Viscometric and volumetric properties of benzene + methyl acetate,or + methyl propanoate,or + methyl butanoate binary systems at 283.15, 298.15 and 313.15 K

Viscosities and densities of three binary liquid mixtures, benzene?+?methyl acetate, benzene?+?methyl propanoate and benzene?+?methyl butanoate, have been measured at 283.15, 298.15 and 313.15?K, and atmospheric pressure. From experimental data, viscosity deviation, excess energy of activation for viscous flow, and excess molar volume were calculated and satisfactorily correlated with Redlich and Kister equation. Empirical and semiempirical equations and the predicted group-contribution method, universal automatic computer, were applied.     

Synthesis of alkyl-α,α-dimethylcyclopropanemethanols and alkylcyclopropyl methyl ketones

Russian Chemical Bulletin -     

Synthesis of methyl α-nitrocrotonate

Summary Methyl -nitrocrotonate has been synthesized by the condensation of methyl nitroacetate with acetaldehyde, acetylation of the methyl -nitro--hydroxybutyrate, and subsequent deacetylation of the resulting product.     

Conversion of methyl ketones and methyl sulfones into α-deutero-α,α-difluoromethyl ketones and α-deutero-α,α-difluoromethyl sulfones in three synthetic steps

Deuterodifluoromethyl ketones and sulfones were assembled in three synthetic steps from methyl ketones and sulfones, respectively. The key synthetic transformation is the deuteration of the difluorocarbanion generated by the release of trifluoroacetate from highly α-fluorinated gem-diols. High levels of deuterium on the “CF₂D” group were routinely observed. This strategy is mild and versatile and it can be applied to both ketones and sulfones without additional concerns of over- or under-fluorination. Additional examples address issues of over-deuteration when compounds with other acidic protons are subjected to the reaction conditions. This process not only demonstrates a new method to install a “CF₂D” group but also extends the scope of trifluoroacetate release to sulfones.     

Liquid–liquid equilibria for mixtures containing water,methanol, fatty acid methyl esters,and glycerol

The liquid–liquid equilibrium (LLE) data, including tie-lines and phase boundaries, were measured for the ternary systems of water + methanol + methyl oleate, water + methanol + methyl linoleate, glycerol + methanol + methyl oleate, and glycerol + methanol + methyl linoleate at temperatures from 298.2 K to 318.2 K under atmospheric pressure. All the LLE data follow the Othmer-Tobias equation. Each ternary system behaves type-I LLE. The areas of two-liquid coexistence region decrease with increasing temperature. The experimental data were applied to test the validity of the UNIFAC model and its modified versions, including UNIFAC-LLE and UNIFAC-Dortmund. The LLE data were also correlated with the NRTL and the UNIQUAC models. The UNIQUAC model yielded better results.     

Phase equilibria of binary mixtures containing methyl acetate,water, methanol or ethanol at 101.3 kPa

Isobaric vapor–liquid equilibria data at 101.3?kPa were reported for the binary mixtures (methyl acetate?+?(water or methanol or ethanol), methanol?+?(water or ethanol) and (ethanol?+?water)). The experimental data were tested for thermodynamic consistency by means of the Wisniak method and were demonstrated to be consistent. The experimental data were correlated using Wilson, NRTL and UNIQUAC models for the activity coefficients and predicted using the UNIFAC and PSRK equation of state for testing theirs capability. The results show that the obtained data for the studied binary systems are more reliable than other published data.     

