Kinetics of oxidation of β-picoline to nicotinic acid over vanadia-titania catalyst. 4. Kinetic model

A kinetic model for the β-picoline oxidation over vanadia-titania catalyst is presented. The model covers the reaction mechanism, temperature dependences and a system of kinetic equations. The activation energies and constants in these equations are calculated.     

Excess heat of mixing of α-picoline withn-alkanes

The excess heats of mixing for binary mixtures -picoline +n-alkanes (C₆ to C₁₀) at 298.15 K were measured and a comparison was made with the Prigogine-Flory-Patterson theory and the extended real associated solution method.

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Zusammenfassung Die molaren Überschubenthalpien binärer Mischungen von -Picolin mit C₆C₁₀ n-Alkanen wurden bei 298.15 K im ganzen Zusammensetzungsbereich gemessen. Die gemessenen H^E Werte wurden mit denen verglichen, die mit Hilfe von Prigogine-Flory-Patterson Theorie und nach der ERAS-Methode berechnet wurden.

     

Synthesis based on β-phenylethylamines. IX. Synthesis of sulfides of β-phenylethylamines and of N-benzyltetrahydroisoquinolines

New bimolecular sulfur-containing -phenylethylamines and N-benzyltetrahydroisoquinolines have been synthesized from formyl derivatives of diaryl sulfides. The possibility of using metals as catalysts for obtaining diaryl sulfides in the reaction of ortho-substituted benzaldehydes with SCl₂ has been shown for the first time.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 731–735, September–October, 1995. Original article submitted November 11, 1994.     

Chelation-controlled cyclization of β-ketoester-substituted and β-ketoamide-substituted allylsilanes.

The first examples of Lewis acid-catalyzed chelation-controlled cyclization reactions are reported. Titanium tetrachloride-initiated cyclization of β-ketoester and β-ketoamide-substituted allylsilanes proceeds in isolated yields of 65–88%, providing a single diastereomeric product in each case.     

Aminoselenenylation of olefins. Syntheses of β-phenylseleno carbamates

(β-Phenylseleno carbamates have been synthesized by reaction of olefins with phenylselenenyl chloride and carbamates in presence of silver tetrafluoroborate. This reaction constitutes a good method for the conversion of olefins to β-functionalized protected amines.     

Addition of Organocuprates to Ketoketenimines. Synthesis of β-enaminoketones

Base-induced ring cleavage of 3-unsubstituted isoxazolium salts followed by reaction of the resulting ketoketenimine with organocuprates affords asymmetric β-enaminoketones in high yields.     

Vapor-phase oxidation of β-picoline to nicotinic acid on V2O5 and modified vanadium oxide catalysts

Modification of V₂O₅ with Ti, Sn, Zr, Nb, and Al oxides improves the activity and selectivity of the vanadium oxide catalyst in vapor-phase oxidation of β-picoline to give nicotinic acid. It is shown that the conversion of β-picoline and the yield of nicotinic acid on two-component V₂O₅-TiO₂, V₂O₅-SnO₂, V₂O₅-ZtrO₂, V₂O₅-Nb₂O₅, and V₂O₅-Al₂O₃ catalysts may be several times those on the V₂O₅ catalyst. It was found that, on passing from V₂O₅ to double-component vanadium-containing catalysts, the proton affinity of active oxygen bonded to vanadium, calculated by the quantum-chemical method, grows simultaneously with the increase in the activity of the catalysts in the oxidation reaction.     

Novel chemistry of β-carbolines. Expedient synthesis of polycyclic scaffolds

Functionalization of β-carbolines is a challenge as numerous natural alkaloids with different biological activities present this heterocycle. The RCM is used herein with allyl-, vinyl-, ethynyl-, and propargyl-β-carbolines to generate additionally fused hetero- and carbocycles, and it is combined with other cyclization processes to achieve great molecular complexity in one synthetic step. Thus, an RCM-Diels-Alder sequence gives pentacyclic compounds related with certain alkaloids. On the other hand, vinylpyrrolo[2,1-a]-β-carbolines and vinyl-β-carbolines give different products upon reaction with activated dienophiles. Thus, a novel domino processes affords complex polycycles like 35-38. Other alkynes like 3-butyn-2-one give a Stevens rearrangement.     

Modified Coumarins. 12. Synthesis of 3,4-Cycloannelated Coumarin β-D-Glucopyranosides

O--D-Glucopyranosides were synthesized using 3,4-cycloannelated hydroxycoumarins as aglycons. Phenolic hydroxyls were O-glycosylated via condensation of coumarin potassium salts with acetobromoglucose in homogeneous medium and in a liquid-liquid system using a phase-transfer catalyst.     

