182 
Alpha-  and  Beta-Ionones. 
A  in.  Jour.  Pharni. 
April,  1909. 
C13H20O.  This  compound,  an  open  chain  ketone,  was  not  the  same 
as  irone  and  had  an  odor  only  slightly  recalling  that  of  violet.  It 
was  moreover  unstable  and  decomposable  by  alkalies.  But  he  found 
that  by  the  action  of  dilute  acids  he  could  convert  it  into  an  isomeric 
ketone,  cyclic  in  structure,  which  had  in  the  fullest  degree  the  violet 
odor,  and  in  very  diluted  form  served  as  the  basis  for  artificial  violet 
perfumes.  The  ketone  first  obtained  was  called  "  pseudo-ionone  " 
and  the  second  product  "  ionone." 
His  earliest  patents  for  this  ionone  were  taken  out  in  1893  and 
U.  S.  Patent  556943  of  March  24,  1896,  speaks  of  this  product  as  a 
"  fragrant  ketone  of  the  formula  C13H20O." 
In  1897,  however,  apparently  independently,  Chuit,  Naef  &  Co.. 
of  Geneva,  called  attention  to  a  violet  essence,  or  ionone,  of  slightly 
different  properties,  and  Tiemann  soon  announced  (Berichte,  1898,  p. 
867)  that  there  existed  two  isomeric  and  physically  different  ionones, 
viz.,  a-ionone  and  ^-ionone,  and  that  one  or  the  other  predominated 
according  as  the  conversion  of  the  pseudo-ionone  was  effected  by 
dilute  acids  (the  method  of  his  1893  patent)  or  by  concentrated  acid 
in  the  cold.  In  the  1898  Berichte  article  Tiemann  gives  the  credit  of 
the  latter  discovery  to  his  French  business  associate,  Edgar  DeLaire, 
and  it  was  DeLaire  who  applied  for  the  U.  S.  patent  November  3, 
1897,  and  to  whom  it  was  issued  March  5,  1898.  It  is  claimed, 
however,  that  a  product  consisting  predominately  of  ^-ionone  (and 
DeLaire'' s  product  always  contains  some  a-ionone)  was  marketed  by 
Chuit,  Naef  &  Co.  in  the  early  part  of  1897,  and  a  process  substan- 
tially that  of  Tiemann  and  DeLaire  had  been  described  by  Barbier 
and  Bouveault  in  the  Bulletin  dc  la  Societe  Chimique  in  1896. 
Be  that  as  it  may,  we  now  have  the  means  of  preparing  an 
artificial  violet  characterized  by  the  predominance  of  either  a-  or 
/3-ionone  and  as  there  is  a  slight  but  appreciable  difference  in  the 
violet  perfumes  made  from  these  two,  both  are  manufactured. 
The  most  important  physical  and  chemical  distinctions  between 
the  two  ionones  may  thus  be  stated : 
a-ionone  /3-ionone 
Specific  gravity  at  200  C   °-93°  °-944 
Boiling  point  at  11  mm.  pressure   i23°-i24°C.  (10  mm.)  i27°-i28°C. 
Boiling  point  at  17  mm.  pressure   i34°-i36°  C.  (18  mm.)  1400  C. 
Refractometer  Nd   1.498  i-521 
Oxime  melts  at   89°-oo0  C.  oily 
Semicarbazone  melts  at   io7°-io8°  C.  1480  C. 
/9-bromphenylhydrazone  melts  at   i42°-i45°  C.  ii5°-ii6°  C. 
