404  Botany  and  Chemistry  of  Essential  Oils.  {^'IS^'im^' 
camphor  group  we  have  just  discussed,  but  differ  from  them  in 
being  open  chain  compounds.    They  are  : 
C10H16O,  Citral  or  geraniol  aldehyde. 
C10H18O,  Citronellic  aldehyde. 
Rhodinol. 
Geraniol  identical  with  linalool,  coriandrol 
and  aurantiol. 
C10H20O,  Citronellic  alcohol. 
These  are  pretty  widely  distributed,  and  occur  generally  associated 
with  terpenes  in  a  good  many  oils. 
Citral. — This  is  found  in  oils  of  orange  peel,  lemon,  lemon  grass, 
citronella,  eucalyptus,  etc.,  and  can  be  prepared  by  oxidizing 
geraniol,  to  which  it  bears  a  very  simple  relation,  viz :  that  of 
aldehyde  to  alcohol. 
It  is  readily  converted  by  heat  into  cymene,  and  the  following 
formula  has  been  assigned  to  it : 
7   CH:CH  . 
(Me)2CHCH/  J^CMe 
CHO— CH 
Isobutylethylin-^-methylacrylic  aldehyde. 
z  CH-CH  . 
(Me)2CHC/  >CMe 
Cymene. 
Geraniol. — The  alcohol  corresponding  to  citral  occurs  in  a  good 
many  oils  and  has  been  given  different  names,  but  it  is  identical 
with  linalool,  coriandrol,  and  possibly  aurantiol  and  rhodinol.  It  is 
found,  to  a  large  extent,  in  the  Indian  grass  oils  (92  per  cent.), 
andropogon,  lemon  grass,  Indian  or  Turkish  geranium,  ginger 
grass  and  vetivert,  in  lavender,  coriander,  linaloe,  petit  grain  and 
bergamot. 
Citronellic  aldehyde  exists  in  large  quantity  in  oil  of  citronella, 
and  is  isomeric,  but  not  identical  with  Borneol  and  geraniol.  On 
reduction  it  yields  citronellyl  alcohol,  which  is  also  found  in  citro- 
nella oil,  and  their  constitution  is  supposed  to  be  /3-methyl  <r-iso- 
butylallylacetaldehyde — 
£^s>CH-CH2-CH:C-Me  CH2-CHO 
with  the  alcohol  CH2OH  replacing  CHO  in  the  formula  f  »r  citraL 
