A January Pi92im'}     Thymol  and  Carvacrol  Problems.  9 
Raikow  and  Momtschillow  3  found  that,  among  a  considerable 
number  of  phenols,  carvacrol  and  thymol  are  precipitated  from 
alkaline  solution  by  carbon  dioxide.  Of  course,  that  would  corre- 
spond to  their  inability  to  decompose  carbonates  to  form  phenol 
alkali  derivatives.  Following  this  up  Raikow4  studied  a  large 
number  of  phenols  to  determine  their  acidity  and,  among  the  various 
solutions  employed  as  reagents,  ammonia  was  found  to  dissolve 
carvacrol  with  no  precipitation  of  a  solid  compound.  Toward 
thymol  it  behaved  in  a  similar  manner.  For  this  work,  thymol  was 
emulsified  with  warm  water  and  this  emulsion  was  employed  in  the 
tests.  Water-glass  was  the  only  salt  solution  found  that  dissolved 
carvacrol,  and  in  it  the  phenol  is  soluble  to  a  considerable  extent. 
There  is  no  formation  of  a  solid  compound  or  precipitation  of 
silicic  acid.  Thymol  dissolves  in  water-glass  also.  Since  these 
phenols  are  insoluble  in  carbonate  solutions  the  solubility  above 
cannot  be  attributed  to  alkali  (carbonate),  in  the  silicate.  Perhaps 
this  conclusion  of  Raikow  should  be  modified,  when  it  is  considered 
that  these  solutions  react  distinctly  alkaline  and  that  hydroxide  may 
actually  exist  in  the  solution.  However,  among  the  salt  solutions 
one  distinction  between  carvacrol  and  thymol  was  observed. 
Thymol  is  soluble  in  a  solution  of  normal  potassium  phospate, 
K3PO4 ;  while  carvacrol  is  not. 
Following  J  amis'  and  Klages'  observations,  Stoermer  and  Kippe  5 
found  that  the  sodium  compound  of  carvacrol  may  be  extracted  as 
such  from  30-40  per  cent,  sodium  hydroxide  solution  directly  with 
ether.  Thymol,  and  several  other  phenols  mentioned,  have  the 
property  of  being  extracted  from  alkaline  solution  with  ether,  petro- 
leum, ether,  ligroin,  benzene,  carbon  disulphide  and  chloroform  as 
the  free  phenol  in  only  very  small  amounts. 
In  19 1 5  Boyd  6  determined  the  degree  of  hydrolysis  of  sodium 
phenoxides  in  aqueous  solution  in  an  attempt  to  determine  their 
relative  acidity.  The  method  of  Shields,7  depending  upon  the  rate 
of  hydrolysis  of  methyl  acetate,  was  adopted.    In  order  that  the 
3  Raikow  and  Momtschilow,  Chem.  Ztg.,  26  (1902),  p.  1237;  through 
J.  C.  S.,  841  (1903).  p.  162. 
4  Raikow,  Chem.  Ztg.,  27  (1,903),  pp.  781,  1125. 
5  Stoermer  and  Kippe,  Ber.,  36  (1903),  p.  3992. 
6  Boyd,  J.  C.  S.,  107  (1915),  P.  1538. 
7  Schields,  Zeit.  phys.  Chem.,  12  (1893),  p.  167. 
