Regioselective synthesis of some novel pyrazoles,isoxazoles, pyrazolo[3,4‐d]pyridazines and isoxazolo[3,4‐d]pyridazines pendant to benzimidazole

2‐Acetyl‐1‐methyl‐1H‐benzimidazole reacts with dimethylformamide‐dimethyl‐acetal (DMF‐DMA) to afford the corresponding E‐1‐(1‐methyl‐1H‐benzimidazol‐2‐yl)‐3‐N,N‐dimethylaminoprop‐2‐enone. The latter compound reacts regioselectively with some nitrilimines and nitrile oxides to afford the corresponding pyrazole and isoxazole derivatives, respectively. These reaction products react with hydrazine hydrate to give the novel pyrazolo[3,4‐d]pyridazine and isoxazolo[3,4‐d]pyridazine derivatives, respectively.     

New 1,3,4‐Oxadiazinoisoquinoline Methine Cyanine Dyes: Synthesis,Photosensitivity and Antibacterial Activity

New heterocyclic ring system including 1,3,4‐oxadiazino[6,5‐c]isoquinoline was prepared and employed as a precursor for preparation of monomethine and trimethine cyanine dyes. The structure of the new compounds was characterized via elemental analysis and mass, ¹H‐NMR, and ¹³C‐NMR spectroscopy. The photosensitivity (electronic transitions inside the dye molecule due to photon absorption) of the new methine cyanine dyes was investigated by studying their visible spectra in absolute ethanol and showed its maxima in the visible range of the spectrum with relatively strong absorption bands. The antibacterial activity of the newly synthesized compounds was evaluated against some bacterial strains, resulting in a promising antibacterial efficacy that recommend the tested compounds as new candidates for further pharmaceutical evaluations.     

Heuristics for the multi-depot petrol station replenishment problem with time windows

In the multi-depot petrol station replenishment problem with time windows (MPSRPTW), the delivery of petroleum products stored in a number of different petroleum depots to a set of petrol distribution stations has to be optimized. Each depot has its own fleet of heterogeneous and compartmented tank trucks. Stations specify their demand by indicating the minimum and maximum quantities to be delivered for each ordered product and require the delivery within a predetermined time window. Several inter-related decisions must be made simultaneously in order to solve the problem. For this problem, the set of feasible routes to deliver all the demands, the departure depot for each route, the quantities of each product to be delivered, the assignment of these routes to trucks, the time schedule for each trip, and the loading of the ordered products to different tanks of the trucks used need to be determined. In this paper, we propose a mathematical model that selects, among a set of feasible trips, the subset that allows the delivery of all the demands while maximizing the overall daily net revenue. If this model is provided with all possible feasible trips, it determines the optimal solution for the corresponding MPSRPTW. However, since the number of such trips is often huge, we developed a procedure to generate a restricted set of promising feasible trips. Using this restricted set, the model produces a good but not necessarily optimal solution. Thus the proposed solution process can be seen as a heuristic. We report the results of the extensive numerical tests carried out to assess the performance of the proposed heuristic. In addition, we show that, for the special case of only one depot, the proposed heuristic outperforms a previously published solution method.     

The Kinetics of Tenoxicam Photodegradation in Solution

Photodegradation of tenoxicam was investigated under different reaction conditions. After 60 min of exposure to UV light, the photodegradation was extensive, and the maximum and minimum in the UV-visible spectrum were shifted to shorter and longer wavelengths, respectively. Ethanol exerted a photostabilizing effect on tenoxicam. Tenoxicam is more stable in acidic and basic media than in neutral solution. Increasing light intensity or temperature causes an increase in the rate of photodegradation. The photodegradation of tenoxicam was found to follow first-order kinetics under all these conditions.     

Steroid sapogenins. XII

Summary An effective procedure is described for the resolution of steroid sapogenins as acetates on silver nitrate-impregnated alumina and silica gel plates. The resolutions are achieved by means of suitable solvent systems which are used either singly or in combination. A p-anisaldehyde reagent is employed for spraying. Clearly defined and well separated spots are obtained independent of the hydroxyl content. The method is rapid and appears adaptable to screening purposes.

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Zusammenfassung Zur Identifizierung von Steroidsapogeninen wird die Dünnschichtchromatographie der Acetate auf Silicagel- oder Aluminiumoxidschichten empfohlen, die mit Silbernitrat imprägniert sind. Zur Entwicklung wird eine Reihe von Lösungsmittelgemischen angegeben, die allein oder in Kombination angewendet werden. Der Nachweis erfolgt mit einem p-Anisaldehyd-Reagens. Unabhängig vom Hydroxylgehalt erhält man scharf begrenzte und gut getrennte Flecke. Die Methode erlaubt eine rasche Orientierung über die Zusammensetzung eines Gemisches.

     

Titanium dioxide plasma treatment

After a review of the literature on titanium production under plasma conditions, the main parameters controlling the reactions (residence time, type and relative quantity of reducer, reaction temperature, etc.) are emphasized. The controlled-atmosphere chamber where the rutile or anatase particles are heated and partly reduced in a crucible by a d.c. plasma torch with Ar-H₂ as plasma gas is described. Study of the temperature dependence of the Gibbs free energy allows one to explain, at least qualitatively, the experimental results obtained which correspond at best to 10% (weight) of TiO₂ reduced to TiO by carbon.     

Microdetermination of secondary aliphatic amines using a copper ion-selective electrode

A simple, accurate, and selective method is described for the microdetermination of aliphatic secondary amines. The method is based on their reaction with carbon disulfide and ammoniacal copper sulfate at 40 °C for 30 min to yield copper dialkyldithiocarbamate. The excess copper is then measured by titration with EDTA or NaDDC using a copper ion-selective electrode. A mean recovery of 98.2% with a standard deviation of 0.8% is obtained for aliphatic secondary amines and their salts having a wide range of pK_a.     

A suggested outline for a geometry syllabus in primary education

In this paper the author attempts to build up an outline for a geometry syllabus in primary education.     

The Behavior of 3,3-Diphenylindan-1,2-dione Towards Alkyl Phosphites

Summary. The reaction of 3,3-diphenylindan-1,2-dione with trimethyl phosphite in dry benzene at room temperature for about 15 h led to the formation of a mixture containing dimethyl (3,3-diphenyl-2-methoxy-1-indenyl)phosphate and dimethyl (3,3-diphenyl-1H-2-oxo-1-indanyl)phosphate, whereas with triisopropyl phosphite, diisopropyl (3,3-diphenyl-2-isopropoxy-1-indenyl)phosphate is the only product. Treatment of the dione with dialkyl phosphites under different experimental conditions gave dialkyl (3,3-diphenyl-1-hydroxy-2-oxo-1-indanyl)phosphates. Reaction mechanisms are presented which account for the experimental results. Structural assignments of the new compounds are based on the spectroscopic evidences and two examples were elucidated by X-ray crystallography.     

The mass spectra of some triterpenoid dehydration products

The mass spectra of ten dehydration and solvolysis products obtained from β-amyrin and glycyrrhetic acid were studied. With the exception of those resulting from ‘backbone’ rearrangement, they exhibited conventional fragmentation due to the ring C chromophore, like the parent alcohols. Only those products with a contracted ring A suffered loss of an isopropyl radical. In the latter type, special fragmentation features were exhibited by the isopropylcyclopentene and by the isopropylidene products. These differences enabled the assignment of probable structures for two unknown derivatives.