Efficient Swern oxidation and Corey–Kim oxidation with ion-supported methyl sulfoxides and methyl sulfides

The Swern oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), and oxalyl chloride in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, gave the corresponding aldehydes and ketones, respectively, in good yields with high purity. Similarly, the Corey–Kim oxidation of various benzylic and allylic alcohols, primary alcohols, and secondary alcohols with two ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀), and N-chlorosuccinimide in the presence of triethylamine in dichloromethane, followed by simple diethyl ether extraction of the reaction mixture, furnished the corresponding aldehydes and ketones, respectively, in good yields with high purity. Both reactions did not produce any unpleasant odor at all. In the Swern oxidation, ion-supported methyl sulfides were recovered in high yields and could be re-oxidized to produce ion-supported methyl sulfoxides A-1 (C₆) and B-1 (C₁₀), for reuse in the same oxidation. In the Corey–Kim oxidation, ion-supported methyl sulfides A-2 (C₆) and B-2 (C₁₀) were recovered in high yields and could be also reused for the same oxidation.     

Facile access to methyl tantalum derivatives by unprecedented phosphorus—methyl bond cleavage of dimethylphenylphosphane

Reactions of the paramagnetic pentacoordinated TaBr₃(PhPMe₂)₂ adduct with strong bases, (RLi (R = Me, Bu) or 1,8-bis(dimethylamino)naphthalene) have been found to give methyltantalum(IV) derivatives as a result of PMe bond cleavage.     

KNaY-zeolite catalyzed dehydration of methyl lactate

A promising catalyst,KNaY was prepared by an ion exchange method with aqueous potassium chloride solution.Comparedwith NaY,KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate.Under the optimized conditions,an improved yield of 37.9 mol%was achieved.     

Conformational, steric and electronic effects on the site- and chemoselectivity of the metal-catalyzed reaction of N-bis(trimethylsilyl)methyl, N-(2-indolyl)methyl α-diazoamides

The Rh(II)- and Cu(II)-catalyzed reactions of N-bis(trimethylsilyl)methyl, N-(2-indolyl)methyl α-diazoamides are investigated to delineate how conformational, steric and electronic factors influence the site- and chemoselectivity of the metallocarbenoid reaction. The N-bis(trimethylsilyl)methyl (N-BTMSM) group is found to be essential in promoting the metallocarbenoid reaction at the N-(2-indolyl)methyl moiety as well as providing subtle but effective conformational influence about the amide N-C(α) sigma bond in diazoamides carrying an N-C(α) alkoxymethyl side-chain, to afford excellent site- and chemoselectivity. In general, the metal-catalyzed reactions are found to favor metallocarbenoid addition to the indole C(2)-C(3) double bond over C-H insertion to give cyclopropanated products (tetracyclic γ-lactams); however, chemoselectivity is also affected by steric effects, as revealed in the N-[2-(3-methylindolyl)]methyl diazoamides, and to some extent by the nature of the catalyst employed, as seen in the N-C(α)-alkoxymethyl diazoamides. The tetracyclic γ-lactams are found to rearrange to give good to high yields of the tricyclic indole derivatives under the metallocarbenoid reaction conditions or under acidic conditions. The propensity of the tetracyclic γ-lactams to undergo rearrangement is found to be dependent on the nature of the α-substituent on the original diazo carbon and the indole N-substituent.     

Fabrication, characterization, and supercooling suppression of nanoencapsulated n-octadecane with methyl methacrylate–octadecyl methacrylate copolymer shell

Supercooling of micro- and nanoencapsulated phase change material is widely observed as their diameters depress to a limitation upon cooling. The aim of this study is to suppress the supercooling of nanoencapsulated n-octadecane (NanoC18) using a novel copolymer consisting of long n-alkyl side chains as shell. Nanoencapsulations of n-octadecane with various compositions of poly(methyl methacrylate-co-octadecyl methacrylate) copolymer as shells were carried out by means of miniemulsion polymerization. Fabrication, morphology, diameter distributions, phase change behaviours, and thermal stabilities of nanocapsules were investigated using Fourier transformed infrared spectroscopy, a field-emission scanning electron microscope, a transmission electron microscope, particle size distribution analysis, differential scanning calorimetry, and thermogravimetric analysis. The results indicate that a series of nanocapsules with core/shell structure and spherical shapes are fabricated with average diameters ranging from 373 to 398 nm. The average thickness of the shells is about 60 nm. All the NanoC18 crystallize into a stable triclinic phase via a metastable rotator phase (R_I) from the liquid phase. The crystallization temperature of n-octadecane within poly(methyl methacrylate) nanocapsules is considerably lower than that in bulk phase. Supercooling is effectively suppressed using the comb-like copolymer with crystallizable n-octadecyl side chains as shell. Octadecyl methacrylate is not only employed as a reactive costabilizer to suppress the influence of Ostwald ripening during the formation of nanocapsules but also as a functional monomer in the composition of the copolymer shell in order to suppress the supercooling of NanoC18.     

