Hydrogenation. --Chlorogenic and ijochlorogeriic acids
T o isolate caffeic acid, 5 g. of sample is dissolved iii 50 nil. of N sodium hydroxide under an atmosphere of nitro-
were hydrogenated in absolute ethanol using 5 % palladium t ) i i charcoal a.; a catalyst. The suspension after hydrogen.itinn was filtered through Celite, the filtrate taken to dryIIC'SS, And the residue taken up in water and lyophilized. T h e theoretical amount of hvdrogen wds absorbed bv each
gen and allowed to stand overnight at room temperature lxfore acidification with an equivalent quantity of sulfuric acid. Caffeic acid is isolated from the saponification mixture by continuous extraction with ether, the ether removed hy distillation, and the residw rccryi;t;illized from water, m. p . 218-220". After removal of the caffeic acid, quinic acid i n a y be isolated by acetone extraction of the dry saporiilic:atioii residue or by formation of the copper acetate cotnplex. Better yields are obtained by acid hydrolysisll of the hydrogenated chlorogenic or isochlorogenic wid, aut1 tht, quinic acid is further identified by preparation of the 1,A.ztriacetylquinlactone.'2 The quinic wid dcrivetl from iwchlorogenic acid is partially lactonizctl, I)ut ~ i i I~I V ~wpoiiiy fied to the correct titration value.
without significant change in neutralizatioi. However, thc optical rotation of hydrogctil ~ < ci-~x~hlorogt~nic. l , \ ! a b --B-l to - : < g o ,\ c d i ;ipproxii i i . c t c l v tli,;. of c.hlorogciii: hvrlrochlorogciiiv .icitl, l w l I"!) , - 2 -
I
!
niiipouiigl (1iiiv:ilcii:.
I)r
Sum mar y .I 1 1 . 3 ~coinpound, ' isochlorogeiiic acid," has 11eeri isolated iroin green coffee. Evidence is Iresentd for the proposed structure, .i-caffeyI:I 1) Ation isomer of chlorogenic
tjuiriic acid.
annbe, J . P / i w m S O C . J u p u i i . 56, 7 1 < . A h t r d c i . i i i German) 13, (1936>,( ' / ? ? ; ~ r . Lpi?/r , 107, I , .l'IOl l!J.ili , (' I
.alsii!
31, PO62 (1936). ik
and Kcvtii;
/+v,
22, ! 1.i;
VI.
Pyridines.
! 1,
ifih!~;
I
$$
I{
1
=
]
