Polyamides, General

Reaction of vinylmagnesium chloride with aliphatic carboxylic acid methyl ester gives a mixture of vinylketone and divinylcarbinol. From methyl pentanoate, a mixture of n-butyl-3-hydroxyl-1, 4-pentadiene and 5-oxo-1-nonene is obtained. While reaction of linear α, β-unsaturated methyl esters with vinylmagnesium chloride yields vinylketones as the main product, the reaction of substituted α, β-unsaturated methyl esters yields triethylenic carbinols. Reaction of acid anhydrides and dibasic acid diesters with vinylmagnesium chloride yields mixtures of alkenones, hydroxy-alkenones and alkenols as the main products. Reaction of acid chloride with excess vinylmagnesium chloride at -40°C to -45°C gives 2-allyl-1, 3-diketones. From propanoyl chloride, a mixture of 4-allylheptane-3, 5-dione (33% yield), 6-heptene-3-one (0.5% yield) and 3-ethyl-1, 4-pentadiene-3-ol (2% yield) is obtained. Reaction of vinylmagnesium chloride with a fatty acid methyl ester in the presence of cuprous chloride gives a 1, 6-diketone. From methyl n-valerate, a mixture of n-tetradecane-5, l0-dione and 5-oxo-1-nonene is obtained.

Here the authors report a catalytic, enantioselective [4+2] cycloaddition of o-quinones with chiral 1-ammonium enolates generated in situ from the reaction of acid chlorides with a cinchona alkaloid based catalyst and Hünig’s base. The cycloadducts are converted into chiral α-hydroxyesters in a two-step alcoholysis/oxidation sequence with full preservation of optical purity. With 10 mol% of the catalyst 1, high yields and excellent enantioselectivities are obtained for different aliphatic and aromatic acid chlorides.

3,5-Disubstituted 1-methyl-1H-1,2,4-triazoles and -pyrazoles were obtained in good to moderate yields by the reaction of N-methyl-N-(phenylsulfonyl)benzohydrazonoyl chloride with nitriles and with acetylenes in the presence of aluminum chloride. The triazoles were also formed by the reaction of acid chlorides with N-methyl-N-(phenylsulfonyl)benzamidrazone which was generated from the hydrazonoyl chloride and ammonia.

Radical reactions mediated by Schwartz reagent and zirconocene(alkene) complex are firstly described. Schwartz reagent is a promising alternative to tributyltin hydride and the first transition metal hydrido complex used as a radical mediator in organic synthesis. A zirconocene(alkene) complex effects single electron transfer to alkyl halide to generate the corresponding alkyl radical. Secondly, serendipitous allylic C-H bond activation of the coordinating alkene of zirconocene(alkene) complex and its application to organic synthesis are summarized. By utilizing equilibrium between zirconocene(alkene) and zirconocene 2-alkenyl hydride, reaction of acid chloride with zirconocene(alkene) provides the corresponding homoallylic alcohol by sequential attacks of the hydride and 2-alkenyl moieties. A set of hydride and 2-alkenyl attacks on 1,4-diketone yields 6-heptene-1,4-diol derivative in high yield with high stereoselectivity. Selective capture of the hydride with diisopropyl ketone gives zirconocene 2-alkenyl alkoxide, which is a useful reagent for stereoselective allylation of aldehyde and imine. alpha-Halo carbonyl compounds undergo radical allylation with the zirconocene 2-alkenyl alkoxide which serves as a substitute for allyltin.

Hexafluoroacetone as Protecting Group and Activation Reagent in Amino Acid and Peptide Chemistry, 7. – Synthesis of γ‐Oxo α‐Amino Acid Derivatives from Aspartic AcidOptically pure γ‐oxo α‐amino acids are obtained on reaction of acid chloride 2 with aromatic and heteroaromatic compounds under Friedel‐Crafts conditions.

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Die Säurechloride bzw.Thioester (I) reagieren mit den Aluminiumalkylen (II) in guten Ausb. zu den Ketonen (III).

The polymerization of 2‐pyrrolidone (1) initiated with its potassium salt (2‐oxo‐1‐pyrrolidinylpotassium) (2) and accelerated by the presence of CO2, was investigated. For the optimal concentration of 2 (≈5 mol‐%) and 0,5 mol‐% CO2, the most suitable polymerization temperature was found to the range between 45 and 55°C. The variation of CO2 concentration, 0,5 < [CO2] < 3 mol‐%, does not affect the polymerization yield under the optimal conditions. The similarity of the course of polymerization in the presence of CO2 directly introduced into the reaction mixture with that in the presence of isolated carboxylate of 1, is considered as a proof that CO2 is transformed into the active potassium carboxylate of 1. The order of polymerization reaction with respect to initiator was found to be ≈0,8 indicating the complexity of the reaction mechanism.

Phase change materials (PCMs) have been integrated into clothing and textiles to provide added value in terms of thermoregulation and thus added comfort to the wearer in intensely hot and cold weather conditions. Since clothing is laundered several times during the service life of the textile, the effects of simulated domestic laundering on the physical and thermal properties of a non-woven textile that contains PCMs were investigated. The thermal properties, such as the thermal degradation, melting, evaporation, and crystallisation were measured by the Thermal Gravimetric Analysis (TGA) and the Differential Scanning Calorimetry (DSC) analytical techniques. The physical properties, such as the microcapsule size distribution, and the microcapsule morphologies of the PCM microcapsules, were measured by the Scanning Electron Microscopy (SEM) and Raman analytical techniques. The primary objective of this study is to determine the effect of repeated laundering at different wash temperatures.

