Hydrazones ketones

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

A sensitive method for the flow injection analysis of Cu + is based on its ability to catalyze the oxidation of di-2-pyridyl ketone hydrazone (DPKH) by atmospheric oxygen. The product of the reaction is fluorescent and can be used to generate a signal when using a fluorometer as a detector. The yield of the reaction is at a maximum when the solution is made basic with NaOH. The fluorescence, however, is greatest in the presence of HCl. Sketch an FIA manifold that will be appropriate for this analysis. 

A series of interesting pyrazolo[3,4-(f pyrimidine derivatives was obtained by a thermal denitrocyclization reaction of hydrazones, e.g. 164 or 166, easily formed from the corresponding aldehyde or ketone hydrazones with halo-nitrouracil derivatives, e.g. 163 (71CC1442, 72CC298). Intermediates 164 or 166 can be isolated and their cyclization in suitable solvents (methanol, DMF, DMSO) provided high yields of the products. Aldehyde hydrazones yielded the corresponding l,7-dihydropyrazolo[3,4-J]pyrimidines, e.g. 165, whereas ketone hydrazones gave l,5-dihydropyrazolo[3,4-pyrimidine derivatives, e.g. spirocyclic compound 167 (Scheme 26). 

This mechanism is supported by the fact that a secondary hydrazone such as (8) yields the azohydrazone (9) rather than the formazan.8 Ketone hydrazones also yield azohydrazones. The coupling of hydrazones of glyoxylic acid (10) with diazonium salts is accompanied by decarboxylation to yield 3-unsubstituted formazans (11). Similarly, hydrazones of mesoxalic acid (12) yield formazans with a carboxyl group in position 3, e.g., 13 (Scheme 2).910 Both 11 and 13 can react with diazonium salts to yield the... 

Derivatives of hydrazine, especially the hydrazide compounds formed from carboxylate groups, can react specifically with aldehyde or ketone functional groups in target molecules. Reaction with either group creates a hydrazone linkage (Reaction 44)—a type of Schiff base. This bond is relatively stable if it is formed with a ketone, but somewhat labile if the reaction is with an aldehyde group. However, the reaction rate of hydrazine derivatives with aldehydes typically is faster than the rate with ketones. Hydrazone formation with aldehydes, however, results in much more stable bonds than the easily reversible Schiff base interaction of an amine with an aldehyde. To further stabilize the bond between a hydrazide and an aldehyde, the hydrazone may be reacted with sodium cyanoborohydride to reduce the double bond and form a secure covalent linkage. 

Amino acids accelerate and proteins retard the rate of Cu(II)-catalyzed oxidation of di-2-pyridyl ketone hydrazone (173) yielding fluorescent compounds. This has been applied for the analysis of amino acids and proteins378. 

Surprisingly, under these conditions di-ferf-butyl ketone hydrazone afforded 1,1-di-ferf-butyltetrathiolane in very low yield (2%) (see similar reaction in Scheme 91). 

Hydrochlorides of 2//-l,2,3-diazaphospholes (Section 4.22.5.1.2) i.e. 3-chloro-3,4-dihydro-2/7-1,2,3-diazaphospholes generated in situ from a ketone hydrazone and PCI3 (see Section 4.22.5.2) are... 

An interesting case of the addition of ketone hydrazone is observed in the reaction of acetone dimethylhydrazone with DMAD, wherein the initial nucleophilic attack is through the imino nitrogen, leading to products such as dimethyl A-isopropylidine-lV-dimethylamino-2-aminomaleate (132) and the dihydropyridine derivative (133). A small amount of the dimethylhydrazone of oxaloacetic ester (134) has also been observed in this reaction (Scheme 20). ... 

In another one-pot process, Nakamura has developed a novel synthesis of pyrroles through the [3+2] coupling of a ketone hydrazone 5 and a vinyistannane <99OL1505>. In this procedure, zincated hydrazone 6 is converted to the gem-Zn/Sn dimetallic intermediate 7 which upon exposure to oxygen directly affords the l-(dimethylamino)pyrroles 8. 

