Steel-promoted oxidation of olefins in supercritical carbon dioxide using dioxygen in the presence of aldehydes

Oxidation of olefins occurs effectively in supercritical carbon dioxide as the reaction medium with dioxygen as the primary oxidant and aldehydes as sacrificial co-oxidants. No catalyst is required, but the reaction is promoted by the stainless steel of the reactor walls. Depending on the substrate, vinylic oxidation or epoxidation can be the prevailing pathway. Epoxidation is particularly effective for substrates with internal double bonds and for long-chain terminal olefins.     

Transformations of organic compounds in supercritical fluid solvents: From experiments to kinetics,thermodynamics, simulation,and practical applications

The results of fundamental studies performed by the author on the reactivity of supercritical fluid solvents are systematized and generalized; practical applications of these solvents are considered. Methods for performing kinetic and physicochemical experiments, processing the data, constructing kinetic models, and calculating the thermodynamics of nonideal supercritical fluids (the parameters of critical points, binodal and spinodal lines, and critical point drifts; the thermophysical properties of reaction mixtures under supercritical conditions; etc.) are described. Attention is focused on the effect of supercritical fluid pressure on the rate constants of chemical reactions. The kinetics and mechanisms of the reactions of 2-propanol dehydration and decomposition of aliphatic nitro compounds in supercritical water and the isomerization of terpene compounds (α-pinene, β-pinene, and turpentine) in supercritical lower alcohols are studied. The formation of nanoparticles in supercritical fluid solvents and the treatment of ultradisperse diamonds in supercritical water are considered. The results formed the basis for the simulation and calculation of acetic acid and phenol oxidation processes in supercritical water and the Fischer-Tropsch synthesis in a supercritical solvent and for the development of a pilot plant for the complete oxidation of trinitroglycerol and diethylene glycol dinitrate in supercritical water.     

Transformations of chloroethylenes in the presence of aprotonic acids

The cationic polymerization of vinyl chloride, vinylidene chloride, and cis- and trans- 1,2-dichloroethylenes with the use of Lewis acid-type catalysts has been studied. Vinylidene chloride is smoothly polymerized in the presence of ZnCl₂ at 40°C to form the dimer, 1,1,3,3-tetrachlorobutene-1, and poly(vinylidene chloride) having somewhat increased crystallinity (45%). Vinyl chloride is polymerized very slowly in the presence of AlCl₃ and TiCl₄ to give dimeric, trimeric, tetrameric, and low molecular weight polymer products. The polymerization is followed by carbonium ion isomerization that leads to reaction products of branched structure. The cis- and trans-1,2-dichloroethylenes react in the presence of AlCl₃ only at 50–60°C, and their polymerization is terminated at the stage of dimer and cyclic trimer formation. A mechanism of carbonium ion-initiated polymerization of chloroethylenes is proposed, and the causes which lead to early termination of polymerization are discussed.     

金属卟啉存在下芳醛氧化反应的研究

本文研究了在金属四苯基卟啉[Co(II)TPP,Fe(III)TPPCl,Mn(III)TPPCl,Zn(II)TPP,Cu(II)TP.TPP=四苯基卟啉]存在下,用氧气氧化芳醛的过程.测定了反应体系的吸氧动力学曲线;观察了氧化过程中金属卟啉的可见光谱的变化;研究了底物,金属卟啉在反应体系中的浓度以及溶剂等因素对反应的影响.结果发现,除能可逆键合分子氧的Co(II)TPP外,不具此种功能的Fe(III)TPPCl和Mn(III)TPPCl也能加速芳醛的氧化反应.然而,它们的催化作用是在金属四苯基卟啉与反应过程中积累起来的过酸作用,卟啉环遭到破坏后观察到的,此时可能形成了某种新的催化活性中心.金属卟啉本身对反应起抑制作用,它只是表观上的催化剂,其催化作用看来不应归结为对分子氧的活化.     

Some thermophysical properties of several solid aldehydes

The present study reports a differential scanning calorimetry (DSC) study of the solid aldehydes: 4-hydroxybenzaldehyde [123-08-0] 1; 4-hydroxy-3-methoxybenzaldehyde (vanillin) [121-33-5] 2; 3-ethoxy-4-hydroxybenzaldehyde (ethyl vanillin) [121-32-4] 3; 3,4-dimethoxybenzaldehyde (veratraldehyde) [120-14-9] 4 and 4-methoxycinnamaldehyde [1963-36-6] 5, in the temperature interval from T=268 K to their respective melting temperatures. Temperatures, enthalpies and entropies of fusion and the heat capacities of the compounds as a function of temperature are reported.     

Transformations of 2-methylthiacyclobutane in the presence of aluminum oxide

The transformations of 2-methylthiacyclobutane at 150–350 °C in the presence of -Al₂O₃ samples with different aprotic acidities were investigated. It was established that the sulfide undergoes isomerization via two pathways, viz., with ring expansion to a five-membered ring and with opening at one C—S bond to give an unsaturated thiol. An experimental confirmation of the consecutive formation of hydrogen sulfide from a one-ring sulfide through a step involving the formation of an unsaturated thiol was obtained for the first time. The transformations are realized as a result of both ionic and polymerization-depolymerization processes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–187, February, 1982.     

