The STOBBE Condensation with Pyrrolyl Aldehydes – a synthesis of indole derivatives

The condensation of pyrrolyl-2-aldehyde or 1-methyl-pyrrolyl-2-aldehyde with dimethyl succinate, using sodium hydride as condensing agent, gave predominantly the halfesters 1a and 1c respectively. Their structure and (E)-configuration

1 i. e., pyrrol ring and COOCH₃ group are in trans position. This nomenclature follows the IUPAC 1968 Tentative Rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970).

were confirmed by their cyclisation to the corresponding indole derivatives 2a–h .     

Effect of chain microstructure on modulus of ethylene–α-olefin copolymers

A family of copolymers of ethylene and α-olefin resins with homogeneous branching distribution, which behaves as elastomers at high short-chain branching levels and acts as typical thermoplastics at low short-chain branching levels, is now available. Control of this broad range of properties stems from the ability to control the molecular architecture more effectively using Dow's INSITE

1 Trademark of The Dow Chemical Co.

technology than in the past. Due to the unique combination of narrow short-chain branching distribution (SCBD) and narrow molecular weight distribution (MWD), these resins provide a unique opportunity to model structure/property relationships in branched ethylene-α-olefin copolymers. The modulus in branched ethylene-α-olefin copolymers with aliphatic branches is shown to be primarily dictated by crystallinity. It is shown that the branch distribution and the branch type have an insignificant effect on the modulus of ethylene copolymers containing aliphatic branches at a given crystallinity. Modulus data have been successfully modeled in such systems using a lamellar fiber-reinforced amorphous matrix composite model. Switching from aliphatic branches to cyclic branches significantly affected the modulus at similar crystallinities. © 1994 John Wiley & Sons, Inc.     

Rheological characteristics and morphologies of styrene–butadiene–maleic anhydride block copolymers

Studies on the morphologies and rheological characteristics of two styrene–butadiene–maleic anhydride block copolymers (SBMa) have been performed. The transmission electron microscopy micrographs show that the morphologies of SBMa change from matrix–island structure to co‐continuous structure. Curves for dynamic modulus varied with frequency (ω) show obvious solid‐like behavior in the low ω region, which is typical for ordered block copolymers or networked materials. Van Gurp–Palmen plots have been used to exploit the thermorheological complexity of two copolymers. The master curves of two copolymers have been acquired through time–temperature superposition principle, and the plateau modulus (G) have been obtained from G′ at ω, where the loss tangent (tan δ) approaches a minimum. Meanwhile, Williams–Landel–Ferry equation has been used to evaluate the free volume parameters. The relaxation time spectra of two copolymers have been calculated and fitted with modified Baumgaertel–Schausberger–Winter model. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The STOBBE Condensation with Dimethyl Homophthalate. Part I

The condensation of methyl 2-thienyl, methyl 2-furyl, and phenyl 2-thienyl ketone with dimethyl homophthalate in the presence of either potassium t-butoxide or sodium hydride as condensing agent, gave predominantly the (z)-half esters

1 The nomenclature of cis/trans isomers follows the IUPAC Tentative rules, Section E, Fundamental Stereochemistry, J. org. Chemistry 35 , 2849 (1970). See also N. R. El-Rayyes, J. prakt. Chem. 315 (2), 300 (1973). (E) = trans-(Heterocyclic ring/CO₂CH₃) (Z) = cis-(Heterocyclic ring/CO₂CH₃)

. The structure and configuration of the products were inferred by chemical and spectroscopic means.     

Porous bead aliphatic-aromatic methacrylate copolymers,I. Effect of polymerization conditions on porous structure formation of methyl methacrylate — di(methacryloyloxymethyl)naphthalene copolymers

The influence of inert porogenic mixture and monomer mixture composition and concentration on specific surface areas, pore size distribution, volumes of pores capable of capillary condensation of nitrogen and true density of copolymers were investigated for a new type of methacrylate monomer system: methyl methacrylate and di(methacryloyloxymethyl)naphthalene. The obtained copolymers exhibit similar character as it is typical for PPS

1 PPS = Porous by Precipitant and Solvent.

styrene-divinylbenzene resins.     