Alkaloids of Arundo donax. XIV. Crystal and Molecular Structure of N-Methyl-tetrahydro- β-carboline

An indole alkaloid of the N-methyl-tetrahydro--carboline series was isolated for the first time from Arundo donax, Poaceae. Its structure was solved by X-ray structure analysis.     

Study on molecular and electronic structures, and spectroscopic properties of azide ruthenium complexes with pyridine and β-picoline ligands

The [Ru(N₃)₂(PPh₃)(py)₃] and [Ru(N₃)₂(PPh₃)₂(β-pic)₂] complexes have been prepared and studied by IR, NMR, UV-Vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl₂(PPh₃)₃] with pyridine, β-picoline and NaN₃ in methanol solutions. The electronic structures of the obtained complexes have been calculated using the DFT/TD-DFT method. The trans effect of triphenylphosphine on the pyridine molecule has been studied using NBO and molecular orbital terms, and impact of the acceptor properties of the halide/pseudohalide co-ligands was indicated.     

Reaction of isocyanides. III - synthesis of β-alkoxy imidoyl cyanides from acetals.

Tert-butyl isocyanide reacts with acetals, in presence of diethylaluminium chloride, to afford α-iminonitriles.     

Soluble Bimetallic Oxoalkoxide Catalysts. IV. Ring-Opening Polymerization of β-Propiolactone

Abstract

The polymerization of β-propiolactone by aluminum-zinc oxoalkoxides corresponding to the structure has been studied. The overall kinetics of the reaction follow a first current order in monomer and a first order in catalyst. Mechanistic studies also indicate that these initiators operate through selective acyl-oxygen cleavage of the lactone ring with insertion in the aluminum-oxygen bond. Moreover, the polymerization proceeds by a perfectly “living” process.     

Acetals of lactams and amides of acids. 72. Investigation of reaction of cyclic β-nitroenamines with p-benzoquinone

The process of condensation of p-benzoquinone with the secondary cyclic enamines 2-(2-nitromethylene)pyrrolidine, -piperidine, and -hexahydroazepine is very much dependent on the size of the saturated ring in these compounds. With increasing ring size, the content of derivatives of 5-hydroxybenzofuran decreases, and the quantity of derivatives of 5-hydroxyindole increases; with the seven-membered enamine, a substituted 6-hydroxyindole is also formed. For enamines of the pyrrolidine and piperidine series, 1,4-bis-2-(2-nitromethylene)pyrrolidono- or piperidinohydroquinones are also recovered.For Communication 71, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 357–362, March, 1992.     

Use of alumina for elimination of sulfinic acid from β-aryl- and β-alkylsulfonyl carbonyl compounds.

Title compounds give α-unsaturated carbonyl compounds by treatment with basic alumina in dichloromethane or diethylether. α-Enones are thus obtained in high yield at room temperature.     

Assessing the activity concentration of β-emitters by means of the end-window g.m. tube

The activity concentrations of β-emitters including ³⁵S (0.15 MeV) and presumably also ¹⁴C (0.14 MeV) may be determined with satisfactory accuracy using an end-window G.M. counter. For single preparations (if weighed), the described procedure warrants that the standard error will not exceed 0.8%, if the amount of substrate is kept below 0.2 mg/cm², and if carrier-free solutions are avoided. With a minimum of 4 preparations per sample solution, the error of the mean should not exceed 0.4%,     

N-glycosides. 9. Reaction of 3,5-O-isopropylidenexylofuranosylamine with β-isothiocyanatoaldehydes. Synthesis of new cyclonucleosides with a hexahydropyrimidine aglycone

The reaction of 3,5-O-isopropylidenexylofuranosylamine p-toluenesulfonate with -isothiocyanatoaldehydes in the presence of triethylamine gives 4,2-anhydro-4-hydroxy-3-(3,5-O-isopropylidene--D-xylofuranosyl)hexahydropyrimidine-2-thiones. The structure of these compounds and their deblocking products was studied by IR, UV, PMR, and ORD spectroscopy and mass spectrometry.For Communication 8, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1252–1258, September, 1993.     

Structure-Activity Relationship of Insecticidal Steroids. IV. 3β-Chlorosubstituted Derivatives of Cholesterol and β-Sitosterol

The toxicity of 3-chlorosteroids 1-8 for colorado beetle (Leptinotarsa decemlineata Say.) larvae was studied by a contact-intestinal method. The most active insect growth and development regulators of the studied compounds are 3-chlorocholest-5-ene (1a), 3-chloro-5,6-diol 6-formate (3b), 3-chloro-7-hydroxy-6-ketone (4a), and 3-chloro-5-bromo-⁴-6-ketone (8).