﻿Dialkylphosphoric 
  and 
  Benzenedisul/phonic 
  Acids. 
  63 
  

  

  retical 
  amount 
  of 
  sulphuric 
  acid. 
  The 
  purity 
  of 
  the 
  three 
  

   disulphonic 
  acids 
  was 
  determined 
  by 
  converting 
  portions 
  of 
  

   their 
  purified 
  potassium 
  salts 
  into 
  the 
  acid 
  chlorides 
  and 
  taking 
  

   the 
  melting 
  points 
  of 
  the 
  acid 
  chlorides* 
  recrystallized 
  from 
  

   ether, 
  and 
  by 
  converting 
  the 
  acid 
  chlorides 
  to 
  the 
  acid 
  amides 
  

   and 
  taking 
  their 
  melting 
  points. 
  For 
  beginning 
  conductivity 
  

   measurements 
  the 
  three 
  isomeric 
  disulphonic 
  acids 
  were 
  made 
  

   up 
  in 
  N/8 
  solutions 
  with 
  freshly 
  distilled 
  water, 
  and 
  for 
  the 
  

   determination 
  of 
  the 
  strengths 
  of 
  the 
  acids 
  as 
  catalytic 
  agents 
  

   in 
  the 
  hydrolysis 
  of 
  ethyl 
  acetate 
  they 
  were 
  made 
  up 
  in 
  N/10 
  

   solutions. 
  The 
  normality 
  of 
  the 
  acids 
  was 
  checked 
  up 
  in 
  every 
  

   case 
  by 
  making 
  titrations 
  with 
  standard 
  sodium 
  hydroxide. 
  

  

  Conductivity 
  and 
  hydrolysis 
  measurements. 
  

  

  The 
  apparatus 
  used 
  in 
  this 
  work 
  was 
  the 
  usual 
  conductivity 
  

   apparatus, 
  a 
  Wheatstone 
  bridge 
  previously 
  calibrated, 
  an 
  ordi- 
  

   nary 
  Ostwald 
  cell 
  whose 
  constant 
  was 
  determined 
  with 
  N/50 
  

   potassium 
  chloride, 
  an 
  alternating 
  induction 
  coil 
  with 
  high 
  fre- 
  

   quency 
  vibrator 
  and 
  telephone 
  receiver, 
  a 
  standard 
  plug 
  resist- 
  

   ance 
  box, 
  a 
  pair 
  of 
  carefully 
  calibrated 
  10 
  cm3 
  pipettes 
  and 
  a 
  

   thermostat 
  kept 
  at 
  25°. 
  

  

  (a) 
  Ionization 
  of 
  dialkylphosphoric 
  acids. 
  — 
  The 
  molecular 
  

   conductivities 
  of 
  the 
  sodium 
  salts 
  of 
  the 
  dialkylphosphoric 
  

   acids 
  were 
  first 
  determined 
  at 
  different 
  dilutions 
  starting 
  with 
  

   N/8 
  solutions. 
  From 
  these 
  measurements 
  the 
  values 
  of 
  fi^ 
  

   were 
  determined 
  by 
  the 
  method 
  of 
  graphic 
  extrapolation 
  

   described 
  in 
  Ostwald-Luther.f 
  To 
  obtain 
  the 
  values 
  of 
  /j.^ 
  

   for 
  the 
  acids 
  the 
  corrected 
  values 
  of 
  the 
  sodium 
  salts 
  were 
  

   diminished 
  by 
  the 
  ionic 
  conductivity 
  of 
  the 
  Na 
  ion 
  (51) 
  and 
  

   increased 
  by 
  that 
  of 
  the 
  H 
  ion 
  (347). 
  The 
  molecular 
  con- 
  

   ductivity 
  of 
  the 
  dimenthylphosphoric 
  and 
  dipropyl 
  phosphoric 
  

   acids 
  were 
  determined 
  in 
  this 
  way. 
  In 
  attempting 
  to 
  dehy- 
  

   drate 
  the 
  sodium 
  diethylphosphate 
  slight 
  decomposition 
  

   occurred 
  giving 
  a 
  value 
  for 
  /jl^ 
  abnormally 
  high. 
  This 
  value 
  

   was 
  therefore 
  rejected 
  and 
  the 
  value 
  of 
  /jl^ 
  for 
  the 
  correspond- 
  

   ing 
  acid 
  determined 
  by 
  Van 
  HoveJ 
  was 
  used. 
  The 
  molecular 
  

   conductivities 
  of 
  the 
  three 
  homologous 
  dialkylphosphoric 
  acids 
  

   were 
  measured 
  for 
  dilutions 
  ranging 
  from 
  N/8 
  to 
  N/1024- 
  . 
  

   The 
  value 
  of 
  /^ 
  for 
  dipropylphosphoric 
  acid 
  obtained 
  by 
  the 
  

   graphic 
  method 
  was 
  verified 
  by 
  direct 
  measurement 
  at 
  high 
  

   dilution. 
  The 
  mean 
  of 
  the 
  two 
  values 
  (389*5) 
  was 
  used 
  in 
  

  

  *Ortho-, 
  143°. 
  Meta-, 
  63°. 
  Para-, 
  139°. 
  

  

  f 
  Ostwald-Luther, 
  Physiko-Chemische 
  Messungen, 
  (2d 
  ed.), 
  414. 
  

  

  X 
  Van 
  Hove, 
  Bull. 
  Acad. 
  Eoy. 
  Belg., 
  1909, 
  282-294. 
  Van 
  Hove 
  determined 
  

   by 
  the 
  conductivity 
  method 
  the 
  dissociation 
  of 
  diethylphosphoric 
  acid, 
  but 
  

   no 
  previous 
  work 
  is 
  reported 
  on 
  the 
  dissociation 
  of 
  its 
  homologues. 
  His 
  

   average 
  value 
  for 
  k 
  was 
  10*03 
  x 
  10~ 
  2 
  . 
  

  

  