152 
Groton  Chloral. 
(  Am.  Jour.  Pharm. 
\  Mar.,  1874.  SuppL 
passing.  At  length  hydrochloric  acid  ceases  to  be  evolved,  and  crude 
croton  chloral  is  obtained — the  process  taking  about  forty-eight  hours 
to  complete.  This  crude  body  is  mainly  ordinary  chloral,  but  mixed 
with  a  variety  of  other  products.  By  fractional  distillation  and  treat- 
ment with  sulphuric  acid — true  croton  chloral  (C4H3C130) — trichlor. 
crotonic  aldehyde  is  obtained.  This  is  a  dense  oily  liquid  of  peculiar 
odor,  somewhat  recalling  ordinary  chloral :  treated  with  a  consider- 
able excess  of  warm  water  it  hydrates  and  dissolves,  and,  upon  cool- 
ing, croton  chloral  hydrate  (C4H3C130,H20)  is  deposited,  but  still  in 
a  crude  form,  most  rank  and  offensive  in  flavor.  It  has  to  be  purified 
by  rather  a  tedious  process,  and  is  obtained,  when  pure,  in  beautiful 
white  silvery  crystals,  with  a  sweetish  melon  flavor,  which  melt  at 
78°  C. 
From  this  it  will  be  quite  evident  (and  it  is  probably  wise  to  note 
it)  that  this  body  does  not  bear  any  relation  to  croton  oil,  or  crotonic 
acid,  obtained  therefrom,  although  its  chemical  constitution  proves  it 
to  be  the  chlorated  aldehyde  of  crotonic  acid. 
Croton  chloral  is  the  substance  represented  by  the  same  term  in 
the  allyl  (C3H5)  group  that  chloral  has  in  the  ethyl  (C2H5)  group.  Its- 
outward  appearance  differs  from  hydrate  of  chloral  by  the  salt  being 
much  lighter,  and  in  flocculent  silvery  crystals — by  its  being  almost 
insoluble  in  cold  water  and  very  soluble  in  alcohol ;  it  is  soluble  in 
hot  distilled  water,  and  rendered  more  easily  so  by  the  addition  of 
25  per  cent,  of  pure  glycerin  ;  it  is  insoluble  in  chloroform. 
It  will  be  remembered  that  hydrate  of  chloral  owes  its  value  as  a 
medicinal  agent  to  the  supposed  elimination  of  chloroform  when  it 
comes  in  contact  with  the  alkalies  of  the  blood,  it  having  been  shown 
that  by  reaction  with  alkalies  chloroform  is  produced.  Crotonic  chlo- 
ral, when  subject  to  the  influence  of  an  alkali,  first  forms  allyl-chlo- 
roform,  a  trichlorated  body  which  is  rapidly  decomposed  into  a  bichlo- 
rated  substance  called  bichlor-allylene.  In  a  communication  to  the- 
British  Medical  Journal,  December  20,  1873,  Dr.  Liebreich  says  : — 
"  Both  chloroform  and  trichlorated  substances  act  in  the  first  stage 
upon  the  brain  ;  in  the  second,  on  the  spinal  cord ;  in  the  third,  on 
the  heart." 
Although  Dr.  Liebreich's  theory  has  met  with  and  still  finds  gen- 
eral favor,  there  are  many  medical  men  who  think  it  has  not  any 
valid  support,  believing  that  chloral  exercises  a  specific  action  of  its- 
own  upon  the  organization,  which  is  not  to  be  reasoned  out  from  an 
exclusively  chemical  basis. 
