Synthesis of 3,4-dihydroxyphenyl-containing polymeric materials from 1,2-polybutadiene and eugenol via thiol—ene addition

Russian Chemical Bulletin - In a search for routes to new promising adhesive materials, 3,4-dihydroxyphenyl groups were introduced for the first time into syndiotactic polybutadiene (1,2-unit...     

Additive poly[3-(trimethylsilyl)tricyclononene-7]: Molecular properties and chain rigidity

With the use of the methods of hydrodynamics, the Kerr electrooptical effect, and dielectric polarization in solution, the molecular properties of a homologous series of poly[3-(trimethylsilyl)tricyclononene-7] samples synthesized via additive polymerization have been studied. Scaling relationships that describe how the intrinsic viscosities, diffusion coefficients, and sedimentation coefficients of macromolecules depend on their molecular masses in toluene at 298 K have been obtained. It has been shown that the additive poly[3-(trimethylsilyl)tricyclononene-7] has enhanced kinetic chain rigidity. According to hydrodynamic data, the length of the Kuhn segment for this polymer does not exceed 6.0 ± 0.6 nm, while the kinetic fragment estimated from electrooptical data is 4.3 nm. In terms of kinetic properties, the studied polymer is similar to wellknown poly[1-(trimethylsilyl)-1-propyne], with the specific morphology of its highly permeable films being determined by the large-scale mechanism of chain orientation.     

An Improved Process for the Enantioselective Synthesis of HCV NS5A Inhibitor Elbasvir (MK-8742) Chiral Amine Intermediate

Russian Journal of General Chemistry - Large-scale enantioselective synthesis of the chiral amine unit of HCV NS5A inhibitor Elbasvir has been accomplished in six steps, with 55% overall yield. The...     

Microporous structure of highly permeable additive silicon-containing polytricyclononenes

The porosity of a number of additive silicon-containing polytricyclononenes from the class of highly permeable polymers has been systematically studied for the first time by the method of low-temperature nitrogen adsorption/desorption. It has been shown that these polymers have a large specific surface area (390?790 m²/g) and are microporous. Dominant pore size ranges from 7 to 10 Å depending on the number of Me₃Si groups in a monomer unit and their relative position.     

The equilibrium and kinetic rigidity of additive poly(trimethylsilyltricyclononenes) with one and two Si(CH<Subscript>3</Subscript>)<Subscript>3</Subscript> groups in monomer unit

The homologous series of additive poly[3-(trimethylsilyl)tricyclononene-7] with two heminal substituents Si(CH₃)₃ in the side cycle of the monomer unit is studied for the first time via the methods of viscometry and static and dynamic light scattering in the range of molecular masses of (29–770) × 10³. The scaling ratios for the intrinsic viscosity and the coefficient of translational diffusion of macromolecules in toluene at 298 K are obtained, and the equilibrium rigidity of the polymer chain is determined. The hydrodynamic and conformation properties of the polymer are compared to an analog with only one Si(CH₃)₃ substituent in the monomer unit. It is found that the introduction of the second side substituent in the heminal position increases the equilibrium rigidity of the additive poly[3-(trimethylsilyl)tricyclononene-7] by 1.4 times and has a far stronger effect on the kinetic rigidity of the polymer. With the use of the ¹Н NMR relaxation method, it is shown that the mobility of side groups of the polymer with two substituents decreases significantly and the correlation times of hydrogen atoms of Si(CH₃)₃ groups exceed some 20 times the corresponding values for the analog with one Si(CH₃)₃ group in the monomer unit cycle.     

Kinetics and thermochemistry of [2π + 2σ + 2σ]-cycloaddition of quadricyclane to tetracyanoethylene

Kinetic data for the unusual [2π + 2σ + 2σ]-cycloaddition of quadricyclane to tetracyanoethylene in toluene have been obtained for the first time. The same reaction in 1,4-dioxane appears to be the most exothermic among known cycloaddition reactions. The entropy of activation and reaction volume differ only slightly from the corresponding parameters of conventional Diels–Alder reactions.     

Molecular Properties of Additive Poly(bis(trimethylsilyl)tricyclonones) with Vicinal and Geminal Side Substituents

The molecular properties of the additive poly(bis(trimethylsilyl)tricyclononene) with the vicinal position of two side groups Si(CH₃)₃ in the monomer unit are studied for the first time, and its conformational and kinetic properties are compared with those of the isomer with the geminal position of the same groups. Using the methods of static/dynamic light scattering and viscometry for the samples of the vicinal isomer, the hydrodynamic parameters of molecules are determined and their molecular mass dependences in toluene are ascertained. In addition, the Kuhn segment length of this isomer is estimated. The kinetic rigidity of vicinal and geminal isomers is evaluated by ¹H NMR relaxation from the mobility of protons in Si(CH₃)₃ groups. The reasons behind different gas permeabilities of the films based on the polymers with the vicinal and geminal positions of Si(CH3)3 side groups in the monomer unit are discussed.     

Synthesis and Properties of Metathesis Polymer Based on 3-Silatranyltricyclo[4.2.1.0<Superscript>2.5</Superscript>]non-7-ene

A new metathesis polynorbornene containing bulky and reactive silatrane side groups is synthesized, and its gas-transport properties are investigated. The metathesis polymerization of 3-silatranyltricyclo[ 4.2.1.0^2.5]non-7-ene is conducted in the presence of the first-generation Grubbs catalyst. The homopolymer is obtained with a nearly quantitative yield of 98% and a molecular mass of M_w = 1.3 × 10⁶ (Ð = 3.7). According to X-ray phase analysis, the homopolymer is amorphous and its glass-transition temperature is 232°С (DSC). The gas permeability of the metathesis polymer for a set of gases, including He, H₂, O₂, N₂, CO₂, and CH₄, is investigated, and the corresponding diffusion and solubility coefficients are determined.