Am.  Jour.  Pharm.  \ 
June,  1883.  j 
Py7ddine  and  Quinoline  Bases. 
33J 
occur  in  coal  tar.  In  properties  tiiese  bodies  resemble  tlie  pyridine  bases„ 
Towards  allvyl  iodides  they  act  lilve  tertiary  amines,  and  on  oxidation  they 
are  transformed  into  pyridine  carbonic  acids.  Pure  quinoline,  free  from 
its  homologucs,  may  be  prepared  by  heating  cinclionine  witb  copper  oxide 
and  caustic  potassa.^  Konigs^  has  made  it  synthetically  by  passing  the 
vapor  of  allyl-aniline,  CfjHjNHCaHj,  over  heated  lead  oxide.  Baeyer,^  by 
treating  hydrocarbostyril  with  i^hosphorus  pentacliloride,  obtained  di- 
chlorquinoline,  which  by  nascent  hydrogen  was  converted  into  quinoline. 
The  dry  distillation  of  acridate  of  calcium  or  of  acrolein-aniline  also  yield* 
quinoline.*  Bottinger^  states  that  the  hydroclilorate  of  aniluvitonic  acid 
when  heated  with  soda  lime  is  converted  into  quinoline.  But  these  methods 
are  only  of  scientific  interest,  and  it  is  to  the  work  of  SkrauiD^  that  we  owe 
a  process  for  the  synthesis  of  quinoline  and  its  homologues  which  is  not 
only  of  the  greatest  theoretical  value  and  of  general  application,  but  at  the 
same  time  it  is  an  economical  method  for  the  production  of  these  bases  in 
quantity.  The  details  of  the  process  have  been  described  in  the  "  American 
Chemical  Journal."  iv,  p.  63. 
The  synthesis  of  lepidine,  the  second  member  of  the  series,  has  been 
effected  by  Dobner  and  Miller.^  The  method  is  analogous  to  that  of  Skraup, 
and  consists  in  heating  a  mixture  of  aniline,  nitrobenzene,  sulphuric  acid 
and  glycol  or  paraldehyde. 
The  quinoline  bases  when  oxydized  are  transformed  into  pyridine-carbonic 
acids,  quinoline  itself  yielding  cinchomeronic  acid  or  pyridine-dicarbonicr 
acid.  This  fact  indicates  a  close  connection  between  the  quinoline  bases 
and  such  alkaloids  as  quinine,  cinclionine  and  their  isomers,  because  these 
two  when  oxidized  are  converted  into  pyridine  di  or  tricarbonic  acids. 
Quinoline,  like  the  pyridine  bases,  has  the  power  of  forming  hydrides  by 
treatment  with  tin  and  hydrochloric  acid.  Wischnegradsky^  obtained  from 
it  tetrahydroquinoline,  and  Jackson^  has  also  described  a  tetrahydroquino- 
line,  both  of  which  are  secondary  bases.  They  are  very  unstable  substances,, 
and  the  weakest  oxydizing  agents  change  them  back  into  quinoline. 
Among  the  substitution-products  of  quinoline  are  the  oxyquinolines  or 
quinophenols  analogous  to  the  naphthols  in  their  mode  of  formation,  pro- 
perties and  general  reactions.  Nitroquinoline,  like  nitronaphthalene, 
readily  yields  the  amine,  and  the  cyanogen  derivatives  can  be  transformed 
in  the  usual  way  into  the  quinoline-carbonic  acids.  In  fact,  the  synthesis 
of  quinoline  and  the  analogies  existing  between  its  derivatives  and  those 
of  napthalene  seem  to  justify  Korner's  structural  formula.  According  to- 
his  hypothesis  quinoline  has  a  structure  analogous  to  that  of  naphthalene,, 
and  bearingthe  same  relation  to  pyridine  that  naphthalene  does  to  benzene  ; 
and  as  one  of  the  CH  groups  of  naphthalene  is  supposed  to  be  replaced  by 
1  Wischnegradsky,  Bei  ichte  der  dentschen  chemischen  Gesellschaft,  xiii,  2HIS. 
2  Ibid,  xii,  453. 
3  Ibid,  xii,  1320. 
*  Grnebe  and  Caro,  Ibid,  xiii,  99. 
6  Ibid,  xiii,  21G5. 
«  Monatshefte  fUrCiiemie,  i,  310,  and  ii,  139  and  171. 
''  Berichte  der  dentschen  chemischen  Gesellschaft,  xiv,  2812. 
^Bulletin  de  la  Societe  Chimique,  xxxiv,  310. 
'Beritclite  der  dentschen  chemisclien  Gesellsciiaft,  xiv,  880. 