Low dielectric,fluorinated polyimide copolymers

Copolymers of fluorinated polyimides and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) have been prepared as films and composite laminates. The addition of BPDA was used as a means to achieve insolubility, making the polymers suitable as aircraft matrix resins. Glass transition temperatures, thermooxidative stabilities, and tensile strengths were increased with increasing BPDA content in the copolymers. Although the addition of BPDA did increase the UV cutoff and decrease the percent transmission slightly, the optical transparency of the polymers was still excellent. Dielectric constants of the copolyimide films ranged from 2.6 to 2.9. Astroquartz II laminates made with these resins had dielectric constant of 3.3–3.4. Flexural strength on unidirectional specimens were in the 1.24–1.41 GPa range and flexural moduli were 41 GPa. © 1994 John Wiley & Sons, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.

     

Preparation and copolymerization of polyvalent metal salts of ethyleneglycol–methacrylate–phthalate

Preparation of polyvalent metal salts of ethyleneglycol–methacrylate–phthalate (EMP) was investigated by the reaction of the Na salt of EMP and chlorides of polyvalent metals such as Al³⁺, Cr³⁺, Fe³⁺, Ni²⁺, Co²⁺, and Cu²⁺. It was found that, among the metal salts obtained the Cr salt could be obtained in the form of (EMP? )_2? Cr(OH) in high purity and good yield where EMP? means EMP residue: (EMP? )_2? Cr(OH) is soluble in chief organic solvents and vinyl monomers such as styrene (St) and MMA. (EMP? )₂Cr(OH) was then copolymerized with St and MMA. As for the physical properties of the copolymers obtained, heat distortion temperature, compressive strength, and Rockwell hardness were generally improved by introducing (EMP? ₂)Cr(OH) into the polymers. Tensile strength, flexural strength, and impact strength were also improved by selecting the most suitable concentration of (EMP? )₂Cr(OH) according to the species of vinyl monomers. Moreover, the physical properties of (EMP? )₂Cr(OH)–MMA copolymers are generally superior to those of (EMP? )₂Cr(OH)–St copolymers. TGA and boiling water resistance of the copolymers were also discussed.     

Stevensanaloge,Durch Nickelkomplexe Katalysierte Umlagerung Von Triarylphosphoryliden Und Darstellung Sowie Strukturbestimmung Von Phosphorylid-Nickeltricarbonylkomplexen

The Stevens rearrangement of the triarylphosphorusylids R₃ P=CHR′ (III) (R′ = H, CH₃, C₂ H₅) to diarylbenzylphosphines (V) is catalyzed by nickel complexes (e.g., (COD)₂ Ni (I)). Attempts to prepare trimesitylphosphine-methylene result in direct formation of dimesityl (mesitylmethyl) phosphine (XII) — the first recorded direct Stevens rearrangement of a phosphorusylid. Phosphorusylids react with nickeltetracarbonyl without rearrangement to give complexes of the type R₃P=CH_a · Ni(CO)₃ (XIV). The structure of XIV has been established by the IR and NMR spectra and confirmed by an X-ray structural determination.

1 B. L. Barnett and C. Krüger, J. Cryst. Mol. Struct., im Druck.

The ylid is bonded to the nickel through the C-atom with resulting hybridization from sp² towards sp³.     

