86 
Diosmin, 
Am.  Jour.  Pharra. 
Feb..  1889. 
DIOSMIN.1 
By  P.  Spica. 
In  the  author's  former  examination  of  the  leaves  of  Barosma  crenata 
and  B.  betulina,2  it  was  found  that  after  the  essential  oil  had  been  re- 
moved, alcohol  extracted  from  the  leaves  a  crystalline  substance,  which 
he  called  diosmin.  The  amount  present  in  the  leaves  varies  very 
much,  not  only  with  the  season  when  they  are  gathered,  but  also  with 
the  age  of  the  plant ;  at  no  time,  however,  is  it  large.  The  best  way 
of  extracting  it  is  first  to  treat  the  leaves  with  light  petroleum  to  re- 
move the  essential  oil  and  waxy  and  resinous  matters,  then  with  cold 
alcohol  of  85  per  cent.,  which  removes  the  chlorophyll  and  acid  ex- 
tractive substances,  and  finally  to  treat  it  with  boiling  alcohol  of  80  to 
85  per  cent.,  which  is  the  best  solvent  for  the  diosmin.  It  is  very 
troublesome  to  purify,  but  this  may  be  effected  by  treating  the  residue 
left  on  evaporation  of  the  alcoholic  solution  successively  with  a  solu- 
tion of  ammonium  carbonate,  cold  alcohol,  and  ether,  and  then  recrys- 
tallizing  repeatedly  from  alcohol  of  80 — 85  per  cent. 
When  pure,  diosmin  is  a  white,  crystalline  powder,  consisting  of 
very  slender  microscopic  needles,  odorless,  tasteless,  and  insoluble  in 
most  solvents.  Its  best  solvent  is  boiling  alcohol  of  80 — 85  per  cent. 
It  melts  at  243 — 244°,  with  decomposition  and  evolution  of  gas.  If 
cautiously  melted  on  platinum  foil,  it  emits  a  pleasant  odor  resembling 
that  of  orange  peel  when  it  begins  to  burn ;  subsequently  the  odor  is 
like  that  of  caramel.  Diosmin  does  not  reduce  Fehling's  solution.  It 
dissolves  in  concentrated  sulphuric  acid,  and  in  solutions  of  the  alkalis 
with  yellow  coloration,  but  at  the  same  time  undergoes  alteration. 
When  diosmin  is  boiled  for  some  time  in  a  reflux  apparatus  with 
dilute  hydrochloric  acid,  or  with  sulphuric  acid  of  3 — 4  per  cent.,  it  is 
resolved  into  a  crystalline  compound,  sparingly  soluble  in  water,  and 
a  substance  easily  soluble  in  water ;  the  latter  has  a  feeble  dextro- 
rotatory power,  and  is  capable  of  reducing  Fehling's  solution.  The 
crystalline  substance  is  moderately  soluble  in  alcohol,  and  still  better 
in  a  mixture  of  alcohol  and  benzene.  It  forms  minute,  orange-yellow 
needles,  for  which  no  definite  melting  point  could  be  obtained,  but  it 
appears  to  be  somewhere  about  145°. 
The  results  obtained  by  the  analyses  of  diosmin  dried  in  a  vacuum 
1  Gazetta,  xviii.,  1-9 ;  reprinted  from  Jour.  Chem.  Soc,  1888,  p.  1310. 
2Am.  Jour.  Phar.,  1886,  p.  478. 
