Pyrazone

Purpuric acid lb 174 Pyrazolidine derivatives la 426 3,5-Pyrazolidindione derivatives lb 20 Pyrazolinone derivatives lb 277 Pyrazolin-5-one derivatives lb 327,329 Pyrazone lb 332 Pyrene lb 379 PyrethrinI lb 18 Pyrethrin II lb 18 Pyrethroids lb 86,87 Pyrethroid insecticides la 359 Pyridine alkaloids la 66 lb 279 Pyridine derivatives lb 119,244 Pyridinium carbinols lb 65 Pyridinium glycols lb 65 Pyridoxal la 157,158,253 Pyridoxamine la 253 Pyridoxine la 253... 

Strontium Strontium complexed with l-phenyl-3-methyl-4-benzoyl- 5-pyrazone AAS 0.007 ng/1 [909]... 

Copper complexes were used as efficient catalysts for selective autoxidations of flavonols (HFLA) to the corresponding o-benzoyl salicylic acid (o-BSH) and CO in non-aqueous solvents and at elevated temperatures (124-128). The oxidative cleavage of the pyrazone ring is also catalyzed by some cobalt complexes (129-131). 

Herbicides 2,4-D, MCPA, Mecoprop, 4-(2,4-DB), TCA, Amitrole, Dalapon, Monuron, Chlorpropham, Endothal, Pyrazon, and DNOC. 

Pharmacokinetics Rapidly and completely absorbed from gastrointestinal (GI) tract. Widely distributed. Metabolized in liver to two active metabolite, p-hydroxy-sulfin-pyrazone and a sulfide analog. Excreted primarily in urine. Not removed by hemodialysis. Half-life 2.7-6 hr. 

The pyridazin-3-ones are interesting because they include herbicides having two different modes of action, distinguished only by small changes in substitution pattern. Thus pyrazon (8) (61GEP1105232) is a photosynthesis inhibitor, while other discussed later are carotenoid biosynthesis inhibitors. The pyridazin-3-one ring is constructed by condensation of phenyl-hydrazine with 3,4-dichloro-2,5-dihydro-5-hydroxyfuran-2-one (9), in turn produced by chlorination of furan-2-carbaldehyde. Amination of (10) then occurs exclusively at the 5-position to give pyrazon (Scheme 4). 

The toluene dioxygenase,1387 benzoate 1,2-dioxygenase1388 and pyrazon dioxygenase1389 all contain [2Fe-2S] clusters and require Fe2+, although the stoichiometries differ as shown in Table 28. It appears very probable that they all contain the [2Fe-2S]Fe2+ site for activation of dioxygen. 

Cobalt-mediated C-H activation of pyrazone 287 with bis(trimethylsilyl) acetylene in the presence of cyclopentadienylcobaltbis(ethene) [CpCo (C2H4)2] afforded pyrido[l,2-a]pyrazin-4-one complex 288, and its decom-plexation with Fe3"" furnished 6,7,8,9-tetrahydro-4H-pyrido[l,2-a]pyrazin-4-one 289 (07CEJ7443). 

Crathome [16] reported a method for the determination of Pyrazon (5-amino-4-chloro-2-phenyl-3-pyridazone) in non saline waters. Pyrazon was isolated from water samples (500mL) by rotary evaporation to dryness in vacuo, extraction of the solid residue with methanol (2><25mL) and further evaporation of the methanol extract (to approx. 2mL). Final concentration (to 0.5mL) was achieved by removal under a stream of nitrogen. 

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