-6- 
9Ber.  Deuts.  Pharm.  Ges.,  1915,  256;  1916,  247. 
6  Commanducci,  Chem.  Zentr.,  1910,  1885. 
1  Ber.,  1892,  1539. 
*  Anz.  Akad.  Wiss.  Krakau,  1909,  333. 
