Oxalacetic acid
Oxalacetic acid
Dinitrophenylhydrazone
+ DNPH
HO C CH2 C COOH
HO C CH2 C
COOH
O
O
O
DNPH
CO
+
CH
C
COOH
2
3
DNPH
The presence of oxalacetic acid may be derived from the reaction of an isomeric form of the
ADNTs.
CH 3
CH 3
O N
NO
O 2N
NO 2
2
2
NH
NH
2
Oxidation at the three double bonds of the isomeric form of 4-ADNT could lead to oxalacetic acid.
CH 3
CH 3
O N
NO2
O 2N
NO 2
O
O
2
NO 2
3
O
H
NH
NH
O
O
OH
H2 O
O3
O
HO
O
Oxalacetic acid
Intermediate aldehydes are possible that also undergo oxidation to the acids with ozone. Thus, it
appears that multiple sources of pyruvic acid are possible in the oxidation of ADNTs by ozone.
Glyoxylic acid was observed and confirmed (HPLC retention time and UV spectrum) by the
DNPH assay technique as a major transformation product; however, it was not observed in the
carboxylic acid profile (UV method), although the reference chemical possesses good chromato-
graphic properties. This suggests that the derivatization conditions, although mild (low pH, room
temperature), convert a precursor product to glyoxylic acid. Glyoxylic acid was observed by the
conductivity method and its formation could result as shown below.
CH3
O
H
H
O 2N
Hydrolysis
O 2N
H
O
HO
O
H
O
O
O
NO2
Glyoxylic Acid
H
H
O
O
Glyoxal
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