The acid-catalyzed condensation of formaldehyde and diphenyl sulfide was carried out in benzene in the presence of p-toluene sulfonic acid. From the products, four poly(methylene diphenyl sulfides) of the following structures were isolated. 相似文献
Novel dicarboxylic acids containing one or two 1,3,4-oxadiazole rings in a molecule were synthesized by the reaction between orthoesters and acid hydrazides These dicarboxylic acids have the following structures: and where R represents a phenylene or an alkylene group and n = 1-4. The polyamides from p-xylylenediamine with these dicarboxylic acids were also prepared. The polymers are generally insoluble in m-cresol but soluble in conc. sulfuric acid. The melting points were estimated at above 350°C. Copolyamides of high molecular weights with aliphatic polyamides were obtained. 相似文献
Polymers of the below form are synthesized via the interfacial polycondensation route. A study has been made of the influence of the nature of the solvents employed and base and reactant concentration. New interfacial solvent systems are presented. 相似文献
A culture of Armillariella mellea species was adapted to carry out microbial transformations of (+), (-), and (±)-α-pinene and (-)-β-pinene . The composition of products obtained indicated that allylic hydroxylation of all substrates was the most characteristic reaction for Armillariella mellea species. The hydroxylation occurred either directly in unchanged pinane skeleton yielding among other compounds verbenol ( ) and verbenone ( ) or was preceded by a cleavage of four-membered rings in substrates to form a menthane skeleton. The latter reaction leads to allylic alcohols and diols, mainly trans-sobrerol ( ) and 7-hydroxy-α-terpineol ( ). 相似文献
have been prepared and their structure confirmed by elemental, infrared and mass spectrometric analysis. In view of their proposed use as antioxidants, solubilities in toluene were measured, and all the compounds were subjected to thermogravimetric analysis in atmospheres of air and nitrogen. The higher mol. wt. novolak materials undergo some form of condensation reaction at moderately elevated temperatures. This reaction could have some relevance to their properties as antioxidants and is also of interest with respect to the behaviour of novolak materials in the hardening of phenolic resins. 相似文献
Poly(acrylonitrile) was modified to give products of the form below via reaction with hydroxylamine and subsequently with group IV organometallic reactants: The products obtained with Cl2MR2 are crosslinked. Properties of the new polymers are briefly characterized. 相似文献
Polyesters of the form below are prepared by the interfacial method. Isolation procedures are presented and discussed. Polymer yield is constant as stirring rate, stirring time and nature of the organic solvent are varied. Molecular weight is constant as stirring rate and organic solvent nature are varied. Molecular weight increases as reaction time increases. No correlation is found between polymer molecular weight and polymer softening range. 相似文献
Phenylphosphonic diisocyanate has been prepared and polymers from its condensation with diamines using the interfacial technique are reported. The polymers are believed to contain the following repeating structure: 相似文献
The effect of polymerization conditions on the rate of polymerization and molecular weights of resulting polymer was studied with N-dithiocarbonyl ethoxycarbonyl-DL -α-alanine. in toluenc, dioxane, nitrobenzene and methyl isobutyl ketone. In dioxane, which is a very suitable solvent to obtain high molecular weight polymers, the molecular weight of resulting polymer decreased with increasing monomer concentration. Basic substances accelerated the rate of polymerization, but decreased the molecular weight of resulting polymer. Water accelerated the rate of polymerization and the decrease of molecular weight was not so large. 相似文献
New functionalised macromers containing perfluoropolyether (PFPE) structures and methacrylic end groups were synthesised and used as modifying additives for acrylic UV-curable systems. Their chemical structure is Rh-Rf-Rh, where and with p ≈ q. Notwithstanding their very low concentration, below 0.5 wt.-%, the fluorinated macromers cause a dramatic change of the surface properties of the films, without changing their curing conditions and their bulk properties. X-ray photoelectron spectroscopy (XPS) measurements showed that the macromers are able to concentrate selectively at the surfaces of the films, depending on their chemical structure and on the kind of substrate employed. 相似文献
N-dithiocarbonyl ethoxycarbonyl-amino acids (III), were synthesized in crystalline form from various amino acids by the addition of ethyl chlorocarbonate to dithiocarbamic acid salt obtained from amino acid and CS2 at low temperature. When the reaction was performed above room temperature, polypeptides could directly be obtained without getting III. Compounds such as III were synthesized from glycine, DL -α-alanine, DL -valine, DL-methionine, L-leucine, glycylglycine, β-alanine, γ-amino-n-butyric acid and ε-amino-n-caproic acid in this paper. III were polymerized to polypeptides in high yields in the presence of a basic catalyst or by heating; acid inhibited the polymerization of III. 相似文献
Summary: The synthetic routes to three series of liquid crystal conducting polymers (based on pyrrole, thiophene, and aniline monomers) are reported and the optimum conditions for polymer preparation are described. These polymers show increased conductivity when laser‐aligned, the greatest effect being shown by the N‐substituted pyrrole‐based system. Information on their liquid crystal and spectroscopic properties and other characteristics are also included.
