2- -phthalazinone oxidation

Chemical Name 1 (2H)-Phthalazinone-(1,3-dimethyl-2-butenylidene)-hydrazone Common Name Mesityl oxide (1-phthalazinyl) hydrezone... 

AO is also effective in metabolizing a wide range of nitrogen-containing heterocycles such as purines, pyrimidines, pteridines, quinolines, and diazanaphthalenes (95). For example, phthalazine is rapidly converted to 1-phthalazinone by AO and the prodrug, 5-ethynyl-2-(l//)-pyrimidone, is oxidized to the dihydropyrimidine dehydrogenase mechanism-based inhibitor, 5-ethynyluracil, by AO (Fig. 4.40) (96). 

Sulfonated poly(arylene ether)s have shown promise for durability in fuel cell systems, while poly-(styrene)- and poly(imide)-based systems serve as model systems for studying structure-relationship properties in PEMs because their questionable oxidative or hydrolytic stability limits their potential application in real fuel cell systems. Sulfonated high performance polymer backbones, such as poly(phe-nylquinoxaline), poly(phthalazinone ether ketone)s, polybenzimidazole, and other aromatic or heteroaromatic systems, have many of the advantages of poly-(imides) and poly(arylene ether sulfone)s and may offer another route to advanced PEMs. These high performance backbones would increase the hydrated Tg of PEMs while not being as hydrolytically sensitive as poly(imides). The synthetic schemes for these more exotic macromolecules are not as well-known, but the interest in novel PEMs will surely spur developments in this area. 

Aldehyde oxidase, a non-microsomal enzyme discussed in more detail below, may also be involved in the oxidation of quinoline to give 2-hydroxyquinoline (Fig. 4.14). The heterocyclic phthalazine ring in the drug hydralazine is oxidized by the microsomal enzymes to phthalazinone. The mechanism, which may involve nitrogen oxidation, is possibly involved in the toxicity of this drug (see chap. 7). Again, other enzymes may also be involved (Fig. 4.15). 

Benzoylphthalazine with sodium hydroxide in dimethyl sulfoxide hydroxylates the phthalazine ring to give, after oxidation, 4-benzoyl-l(2H)phthalazinone (Scheme 16) (85CPB4193). 

Smith and Otremba138 have found that the sodium borohydride reduction of 2-methyl- and 2-ethyl-phthalazinium iodide (113) in aqueous medium results in good yields of the corresponding 1,2-dihydrophthalazines (114). The dihydrophthalazines were found to be stable to excess sodium borohydride in refluxing methanol but underwent a facile air oxidation to phthalazinones (115). The borohydride reduction of 2-benzyl-phthalazinium chloride proceeded with apparent partial debenzylation, for a 31% yield of the parent 1,2-dihydrophthalazine (114, R = H) was isolated as the 2,2-dimethyl quaternary salt. 

Phthalazine (45) with benzonitrile oxide gave l(2fl)-phthalazinone (47) via the unisolated intermediate (46) (reactants, PhH, reflux, 3 h 25%). ... 

Biological oxidation of phthalazine (45) also gave l(2fl)-phthalazinone (47) [Streptomyces viridospoms T7a culture, phthalazine, 37°C, 3 days 46% ... 

Phenyl-l(2/i/)-phthalazmone (3) gave l-chloro-4-phenylphthalazine (4) (POCI3, 85°C, 4h 79%) 4-p-dimethylaminophenyl-4-phenyl-3,4-dihy-dro-l(27/)-phthalazinone (5) gave l-chloro-4-p-dimethylaminophenyl-4-phe-nyl-3,4-dihydrophthalazine (6) (PCX ls, 80°C, 6h 58%) and thence 1-chloro-4-phenylphthalazine (4) (POCI3, reflux, 6h 71% note nuclear oxidation by loss of PhNMc2) " as might be expected, the substrate (5) also afforded... 

The term oxyphthalazine is used here to cover compounds such as the tautomeric phthalazinone (1), its nontautomeric 0-methyl (2), and iV-methyl derivatives (3 and 4), the extranuclear hydroxymethylphthalazine (5), the phthalazinequinone (6), the phthalazine A -oxide (7), and related derivatives. 

The important phenomenon of chemiluminescence clearly falls within the scope of this chapter because the oxidation of luminol [5-amino-1,4(2H,31il)-phthalazi-nedione (8)] or related phthalazinones by hydrogen peroxide is commonly used to produce light in this way. However, the whole specialized subject, including the use of chemiluminescence in analysis and of biochemiluminescence in diagnostic... 

