﻿60 
  Drushel 
  and 
  Felty 
  — 
  P 
  reparation, 
  etc., 
  of 
  

  

  conditions 
  which 
  give 
  the 
  best 
  yield 
  of 
  these 
  acids. 
  The 
  

   xanthate 
  method 
  uses 
  as 
  starting 
  out 
  material 
  in 
  each 
  case 
  

   the 
  corresponding 
  amidobenzenesiilphonfc 
  acid, 
  and 
  involves 
  

   the 
  following 
  steps 
  to 
  obtain 
  the 
  potassium 
  salt 
  of 
  the 
  benzene- 
  

   disulphonic 
  acid 
  : 
  (1) 
  diazotization 
  of 
  the 
  amidosulphonic 
  acid, 
  

   (2) 
  action 
  of 
  the 
  diazo 
  compound 
  with 
  potassium 
  xanthate 
  to 
  

   form 
  the 
  xanthate 
  ester, 
  (3) 
  hydrolysis 
  of 
  the 
  xanthate 
  ester 
  to 
  

   form 
  the 
  potassium 
  salt 
  of 
  thiophenolsulphonic 
  acid 
  and 
  its 
  

   oxidation 
  to 
  the 
  disulphide 
  of 
  potassium 
  benzenesulphonate, 
  

   and 
  finally 
  (4) 
  oxidation 
  of 
  the 
  disulphide 
  to 
  potassium 
  ben- 
  

   zenedisulphonate 
  by 
  means 
  of 
  potassium 
  permanganate. 
  The 
  

   steps 
  and 
  conditions 
  for 
  the 
  formation 
  of 
  the 
  potassium 
  o- 
  and 
  

   ^-benzenedisulphonates 
  are 
  essentially 
  the 
  same, 
  starting 
  with 
  

   o- 
  and 
  j?-amidobenzenesulphonic 
  acids. 
  

  

  Several 
  points 
  are 
  of 
  importance 
  in 
  carrying 
  out 
  the 
  pro- 
  

   cesses 
  previously 
  mentioned. 
  Diazotization 
  of 
  the 
  amidoben- 
  

   zenesulphonic 
  acids 
  by 
  passing 
  JNT 
  2 
  3 
  gas 
  through 
  a 
  suspension 
  

   of 
  the 
  amidosulphonic 
  acids 
  in 
  cold 
  water 
  is 
  unsatisfactory 
  

   since 
  the 
  amidobenzenesulphonic 
  acids 
  as 
  well 
  as 
  their 
  diazo 
  

   compounds 
  are 
  only 
  slightly 
  soluble 
  in 
  cold 
  water, 
  and 
  an 
  

   attempt 
  to 
  diazotize 
  in 
  this 
  way 
  results 
  merely 
  in 
  the 
  super- 
  

   ficial 
  diazotization 
  of 
  the 
  solid 
  particles, 
  and 
  rarely 
  results 
  in 
  

   the 
  diazotization 
  of 
  more 
  than 
  20 
  per 
  cent 
  of 
  the 
  amidoben- 
  

   zenesulphonic 
  acid, 
  even 
  after 
  passing 
  the 
  1N" 
  2 
  3 
  for 
  several 
  

   hours. 
  The 
  most 
  satisfactory 
  method 
  proved 
  to 
  be 
  a 
  slight 
  

   modification 
  of 
  Fischer's 
  process. 
  The 
  amidosulphonic 
  acid 
  

   was 
  treated 
  with 
  about 
  an 
  equal 
  weight 
  of 
  water 
  and 
  to 
  this 
  

   was 
  added 
  a 
  cold 
  saturated 
  solution 
  of 
  the 
  theoretical 
  amount 
  

   of 
  sodium 
  nitrite, 
  resulting 
  in 
  immediate 
  diazotization 
  with 
  

   evolution 
  of 
  heat, 
  probably 
  according 
  to 
  the 
  equation 
  : 
  

   C 
  6 
  H 
  4 
  ]SrH 
  2 
  .S0 
  3 
  H 
  + 
  NaN0 
  2 
  ='C 
  6 
  H 
  4 
  N 
  2 
  OH.S0 
  3 
  Na 
  + 
  H 
  2 
  0. 
  The 
  

   mixture 
  was 
  at 
  once 
  treated 
  at 
  room 
  temperature 
  with 
  the 
  cal- 
  

   culated 
  amount 
  of 
  concentrated 
  hydrochloric 
  acid 
  with 
  stirring. 
  

   Reaction 
  took 
  place 
  at 
  once 
  with 
  the 
  separation 
  of 
  the 
  diazo 
  

   compound 
  : 
  C 
  6 
  H 
  4 
  N 
  2 
  OH.S0 
  3 
  Na 
  + 
  HC1 
  = 
  C 
  e 
  H 
  4 
  ]S" 
  a 
  S0 
  8 
  + 
  NaCl 
  

   4- 
  H 
  2 
  0. 
  To 
  make 
  the 
  separation 
  of 
  the 
  diazo 
  compound 
  as 
  

   complete 
  as 
  possible 
  the 
  mixture 
  was 
  chilled 
  in 
  an 
  ice 
  bath, 
  

   then 
  quickly 
  filtered 
  on 
  a 
  porcelain 
  funnel 
  with 
  suction 
  and 
  

   washed 
  with 
  a 
  little 
  ice-water. 
  The 
  diazo 
  compound 
  was 
  

   made 
  into 
  a 
  thin 
  mush 
  with 
  water 
  and 
  added 
  in 
  small 
  portions 
  

   to 
  the 
  calculated 
  amount 
  of 
  potassium 
  xanthate 
  dissolved 
  in 
  

   about 
  ten 
  times 
  its 
  weight 
  of 
  water 
  and 
  heated 
  on 
  the 
  steam 
  

   bath 
  to 
  65° 
  or 
  70°. 
  Vigorous 
  reaction 
  took 
  place 
  at 
  once 
  with 
  

   copious 
  evolution 
  of 
  nitrogen 
  after 
  the 
  addition 
  of 
  each 
  portion 
  

   of 
  diazo 
  compound. 
  At 
  the 
  temperature 
  used 
  the 
  xanthate 
  

   ester 
  formed 
  was 
  immediately 
  hydrolyzed 
  chiefly 
  to 
  the 
  corre- 
  

   sponding 
  thiophenolsulphonate. 
  These 
  reactions 
  may 
  be 
  

  

  