Showing papers on "Hydrazone published in 1996"
TL;DR: The application of the DNPH method has led to the identification of 2,4-dinitrochlorobenzene as another interfering compound after sampling of air with high nitrogen dioxide content when using hydrochloric acid as catalyst.
Abstract: A method for the rapid and convenient identification of chemical interferences in the determination of aldehydes and ketones in air samples using the 2,4-dinitrophenylhydrazine (DNPH) method is described. The ratio of absorptions at 360 and 300 nm is characteristic for groups of related aldehydes and ketones as well as for the main interferents. It has been determined by UV/visible spectroscopy of pure standard compounds and confirmed by HPLC analysis with UV/visible detection of complex hydrazone mixtures. The application of this method has led to the identification of 2,4-dinitrochlorobenzene as another interfering compound after sampling of air with high nitrogen dioxide content when using hydrochloric acid as catalyst. The possibilities and limitations of the dual-wavelength detection with the DNPH method are discussed for mixtures of standards and real samples from car exhaust.
72 citations
49 citations
43 citations
TL;DR: The synthesis and the analgesic activity of the new functionalized arylcarbaldehyde 4-(1-phenyl-3-methylpyrazolo[3,4-b]pyridine) hydrazone derivatives 5a-m are described and the compounds 5f, 5g, 5j and 5k were strongly active showing a good analgesic profile.
42 citations
40 citations
TL;DR: In this paper, the carbonyl group was regenerated from phenylhydrazones through oxidative hydrolysis using hypervalent organoiodine(III) reagents.
39 citations
TL;DR: In this article, the three possible isomers of thia-tryptophan were obtained as the ethyl esters from corresponding methyl oxime ethers by reduction of the oxime double bond.
36 citations
TL;DR: A series of monometallic palladium(II) complexes with phenyl 2-pyridyl ketone benzoylhydrazone (H2L) has been synthesized and characterized as discussed by the authors.
Abstract: A series of monometallic palladium(II) complexes with phenyl 2-pyridyl ketone benzoylhydrazone (H2L) has been synthesized and characterized. The spectroscopic and diffractometric data have revealed a versatile ligand behaviour which mainly depends on the the palladium salt reagent. From the reaction of palladium acetate a cyclopalladated complex, [PdL(MeCN)], was isolated, the exact nature of which has been established by X-ray diffraction. With palladium chloride two complexes, [Pd(HL)2] and [Pd(HL)Cl], were obtained with the monodeprotonated hydrazone behaving as an N,N-bidentate and N,N,O-terdentate ligand, respectively.
32 citations
TL;DR: The title compound 1 was synthesized by the reaction of 2,4,6-tri-t-butylphenyllithium with O-ethyl thioformate.
Abstract: The title compound 1 was synthesized by the reaction of 2,4,6-tri-t-butylphenyllithium with O-ethyl thioformate or that of 2,4,6-tri-t-butylbenzaldehyde hydrazone with disulfur dichloride in the presence of triethylamine. The thioaldehyde 1 is a purple crystalline compound which is thermally quite stable; only around 200 °C it underwent intramolecular cyclization to give 6,8-di-t-butyl-3,4-dihydro-4,4-dimethyl-1H-2-benzothiopyran 9. The X-ray crystallographic analysis of 1 revealed that the thioformyl group is almost perpendicular to the aromatic ring. The reaction of 1 with 1-cyano-1-methylethyl radicals afforded 9, while that with t-butyl radicals gave 1,3,5-tri-t-butyl-2-t-butylthiomethylbenzene and t-butyl 2,2-dimethyl-1-(1,3,5-tri-t-butylbicyclo[2.2.0]hexa-2,5-dien-2-yl)propyl sulfide in addition to 9. Some Grignard reagents and organolithiums reacted with 1 gave carbophilic, thiophilic, double addition products and some others depending on the kind of the organometallic reagents. Hydrazine and butyl...
30 citations
TL;DR: With three ketones the reaction with 2,4-DNPH resulted in mixtures of the isomeric hydrazones which were separated by HPLC and GC and identified by mass spectroscopy and 1H nuclear magnetic resonance spectroscopes, leading to problems in quantification and interpretation of Chromatographic results.