Tautomeric phthalazinones undergo several reductive or oxidative reactions, the most important of which is the production of phthalazinequinones or semiquinones. The following examples illustrate such reactions. 

Phenylphthalazin-2-ium-2-benzimidate (211) underwent ring fission, aerial oxidation, and recyclization in alkali to give 2-benzamido-4-phenyl-l(2//)-phthalazinone (212) (KOH, EtOH, HjO, reflux, 3 h 49%). ... 

Note The formation of phthalazinones from phthalazine N-oxides has been exemplified in Section 11.1.1. 

Note Acylphthalazines have been made by primary synthesis (see Chapter 8), Reissert-type additions to simple phthalazines (Section 9.1.3), oxidation of alkylphthalazines (Section 9.2.2), displacement of halogeno substituents (Section 10.3.4), acylation of tautomeric phthalazinones (Section 11.1.2.2), oxidation of extranuclear hydroxyphthalazines (Section 11.2.2), or as illustrated in these examples. 

Methoxy-2-methyl-5-nitro-1 (2/7)-phthalazinone 4-Methoxy-2-methyl-8-nitro-1 (2/7)-phthalazinone 2-Methoxymethyl- l-oxo-4-pheny 1-1,2-dihydro-6-phthalazinecarbonitrile l-Methoxy-4-methylphthalazine l-Methoxy-4-methylphthalazine 3-oxide... 

Methoxy-5,6(l//,27/)-phthalazinedione 1-Methoxyphthalazine 3-oxide 4-Methoxy-1 (2//)-phthalazinone... 

Penty lamino-1 (20)-phthalazinone 4-Pentyl-1 (2H)-phthalazinone 4-Phenethyl- l(2H)-phthalazinone l-Phenoxy-4-phenylphthalazine 4-Phenoxy-2-phenyl-1 (2H)-phthalazinone 1 -Phenoxyphthalazine 1-Phenoxyphthalazine 3-oxide 1 -(Af-Phenylhydrazino)phthalazine 1 -Phenyl-4-pheny Ithiophthalazine 4-Phenyl- 1-phthalazinamine 1 -Phenylphthalazine... 

Propoxyphthalazine 3-oxide 4-Propoxy-2-propyl-1 (2H)-phthalazinone 1 -Propylaminophthalazine... 

In another grafting to procedure, four polymers [PVDF, polysulfone (PSF), poly(2,6-dimethylphenylene oxide) and poly(phthalazinone ether ketone)] were chemically bonded to MWNTs using ozone-mediated process. Compared with pristine MWCNTs and PSF-modified MWCNTs, PVDF-modified MWCNTs were more efficient as additives that enhance the mechanical strength and electrical conductivity of PVDF. ... 

A suitable polymer material for preparation of carbon membranes should not cause pore holes or any defects after the carbonization. Up to now, various precursor materials such as polyimide, polyacrylonitrile (PAN), poly(phthalazinone ether sulfone ketone) and poly(phenylene oxide) have been used for the fabrication of carbon molecular sieve membranes. Likewise, aromatic polyimide and its derivatives have been extensively used as precursor for carbon membranes due to their rigid structure and high carbon yields. The membrane morphology of polyimide could be well maintained during the high temperature carbonization process. A commercially available and cheap polymeric material is cellulose acetate (CA, MW 100 000, DS = 2.45) this was also used as the precursor material for preparation of carbon membranes by He et al They reported that cellulose acetate can be easily dissolved in many solvents to form the dope solution for spinning the hollow fibers, and the hollow fiber carbon membranes prepared showed good separation performances. 

Nafion (Fu et al. 2008). However, the corresponding proton conductivity value is lower. The methanol crossover, however, is only one-third of that found in Nafion 115, compared at the same thickness. Although the PSf membrane has lower proton conductivity than Nafion, the lower production cost and methanol crossover make it a promising alternative for DMFC. Sulfonated poly(phthalazinone ether ketone) (SPPEK) has been discovered as a new kind of PEM for DMFC due to its superior performance in terms of chemical and oxidative resistances, mechanical strength, and thermal stability (Gao et al. 2003). Tian et al. reported that SPPEK prepared from direct polymerization of presulfonated monomer has better performance than that of postsulfonation (Tian et al. 2005). Unfortunately, with direct polymerization it was hard to control the DS and location of sulfonation. 

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