Phenazines 1-hydroxy

Ammo-dibenzo [a, c] phenazin-hydroxy phenylat->(9 oder 14) 26 II330. 

Conflicting reports on the nitration of phenazine have appeared, but the situation was clarified by Albert and Duewell (47MI21400). The early work suggested that 1,3-dinitroph-enazine could be prepared in 66% yield under standard nitration conditions however, this proved to be a mixture of 1-nitrophenazine and 1,9-dinitrophenazine (24). As with pyrazines and quinoxalines, activating substituents in the benzenoid rings confer reactivity which is in accord with valence bond predictions thus, nitration of 2-methoxy- or 2-hydroxy-phenazine results in substitution at the 1-position. 

Ring substituents show enhanced reactivity towards nucleophilic substitution, relative to the unoxidized systems, with substituents a to the fV-oxide showing greater reactivity than those in the /3-position. In the case of quinoxalines and phenazines the degree of labilization of a given substituent is dependent on whether the intermediate addition complex is stabilized by mesomeric interactions and this is easily predicted from valence bond considerations. 2-Chloropyrazine 1-oxide is readily converted into 2-hydroxypyrazine 1-oxide (l-hydroxy-2(l//)-pyrazinone) (55) on treatment with dilute aqueous sodium hydroxide (63G339), whereas both 2,3-dichloropyrazine and 3-chloropyrazine 1-oxide are stable under these conditions. This reaction is of particular importance in the preparation of pyrazine-based hydroxamic acids which have antibiotic properties. 

Phenanthro[l,2-d][l,2,3]selenadiazole, 10,11 dihydro- H NMR, 6, 348 synthesis, 6, 353 Phenanthro[b]thiophenes synthesis, 4, 914 Phenanthro[4,5-bcd]thiophenes synthesis, 4, 883, 907, 914 Phenanthro[9,10-ej[l, 2,4]triazines synthesis, 3, 434 Phenarsazin synthesis, 1, 561 Phenazine dyes, 3, 196-197 nitration, 3, 177 UV Spectra, 2, 127 Phenazine, 3-amino-2-hydroxy-in colour photography, 1, 374 Phenazine, 1-chloro-nucleophilic substitution, 3, 164-165 5-oxide... 

Some impurities may be found under these GC conditions quinoxaline, phenazine, tetrahydrophenazine, nitroanilines, hydroxy anilines, chloronitrobenzenes, hydroquinone, diami-nophenazine, aminohydroxyphenazine 30 m DB-17 column, 100-275° at 6°/min. 

Phenazines — These are dibenzopyrazine derivatives with fnnctional groups (hydroxy-, carboxy-) at C, and Cg and an oxygen or methyl gronp at Nj and N,o. There are also more complex structures, substituted phenazines, terpenoidal, and carbohydrate-containing phenazines and phenazines derived from saphenic acid. ... 

The best-studied system producing antibiotics in the rhizosphere are fluorescent pseudomonads, producing up to seven different compounds, as summarized in Fig. 9 2-hydroxyphenazine-l-carboxylate, phenazine-l-carboxylate, 2-hydroxy-phenazine, pyrrolnitrin, pyocyanine, 2.4-diacetylphloroglucinol. and pyoluteorin (48). Nine genes have been identified in the synthesis of phenazine-1-carboxylic... 

On the other hand, there is at least one case of an aromatic amine without a hydroxy group in the 2-position, namely 1-aminophenazine (25) which, after the initial diazotiza-tion, is oxidized within minutes by air or additional nitrous acid to the quinone diazide 26 (equation 9)46. In the corresponding diazotization of 2-aminophenazine the proportion of the quinone diazide (isomer of 26) amounted to only 16%, but 30% unsubstituted phenazine was also found. The phenazine may have resulted from the overall redox reaction. 

Phenazines can be obtained from o-nitrodiphenylamines by reduction or from o-aminodiphenyla-mines by oxidative techniques. The preferred method is that of phenazine 9,10-dioxides from benzofuran, thus benzofuroxans, itself with hydroquinone, gives the 2-hydroxy derivative (Scheme... 

The accumulation of phenazine-1,6-dicarboxylic acid (154) by mutants of Pseudomonas phenazinium148 which normally produce hydroxy-phenazine derivatives supports a role for (154) in phenazine biosynthesis. In further studies143 with Ps. phenazinium the sequence of hydroxylative steps leading to the various phenazines has been deduced143 148 to be that illustrated in Scheme 15 the biosynthesis deduced for iodinin (156) is in agreement with earlier conclusions about its formation in cultures of another organism (Brevibacterium iodinum ).146... 

Phenazin 7,8-Dichlor-1-hydroxy- -10-oxid E9b/2, 282 (5,6-Cl2-benzofuroxan + 1,2-Dioxo-cyclohexan)... 

Phenazin 2-Hydroxy-3-nitro- -5,10-bis-oxid E9b/2, 283 (Benzofuroxan + 2-N02 — hydroquinon)... 

In the mass spectrum of phenazine an intense molecular ion at w/z 180 with significant contributions from the doubly charged molecular ion is observed fragmentations by loss of CN, HCN and C Hj (M-27) are characteristic. The mass spectrum of phenazine and isomeric hydroxy- and methoxyphenazine-1-carboxylic acids have been investigated in detail. Phenazine A -oxide shows an M O ion together with an intense M—CjHj ion and M-CO ion (w/z 168). ... 

Phenazines bearing electron-donating substituents are activated towards nitra-2-Substituted amino-, hydroxy- and methoxyphenazines are nitrated at posi-... 

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