Synthesis of dimethyl Β-oxoadipate

Acetoacetic ester and Meldrum's acid provide a new and simple synthesis of dimethyl -oxoadipate. This compound is a synthone for some natural and biologically active compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1227–1229, May, 1991.     

Crystallization,melting and spherulitic structure of Β-nucleated random propylene copolymers

The characteristics of crystallization, melting and spherulitic growth of a random propylene copolymer (PRC) containing small amount of ethylene were studied in the presence of a selective -nucleating agent (calcium pimelate). It was established that the products of isothermal and non-isothermal crystallization are very rich in -modification but have mixed polymorphic composition. The formation of -modification may be attributed to -transition on the surface of growing -spherulites resulting in -twin-spherulites. During melting of PRC of -modification, the characteristics observed with -nucleated propylene homopolymers, namely, a -recrystallization of recooled samples and separated melting of non-recooled samples (i.e. the melting memory effect), as well as a -recrystallization leading to a perfection of the structure within the -modification, are also demonstrated. The disturbance of regularity of the polymer chain highly reduces the tendency to -crystallization. In contrast to the observations with propylene homopolymers, the growth rate of -modification (G ) is higher than that of -modification (G ) and no critical crossover temperature can be found (T()=413 K) below whichG >G . The experimental results show that a partial disturbance of chain regularity by incorporation of comonomer units considerably reduces the tendency to -crystallization.This research was supported by the National Scientific Research Fund (OTKA), the author is grateful for it. Thanks are due to Professor Géza Bodor for his help in X-ray diffractometric investigations and to Ms. Tünde Lócska for her prudential technical assistance in the optical experiments.     

Ethylene dinitrodiamine in the addition reaction to α, Β-unsaturated ketones

Summary The addition of ethylene dinitrodiamine to , -unsaturated ketones was investigated and it was established that the former is readily added to unsaturated ketones with formation of new N-nitroketones.     

Hydrolysis of fluoroalkyl-containing Β-aminovinyl ketones

The kinetics of hydrolysis of fluoroalkyl-containing -aminovinyl ketones R¹C(O)CHC(NHR³)R², in which the substituents CF₃ and HCF₂CF₂ are in the ketone (R¹) or enamine parts of the molecule (R²), was studied. In acid (pH < 5) and alkaline (pH > 10) media, they hydrolyze with the formation of the corresponding amines and -diketones. In an alkaline medium, the -diketones undergo cleavage to fluorinated acids and methyl ketones. The rate constants of hydrolysis in an acid medium change within a range of four orders, depending on the nature of the substituents. The presence of a fluoroalkyl group at the enamine reaction center increases the hydrolysis rate. In an alkaline medium, the rate constants vary within one order.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 664–669, March, 1991.     

Binding energies of metal monocations to Β-lactones and Β-lactams. A theoretical study of cyclization effects

Ab initio calculations have been performed to study the association of-propiolactam and-propiolactone and their aliphatic analoguesN-methyl acetamide and methyl acetate with different metal monocations: Li⁺, Na⁺, Mg⁺, and Al⁺, in an effort to investigate cyclization effects on the gas-phase basicities of amides and esters, when the reference acid is not a proton. Similarly to what was found for protonation,N-methyl acetamide and-propiolactam are more basic than methyl acetate and-propiolactone, when the reference acids are the aforementioned metal monocations. However, cyclization effects on the corresponding binding energies for both kind of compounds do not parallel those observed for protonation energies, and-lactone is as basic as methyl acetate when the reference acid is Li⁺ and slightly more basic than methyl acetate when the attaching ion is Na⁺. This implies that when the interactions of the bases with the reference acids are essentially electrostatic the reactivity patterns change with respect to those observed when the interactions are essentially covalent.     

