The review focuses on the methods of synthesis of 2-(1-alkoxyalkylidene)-1,3-dicarbonyl compounds and their chemical transformations. The reactivity of such compounds toward various mono- and dinucleophilic reagents is considered. The potential of these compounds for synthesis of different acyclic, carbo- and heterocyclic molecules is demonstrated. Special attention is paid to the practical use of 2-(1-alkoxyalkylidene)-1,3-dicarbonyl compounds and their derivatives, which are of interest in medicine and for design of new materials. The bibliography includes 226 references.

The use of 2-(1-alkoxyalkylidene)-1,3-dicarbonyl compounds in organic synthesis

Abstract Thermosetting polymers have higher heat resistance, chemical resistance, mechanical characteristics and structural integrity than thermoplastic polymers due to their three-dimensional networks of covalent bonds. The current status and challenges in the field of thermosetting polymer modified asphalts are reviewed in this article. Firstly, classification and application of thermosetting polymers are briefly introduced, and modification approaches of polymer modified asphalts are compared. Crucial factors in selecting polymers for asphalt modification are then analyzed. Further, the cure mechanisms, preparation methods and properties of thermosetting polymers, including epoxy resin, polyurethane, polyurea, unsaturated polyester resin, phenolic resin, furan resin and amino resin, for asphalt modification are discussed. Especially, the effect of components of epoxy resin and polyurethane on the properties of modified asphalts is described. To develop eco-friendly and sustainable asphalt materials, this article also reviews the use of bio-based thermosetting polymers, including epoxy resin, polyurethane and phenolic resin, in asphalt modification. Finally, self-healing and recyclable thermosetting polymer modified asphalts are highlighted as promising solution to the challenges of healability and recyclability of thermosetting polymers in asphalt modification after long-term service.

Thermosetting Polymer Modified Asphalts: Current Status and Challenges

A series of novel 3-[4-phenyl-1-piperazinyl]-1-[5-methyl-1-(2-pyrimidinyl)-4-pyrazolyl]-1-trans-propenes and related compounds were synthesized and evaluated by their cytotoxic activity against several tumor cell lines in vitro and in vivo antitumor activity against some tumor models when administered both intraperitoneally and orally. Compounds with the 3-chloropyridin-2-yl group (9g) and the 3-fluoro-5-substituted phenylpiperazinyl group (29b, c, and e) showed significantly potent cytotoxicity by in vitro testing. Among them, the 3-cyano-5-fluorophenyl derivative (29b) exhibited potent antitumor activity against several tumor cells including human carcinoma without causing undesirable effects in mice.

Synthesis and Antitumor Activity of Novel Pyrimidinyl Pyrazole Derivatives. III. Synthesis and Antitumor Activity of 3-Phenylpiperazinyl-1-trans-propenes

Graphene oxide (GO) with 0.2, 0.5, and 1.0 wt% loading was used to modify warm-mix epoxy asphalt binders (WEABs). The thermal stability, structure of GO, rotational viscosity-curing time performance, dynamic moduli, glass transitions, damping ability, mechanical performance, and phase-separated morphology of GO/epoxy asphalt composites were investigated in the laboratory. GO significantly enhanced the thermal stability of the pure WEAB. X-ray scattering analysis revealed that GO layers were delaminated in the epoxy asphalt binder. GO accelerated the cure reaction of the pure WEAB and thus resulted in higher rotational viscosity of GO/epoxy asphalt composites. Furthermore, the viscosity of the modified WEABs slightly increased in the GO content. GO increased the dynamic moduli and Tgs of both epoxy and asphalt for the pure WEAB. However, the damping ability of GO/epoxy asphalt composites was similar to that of the pure WEAB. Confocal microscopy observations revealed that GO was dispersed in both asphalt and epoxy phases of the phase-separated WEAB. The asphalt domains in the continuous epoxy phase became more spherical and uniform with the existence of GO. Moreover, the dispersion of epoxy in the discontinuous asphalt phase became more evident. The mechanical properties of the pure WEAB were greatly improved with the addition of GO. The tensile toughness and strength of the pure WEAB increased by 31% and 33%, respectively, with the addition of 0.2 wt% GO. 

Viscosity‐curing time behavior, viscoelastic properties, and phase separation of graphene oxide/epoxy asphalt composites

https://www.cup.uni-muenchen.de/ac/kluefers/homepage/publ_pdf/gottschaldt_2004.pdf

Binuclear copper(II) complexes of 5-N-(β-ketoen)amino-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranoses: Synthesis, structure, and catecholoxidase activity

The graphene oxide (GO) was used to improve the mechanical performances of epoxy asphalt (EA) by preparing GO/EA composite. The influence of the GO dosage on the micro-structure, curing rheology, mechanical and thermal properties of GO/EA was investigated. According to the XRD and Fourier transform infrared spectra, the GO was exfoliated in the EA matrix and modified EA by non-covalent strategy. GO decreased the rotational viscosity of EA and increased the pot life. The GO/EA with 0.1 wt.% GO showed excellent toughness that the elongation at break was increased by 164%, and the tensile and pull-off adhesion strength were nearly equal to that of EA. The addition of GO improved the original thermal decomposition temperature (T 5%), glass transition temperature (T g), compatibility and stiffness of the EA. The improved mechanical and thermal properties of GO/EA may be attributed to (1) excellent performances of GO and (2) inhibiting effect of GO on the EA curing process.