Thermal behavior and degradation mechanisms of three polyester resins, namely bisphenol A based, isophthalic acid based, and general purpose were studied. These resins were cured with styrene in the presence of benzoyl peroxide (BPO) and methyl ethyl ketone peroxide (MEKP) as initiators. The cured resins were studied by thermogravimetric analysis and mass spectrometry. From the thermogravimetric data it was observed that the cured bisphenol‐A‐based polyester resin was thermally more stable than the cured isophthalic acid‐based and general purpose polyester resins. It was also observed that polyester resins cured with MEKP are thermally more stable than benzoyl peroxide‐cured products. Thermogravimetric analysis data shows that there are two first‐order degradation reactions during thermal degradation in nitrogen atmosphere. The first degradation step involves the scission of cross‐links/weak links with the liberation of free linear chains. The second step involves a random scission of the free linear chains into smaller fragments. The framentation patterns of the polyester resins were identified by mass spectrometery. Possible mechanisms for the degradation of the cured polyesters accounting for the experimental observations are discussed.

ABSTRACTThe effect on the physical properties and solubility of corn protein (zein) films was studied after reaction of zein with polyethylenemaleic anhydride (PEMA). Reactions were carried out in dimethylformamide (DMF) solution where the concentration of PEMA was varied between 0 and 6%. After reaction at room temperature, cast films were prepared, and the physical and solubility properties were determined. Incorporating more than 2% PEMA provided films with increased tensile strength and elongation. Incorporating 6% PEMA provided films with higher tensile strength (32–42 MPa) and improved solvent resistance (100–21% solubility) relative to control. If the films were heated in an oven, the film's solubility decreased further. Solution rheology experiments demonstrated that the zein and PEMA formed a cross‐linked gel with time in DMF. Dynamic mechanical analysis experiments have shown that the PEMA‐modified zein films undergo a dramatic loss in modulus on reaching 116°C, whereas the control experiences this loss at 98°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40122.

Effect of electron beam irradiation and degree of boric acid loading on the properties of styrene-butadiene rubber

Polymer biocomposites are sustainable and environmentally friendly materials that can be applied to the building, furniture, aerospace, and automotive industries. In this study, biocomposites made of coconut shell-reinforced epoxy resin were prepared and characterised. Initially, the coconut shells were 200 mesh. Then, they were milled by using a ball mill for 10, 20, 30, and 40 h. The biocomposites were manufactured by using a compression method while keeping a constant ratio of filler and matrix at 85 vol.%: 15 vol.%. The effects of ball milling duration on the thermal degradation and physical properties of biocomposites were examined. The thermal degradation of coconut shell biocomposite occurred at 250 – 400 °C. Its thermal degradation temperature increased with the increasing milling times. The density of the coconut shell biocomposite was 1.087 g/cm3 for 0 h (without milling the fillers). Its density increased to 1.248 g/cm3 for 40 h of milling duration. Meanwhile, the porosity of coconut shell biocomposite decreased from 17.5% (0 h milling duration) to 12.1% (40 h milling duration). It was found that there was a correlation between thermal degradation and physical properties (density and porosity). This study revealed that the thermal degradation and physical properties of the biocomposites can be enhanced by decreasing the size of the fillers.

Petroleum-based plastics are mass produced to meet customers’ demand due to their low cost and versatility. However, plastic waste has become a serious environmental problem. Hence, degradable plastics from renewable sources (e.g. biomass) are now trending for their “green” properties. In this paper, properties of biofilms made from whole seaweed (WS), Kappaphycus sp. and pure kappa-carrageenan powder (PC) were compared. Glycerol, as plasticizer, was added at differing amounts (1%, 2%, 3%, 4% and 5%, v/v) and their appearance, physical and mechanical properties, solubility, and biodegradability were studied. As results, for colour difference and transparency, WS-1% showed higher ?E at 17.09 ± 0.85 with highest opacity at 13.73 mm-1 and least ?E was at 2.73 ± 0.13 for PC-5% with opacity at 0.49 mm-1. For mechanical properties, PC-1% has the highest tensile strength and elastic modulus at 26.63 ± 2.18 MPa and 253.53 ± 19.43 MPa, respectively, whereas WS-5% has the lowest at 0.71 ± 0.15 MPa and 2.47 ± 0.44 MPa, respectively. As for biodegradability, by the first week, WS-5% lost 80% of its weight and PC-1% only lost 3%. Overall, PC biofilms showed better quality in terms of mechanical and physical properties but WS biofilms were faster to degrade and dissolve in water. Glycerol concentration affects most of the properties except for mechanical properties for WS and solubility of both. This study suggests that PC may be a better base material for stronger biofilms but WS are a better choice from environmental and cost aspects.

It was demonstrated that non‐homopolymerizing derivatives of 6‐caprolactam: 7‐cyclohexyl‐1‐aza‐2‐cycloheptanone (I) and 7‐isopropyl‐5‐methyl‐1‐aza‐2‐cycloheptanone (II) were polymerizing with 6‐caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).