n8  Urethanes  of  Thymol  and  Carvacrol.  {^l^'^mi™' 
Application  to  Hydrothymoquinone. —  Since  hydroquinone  16 
yields  a  diurethane,  hydrothymoquinone  was  treated  with  two  mols 
of  phenyl  isocyanate  in  slight  excess  and  heated  in  petroleum,  using 
10  cc.  per  gram  of  phenol.  The  phenol  melted  on  warning  and  gave 
a  clear  solution,  which  after  about  15  minutes  heating  began  to 
deposit  crystals  as  spherules  about  1  mm.  in  diameter.  The  cooled 
reaction  mixture  was  filtered  and  rerluxed  again  when  a  small 
quantity  was  recovered.  For  this  preparation  2  grams  of  phenol 
were  taken  and  the  following  recovery  made  : 
Yield  in  grams  Per  cent.  m.'  p. 
4.765  81.6  229-230° 
.095  1.6  210-220° 
Another  lot  was  prepared  starting  with  4  grams  of  phenol. 
When  the  isocyanate  was  added  to  this,  reaction  took  place  at  once, 
even  before  dilution  with  petroleum  or  heating  because  a  residue 
formed  which  later  was  found  to  be  insoluble  in  the  boiling  reaction 
mixture.  From  this  mixture  9.25  g.  were  recovered,  representing  a 
yield  of  84  per  cent. 
These  high  yields  indicate  that  both  hydroxyl  groups  react  and 
that  a  diurethane  results.  This  is  also  wholly  indifferent  toward 
an  alkali  solution  in  the  cold,  indicating  the  absence  of  hydroxy! 
groups. 
Analysis  by  the  Kjeldahl  method  gave  satisfactory  results  in 
this  case. 
T.  0.2936  g.  required  15.24  cc  X/10  HC1. 
II.  0.3139  g.  required  15.23  cc  N/10  HCL 
Found  Theory  for  C4H:,,X204 
Xitrogen     I.    7.27  p.  c.  6.93  p.  c. 
II.    6.83  " 
However,  to  remove  uncertainty  as  to  the  accuracy  of  this 
method,  which  seems  to  fail  on  the  other  urethanes,  nitrogen  was 
determined  by  Dumas'  method. 
I.  0.2302  g.  gave  15.8  cc  N,  at  24°  and  702  mm.' 
Found  Theory 
Xitrogen  7.36  p.  c.  6.93  p.  c. 
"fnape,  Ber.,  18  (1885),  P-  2429. 