Enhanced mechanical performances of epoxy asphalt adhesives modified by graphene oxide

As a green material for high‐performance paving, cold‐mixed epoxy asphalt (CEA) should be improved in compatibility, mechanical performance, and thermal stability. This work is going to estimate the potential of graphene oxide (GO) as an additive for preparing GO/CEA composites with different GO content from 0 to 0.2 wt%. The influences of GO on the structure and performances of CEA were evaluated by Fourier transform‐infrared spectrum, fluorescence microscopy, viscosity, thermogravimetric analysis, tensile test, and dynamic mechanical analysis. Results showed that the functional groups on GO reacted with CEA and improved the compatibility of epoxy resin and asphalt. The viscosity of the GO/CEA composites increased slightly and the pot life decreased significantly, with GO loading increasing. The cured GO/CEA composite with 0.1 wt% GO had the best heat resistance and showed a gentle thermal decomposition. GO improved the toughness of the cured CEA and had a certain weakening effect on its strength. The introduction of GO lowered the glass transition temperature of the cured CEA from 51.4 to 47.1 °C and decreased its storage modulus. The preliminary exploration of this study shows that the modification of GO for CEA is feasible, and it is expected to prolong the service life of CEA.

Exploiting graphene oxide as a potential additive to improve the performance of cold‐mixed epoxy asphalt binder

5-(2-Methylthio-4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol was synthesized by asymmetric coupling, and the corresponding diacetylene monomers were also prepared in good yields. These monomers could be dissolved in common organic solvents. The monomers can be polymerized in the solid state using heat, light or γ-radiation. In addition, micro- and macroscopic third-order susceptibilities were measured by the degenerate four-wave mixing (DFWM) method for the yielded polymers.

Synthesis and solid-state polymerization of 5-(2-methylthio-4-methylpyrimidin-5-yl)penta-2,4-diyn-1-ol and of several of its derivatives

Biobased cold-mix epoxy asphalt (BCEA) was prepared by adopting biodiesel and epoxy soybean oil as asphalt solvent and compatibilizer. The strength and toughness attenuation laws under freeze–thaw (FT) cycles of BCEA were studied through tensile tests, flexural tests, and dynamic mechanical analysis. The attenuation mechanism was explored through scanning electron microscopy, Fourier transform infrared spectroscopy and water absorption tests. The results showed that the first FT cycle significantly weakened the strength and toughness of BCEA. After the third cycle, the attenuation rate of storage modulus, loss tangent, and glass transition temperature of BCEA declined. The attenuation mechanism of BCEA is as follows: (1) post-curing and destruction of the cross-linking network, (2) agglomeration and aging of asphalt, and (3) diffusion and reaction of water. This research provided a theoretical basis for the application of BCEA. 

Strength and toughness attenuation mechanism of biobased cold-mixed epoxy asphalt under freeze–thaw cycles

Cold-mixed epoxy asphalt (CEA) is an emerging energy-saving and environment-friendly material for steel bridge decks, overload roads, and airfield pavement. Occasionally, CEA suffers from impact with high strain rates, which will be extremely detrimental to the pavement’s safety and stability. Since little research deals with this dynamic mechanical behavior, this study aims to clarify the dynamic mechanical performance of CEA mixtures (CEAM) under high strain rates. First, this study evaluated the quasi-static strength evolution by Marshall stability tests. The Marshall stability of CEAM more than quadrupled within the first 20 h and 1.6 times up again when exposed at 60°C, while its flow value showed the opposite trend. Then, the dynamic mechanical behavior under different high strain rates and temperatures was investigated by split Hopkinson pressure bar tests. Results showed that the peak strain rate (146–316 s−1) was 1.7–2.0 times greater than the average strain rate (84–162 s−1). The strain–stress curves became steep as the temperature and the pressure ascended. Under the same test conditions, the peak stress and the peak dynamic modulus of CEAM were 1.7 times larger than that of cement concrete. CEAM absorbed more energy below 25°C than 60°C. All the CEAM had binder failure, and the crushed specimens had aggregates broken. The constitutive model of CEAM was established based on the statistical damage theory and the modified Weibull distribution function. Besides, multiparametric regression analysis proved a demarcation point during the impact. 

Dynamic Mechanical Behavior of Cold-Mixed Epoxy Asphalt under High Strain Rates

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