Synthesis of ethyl alkylidene alpha cyanoacetates under ultrasound irradiation

Condensation of ketones with ethyl cyanoacetate catalysed by ammonium acetate-acetic acid results in ethyl alkylidene alpha cyanoacetate in 31-89% yield under ultrasound irradiation.     

A convenient one-pot synthesis of 3-amino-2, 5-dihydropyridazine and pyrimidine derivatives in the presence of high surface area MgO as a highly effective heterogeneous base catalyst

A new and efficient method for the preparation of 3-amino-2,5-dihydropyridazines from three-component reactions of (phenyl-hydrazono)-propan-2-one, aldehydes, and malononitrile or ethyl cyanoacetate in the presence of magnesium oxide (MgO) as a highly effective heterogeneous base catalyst is presented. Also, the three-component reactions of aldehydes, amidine systems, and malononitrile or ethyl cyanoacetate for the formation of 4-amino-5-pyrimidine carbonitrile and pyrimidinone derivatives, respectively, are investigated. The salient features of these methods include high conversions, short reaction times, cleaner reaction profiles, and the use of inexpensive and readily available catalyst.     

Synthesis of ethyl alpha-cyanocinnamates catalyzed by KF-Al2O3 under ultrasound irradiation

Knoevenagel condensation of ethyl cyanoacetate with aromatic aldehyde catalyzed by KF-Al2O3 in ethanol results ethyl alpha-cyanocinnamates in 97-99% yield under ultrasound irradiation.     

Synthesis of ethyl α-cyanocinnamates under ultrasound irradiation

Knoevenagel condensation of ethyl cyanoacetate with aromatic aldehydes catalyzed by pyridine results ethyl α-cyanocinnamates in 80–96% yields under ultrasound irradiation.     

Lipase-ultrasound assisted synthesis of polyesters

Poly (ethylene glutarate), poly (ethylene malonate) and poly (ethylene phthalate), were enzymatically synthesized by immobilized Candida antarctica lipase B in solvent free conditions. The synthesis of these polyesters was based on the ester-ester exchange reaction between ethylene glycol diacetate and di-ethyl glutarate, di-benzyl malonate, di-n-octyl phthalate to produce poly (ethylene glutarate), poly (ethylene malonate) and poly (ethylene phthalate), respectively. The effect of ultrasound and PET polymeric beads was evaluated and showed to improve the synthesis of all polyesters. Ultrasound, as a green solvent-free technology, showed high potentiality for the polyester synthesis intensification.     

Inhibition of the kinetics of chelation of nickel (II) with malonate ion by β-cyclodextrin

Relaxation times, determined by the pressure-jump technique, for the kinetics of chelation of nickel (II) by malonate ion are significantly prolonged by the addition of β-cyclodextrin to aqueous solutions.The effect is due to inclusion of the malonate into the β-cyclodextrin cavity. In fact addition of glucose in a 7:1 ratio to malonate ion does not affect the kinetics of complexation with Ni²⁺. The effect is also specific to the size of the ring since α-cyclodextrin and γ-cyclodextrin do not show any effect on the above relaxation times.The kinetic data are interpreted to indicate a competitive inhibition process. β-cyclodextrin is bound to the anion and prevents its chelation reaction with Ni²⁺. The mechanism treats the data quantitatively with an inclusion formation constant between malonate and β-cyclodextrin of the order of 10²M^?1.     

Ultrasound promoted synthesis of 2-aroyl-1,3,5-triaryl-4-carbethoxy-4-cyanocyclohexanols

Synthesis of 2-aroyl-1,3,5-triaryl-4-carbethoxy-4-cyanocyclohexanols from chalcones with ethyl cyanoacetate is carried out in excellent yields with KF/basic alumina as catalyst under ultrasound irradiation.     

A one-pot microwave-assisted synthesis of pyrido[2,3-d]pyrimidines

A high yield multicomponent reaction providing multifunctionalized pyrido[2,3-d]pyrimidines with up to four diversity centers in a one-pot microwave-assisted cyclocondensation of alpha,beta-unsaturated esters, amidine systems and malononitrile (or ethyl cyanoacetate) is described.     