Photoinduced hydrogen evolution in an artificial system containing photosystemⅠ,hydrogenase,methyl viologen and mercaptoacetic acid

Hydrogen evolution was detected in an artificial system composed of light-harvesting unit of purified photosystem I,catalyst of hydrogenase,methyl viologen and electron donor under radiation.Absorption spectral features confirmed that electron transfer from electron donors to proton was via a photoinduced reductive process of methyl viologen.     

ω-Iodoalkyl(methyl)malonate Esters

Abstract

ω-Iodoalkyl(methyl)malonate esters have potential utility in the bioconjugate chemistry of steroids. A representative set of these esters with a variety of protecting groups and alkyl groups has been prepared. The compounds offer a range of elution values on silica, as well as several convenient deprotection options.

ω-Bromoalkyl(methyl)malonate esters are precursors of chalcogenobarbiturates, which, in radiolabeled form, may be useful as brain imaging agents.[1] Grigsby, R.A., Irgolic, K.J. and Knapp, F.F. 1983. Synthesis and spectral properties of diethyl organylchalcogenoalkyl(alkyl)malonates and 5-alkyl-5-(organylchalcogenoalkyl)barbiturates. J. Organomet. Chem., 259: 171–181.  [Google Scholar] Recently, we have become interested in the analogous ω-iodoalkyl(methyl)malonate esters because of their possible utility in the bioconjugate chemistry of steroids. It is known that steroids can be conjugated to platinum through a malonate moiety.[2] Gandolfi, O., Apfelbaum, H.C., Migron, Y. and Blum, J. 1989. Syntheses of cis-dichlorodiammineplatinum analogs having steroidal hormones bound to the metal atom via malonato bridges. Inorg. Chim. Acta, 161: 113–123.  [Google Scholar] Such platinated steroids are significant because of their potential as tissue-selective antitumor agents.     

Zinc(II) complexes containing N′-aromatic group substituted N,N′,N-bis((1H-pyrazol-1-yl)methyl)amines: Synthesis,characterization, and polymerizations of methyl methacrylate and rac-lactide

A novel series of Zn(II) complexes [L_nZnCl₂] (L_n = L_A ? L_F) based on N,N′,N-bis((1H-pyrazol-1-yl)methyl)amine bidentate ligands, N,N-bis((1H-pyrazol-1-yl)methyl)-3,5-dimethylaniline [L_A], N,N-bis((1H-pyrazol-1-yl)methyl)-2,6-dimethylaniline [L_B], N,N-bis((1H-pyrazol-1-yl)methyl)-2,6-diethylaniline [L_C], N,N-bis((1H-pyrazol-1-yl)methyl)-2,6-diisopropylaniline [L_D], N,N-bis((1H-pyrazol-1-yl)methyl)-4-bromoaniline [L_E] and N,N-bis((1H-pyrazol-1-yl)methyl)benzhydrylamine [L_F], has been synthesized and characterized. X-ray structures of these Zn(II) complexes showed a distorted tetrahedral geometry. No interaction exists between the N_amine and the Zn(II) center in the [L_nZnCl₂] (L_n = L_A ? L_F) complexes, resulting in formation of an eight-membered chelate ring. [L_FZnCl₂] exhibited the highest catalytic activity (3.95 × 10⁴ g PMMA/mol·Zn·h) for the polymerization of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) at 60 °C and yielded high molecular weight (M_w) (11.0 × 10⁵ g/mol) of poly(methylmethacrylate) (PMMA). All the complexes resulted in syndiotactic enriched PMMA with high T_g (125–131 °C). The steric bulk of ligand architecture plays an influential role in controlling the catalytic activity and stereoregularity of the resultant PMMA. Further, alkyl derivatives [L_nZnMe₂] (L_n = L_A ? L_F) of synthesized Zn(II) complexes, generated in situ, showed moderate to high activities toward ring opening polymerization (ROP) of rac-lactide (rac-LA) and yielded heterotactic polylactide (PLA) with P_r up to 0.95 at ?50 °C. The activity and stereoselectivity toward ROP of rac-LA by these dimethyl Zn(II) complexes should be considered as a combined effect of steric hindrance and electronic density around the metal center.     