Fracture behavior of coated/uncoated graphite-epoxy composites

The static delamination behavior of graphite/epoxy composite specimens subjected to mode I tensile opening (using UDCB

1 Uniform double cantilever beam.

specimens), and pure mode II shear loading (using ENF

2 End-notched flexural.

specimens) were studied. The graphite epoxy composites for the study were made from commercially treated fibers, with and without an electropolymerized interlayer. The mode I fracture energy (G_IC) was found to be significantly higher (more than 50 percent) for the coated fibers. However, this improvement was accompanied by a high reduction (more than 3 times) in the mode II fracture energy (G_IIC). This effect is apparently related to poor adhesion between the interlayer and the epoxy resin, which may be corrected by use of a “top layer” of appropriate composition to form chemical bonds between the phases. The fracture toughness (K_IC) of composites made with commercially treated fibers was also evaluated, using double side-notched specimens.     

Dicyclopentadienoxidation. II 5. Katalysierte Flüssigphasenoxidation von Dicyclopentadien

Dicyclopentadiene Oxidation. II. Catalyzed Liquid-Phase Oxidation of Dicyclopentadiene The liquid-phase oxidation of dicyclopentadiene 1 by molecular oxygen was studied in the presence of MoO₂(acac)₂

1 Acac- Acetylacetonat

as a typical epoxidation catalyst. The yield of the mono-epoxides 2 and 3 is increased to 56,4% (uncatalyzed reaction: 43,6%). The ratio of the two mono-epoxides is decreased to 2/3 = 2,6 in relation to the uncatalyzed reaction ( 2/3 = 7,1). The influence of temperature, conversion and solvents is described. The bisepoxide 4 is formed at lower conversions than in the uncatalyzed reaction. But also at higher conversions of 1 not more than 10% of the bisepoxide 4 is formed     

Microstructure and glass‐transition temperature of novel star N‐SIBR

In this study, a polymeric N‐functionalized mutilithium (N‐M‐Li) compound was prepared from commercial divinylbenzene (DVB) and lithiohexamethyleneimine (LHMI), and star‐shaped copoly(styrene–butadiene–isoprene) was obtained by anionic polymerization using preformed N‐M‐Li as initiator, tetramethylethlenediamine (TMEDA) as polar modifier, and cyclohexane as solvent. The microstructure and the glass–transition temperature (Tg) of copolymers were characterized by ¹H NMR and differential scanning calorimetry (DSC), respectively. It showed that the non‐1,4‐structure content and the Tg of copolymers increased with the increase of TMEDA dosage or the decrease of polymerization temperature; however, the effects of the initiator concentration and DVB dosage on them were not obvious. We also obtained the relationships between the non‐1,4‐structure content of copolymers and the Tg of copolymers respectively, and between the ln(T/Li) (TMEDA/N‐M‐Li, mole ratio) and the non‐1,4‐structure content of copolymers, as follows: Tg (°C) = 0.6258C_{non 1,4}?55.93 and C_{non 1,4} = 20.79 ln K+59.11, where K is T/Li value. Therefore on the basis of experimental results, we realize polymer design according to our practical requirements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5848–5853, 2006     

Gel permeation chromatography: Physical characterization and chromatographic properties of porasil

Porasil

1 Porasil is the Water Associates registered trademark for a powdered porous silica chromatographic substrate.

porous silica has been characterized by the methods of gas adsorption–desorption isotherms, mercury porosimetry, and electron microscopy. The pore structure has been shown to be quite heterogeneous, particularly at the surface of the particles. From the same sample of Porasil, columns were packed and calibrated in a gel permeation chromatograph. The availability of high molecular weight fractions of polystyrene allowed the exclusion limit of these materials to be determined for the first time. The heterogeneous pore structure did not seem to affect the effectiveness of these materials for macromolecular separation.     

