On standing at room temperature, the ethanol solution of ascorbic acid (AAH
2), 5, 6-isopropylidene ascorbic acid (Ip-AAH
2) or dehydroascorbic acid (DHA) and a variety of amines (Table I) in the ratio 1 : 2 moles was discoloured to brown under autoxidative decomposition. It is evident that 1)O
2 was required for the browning discoloration of AAH
2-amine system, but not required for the browning of DHA-amine system ; 2) the browning intensities of the assayed amines were in the following order : primary amines>secondary amines>tertiary amines ; and it was proportional to their pKa value. As a decomposed product dioxalamide II was obtained from the system of 1) AAH
2 and the amines showed in Table I and 4, 2) Ip-AAH
2 and the arylamines in Table II, 3) DHA and the arylamines in Table III and IV. Oxalamide II and another two deposits, arylamine salt of 2-dehydroxy-2-arylamino ascorbic acid (I) and 2, 3-didehydroxy-2, 3-diarylamino ascorbic acid (III), were separated from the browning solution of AAH
2-arylamine system. Five more decomposed were obtained from the mother solution : N, N'-mesoxalamide hydrate (IV), N-aryloxamic acid (V), azobenzene derivatives (VI), glyceric acid (VII) and L-threonic acid (VIII). 82.5% of the specific radioactivity was measured in II obtained from AAH
2-
14C
1 and p-toluidine. From this result it was deduced that II was formed by fragmentation of the C
2-C
3 bond and IV and VII formed by fragmentation of the C
3-C
4 bond of AAH
2. AAH
2 was decomposed to II, IV etc. through AAH·freeradically under autoxidation.
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