Abstract: Aldehydes and ketones readily react with 2,4-dinitrophenylhydrazine (2,4-DNPH) to form the corresponding hydrazones. This reaction has been frequently used for the quantification of airborne carbonyl compounds. Since unsymmetrical aldehydes and ketones are known to form isomeric 2,4-dinitrophenylhydrazones (syn/ anti-isomers), the influence of isomerization on the practicability and accuracy of the 2,4-DNPH-method using 2,4-dinitrophenylhydrazine-coated solid sorbent samplers has been studied with three ketones (methyl ethyl ketone (MEK), methyl isopropyl ketone (MIPK), and methyl isobutyl ketone (MIBK)). With all three ketones the reaction with 2,4-DNPH resulted in mixtures of the isomeric hydrazones which were separated by HPLC and GC and identified by mass spectroscopy and (1)H nuclear magnetic resonance spectroscopy. The isomers show similar chromatographic behaviour in HPLC as well as in GC, thus leading to problems in quantification and interpretation of chromatographic results.
27 citations
TL;DR: A barium complex with pyruvic acid isonicotinoyl hydrazone (H 2 L) has been synthesized and its crystal structure was determined by X-ray diffraction analyses as mentioned in this paper.
TL;DR: The proposed method was successfully applied to the determination of copper(II) in tap water and biological material and the relative standard deviation for ten determinations of 0.06 ng cm(0-3) of copper
Abstract: A spectrophotometric method was developed for the determination of ultratrace amounts of copper(II) based on its catalytic effect on the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline to produce an intensely coloured dye (λmax= 525 nm) in the presence of hydrogen peroxide. In this reaction, pyridine acted as an effective activator for the catalysis of copper(II). By measuring the absorbance of the dye, copper(II) can be determined at the 0.002–0.1 ng cm–3(3.1 × 10–11–1.6 × 10–9 mol dm–3) level. The relative standard deviation for ten determinations of 0.06 ng cm–3 of copper(II) was 2.6%. The proposed method was successfully applied to the determination of copper(II) in tap water and biological material.
TL;DR: The title compound is bis(8-B-4)-1,3,5-tris[2-[(N,N-dimethylhydrazono)methyl]-phenyl)]b oroxin, a tridehydro cyclic trimer of the expected simple benzaldehyde hydrazone and the first triphenylboroxin derivative found to possess two B chelating interactions.
Abstract: Condensation of 2-formylbenzeneboronic acid and 1,1-dimethylhydrazine afforded the title compound, bis(8-B-4)-1,3,5-tris[2-[(N,N-dimethylhydrazono)methyl]-phenyl)]b oroxin, C27H33B3N6O3, a tridehydro cyclic trimer of the expected simple benzaldehyde hydrazone and the first triphenylboroxin derivative found to possess two B chelating interactions. The double chelation induces molecular asymmetry but effects only a slight puckering in the central boroxin ring.
TL;DR: Laccase from Coriolus hirsutus catalyzes the oxidative condensation reaction between 3-methyl-2-benzothiazolinone hydrazone and 3-dimethylaminobenzoic acid to form a blue indamine dye, where dye is not formed when peroxidase alone is present.
TL;DR: An efficient and stereocontrolled preparation of the (2 S, 3 R )-1,2-acetonide from hydrazone was described in this article, leading to a (D)-phenylalaninol derivative, potentially useful for the design of HIV protease inhibitors.
Abstract: An efficient and stereocontrolled preparation of the (2 S ,3 R )-1,2-acetonide 15 , from hydrazone 10 , leading to a (D)-phenylalaninol derivative, potentially useful for the design of HIV protease inhibitors, is described.
TL;DR: 1-Adamantyl tert-butyl ketone hydrazone reacts with disulfur dichloride in dichloromethane to give 5-(1-adamantyl)-5-tert-butyltetrathiolane.
TL;DR: In this article, the structure assignment of 1,4-adducts with enamino forms has been revisited for some 5-and 3-hydroxypyrazoles, as well as the structure of the pyrazole ring in all such compounds.
TL;DR: In this article, a new ligand, formylferrocenyl-2-(5-norbornenoyl) hydrazone (HFfnh), was proposed.
TL;DR: The o-substituted 3-(arylhydrazono)methyl-2-oxo-1,2-dihydroquinoxalines were synthesized to investigate the tautomeric behavior between the hydrazone imine A and diazenylenamine B forms in a series of mixed dimethyl sulfoxide/trifluoroacetic acid media as discussed by the authors.