Synthesis of polystyrene microgel with glucose as hydrophilic segment via controlled free-radical polymerization

4-Vinylbenzyl glucoside peracetate (1) was copolymerized with divinylbenzene (DVB) using 1-phenyl-1-(2′,2′,6′,6′-tetramethyl-1′-piperidinyloxy)ethane (2) as an initiator in m-xylene at 138 °C for 20 h ([DVB]/[2]=28; [DVB]=0.62 mol L⁻¹). The copolymerizations were performed using the mole fraction of 1 in the total feed of 1 and DVB (F₁: [1]/[1]+[DVB]) ranging from 0.11 to 0.38 that produced the polystyrene (PSt) microgel with acetyl glucose, 3, in 46-53% yields. Dynamic laser light scattering (DLS) measurements showed that 3 was stably suspended in toluene as particles with average diameters (d's) ranging from 12 to 22 nm. A static laser light scattering (SLS) measurement gave the average molar mass, M_w,SLS, of 3 that ranged from 9.69×10⁴ to 6.96×10⁵. The numbers of the 1, 2, and DVB units in 3 (N₁, N₂, and N_DVB, respectively) were from 111 to 238, from 17 to 208, and from 350 to 4510, respectively. The deacetylation of 3 was achieved by treatment with sodium methoxide in dry 1,4-dioxane to produce the PSt microgel with glucose as the hydrophilic segment, 4. The solubilities of 4 in toluene, CHCl₃, THF, 1,4-dioxane, pyridine, DMF, DMSO, and H₂O, and the mixture of H₂O and 1,4-dioxane were examined, indicating that a hydrophilic property had been effectively introduced into 4.     

Thermal analysis of poly(phenylene sulfide) polymers. I: Thermal characterization of PPS polymers of different molecular weights

Thermal properties of Fortron®

1 ®Registered trademark of Hoechst Celanese Corporation.

poly(phenylene sulfide) (PPS) polymers of different molecular weights were studied by DSC. Crystallization studies revealed that the ability of these polymers to crystallize decreases with increasing molecular weight. The Avrami equation poorly describes the isothermal crystallization of PPS. Lamellar crystallization was observed for the lowest molecular weight sample. For the other, higher molecular weight polymers the Avrami exponent is always between 2 and 3, suggesting development of distorted spherulites with heterogeneous nucleation. The temperature dependence of the solid and melt heat capacities have been determined. The solid specific heat capacity did not exhibit a molecular weight dependence. The heat capacity increase at the glass transition, T_g, has been calculated to be 28.1 J°C^?1 mole^?1. The equilibrium melting point of PPS has been estimated to be 348.5°C using the Hoffman–Weeks method. The T_g of PPS increases with molecular weight. The T_g of the highest molecular weight evaluated is 92.5°C. A DMA relaxation peak corresponding to the onset of the phenylene ring rotation occurs at ?92°C. Only the highest molecular weight could be quenched to a completely amorphous state.     

Mowrah (Madhuca latifolia) seed saponin. Toxicological studies

Mowrah seed (Madhuca latifolia) meal

1 Meal refers to solvent extracted material.

contains high levels of saponin (7%) making it unsuitable for incorporation in animal feedstuff formulations. The saponin from mowrah seed meal was isolated and purified by paper chromatography. This was used for in vitro tests as well as pharmacological and acute toxicity studies for a better understanding of its properties and toxicity. The oral, intraperitoneal and intravenous LD₅₀ of mowrah saponins in mice are 1 g, 15–20 mg and 15 mg/kg body weight respectively. Processing of the meal to remove or inactivate the saponin will be essential prior to its incorporation in animal feeds.     

Siloxane modification of polyamides

Polyamide–polydimethylsiloxane block copolymers were made by the BuLi or LiOSi(CH₃)₂OSi(CH₃)₂OLi catalysed polymerisation of hexamethylcyclotrisiloxane terminated by and using this substituted siloxane to initiate the polymerisation of lauryllactam or caprolactam in toluene solvent in the presence of lithium aluminium hydride as the catalyst. One or 2% of the polycaprolactam-polydimethylsiloxane block copolymers were mixed with nylon 6 and discs moulded. The presence of silicone in the surface was demonstrated by determining the critical surface tensions of wetting using ethanol–water mixtures as the contact-angle test liquids. A polylauryllactam–polydimethylsiloxane block copolymer compatible with polyethylene was similarly studied. An important application for such composites is to provide a dry lubricated surface, therefore the kinetic coefficients of friction of steel against these copolymer-treated nylon 6 samples were determined demonstrating at best a reduction to one third that of the untreated control.     

