﻿Dialkylphosjphoric 
  and 
  Benzenedisulphonic 
  Acids. 
  59 
  

  

  in 
  preparing 
  the 
  silver 
  oxide 
  to 
  wash 
  it 
  thoroughly 
  and 
  

   repeatedly 
  with 
  boiling 
  distilled 
  water 
  in 
  order 
  to 
  remove 
  

   every 
  trace 
  of 
  alkali 
  and 
  sodium 
  nitrate 
  resulting 
  from 
  the 
  

   precipitation 
  of 
  the 
  silver 
  oxide 
  by 
  the 
  action 
  of 
  sodium 
  

   hydroxide 
  upon 
  a 
  dilute 
  hot 
  solution 
  of 
  silver 
  nitrate. 
  The 
  

   free 
  disulphonic 
  acid 
  containing 
  a 
  little 
  silver 
  disulphonate 
  was 
  

   separated 
  by 
  filtration 
  from 
  the 
  silver 
  chloride 
  and 
  treated 
  with 
  

   hydrogen 
  sulphide 
  in 
  excess. 
  The 
  precipitated 
  silver 
  sulphide 
  

   was 
  filtered 
  off 
  and 
  the 
  filtrate 
  heated 
  to 
  boiling 
  to 
  remove 
  the 
  

   excess 
  of 
  hydrogen 
  sulphide. 
  The 
  solution 
  was 
  tested 
  for 
  

   silver 
  and 
  for 
  halogen 
  and 
  was 
  found 
  to 
  be 
  free 
  from 
  both. 
  

   It 
  was 
  an 
  aqueous 
  solution 
  of 
  pure 
  m-benzenedisulphonic 
  acid 
  

   of 
  about 
  N/5 
  concentration. 
  The 
  solution 
  was 
  standardized 
  

   against 
  decinormal 
  sodium 
  hydroxide 
  and 
  then 
  diluted 
  with 
  

   freshly 
  distilled 
  water 
  to 
  N/8 
  concentration 
  for 
  beginning 
  the 
  

   conductivity 
  measurements. 
  

  

  For 
  the 
  introduction 
  of 
  the 
  sulphonic 
  acid 
  group 
  (S0 
  3 
  H) 
  

   into 
  the 
  benzene 
  ring 
  in 
  positions 
  other 
  than 
  meta 
  to 
  acid 
  

   groups 
  already 
  in 
  the 
  ring 
  several 
  methods 
  have 
  been 
  pro- 
  

   posed. 
  P. 
  Klason* 
  acted 
  upon 
  the 
  diazo 
  salt 
  of 
  sulphanilic 
  

   acid 
  with 
  alcoholic 
  potassium 
  sulphide 
  to 
  introduce 
  sulphur 
  in 
  

   the 
  para 
  position 
  to 
  the 
  sulphonic 
  acid 
  group. 
  He 
  obtained 
  

   the 
  potassium 
  salt 
  of 
  ^>-thiophenolsulphonic 
  acid 
  (KSC 
  6 
  H 
  4 
  S0 
  3 
  K, 
  

   1, 
  4) 
  which 
  on 
  oxidation 
  with 
  potassium 
  permanganate 
  gave 
  

   potassium 
  jp-benzenedisulphonate. 
  C. 
  J. 
  Blanksmaf 
  and 
  J. 
  J. 
  

   PolakJ 
  prepared 
  the 
  ortho- 
  and 
  paranitrobenzenedisulphides 
  

   by 
  the 
  action 
  of 
  sodium 
  disulphide 
  upon 
  the 
  corresponding 
  

   chlornitrohenzenes. 
  These 
  disulphides 
  (N0 
  2 
  C 
  6 
  HjS.SC 
  6 
  H 
  4 
  N0 
  2 
  ) 
  

   on 
  oxidation 
  gave 
  the 
  corresponding 
  nitrobenzenesulphonic 
  

   acids 
  (C 
  6 
  H 
  4 
  N6 
  2 
  .S03H). 
  In 
  1890 
  the 
  xanthate 
  method 
  of 
  

   P. 
  Leuckart§ 
  was 
  published. 
  This 
  was 
  shown 
  by 
  ErhardtJ 
  

   Kuhnau^f 
  and 
  others 
  to 
  be 
  a 
  general 
  method 
  of 
  preparing 
  

   various 
  sulphonic 
  acids 
  free 
  from 
  their 
  isomers. 
  Polak,*"* 
  

   Walterff 
  and 
  Armstrong 
  and 
  Worley^J 
  used 
  this 
  method 
  for 
  

   the 
  preparation 
  of 
  o- 
  and 
  ^-benzenedisulphonic 
  acids. 
  None 
  

   of 
  these 
  investigators, 
  however, 
  described 
  the 
  xanthate 
  method 
  

   with 
  sufficient 
  particularity 
  to 
  make 
  a 
  fair 
  yield 
  of 
  the 
  disul- 
  

   phonic 
  acids 
  possible 
  without 
  further 
  experimentation. 
  Since 
  

   the 
  disulphonic 
  acids 
  can 
  be 
  obtained 
  entirely 
  free 
  from 
  their 
  

   isomers 
  it 
  was 
  deemed 
  desirable 
  to 
  determine 
  more 
  closely 
  the 
  

  

  *Klason, 
  Ber. 
  d. 
  d. 
  Chem. 
  Gesell, 
  xx, 
  350. 
  1887. 
  

  

  f 
  Blanksma. 
  Rec. 
  tvav. 
  chim. 
  Pays-Bas, 
  xix. 
  111, 
  1900. 
  

  

  jPolak, 
  Rec. 
  trav. 
  chim. 
  Pays-Bas, 
  xxix, 
  419, 
  1910. 
  

  

  §Leuckart, 
  J. 
  pr. 
  Chem., 
  xli, 
  179, 
  1890. 
  

  

  ||Ehrhardt, 
  J. 
  pr. 
  Chem., 
  xii, 
  184, 
  1890. 
  

  

  ^T 
  Ruhnau, 
  J. 
  pr. 
  Chem., 
  xli, 
  184, 
  1890. 
  

  

  **Polak, 
  1. 
  c. 
  

  

  ffL. 
  E. 
  Waller, 
  Proc. 
  Chem. 
  Sec, 
  xi, 
  141, 
  1895. 
  

  

  XX 
  Armstrong 
  and 
  Worley, 
  Proc. 
  Roy. 
  Stic, 
  xc, 
  8G-7, 
  1914. 
  

  

  