Nouria A. Al-Awadi

Efficient synthesis of 3-aroylcinnolines from aryl methyl ketones

Abstract An efficient synthesis of 3-aroylcinnolines starting from the appropriate aryl methyl ketones is described. The latter were converted in two steps to the corresponding 3-oxo-3-aryl-2-arylhydrazonopropanals, which upon acid catalyzed cyclization in conc. sulfuric acid or polyphosphoric acid (PPA) led to the corresponding 3-aroylcinnolines.

Chemistry of 2-arylhydrazonals: utility of substituted 2-arylhydrazono-3-oxoalkanals as precursors for 3-oxoalkanonitriles, 3-aminoisoxazole and 1,2,3- and 1,2,4-triazoles

Efficient routes to 2-arylhydrazono-3-oxoalkanonitriles, 1,2,3- and 1,2,4-triazoles, and 3-aminoisoxazole utilising the oximes of the title hydrazones are reported. The behaviour of the oximes on pyrolysis in the gas phase and by flash vacuum is analysed. X-ray crystallography were used to confirm the structure of the triazole 10b and the 3-oxoalkanonitrile 12f.

Kinetics and mechanism of thermal gas-phase elimination of ?-substituted carboxylic acids: role of relative basicity of ?-substituents and acidity of incipient proton

2-Phenoxypropanoic acid together with five of its aryl derivatives, its phenylthio and its N-phenylamino analogues were pyrolyzed at 494–566 K. The reactions were homogeneous, polar and free from catalytic and radical pathways, and obeyed a first-order rate equation. The limits of the Arrhenius log A (s−1) and E (kJ mol−1) values obtained for these reactions averaged 11.98 ± 1.71 and 158.1 ± 17.4, respectively. Analysis of the pyrolysates showed the elimination products to be carbon monoxide, acetaldehyde and the corresponding phenol, thiophenol or aniline compounds. The pyrolysis of 2-phenoxy- and 2-(N-phenylamino)-1-propanol was also investigated over the temperature range 638–792 K. The kinetic results and products analysis lend support to a reaction pathway involving a five-membered cyclic polar transition state. Copyright

Kinetics and mechanism of pyrolysis of sulphonyl hydrazones and oximes. Part 2—Structural effects and molecular reactivity

The kinetics and products of the pyrolytic reaction of six tosyl arenecarboxaldoximes were studied over the temperature range ca 334 – 401 K to yield the following Arrhenius log A/s−1 and Ea / kJ mol−1, respectively: 10.92 and 98.25 for tosyl benzaldoxime and 10.83 and 100.4 for m-nitro-, 10.66 and 97.53 for p-chloro-, 11.80 and 107.8 for m-chloro-, 11.60 and 101.5 for p-methyl- and 10.84 and 97.75 for p-methoxybenzaldehyde O-[(4-methylphenyl)sulphonyl]oxime. At 500 K, the oxime compounds were found to be 9.4 × 103 – 2.7 × 104-fold more reactive than their hydrazone analogues. Copyright

A Facile Synthesis of New Monoazo Disperse Dyes Derived from 4-Hydroxyphenylazopyrazole-5-amines: Evaluation of Microwave Assisted Dyeing Behavior

A series of new monoazo disperse dyes containing pyrazolopyrimidine moieties was synthesized by coupling malononitrile or 3-aminocrotononitrile with 4-hydroxy- benzenediazonium chloride. Treatment of the resulting products with hydrazine hydrate yields the corresponding 4-arylazoaminopyrazoles, which then react with either 2,4-pentanedione and enaminonitriles or aryl-substituted enaminoketones to give the target pyrazolopyrimidine monoazo disperse dyes. Structural assignments of the dyes were made using both NMR spectroscopic and X-ray crystallographic methods. A high temperature dyeing method, by microwave irradiation, was employed with polyester fabrics. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing and perspiration fastness levels.