Ternary copolymer of poly(ethylene oxide), terephthalyl chloride,and lithium 2,5-diaminobenzene sulfonate for ionic conduction

The ternary copolymers of poly(ethylene oxide) (PEO), terephthaloyl chloride (TPC), and lithium 2,5-diaminobenzene sulfonate (LDABS) have been synthesized by the separated copolymerization PEO, TPC, and LDABS. Three ternary copolymers, PEO_0.12–TPC_0.50–LDABS_0.38, PEO_0.24–TPC_0.50–LDABS_0.26 and PEO_0.36–TPC_0.51–LDABS_0.13, are thermally stable and mechanically strong ionic conductors. The combination of immobilized anionic groups incorporated into the copolymer to increase the mobile cation concentration and of PEO introduced to enhance ionic conductivity via flexible chain motion. PEO_0.24–TPC_0.50–LDABS_0.26 was found to be a good polymeric material with good mechanical properties and a high ionic conductivity of 8.37 × 10⁻⁶ S/cm at 25°C. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 835–840, 1998     

Novel Rubbers from the Cationic Copolymerization of Soybean Oils and Dicyclopentadiene, 2 – Mechanical and Damping Properties

A series of various soybean oil/dicyclopentadiene (DCP) thermosetting copolymers with renewable carbon percentages of 53–86% have been prepared by cationic copolymerization of regular (SOY) or 100% conjugated soybean oils (C₁₀₀SOY) with DCP initiated by NFO ethyl ester modified and SOY‐ and C₁₀₀SOY‐diluted BF₃ diethyl etherate. The effects of stoichiometry, the type of soybean oil, and the initiator on the mechanical and damping properties of the copolymers have been investigated. The materials exhibit compressive stress/strain behavior ranging from soft rubbers to tough and ductile plastics, and possess good damping properties. They represent promising new materials for efficient sound and vibration damping applications over a broad temperature and frequency range.

     

Synthesis, Characterization, and Degradation of Copolymer from Trans-4-hydroxy-L-proline and L-lactide

A series of novel copolymers of trans-4-hydroxy-L-proline (Hpr) and L-lactide (LLA) were synthesized by ring opening copolymerization, using stannous octoate as a catalyst. These new copolymers have pendant amino functional groups along the polymer backbone chain. Various techniques, including ¹H NMR, IR, DSC, and the use of a Ubbelohde viscometer, were used to elucidate structural characteristics, thermal properties, and degradation behavior of the resulting copolymers. Data showed that the optimal reaction condition for the synthesis of the copolymers was obtained using 3 wt% stannous octoate at 140C for 24 h. The DSC analysis demonstrated amorphous structure for most of the copolymers. The glass transition temperatures (T _g) of the copolymers shift to a higher temperature with increasing Hpr/LLA molar ratio. In vitro degradation of these poly(N-CBz-Hpr-co-L-LA) was evaluated by weight loss measurements.     

Novel Thermosets from the Cationic Copolymerization of Modified Linseed Oils and Dicyclopentadiene

A series of soft to tough copolymers have been prepared by the cationic copolymerization of the modified linseed oils Dilulin or ML189 with DCPD. Soxhlet extraction and solid‐state ¹³C NMR spectra indicate that the bulk copolymers consist of a cross‐linked oil/DCPD network interpenetrated with certain amounts of soluble components. The T_gs of the resulting Dil/DCPD and ML189/DCPD copolymers are in the range 15–83 and 8–77 °C, respectively, and increase linearly with the increase of the DCPD amount. The room‐temperature storage moduli range from 4.43 × 10⁶ to 1.52 × 10⁹ Pa for the Dil/DCPD copolymers and from 3.72 × 10⁶ to 1.44 × 10⁹ Pa for the ML189/DCPD copolymers.