Nitrophenoxyacetic acid

Nitrophenoxyacetic acid [1878-87-1] M 197,2, m 150-159 , pK 2.90, Crystd from water, and dried over P2O5 under vacuum.. 

Sassanella TM, F Fukumori, M Bagdasarian, RP Hausinger (1997) Use of 4-nitrophenoxyacetic acid for detection and quantification of 2,4-dichlorophenoxyacetic acid 2,4-D/a-ketoglutarate dioxygenase activity in 2,4- D-degrading microorganisms. Appl Environ Microbiol 63 1189-1191. 

Dihydro-l,4-benzoxazin-3-ones and -benzothiazin-3-ones are synthesized by the reductive cyclodehydration of 2-nitrophenoxyacetic acids or their thioxy equivalents and as these heterocycles have an active methylene group it is a simple matter to prepare 2-substituted derivatives by condensation reactions with aldehydes and other carbonyl compounds (Scheme 123) (79AP302). 

Sometimes a cathodic substitution reaction takes place during the reduction of ortho-substituted nitrobenzenes thus the reduction of 2-nitrophenoxyacetic acid (21) in 2 N hydrochloric acid (50% ethanol) yielded 5-chloro-2H-l,4-benzoxazin-3(4H)-one (22), Y = C1) rather than the expected cyclic hydroxamic acids02 in the presence of another nucleophile Y (e.g., thiocyanate) ring substitution with this reagent occurs. 

The 2,4-dichlorophenoxyacetic acid/a-ketoglutarate dioxygenase could accept 4-nitrophenoxyacetic acid to produce colored 4-nitro-phenol (Sassanella et al. 1997). It was pointed out, however, that a number of strains that were able to degrade 2,4-dichlorophenoxy-acetic acid were unable to accept the surrogate substrate. 

Of the nitrophenoxyacetic acids only the w-derivative is an active compound. One is inclined, also by comparing molecular models, to suppose that mesomerism in the 0- and />-nitro-acids influences the spatial form of the molecule in an unfavourable ways. 

In one of our alternative approaches the lactol unit of the 2,4-dihydroxy-2i/-l,4-benzoxazin-3(4//)-one skeleton was developed by oxidation of the unsubstituted methylene function (Fig. (9)) [114]. The starting cyclic hydroxamic acids have been prepared by catalytic transfer hydrogenation of appropriate 2-nitrophenoxyacetate precursors with the sodium borohydride/Pt-C method. The oxidative transformation intended caused a need for protection of the hydroxamic acid moiety. From several... 

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