The sonochemical arylation of malonic esters mediated by manganese triacetate

The intermolecular arylation of malonate esters in acetic acid solution in the presence of manganese(III) triacetate is known to proceed via an Electron Transfer mechanism. Under sonication, this reaction undergoes only minor changes. In contrast, the intramolecular reaction of dimethyl alpha-(3-phenylpropyl)malonate provides a new case of sonochemical switching, with the formation of compounds 7-9, while conventional thermal conditions generate only the bicyclic compound 6. Reactions using the more powerful oxidant, cerium ammonium nitrate are governed by the formation of the nitrate ester 11. Compounds 7-9 are isolated in yields lower than with MnTA, and in proportions depending on the conditions, thermal or sonochemical.     

Ultrasound-assisted one-pot, three-component synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones

Triethylamine was found to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-diones by one-pot reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in ethanol under ultrasonic irradiation. The advantages of this method are the use of an inexpensive and readily available catalyst, easy workup, improved yields, and the use of ethanol as a solvent that is considered to be relatively environmentally benign.     

吲哚喹嗪类化合物的1H NMR及立体化学研究

以对应的光学活性四氢β-咔啉在相转移条件下经Aldol缩合、脱水生成的光学活性吲哚喹嗪,与例如丙二酸二甲酯发生Michael加成时,显示高度的立体专属性。作为有广泛用途的建筑块,本文提供了六个代表性化合物的2D-NMR的同核二维相关谱(COSY)和同核欧沃豪斯谱(NOESY)。根据实验测得的NOE关系,满意地指定了化合物中新引人的手性碳的构型,借助分子模型,讨论了它们的构象及Michael反应的反应活性差异。     

The Michael reaction catalyzed by KF/basic alumina under ultrasound irradiation

The Michael reaction of chalcones as acceptors with various active methylene compounds such as diethyl malonate, nitromethane, cyclohexanone, ethyl acetoacetate and acetylacetone as donors catalyzed by KF/basic alumina results in adducts in high yield within a shorter time under ultrasound irradiation.     

Osmotic compressibility and correlation range of the system polystyrene-diethyl malonate very near its critical point

The angular dependence of the scattered light intensity was measured by use of a capillary cell for the system polystyrene-diethyl malonate very near its critical point. Multiple scattering was well eliminated and reliable light scattering data in the critical region were obtained.     

EPR study of radiation-induced radicals in glutaric and amino acid derivatives in solid state

Gamma radiation-induced radicals of 2-methylglutaric acid (2MG), diethyl amino malonate hydrochloride (DEAMHCl), ethyl malonate monoamide have been investigated at room temperature by the electron paramagnetic resonance technique. The type of radicals formed and their room temperature stability were evaluated. Three different radicals have been detected. The free radicals formed in compounds were attributed to the HOOCCH₃?CH₂CH₂ COOH, CH₃?HCO₂CHNH₂COCH₂CH₃ HCl and NH₂COCH₂COO?HCH₃ radicals, respectively. The results were found to be in good agreement with the existing literature data and theoretical predictions conformation.     

Infrared spectra of oxalate, malonate and succinate adsorbed on the aqueous surface of rutile, anatase and lepidocrocite measured with in situ ATR-FTIR

The adsorption of oxalate, malonate and succinate on anatase, rutile and lepidocrocite, was studied by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) at aqueous concentrations of 200 μM between pH 9 and 3. Clear spectral differences between the aqueous species and the surface adsorbed species for all three dicarboxylates are taken as strong evidence for inner-sphere adsorption. The characteristically different spectra on each oxide reveal surface specific interactions and could be used as a diagnostic tool, e.g., to probe the relative abundance of anatase and rutile on the surface of TiO₂ samples. Spectral changes between pH 7.0 and 3.0 show that two to three different surface complexes of oxalate and one to three surface complexes of malonate and succinate are formed on each of the three surfaces. While the exact structures of each complex can currently not be derived, important differences between the dicarboxylates can be identified. Only adsorbed oxalate exhibits two strong bands above 1670 cm⁻¹, as expected for a five- (bidentate chelating) or six-membered (bidentate bridging) ring structure with one oxygen of each carboxylic group coordinated to surface sites and two CO double bonds pointing away from the surface. The absence of clear CO double bond vibrations above 1620 cm⁻¹ show that malonate and succinate adsorb differently, with one or both of the carboxylic groups independently forming monodentate hydrogen bonded, bidentate chelating (four-ring) or bidentate bridging (five-ring) structures. Oxalate is the only one of the three dicarboxylates that formed additional surface complexes at low pH on rutile and anatase and lead to rapid dissolution of lepidocrocite below pH 5.0.     