Summary: The synthesis and polymerization of novel 18‐crown‐6 and 24‐crown‐8 bis aryl trifluorovinyl ethers is described. Thermally induced polymerization yields linear crown ether fluoropolymers with hexafluorocyclobutyl linkages. The polymers exhibit Tg's above 120 °C and show good thermal stability with no appreciable weight loss below 350 °C. Incorporation of crown ether macrocycles into the polymer is expected to increase cationic uptake of an otherwise electroneutral fluoropolymer.
Summary: Degradation studies of cis‐1,4‐polyisoprene were carried out using first and second generation Grubbs catalysts to achieve end‐functionalized acetoxy oligomers in both an organic solvent and a latex phase at room temperature. Well‐defined acetoxy telechelic polyisoprene structures were obtained in a selective manner with a range of from 10 000 to 30 000, with a polydispersity index of around 2.5.
Structure produced by the metathetic depolymerization of hydroxy telechelic cis‐1,4‐polyisoprene. 相似文献
A bridged silsesquioxane was obtained from a precursor synthesized by the reaction of glycidoxypropyl(trimethoxysilane) (2 mol) with cyclohexylamine (1 mol). The polycondensation in the presence of formic acid produced a hybrid material exhibiting a short-range order based on elongated organic channels accommodating the pendant cyclohexyl fragments, bounded by inorganic domains. The presence of functional groups in the organic channels (tertiary amine, ether, hydroxyl), can be used to retain small organic molecules capable of forming hydrogen bonds. Aspirin was used as a probe to illustrate this possibility.
1,1,2,2-Tetraphenyl-1,2-diphenoxyethane (TPPA) initiates at 70°C the polymerization of methyl methacrylate. In the first period oligomers of the type 1 with two phenoxydiphenylmethyl end groups (Pn ≈ 1 – 20) are formed by primary radical termination. These telechelics are effective initiators of the further free radical polymerization of vinyl monomers. 相似文献
The infrared spectrum of polymethacrylonitrile (PMAN) exhibits noticeable change on heat-treatment up to 240°C, the color of the sample changed from yellowish at 120°C, through yellow and red, to deep red at 210°C or above. A new structure was proposed as a plausible structure for the chromophore of the heat-treated PMAN film, on the basis of comprehensive consideration of details of the spectral change in reference to the corresponding spectral change of polyacrylonitrile (PAN) and the spectra of compounds having similar structures. Subsequent treatment of the deep-red PMAN with hot water further drastically changed the infrared spectrum, and in turn the color changed from deep red to yellowish. The spectrum of the hydrolyzed product was in complete agreement with that of the copolymer of methacrylonitrile and methacrylic acid. Thus the structure was found to be from infrared spectral comparison. 相似文献
From the partial hydrolysates of the lipopolysaccharides from strains 2 (Sh. flexneri 1b) and 1290/63 (Sh. flexneri var. Y) we isolated in both cases a Rha-Rha-disaccharide. After trimethylsilylation, gas liquid chromatographic purification and mass spectrometry we could show that the rhamnose molecules of both disaccharides were linked to each other by a 1,3-glycosidic bond. As we could estimate the other linkages in the O-specific side chains of these lipopolysaccharides in recent studies, we are now able to present the following structures for the repeating units: In addition, we found in the lipopolysaccharide of strain 1290/63 rather big quantities of a poly-α-(1,4)-glucan. 相似文献
Phenylphosphonic diisocyanate has been prepared and polymers from its condensation with hydrazines using the interfacial technique are reported. The polymers are believed to contain the following repeating structure: 相似文献
Summary: The polycondensation of 1‐ethynyl‐2,5‐dihexyl‐4‐iodobenzene in the presence of 1‐ethynyl‐2,5‐dihexyl‐4‐(2‐phenylethynyl)benzene proceeds according to the mechanism of initiated chain growth polycondensation. It has allowed the synthesis of oligomers with a desired molecular weight and a narrow molecular weight distribution. The reasons for the side reaction leading to the formation of diyne compounds are revealed and the presumed mechanism is given. This opens prospects for the preparation of defectless poly(p‐phenyleneethynylene)s with required molecular weights and narrow molecular weight distributions.