Compatibility Range in Polymer Mixtures. An approach using analogue calorimetry and group contribution procedures

The mixing enthalpies of blends of polymethylmethacrylate (PMMA) with poly(styrene-co-acrylonitrile) (SAN) were investigated by analogue calorimetry through the determination of the excess enthalpies of pseudobinary model mixtures corresponding to the addition of methyl-i-butyrate to a binary mixture of acetonitrile or propionitrile plus toluene or ethylbenzene. A group contribution procedure, based on UNIQUAC equation, was also devised and the polymeric mixing enthalpies were calculated from properly defined group contributions. Enthalpies for polymeric interactions were introduced into the Flory-Huggins equation and the miscibility window of PMMA-SAN mixtures was calculated. The results show a qualitative agreement with the experimental miscibility data and indicate that both the analogue calorimetry and the group contribution procedures yield correct results when acetonitrile, and not propionitrile, is chosen as the model for the polyacrylonitrile repeat unit of the copolymer. This revised version was published online in July 2006 with corrections to the Cover Date.     

Homologous SNV Reaction: Synthesis of l‐Methyl‐4‐[4′‐phenylsulfonyl‐1′,3′‐butadienyl]pyridinium Iodide and Its Reactivity with Thiol Groups Giving Rise to the Chromophoric Thioether

Thioether 4‐[(1′E,3′E)‐4′‐phenylsulfanyl‐1,3′‐butadienyl]pyridine 8 and sulfone 4‐(4′‐phenylsulfonyl‐1′,3′‐butadienyl)pyridine 14 were prepared by reaction of the carbanions derived from allylic thioether or allylic sulfone with isonicotinaldehyde. The reaction with the sulfonyl carbanion occurred at the α position and on heating the alcolate gave the dienic sulfone 14 . The corresponding pyridinium iodide 10 and 15 were prepared by reaction with methyl iodide, respectively, on pyridine derivates 8 and 14 . The dienic pyridinium thioether 10 showed a long wavelength absorption band centered at 420 nm. The reaction of dienic pyridinium sulfone 15 with thiophenol gave the dienic pyridinium thioether 10 by a nucleophilic vinylic substitution. The reaction of sulfone 15 with glutathione was of second order and the rate constant was 8.5 M^?1s^?1 at 30°C and pH 7, about 500 times smaller than the rate constant observed with (E)‐1‐methyl‐4‐(2‐methylsulfonyl‐1‐ethenyl)pyridinium iodide 1 . The dienic pyridinium thioether 10 was a negative solvatochrome.     

Regioselective replacement of nitro groups in 2,4,6-trinitrotoluene under the action of alkanethiols. Synthesis of ortho-(alkylthio)-substituted nitrotoluenes and their oxidation to sulfoxides and sulfones

The reactions of 2,4,6-trinitrotoluene with alkanethiols in the presence of K₂CO₃ (the molar ratio of the reactants is 1 : 1 : 1) in dipolar aprotic solvents result in selective replacement of the ortho-nitro group to form 2-alkylthio-4,6-dinitrotoluenes, which can be oxidized to the corresponding sulfoxides or sulfones. The second ortho-nitro group can be replaced under the action of one more equivalent of alkanethiol on sulfides as exemplified in PhCH₂SH.     

Heterocyclization of thioamides containing an active methylene group (review)

Data from the last six years on the heterocyclization of thioamides containing an active methylene group are analyzed and classified. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1763–1800, November, 2008.     

正规Cayley图

综述了自１９９０年以来１２－传递图研究的一些新成果，正规Ｃａｙｌｅｙ图的相关结论。     

Experimental and Computational Study on the Anti-Markovnikov Hydrofunctionalization of Olefins Using Glycine-Extended AQ-Auxiliaries

Two similar tridentate directing groups derived from glycine and 8-aminoquinoline were shown to enable the palladium-catalyzed anti-Markovnikov hydrofunctionalization of 4-pentenylamine with drastically different efficiencies. A computational investigation into the origin of the reactivity difference between these isomeric, carbonyl-transposed auxiliaries suggests that protonation state, thus charge of the substrate-metal complex prior to nucleopalladation is key. These investigations have culminated in a directing group design that can undergo Pd-catalyzed hydrofunctionalization under relatively mild conditions, as low as room temperature.     

Topological Hypergroups in the Sense of Marty

In this paper, we introduce the concept of topological hypergroups as a generalization of topological groups. A topological hypergroup is a nonempty set endowed with two structures, that of a topological space and that of a hypergroup. Let (H, ○) be a hypergroup and (H, τ) be a topological space such that the mappings (x, y) → x ○ y and (x, y) → x/y from H × H to 𝒫*(H) are continuous. The main tool to obtain basic properties of hypergroups is the fundamental relation β*. So, by considering the quotient topology induced by the fundamental relation on a hypergroup (H, ○) we show that if every open subset of H is a complete part, then the fundamental group of H is a topological group.

It is important to mention that in this paper the topological hypergroups are different from topological hypergroups which was initiated by Dunkl and Jewett.     

Synergistic Effect of Oxalate and Ethylene Glycol on the Formation of SnO2 Rods

SnO₂ rods have been synthesized by using tin (II) chain‐like complexes as precursors in which oxalate and ethylene glycol act as co‐ligands. On the basis of experimental analysis, a reasonable formation mechanism of rods is discussed, which is further supported by Fourier transform infrared spectroscopy (FT‐IR). These results show that the synergistic effect of oxalate group and ethylene glycol plays an important role in the formation of long SnO₂ rods.     

Crown ether complexes of tin(II) trifluoromethanesulfonate

The treatment of tin(II) trifluoromethanesulfonate with three differently-sized crown ethers [12]crown-4, [15]crown-5 and [18]crown-6 results in the formation of tin complexes that exhibit dramatically different structural features. The compounds are investigated using experimental techniques and density functional theory calculations.