Convenient synthesis of polyfunctional dihydrothiophenes with tandem reaction of 1,3-thiazolidinedione,aldehyde, arylamine and ethyl cyanoacetate

Abstract  

New, highly-functionalized dihydrothiophenes are conveniently synthesized from the novel tandem, four-component reactions of 1,3-thiazolidinedione, aldehyde, arylamine, and ethyl cyanoacetate, catalyzed by triethylamine. The reaction mechanism involves the use of Knoevenagel condensation, Michael addition, and ring-opening of 1,3-thiazolidinedione, followed by intramolecular ring closure process. The reaction is diastereoselective and only trans-2,3-dihydrothiophenes were produced in moderate yields. The functionalized dihydrothiophenes can be converted efficiently to the corresponding thiophenes by DCC dehydrogenation reaction.     

查尔酮及其与丙二酸二乙酯Michael加成产物的合成与光谱学性质

以取代苯甲醛和苯乙酮,用水作溶剂,以碳酸钠为催化剂,制备了一系列查尔酮化合物.将所得查尔酮与丙二酸二乙酯及碳酸钾置于玛瑙研钵中常温无溶剂研磨,得到相应的Michael加成产物.采用紫外光谱和红外光谱法对合成出的查尔酮化合物以及相应的查尔酮与丙二酸二乙酯的Michael加成产物进行了分析,研究不同取代基对紫外吸收波长和红...     

Knoevenagel reaction in water catalyzed by amine supported on silica gel

Summary An environmentally benign and sustainable Knoevenagel reaction of aldehyde with ethyl cyanoacetate has been achieved at ambient temperature in water employing 3-aminopropylated silica gel (NAP) as a catalyst. Wide applicability of the reaction is illustrated by the results that not only arylaldehydes of both electronic characters but also aliphatic aldehydes afforded the products. The reaction condition was so mild that aldehydes having acid- or base-sensitive substituents provided substituted α-cyano-α, β-unsaturated esters. The catalyst has been efficiently recycled more than five times without any pre-treatment. Catalyst loading was successfully reduced to 0.0029 mmol% (TON = up to 9,226). This protocol was also applicable to the Knoevenagel reaction of malononitrile in good yields in water.     

A simplified green chemistry approaches to synthesis of 2-substituted 1,2,3-triazoles and 4-amino-5-cyanopyrazole derivatives conventional heating versus microwave and ultrasound as ecofriendly energy sources

Cyanoacetamides 3 were prepared via reacting ethyl cyanoacetate with benzylamine. Yields and reaction times needed for reaction completion at room temperature, by microwaves (μω) heating and under ultrasound (US) irradiations are compared. The formed cyanoacetamides were coupled with aromatic diazonium salts and the formed arylhydrazones were used as precursors to title triazoles and pyrazoles via reacting the former with hydroxylamine and chloroacetonitrile. Yields of products formed via conventional heating are compared with those of μω and US irradiation.     

Thermal and dielectric studies of nickel malonate dihydrate single crystals

Single crystals of nickel malonate dihydrate were grown by the gel technique, employing the single diffusion method. Thermal dehydration of the crystal was investigated by thermogravimetric and differential thermal analyses. The title compound exhibits a steady thermal behaviour at higher temperature range of 350-800 °C. The dielectric properties of the prepared sample were analyzed as a function of frequency in the range of 1 kHz-1 MHz and at temperatures between 40 and 140 °C.