Phase behavior and modeling of the poly(methyl methacrylate)–CO2–methyl methacrylate system

Cloud-point data for the system poly(methyl methacrylate) (PMMA)–CO₂–methyl methacrylate (MMA) are measured in the temperature range of 26 to 170°C, to pressures as high as 2500 bar, and with cosolvent concentrations of 10.4, 28.9, and 48.4 wt.%. PMMA does not dissolve in pure CO₂ to 255°C and 2550 bar. The cloud-point curve for the PMMA–CO₂–10.4 wt.% MMA system exhibits a negative slope that reaches 2500 bar at 105°C. With 28.9 wt.% MMA the cloud-point curve remains relatively flat at ∼900 bar for temperatures between 25 and 170°C. With 48.4 wt.% MMA the cloud-point curve exhibits a positive slope that extends to 20°C and ∼100 bar. Pressure-composition isotherms are also reported for the CO₂–MMA system at 40.0, 80.0, 105.5°C. This system exhibits type-I phase behavior with a continuous mixture–critical curve. The Peng–Robinson (PR) and SAFT equations of state model the CO₂–MMA data reasonably well without any binary interaction parameters, although the PR equation provides a better representation of the mixture-critical region. It is not possible to obtain even a qualitative fit of the PMMA–MMA–CO₂ data with the SAFT equation of state. The SAFT model qualitatively shows that the cloud-point pressure decreases with increasing MMA concentration and that the cloud-point curve exhibits a positive slope for very high concentrations of MMA in solution.     

Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides

Iron-catalyzed δ-selective conjugate addition of methyl and cyclopropyl Grignard reagents to α,β,γ,δ-unsaturated esters and amides took place in good yields to give products exclusively with cis-β,γ-olefinic bond.     

Synthesis of tris(β,β,γ-oximinoalkyl)amines from aliphatic nitro compounds and methyl vinyl ketone

A general strategy for the assembly of previously unknown tris(β,β,γ-oximinoalkyl)amines from aliphatic nitro compounds and methyl vinyl ketone is described. The strategy involves N,N-bis(siloxy)enamines as key intermediates. The latter are accessible by double silylation of alkylnitro compounds. Nickel(II) and copper(II) complexes of tris(β,β,γ-oximinoalkyl)amines are prepared and structurally characterized.     

Simultaneous GC determination of turpentine, camphor, menthol and methyl salicylate in a topical analgesic formulation (Dologex®)

Summary A gas chromatographic assay has been developed for the simultaneous quantitative determination of turpentine, camphor, methol and methyl salicylate in a topical formualtion (Dologex^?). Eucalyptol was used as the internal standard. Compounds were separated on a cross-linked 5% phenyl polydimethylsiloxane capillary column and detected by FID. The method was validated on the basis of selectivity, recovery, linearity, precision and accuracy. Calibration graphs were linear for each analyte in the range studied. Intra and inter-day precision (coefficient of variation,CV) did not exceed 2%. The applicability of the method was demonstrated in a stability study of these compounds in samples of the formulation which had been maintained under different temperature conditions for six months.