554  Derivatives  of  Benzoic  Sulphinide.  {^'^St™* 
method  of  working  being  found  to  be  as  follows  :  20  grams  of  the 
amide  and  8  grams  of  caustic  potash  were  dissolved  in  2  litres' of 
water  in  a  large  flask  and  placed  on  the  water-bath.  A  concen- 
trated solution  of  35  grams  of  potassium  permanganate  was  then 
added  by  degrees,  the  flask  being  kept  hot  until  only  a  slight  pink 
color  remained,  an  operation  lasting  about  six  or  eight  hours.  A 
little  alcohol  was  then  added,  and  the  liquid  filtered  and  evaporated 
to  about  75  cc.  While  still  hot,  the  sulphinide,  together  with 
some  unaltered  amide,  was  precipitated  with  strong  hydrochloric 
acid  ;  to  separate  them  the  mixed  precipitate  was  boiled  with  water, 
neutralized  with  chalk,  filtered  and  allowed  to  cool,  the  amide  crys- 
tallizing out  in  long  white  needles.  On  further  evaporation  the 
calcium  salt  of  the  sulphinide  was  obtained.  These  all  crystallize 
in  radial  groups  of  white  needles,  having  the  same  tastes  as  the  sul- 
phinides  themselves,  and  containing  Jx/2  molecules  of  water  of  crys- 
tallization. From  these  calcium  salts  the  pure  sulphinides  were 
obtained  by  precipitation  with  strong  hydrochloric  acid. 
Par afluoro sulphinide,  thus  prepared,  crystallizes  from  hot  water  in 
long  white  needles,  which  break  up  on  drying  into  granules ;  from 
a  dilute  solution  it  may  be  obtained  in  small  transparent  rhombs. 
Its  melting-point  is  200-202 0  (uncorrected).  Its  taste  is  almost 
purely  sweet,  a  slight  bitter  after-taste  being  perceptible.  It  is 
probably  as  sweet  as  benzoic  sulphinide. 
Parachlorosidpliinide  crystallizes  in  thin  pearly  scales,  melting  at 
2 1 8°.  It  is  slightly  less  soluble  than  the  fluorine  compound.  Jt  has 
both  a  sweet  and  a  bitter  taste,  the  latter  being  the  more  intense. 
Parabromosidphinide  also  possesses  both  tastes,  but  in  a  less 
marked  degree,  and  para-iodosidphinide  has  only  a  slight  bitter 
taste.  The  latter  crystallizes  in  fine  white  needles  and  melts  at 
230-2320.  On  boiling  with  dilute  hydrochloric  acid,  /-chlorosul- 
phinide  is  converted  into  the  acid  ammonium  salt  of  /»-chlorortho- 
sulphobenzoic  acid,  just  as  benzoic  sulphinide  is  into  that  of  ortho- 
sulphobenzoic  acid. 
With  regard  to  the  tastes  of  these  halogen  derivatives,  it  is  found 
difficult  to  describe  the  differences  accurately ;  they  have  been 
tasted  by  several,  the  majority  of  whom  agree  with  the  author  in 
his  description.  "  It  is,  however,  impossible  to  make  accurate  com- 
parison between  a  sweet  and  a  bitter  taste  as  regards  the  relative 
intensity  of  the  two." 
