356 
Indian  Grass  Oils. 
Am.  Jour.  Pharm. 
July,  1890. 
genus  Andropogon,  but  there  is  some  confusion  as  to  the  particular, 
species  from  which  the  individual  oils  are  obtained. 
Citronella  Oil. — The  commercial  varieties  are  often  adulterated 
with  kerosene  ;  the  pure  oil  is  a  clear,  greenish-yellow  liquid  with 
a  sharp  burning  taste  and  a  strong  aromatic  odor.  Its  sp.  gr.  at 
i6°  is  0-8770,  at  26-5°,  0-8750.  It  distils  between  200°  and  2400, 
leaving  10  per  cent,  of  a  thick  oily  residue,  having  a  pungent  odor. 
It  gives  most  of  the  reactions  of  aldehydes,  combining  with  hydro- 
gen sulphites  and  with  phenylhydrazine,  although  not  with  am- 
monia ;  it  also  reacts  with  acetic  and  benzoic  chlorides,  and  gives  a 
mirror  with  an  ammoniacal  silver  solution.  Two  litres  of  the  oil 
were  distilled  in  a  current  of  steam,  and  collected  in  fractions  of 
1,100  cc.  and  400  cc.,the  residue  of  500  cc.  not  being  readily  volatile. 
The  first  fraction  (1,100  cc.)  was  treated  with  a  solution  of  sodium 
hydrogen  sulphite,  the  mixture  being  kept  cool  with  ice  and  water. 
The  liquid  solidified  to  a  white  magma,  and  the  sodium  hydrogen 
sulphite  compound  was  then  pressed  between  flannel  and  washed 
with  ether  ;  the  filtrate  yielded  350  cc.  of  residual  oil.  The  sodium 
hydrogen  sulphite  compound  was  mixed  with  dry  sodium  carbonate 
and  distilled  in  a  current  of  steam  ;  about  700  cc.  of  aldehyde  was 
thus  obtained.  This  was  shown  by  analyses,  and  a  vapor-density 
determination,  to  have  the  formula  C10H18O,  and  is  thus  isomeric 
with  borneol  and  geraniol.  The  author  names  it  citronellic  alde- 
hyde, and  considers  it  to  be  /9-methyl-<5-isobutylallylacetaldehyde, 
C4H9-CH:CH-CH(CH3)-CH2-CHO,  since  this  formula  is  most  in 
accordance  with  its  reactions.  It  unites  with  2  atoms  of  bromine, 
and  when  reduced  with  sodium  amalgam  and  acetic  acid  it  yields 
citronellyl  alcohol,  C10H20O,  boiling  at  225-2300  ;  this  decolorizes 
bromine  solution,  and  has  a  pleasant  odor  of  roses.  It  forms  com- 
pounds with  phenylhydrazine,  with  aniline  and  paratoluidine,  and 
with  acetic  acid,  but  these  products  have  not  yet  been  isolated.  It 
is  dextrorotatory,  and  when  oxidized,  appears  to  yield  fatty  acids  ; 
with  potassium  permanganate,  it  yields  a  mixture  of  acids  smelling 
strongly  of  ordinary  valeric  acid.  When  treated  with  phosphoric 
anhydride,  some  large  colorless  plates  (melting  at  1400)  were 
deposited,  and  two  oils  formed,  one  boiling  at  J 75°,  which  was 
shown  by  analysis  to  be  an  impure  terpene,  and  one  boiling  above 
3000,  which  had  a  pleasant  odor  resembling  the  high-boiling 
fractions  of  citronella  oil. 