Synthesis of Some Novel Pyrazolo[1,5-a]pyrimidine Derivatives and Their Application as Disperse Dyes

A series of novel monoazo-disperse dyes containing pyrazolo[1,5-a]pyrimidine structures were synthesized starting with the coupling reaction between ethyl cyanoacetate and 4-hydroxybenzenediazonium chloride, followed by treatment of the resulting hydrazone product with hydrazine hydrate. The pyrazolohydrazone 6 is then treated with either 2,4-pentandione and enaminonitrile or aryl-substituted enaminoketones to give the target pyrazolo[1,5-a]pyrimidine dyes 7 and 15a-d. Structural assignments to the dyes were made using NMR spectroscopic methods. A new high temperature method, using microwave heating, was employed to apply these dyes to polyester fibers. Most of the dyed fabrics tested displayed moderate light fastness and excellent washing fastness properties.

Chapter 1 Recent Developments in Pyridazine and Condensed Pyridazine Synthesis

Publisher Summary This chapter discusses recent developments in pyridazine and condensed pyridazine synthesis. Today, the pyridazine nucleus and its 3-oxo derivatives have been recognized as versatile pharmacophores. This key subunit is constituted in many biologically active substances with a broad range of biological and pharmaceutical activities including inhibitors of PED III, IV, a 1 - and a 2 - adrenoceptors, antibacterial and antifungal activities, 5-lipoxygenase inhibitors and inhibitors of interleukin, b-production. This chapter surveys recent reported synthetic approaches to pyridazines and highlights new methodologies. It discusses synthesis of pyridazine by two bond formation (via 3+3 atom and 4+2 atom), by combining alkylpyridazinylcarbonitrile with a,b-unsaturated nitriles, and by coupling aromatic diazonium salts with carbon nucleophilic 4 atom fragments. It also discusses the synthesis of condensed pyridazine via one bond formation (5+1 combination) and by utilizing functionally substituted arylhydrazones precursors via one bond formation.

Gas-phase pyrolytic reactions of N-ethyl, N-isopropyl, and N-t-butyl substituted 2-aminopyrazine and 2-aminopyrimidine

The rates of gas-phase elimination of N-ethyl (1), N-isopropyl (2), N-t-butyl (3) substituted 2-aminopyrazine and N-ethyl (4), N-isopropyl (5), and N-t-butyl (6) substituted 2-aminopyrimidine have been measured. The compounds undergo unimolecular first-order pyrolytic reactions. The relative rates of the primary:secondary;tertiary alkyl homologues at 600 K are 1:14.4:38.0 for the pyrazines and 1:20.8:162.5 for the pyrimidines, respectively. The reactivities of these compounds have been compared with those of the alkoxy analogues and with each other. Product analyses, together with the kinetic data, were used to outline a feasible pathway for the elimination reaction of the compounds under study.

Heavy metal effects on physicochemical properties of non-aggregated azaphthalocyanine derivatives

Two series of peripherally substituted azaphthalocyanines (AzaPcs) containing different transition metals (Al(III), Zn(II), Ga(III), In(III) and Fe(II)) were synthesized and studied for their photophysical properties. As confirmed by UV-vis and 1H NMR analyses, the non-aggregation behavior was effectively induced by the applied bulky peripheral substituents which had no effect on the photophysical properties. Tuning the Q-band position was clearly achievable by using different central heavy metals which have considerable effects on the fluorescence quantum yield and singlet oxygen generation efficiency. This comparative study showed an interesting linear relationship between the former and atomic number of the central metal. The indium containing complexes exhibited the best result due to the heavy metal effect and therefore could be promoted as a potential photosensitizer in photodynamic therapy (PDT) application.

Pyrolysis of aminonitriles, cyanohydrazones, and cyanoacetamides. Part I. Elimination reaction of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles and substituted benzaldehyde cyanoacetylhydrazones

Pyrolysis of the Schiff bases of 1-arylmethyleneamino-1,2-dihydro-4,6-dimethyl-2-oxopyridine-3-carbonitriles (1–5) has been studied. These compounds eliminate via a six-membered transition state to produce substituted benzonitriles and 2-hydroxy-4,6-dimethylpyridine-3-carbonitrile. These eliminations are unimolecular first-order reactions. The kinetic data gave a good correlation with σ0 values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open-chain substituted benzaldehyde cyanoacetylhydrazones (6–9) analogues.