Expanded nitrophenolates

Oturan et al. [134] expanded their synthetic work to the degradation of 0.5 1 mM chlorophenoxyacid herbicides by EFR on a Hg pool. Aromatic ring cleavage was found upon exhaustive electrolysis (see Table 4). A number of polyhydroxyphenols and quinones were identified as intermediates. These authors have also considered the degradation of p-nitrophenol [135] and the herbicides 2,4-D or 2,4-dichlorophenoxyacetic acid [136] by the same technique using a carbon-felt cathode. 

The spectrum shown in Figure 26.24 is of 2-nitrophenol. It is helpful to look also at the coupling constants for the benzene ring found in Table 26.4. Because the spectrum is expanded, it is now possible to see couplings (about 8 Hz), as well as couplings (about 1.5 Hz). couplings are not observed ( / =0). Each of the protons on this compound is assigned on the spectrum. Proton H appears down-field at 8.11 ppm as a doublet of doublets ( / =8 Hz and =1.5 Hz) H, appears at 7.6 ppm as a triplet of doublets = c... 

Example The metastable decay of the o-nitrophenol molecular ion, m/z 139, by loss of NO to yield the [M-NO] ion, m/z 109, has been studied on a single-focusing magnetic sector instrument (Fig. 9.13) [56]. The mass spectrum shows a flat-topped peak of low intensity expanding over three mass units. Some minor and narrow regular peaks corresponding to fragment ions formed within the ion... 

In Figures 7.69 and 7.70 the expanded ring-proton spectra of 2-nitrophenol and 3-nitrobenzoic acid are presented. The phenol and acid resonances, respectively, are not shown. In these spectra, the position of each subpeak is given in Hertz. For these spectra, it should be possible not only to assign peaks to specific hydrogens but also to derive tree diagrams with discrete coupling constants for each interaction (see Problem 1 at the end of this chapter). 

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