Effects of medium and chemical modification on thermal characteristics of Β-lactoglobulin

The thermal properties of -lactoglobulin (-LG) were studied by differential scanning calorimetry (DSC) under different medium conditions.pH, neutral salts, protein perturbants, and polyols all affected the DSC characteristics of -LG. Acylation with fatty acids also changed the thermal properties, particularly peak width at half-height. The results suggest that the structural stability of -LG is controlled by non-covalent forces, particularly electrostatic and hydrophobic interactions. Disulfide bonds did not contribute to the thermal response of -LG. Fatty N-acyl-amino acids caused marked increases in thermal stability and decreases in denaturation enthalpy, and additional peaks were observed in the presence of some palmitoyl derivatives.Contribution No. 2310, Centre for Food and Animal Research.We thank D. Raymond for her excellent technical assistance.     

Interpenetrating inclusion lattices: Comparison of the Β-hydroquinone and ellipsoidal clathrate structures

Crystallization of 2,7-dimethyltricyclo[43.1.1^3,8]undecane-syn-2,syn-7-diol 2 from acetonitrile or dichloro-methane yields the compounds (2)₄-(guest) in space group 14₁/acd which are further examples of the ellipsoidal clathrate structure. Both enantiomers of 2 are linked through (O-H)₄ cycles of hydrogen bonds to form a three-dimensional sublattice. Two inversion related sublattices interpenetrate thereby generating a superlattice with guest-occupied voids situated between the two individual sublattices. The two X-ray structures are compared and contrasted with that of Powell’s (hydroquinone)₃ (SO₂) clathrate compound. Translated fromZhurnal Strukturnoi Khimii, Vol. 40, No. 5, pp. 822–831, September–October, 1999.     

Reaction of Β-oxonitrones — Imidazoline and pyrroline derivatives — With nucleophilic reagents

The reaction of -oxonitrones — imidazoline derivatives — with hydroxylamine, phenylhydrazine, and semicarbazide takes place at the carbonyl group with retention of the nitrone group. Stable nitroxyl radicals — spiroimidazoisoxazole derivatives — are formed in the oxidation of -hydroximinonitrones. The recyclization of the -oxonitrones, which takes place in an acidic medium, as well as by the action of hydrazine and thiosemicarbazide, leads, respectively, to pyrroline and pyrazole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 912–919, July, 1991.     

Synthesis of 2-functionally substituted oxazolines and oxazolidines from methyl bromopropiolate and Β-amino alcohols

The reaction of methyl bromopropiolate with -amino alcohols containing a primary amino group generally results in the formation of 2-(methoxycarbonylmethyl)-²-1,3-oxazolines, while in the reaction with N-methyl- and N,N-dimethyl-substituted -aminoalcohols, 2-(methoxycarbonylmethylene)-1,3-oxazolidines, or their salts are formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 406–409, March, 1991.     

Meldrum's acid — A reagent for the synthesis of unsaturated γ-lactones and Β-acylacrylic acids

The thermal cyclization of 2,2-dimethyl-5-(2-aryl-2-oxoethyl)-1,3-dioxan-4,6-diones forms 5-aryl-, butenolides. Regioselective chlorination of 2, 2-dimethyl-5-[2-aryl(alkyl)-2-oxoethyl]-1,3-dioxane-4,6-diones by SO₂Cl₂ gives the 5-chloro derivatives; these are cleaved by aqueous AcOH to the E--acylacrylic acids, which are synthones for unsaturated -lactones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp.1212–1214, May, 1991.     

Synthesis of substituted 2-phenyl-4-piperidinones from styryl Β-dimethylaminoethyl ketones and their steric structure

The difficultly obtainable substituted 2-phenyl-4-piperidinones were synthesized by the reaction of styryl -dimethylaminoethyl ketone hydrochlorides with aqueous solutions of ammonia or alkylamines. It was found using ¹H and ¹³C NMR spectroscopy methods that the cyclization process proceeds with the formation of pure stereoisomers of 4-piperidones with an equatorial disposition of all the substituents in the ring. The temperature for performing the cyclization is dependent on the number and position of the methyl substituents in the molecule of the starting substituted styryl -dimethylaminoethyl ketones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 224–227, February, 1991.     