Transformations of n- butylpyridines in the presence of alumina-chromia catalysts

Summary Together with a partial cracking of the butyl group, 2-n-butylpyridine under the conditions of contact with alumina-chromia catalyst at 500–600 underwent dehydrocyclization at the nitrogen atom with the formation of indolizine, and at the carbon atom with the formation of quinoline. Indolizine and quinoline were also identified in the transformation products of 3-n-butylpyridine.Translated from Izvestiya Akademii Nauk SSSR, Khimicheskaya, No. 12, pp. 2216–2218, December, 1965     

Thermal properties of tetraalkylammonium bromides in several solvents

The enthalpies of solution of tetraethyl- and tetra-n-hexylammonium bromides have been measured in mixtures of formamide with ethylene glycol at 298.15 and 313.15 K in the whole mole fraction range by the calorimetric method. The standard enthalpies of solution in binary mixtures have been calculated with Redlich–Rosenfeld–Meyer type equation. The enthalpy and heat capacity parameters of pair interaction of organic electrolytes with EG in FA and with FA in EG have been computed and discussed. The enthalpy interaction parameters of single ions with EG in FA medium have been evaluated and compared with those for ion–water and ion–MeOH interaction in FA. The standard heat capacities of solution have been evaluated. The excess enthalpies of solution, Δ_sol H ^E, of Et₄NBr, Bu₄NBr, and Hex₄NBr have been determined. The Δ_sol H ^E values are positive for Et₄NBr and negative for Bu₄NBr and Hex₄NBr and become more negative from Bu₄NBr to Hex₄NBr.     

IOn-exchange behaviour of several elements in mixed solvents

The distribution coefficients between the cation- and anion-exchangers Dowex 50 and Dowex 1, and aqueous solutions containing nitric or hydrochloric acid and organic solvents with or without amines or complexing agents, have been obtained for a number of metals including uranium, thorium, cerium, iron, copper, and nickel. The organic solvents were methanol, acetone and dimethylformamide; the amines were tributylamine and tribenzylamine, and the complexing agents EDTA and citric acid. Both batch and column methods were used.     

Behaviour of aminoacids and aliphatic aldehydes in dipolar aprotic solvents: Formation of oxazolidinones—behaviour of aminoacids and aliphatic aldehydes in dipolar aprotic solvents

Reactions of aliphatic branched aldehydes with proline in dimethyl sulfoxide or acetonitrile solution afford oxazolidin-5-ones with high diastereoselection. Linear aldehydes afford aldolic/crotonic condensation products; with short reaction times, the presence of Oxazolidinones can be detected in the pmr spectra. Acyclic aminoacids and branched aldehydes yield a reaction mixture the pmr and ir spectra of which give evidence for iminic-oxazolidinone equilibria. The structure of (2R,5S)-2-trichloromethyl-1-aza-3-oxabiciclo-[3.3.0]octan-4-one has been confirmed by X-ray diffraction analysis.     

Reactions of unsaturated aldehydes with cyclopentadiene in solvents of various polarities

The rate constants of cycloaddition of cyclopentadiene to unsaturated aldehydes in different solvents cannot be correlated with a single parameter, in particular, the Brownstein parameter. The data set can be fitted only by multiparameter equations in which the decisive factor increasing the reaction rate is the capability of a solvent for electrophilic solvation. The same parameter also governs the ratio of the endo and exo isomers of the addition product.     

Transformations of mercury species in the presence of Elbe river bacteria

The influence of Elbe river bacteria isolated from suspended particulate matter (SPM) on dynamic species transformation of mercury was investigated. Experiments were carried out in the presence of bacteria (batch cultures) and in sterile tapwater as a control. For the methylation of inorganic mercury ions by bacteria several cofactors are under discussion. In this work, methylcobalamin, methyl iodide and S-adenosylmethionine were tested as biogenic methyl donors and trimethyl-lead chloride, trimethyltin chloride and dimethylarsenic acid as abiotic methyl donors. Transmethylation reactions as examples of abiotic methyl transfers have higher effectiveness in the formation of methylmercury (CH₃Hg⁺) than methylation with biogenic compounds. This result was observed in batch cultures as well as in sterile water. SPM-bacteria inhibit methyl transfer to mercury(II) ions. This is not only due to passive adsorption processes of mercury(II) to bacterial cell walls; methylmercury is also decomposed very rapidly by SPM-bacteria and is immobilized as mercury(II) by the cells.     

Transformations of isobutylene in the presence of various types of zeolites

Conclusions In contrast to zeolites with ultrahigh silica content, type A, X, Y, and M zeolites in the Na form and also those modified by decationization, cation exchange, and addition of-Al₂O₃, Al₂O₃-SiO₂, Pt, and Rh show a low activity in the aromatization reaction of C₃-C₄ olefins at 450–550°C at times of contact of 2–14.4 sec. The zeolites studied become rapidly deactivated as the result of intense coke formation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1300–1304, June, 1981.     

Transformations of eucarvone and eucarvole oxides in the presence of acids

Conclusions The eucarvone and eucarvole oxides are opened by acids at the C³-O bond with a retention of the carbon structure. The stereospecific trans-1,2-opening of the epoxide ring is observed in the first case; the cis-1,2-opening and 1,4-addition also occurs in the second case.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 672–674, March, 1984.