TL;DR: The title azine was obtained by a reaction of the corresponding fluorenone hydrazone and p-substituted benzaldehyde, and was assigned to be (s-trans/E) form as mentioned in this paper.
Abstract: The title azine was obtained by a reaction of the corresponding fluorenone hydrazone and p-substituted benzaldehyde. The hydrazone formed from the unsymmetrical fluorenone afforded configurational isomers; the E-isomer was thermodynamically more stable than the Z-isomer. The structure of the title azines, derived from symmetrical fluorenone, was assigned to be (s-trans/E) form. The azines from unsymmetrical fluorenone gave isomeric mixtures due to the 9-iminofluorene moiety. The electronic spectra of these azines show an intramolecular charge transfer; the red shift beyond 250 nm is observed in the case of 9-[p-(diethylamino)benzylidenehydrazono]-2,4,7-trinitrofluorene, compared to the mother azine. 9-[p-(Pentyloxy)benzylidenehydrazono]-2,7-dinitrofluorene and some of the homologs possess a liquid-crystalline property; the phase-transition temperature of the dinitro compound is K (172 °C) M1 (185) M2 (187) I between the crystalline and liquid phases.
TL;DR: The structural results clearly indicate that 1-butyl-3-cyano-6-hydroxy-4-methyl-5-(2-thiazolylazo)-2(1H)-pyridone, (C 14 H 15 N 5 O 2 S), exists primarily as the hydrazone tautomer in the solid state as discussed by the authors.
TL;DR: The single-crystal X-ray structure determination of the title compound, C15H16N4O, reveals that the molecule is in the keto tautomeric form and that the azomethine C=N double bond has the E configuration as mentioned in this paper.
Abstract: The single-crystal X-ray structure determination of the title compound, C15H16N4O.H2O, reveals that the molecule is in the keto tautomeric form and that the azomethine C=N double bond has the E configuration. The water molecule is hydrogen bonded to the hydrazone molecules to form a network structure in the crystal lattice. The crystal structure is stablilized by N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds.
Patent•
12 Dec 1996TL;DR: In this paper, a process for producing a hydrazide of the formula: ##STR1## is disclosed, where a mixture of Grignard reagents are used in a suitable organic solvent, and the reaction is conducted at a temperature of about +30° to about -40° C.
Abstract: A process for producing a hydrazide of the formula: ##STR1## is disclosed. The process comprises reacting a hydrazone of the formula: ##STR2## wherein said hydrazone is in toluene, with a mixture of Grignard reagents, wherein said Grignard reagents are in a suitable organic solvent; wherein: (A) Z is a suitable carbonyl protecting group; (B) R is a suitable --OH protecting group; (C) R 1 is selected from: H, a non-enolizable alkyl, a non-enolizable substituted alkyl, aryl, substituted aryl, --S-aryl, --S-(substituted aryl), --S-alkyl, --S-(substituted alkyl), alkoxy, substituted alkoxy, aryloxy, or substituted aryloxy; (D) said mixture of Grignard reagents comprises R 2 MgX in admixture with R 3 MgX; (E) R 2 is a suitable alkyl, substituted alkyl, alkenyl, alkynyl, aryl, substituted aryl, or aralkyl group capable of adding to the --C═N group of the hydrazone to produce the hydrazide; (F) R 3 is a suitable alkyl, substituted alkyl, aryl or substituted aryl group that is more sterically hindered than said R 2 group; (G) X is independently selected from Cl, Br or I for each Grignard reagent; (H) when said hydrazone is a compound of Formula 2.0 then the reaction is conducted at a temperature of about +30° to about -40° C.; and (I) when said hydrazone is a compound of Formula 2.1 then the reaction is conducted at a temperature of about +40° to about -20° C.
TL;DR: The Lewis acid mediated cyclization of β-oxygen substituted allylic stannanes 1,2, and 9, bearing a hydrazone group at the terminus of the carbon chain, afforded the corresponding trans-β-amino cyclic ethers 3a,4a and 10, respectively, with very high diastereoselectivities in high chemical yields as mentioned in this paper.
TL;DR: A magnesium complex with pyruvic acid isonicotinoyl hydrazone (H2L) has been synthesized and its crystal structure determined by X-ray diffraction analyses as mentioned in this paper.