用于毛细管电泳手性分离的一种新的手性选择剂－ Β环糊精聚合物

用新合成的Β 环糊精聚合物(EP-Β-CD),并以天然环糊精(Β-CD) 和羧甲基环糊精(CM-Β-CD)手性拆分剂作对比,选取扑尔敏、山梗菜碱、维拉帕米为测试物􀁯优化分离条件􀁯研究了EP-Β-CD的拆分能力􀁯并与其它两种拆分剂进行了比较。     

σ-Complexes of transition metals in organic synthesis. 9. Reactions of allyl organomanganese compounds with γ-bromine derivatives of esters of α, Β-unsaturated carboxylic acids

The allyl Mn(II) organic compounds R¹CH=C(R²)CH₂MnCl (R¹=H, Me; R²=H, Me, Bu), obtained in situ from Grignard reagents and Li₂MnCl₄, react with esters of 4-bromocrotonic, (2-bromobutylidene)-, (4-bromo-2-butenylidene)-, (2-bromoisobutylidene) malonic, and (2-bromoheptylidene)cyanoacetic acids in THF at –78 to +20C to give derivatives of substituted cyclopropanecarboxylic or cyclopropane-1, 1-dicarboxylic acids. These derivatives contain a fragment of the allyl type. When ethers of 2-(bromomethyl)acrylic, 4-bromo-2-methyl-, and 4-bromo-3-methyl-2-butenoic acids are used, cross-combination products result.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 656–663, March, 1991.     

NMR spectra of cyclic nitrones. 6. Tautomeric equilibrium of Β-oxo-nitrones — 3-Imidazoline 3-oxide derivatives

It is demonstrated by ¹³C NMR spectroscopy that -oxo nitrones (3-imidazoline-3-oxide derivatives) exist in the form of an equilibrium mixture of three tautomeric forms with preponderance of the enolo nitrone and enehydroxylamino ketone forms.For communication 5, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 192–195, February, 1991.     

Chemiluminescence activated by Β- diketonate complexes of Eu3+ in the thermolysis of diphenyldiazomethane in the presence of oxygen

Chemiluminescence activated by the chelates Eu(tta)₃phen and Eu(dbm)₃phen in the thermal decomposition of diphenyldiazomethane in benzene in the presence of oxygen was examined at 333 K. The following photophysical characteristics of the luminescence emitter, excited triplet benzophenone (BP), were found: the phosphorescence quantum yield ϕ _BP ⁰ = 1.0 × 10⁻⁵, the true lifetime τ _BP ⁰ = 7 × 10⁻⁸ s, and the rate constant of radiative deactivationk _{r, BP} = ϕ _BP ⁰ τ _BP ^{0 −1} = 160 s⁻¹.     

Investigation of thermal properties of ruthenium(III) Β-diketonate precursors for preparation of RuO2 films by CVD

By means of a tensimetric flow method and a static method with a silica-membrane zero gauge, the dependence of vapour pressure on temperature was obtained for tris(2,4-pentanedionato)ruthenium(III), Ru(aa)₃, and tris(1,1,1-trifluoropentane-2,4-dionato)ruthenium(III), Ru(tfa)₃. The thermodynamic characteristics of vaporization and sublimation of these complexes were determined. The processes of thermal decomposition of the vapour of the compounds in vacuum, hydrogen and oxygen were investigated by using mass spectrometry in the temperature range 170–550C for Ru(aa)₃ and 150–620C for Ru(tfa)₃. The threshold temperatures of the stability of the vapour of the complexes and the rate constants of the thermolysis processes were determined. The main gaseous products of the thermal decomposition and the dependences of their composition on the presence of hydrogen and oxygen were established.