io  Thymol  and  Carvacrol  Problems.      { A January Pi^i m* 
results  might  be  compared  with  earlier  work  the  hydrolysis  was 
measured  in  iV/32  solution.  The  sparing  solubility  of  some  of  the 
phenols  made  it  necessary  to  employ  solutions  of  much  lower  con- 
centration and,  since  the  hydrolysis  constant  was  found  to  diminish 
somewhat  with  increasing  dilution,  a  modified  formula  was  used 
=  constant,  instead  of  -7— ^  ^7  =        for  calcu- 
(1  —  *)v«     —  •  '    (i—x)v 
lating  the  observed  results  to  a  concentration  of  V32. 
Relative  Acidities  of  Phenols  at  25  °. 
Percentage 
Ka  at  V32.       hydrolysis  at  V32.  Ka. 
Phenol                                        0.000104                5-60  1.15  X  io1 
Carvacrol                                    0.000267                8.83  045  X  io1' 
Thymol                                          0.000373                10.34  0.32  X  io11 
Kk  is  the  hydrolysis  constant  for  the  sodium  derivatives  at 
25 0  and  V32  dilution.  For  carvacrol  and  thymol  this  was  not  ob- 
tained directly,  but  was  calculated  from  the  degree  of  hydrolysis 
by  means  of  the  formula 
**  _  K 
In  column  2  are  given  the  degrees  of  hydrolysis  of  the  sodium  deriva- 
tives of  V32,  and  the  values  for  carvacrol  and  thymol  were  calculated 
from  data  obtained  at  higher  dilution  by  means  of  the  modified 
formula.  Column  3  contains  the  dissociation  constants  K,  for  the 
free  phenols  in  aqueous  solution  at  250,  calculated  from  the  hydro- 
lysis  constants,  according  to  the  equation  K  =  ~ ,  Kw  the  disso- 
ciation  constant  for  water,  being  taken  as  1.2  X  10  ~34-  The  mean 
value  for  phenol  calculated  at  the  dilution  at  which  it  was  deter- 
mined becomes  1.26  X  10  ~10>  agreeing  well  with  Walker's  value 
of  1.3  X  10  ~10. 
In  1885  Lustig8  prepared  the  sodium  derivative  of  carvacrol 
by  dissolving  this  phenol  in  4  to  5  volumes  of  petroleum  ether  (b.  p. 
50-600)  and  adding  sodium.  A  lively  evolution  of  hydrogen  took 
place  with  a  rise  in  temperature  and  a  flocculent  precipitate  ap- 
peared. This  dried  to  a  fine  white  crystalline  powder  which  decom- 
8  Lustig,  Ber.,  19  (1886),  p.  II. 