All hydrazones show a significant absorption band due to the C —N double bond at 1600-1645 cm-1 for ketone hydrazones, and at 1600-1610 cm"1 for the aldehyde derivatives. Mass spectra are characterized by a typical fragmentation pattern and a base peak corresponding to the methoxymethyl fragment6. 

In the latest development of his elegant work with hydrazone derivatives, Andrew Myers of Harvard reports (J. Am. Chem. Soc. 2004,126, 5436) that Sc(OTf), catalyzes the addition of l,2-bis(r-butyldimethylsilyl)hydrazine, to aldehydes and ketones to form the t-butyldimethylsilylhydrazones. Addition of tBuOH/tBuOK in DMSO to the crude hydrazone effects low temperature Wolff-Kishner reduction. Alternatively, halogenation of ketone hydrazones can lead to vinyl halides such as 11, or the 1,1-dihalo derivatives, depending on conditions. Halogenation of aldehyde hydrazones provides the 1,1-dihalo derivatives such as 13. 

Oxidation of 2-azidophenyl ketone hydrazones (455) affords the 2-azidophenyldiazoalkanes (456) which can be cyclized thermally to 1,2,3-benzotriazines (457) (75JCS(Pl)3l). Similarly, 2-aminophenyl ketone hydrazones (458) give 1,2,3-benzotriazines (457) on oxidation with lead tetraacetate (75JCS(Pl)3l). 

Ketone hydrazones can be converted into aliphatic diazo compounds which are, in contrast to nonfluorinated analogs, quite stable at room temperature. 2-Diazo-l,l,1-trifluoropropane is obtained as a solution in diethyl ether or pentane by the oxidation of l,l,l-trifluoropropan-2-one hydrazone using silver oxide.243 Analogously, phenyl trifluoromethyl ketone hydrazone is oxidized to the diazo compound 6 by mercury(II) oxide in alkaline media.362 Bis(per-fluoromethyl)- 7 and bis(perfluoroethyl)diazomethane are prepared by lead(IV) acetate oxidation of the corresponding hydrazones in benzonitrile solution at 0-25 c.244,245... 

Aryl ketone hydrazones are oxidized and fluorinated by fluorine to give a mixture of mono and difluoro hydrocarbons [74 (equation 10)... 

No isomers were detected in the copper and nickel complexes of the strongly polarized o,o -dihydroxyazobenzene (89), the l-(2-hydroxyphenylazo)-2-naphthols (90), or the 1-phenyl-3-methyl-4-(2-hydroxyphenylazo)-5-pyrazolones (91). These compounds exist predominantly in the quinone hydrazone (92 and 93) and ketone hydrazone (94) forms, respectively (Section... 

Another flow injection method coupled with catalytic fluorimetric detection was described for EDTA [39]. The method is based on the catalytic inhibition effect of EDTA on the catalytic action of Cu(II) on the oxidation of di-2-pyridyl ketone hydrazone by H2O2. Concentrations of 0.4-2 pg/mL of EDTA could be determined. 

Vinyl iodides. The reaction of iodine in the presence of triethylamine with ketone hydrazones can result in gem-diiodides or vinyl iodides (4, 260). Hindered hydrazones are converted mainly into the latter products however, yields are generally only moderate. 

Vinyl iodides1 or selenides.2 Some time ago Barton and Stemhall reported the conversion of ketone hydrazones to a mixture of vinyl iodides and gem-diiodides by reaction with iodine in the presence of triethylamine (4, 260). Formation of vinyl iodides is significantly enhanced if a strongly basic pentaalkylguanidine (11, 249-250) is used in place of triethylamine. Formation of diiodides is also suppressed by addition of the hydrazone to a solution of the base and an electrophile. 

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