Low Solubility In Organic Solvents Research Articles

Methylated Biochemical Fulvic Acid-Derived Hydrogels with Improved Swelling Behavior and Water Retention Capacity.

Although humic acids (HAs) have been used to prepare absorbent hydrogels, their applications in many areas, such as agriculture, wastewater treatment and hygienic products, are not satisfactory due to their low solubility in organic solvents. In this work, biochemical fulvic acid (BFA), as a kind of HA, was initially methylated for preparation of the methylated BFA (M-BFA), which contributed to enhancing the solubility in organic solvents. Then, M-BFA reacted with N,N'-methylene diacrylamide (MBA) in the N,N-Dimethylacrylamide (DMAA) solution, and the expected hydrogel (M-BFA/DMAA) was successfully obtained. XPS confirmed that there were more C=O and C-N groups in M-BFA/DMAA than in DMAA; thus, M-BFA/DMAA was able to offer more reactive sites for the water adsorption process than DMAA. The combined results of BET and SEM further demonstrated that M-BFA/DMAA possessed a larger BET surface area, a larger pore volume and a more porous structure, which were favorable for the transfer of water and accessibility of water to active sites, facilitating water adsorption and storage. In addition, the swelling ratio and water retention were investigated in deionized (DI) water at different conditions, including test times, temperatures and pHs. Amazingly, the swelling ratio of M-BFA/DMAA was 10% higher than that of DMAA with the water retention time from 100 to 1500 min. Although M-BFA/DMAA and DMAA had similar temperature sensitivities, the pH sensitivity of M-BFA/DMAA was 0.9 higher than that of DMAA. The results proved that M-BFA/DMAA delivered superior water retention when compared to the pristine DMAA. Therefore, the resultant materials are expected to be efficient absorbent materials that can be widely used in water-deficient regions.

Low-temperature aerobic oxidation of alcohols to aldehydes over La1-xKxMnO3 nanofiber tubes: Issues on O2 adsorption and activation

Aerobic oxidation of alcohols to aldehydes is a green and prospective route to synthesize fine chemicals, but the high activation barrier and low solubility in organic solvents of O2 make this technology a challenge. Herein, we report an electrospinning synthesis of K doped LaMnO3 perovskite (La1-xKxMnO3), with nanofiber tube (NFT) structure, for efficient liquid-phase aerobic oxidation of alcohols to aldehydes at low temperature. The NFT structure improves the capacity of material to capture O2, the generated oxygen vacancy, caused by K doping, increases the sites to adsorb O2, and the evolved (110) lattice plane promotes the ability to activate O2. The optimized La0.95K0.05MnO3 shows above 93 % conversion and selectivity, even is conducted at 50 °C, for 3 h, which is the lowest temperature reported for aerobic oxidation of alcohols using noble metal-free catalysts. Simulated calculations suggest that the O-O bond can be automatically ruptured if O2 is adsorbed on the (110) lattice plane of the material.

The Preparation of Electrolyte Hydrogels with the Water Solubilization of Polybenzoxazine.

Polybenzoxazine (PBZ) exhibits excellent heat resistance, and PBZ derivatives have been designed and synthesized to achieve high performance. However, the application range of PBZ is limited by the strong interactions between molecular chains and its low solubility in organic solvents, thereby limiting its processability. This study focused on the benzoxazine structure as the molecular backbone of new hydrogel materials that can be applied as electrolyte materials and prepared functional gel materials. Here, we prepared hydrogels by water-solubilizing PBZ derivatives, which typically exhibit low solubility in organic solvents. Although studies on the hydrophilization of PBZ and its complexation with hydrophilic polymers have been conducted, no studies have been performed on the hydrogelation of PBZ. First, the phenol in the organic solvent-insoluble PBZ thin film obtained after the thermal ring-opening polymerization of the monomer was transformed into sodium phenoxide by immersion in a NaOH aqueous solution to water-solubilize it and obtain a hydrogel thin film. Although the hydrogel thin film exhibited low mechanical strength, a free-standing hydrogel film with improved strength was obtained through the double network gelation method with an acrylamide monomer system. The physical properties of the polymer composite hydrogel thin film were evaluated. The ionic conductivity of the hydrogel thin films was in the order of 10-4 S cm-1, indicating the potential of PBZ as an electrolyte hydrogel material. However, improving its ionic conductivity will be undertaken in future studies.

Exploring the coordination of peptide bonds towards beryllium with carboxamides, esters and ketones

AbstractTwo carboxamide complexes of BeCl2 with NH functions have been prepared and structurally characterized. Bis(2‐pyrrolidone) beryllium(II) chloride and bis(N‐phenyl acetamide) beryllium(II) chloride show extensive hydrogen bond networks in the solid state, which leads to low solubility in organic solvents. Related complexes bis(phenyl acetate) beryllium(II) chloride and bis(acetophenone) beryllium(II) chloride have also been prepared and structurally characterized. These lack hydrogen bonds in the solid state and are therefore highly soluble in chlorinated solvents.

Synthesis and ESR studies of multiphenyl porphyrins

The synthesis of tetra biphenyl and tetra triphenyl derivatives of porphyrin has been achieved with relative ease, and although the compounds show the expected low solubility in organic solvents, their tendency to form aggregates was observed. They are sufficiently dispersed to allow characterization by 1H, 13C, mass spectrometry, and determine their photophysical properties. The presence of 8 hydroxyl groups and 12 aromatic rings in the structure of the porphyrin showed to be able to stabilize the superoxide anion. This approach allows the possibility of using these compounds as building blocks and could be applicable to synthesizing other highly structurally uniform and well-defined porphyrin derivatives in good yields.

Chitosan as a Valuable Biomolecule from Seafood Industry Waste in the Design of Green Food Packaging

Chitosan is a versatile biomolecule with a broad range of applications in food and pharmaceutical products. It can be obtained by the alkaline deacetylation of chitin. This biomolecule can be extracted using conventional or green methods from seafood industry residues, e.g., shrimp shells. Chitin has limited applications because of its low solubility in organic solvents. Chitosan is soluble in acidified solutions allowing its application in the food industry. Furthermore, biological properties, such as antioxidant, antimicrobial, as well as its biodegradability, biocompatibility and nontoxicity have contributed to its increasing application as active food packaging. Nevertheless, some physical and mechanical features have limited a broader range of applications of chitosan-based films. Green approaches may be used to address these limitations, leading to well-designed chitosan-based food packaging, by employing principles of a circular and sustainable economy. In this review, we summarize the properties of chitosan and present a novel green technology as an alternative to conventional chitin extraction and to design environmentally friendly food packaging based on chitosan.

(Invited) Synthesis of Disilane-Bridged Aromatic Compounds for the Luminescent Materials

π-Conjugated molecules with electron-donating (D) and -accepting (A) groups such as D-π-A compounds have been focused on strong photo/electro-luminescent materials by intermolecular charge transfer (ICT). However, π-conjugated molecules cause concentration quenching due to π-π stacking in the aggregated state, and these compounds display the low solubility in organic solvents. To develop functional organic luminophores, we synthesized the disilane-modified aromatic compounds. Conformational studies were investigated by X-ray diffraction and variable-temperature NMR experiments. These molecules display high solubility derived from the suppression of intermolecular interaction by large SiMe2 moieties and stimuli-responsive emission properties from σ-π conjugation, displaying blue-green ICT emission in the solid state with higher quantum yield.

Evaluation of Lignins of Trunk and Roots from Citrus sinensis L. Osbeck: A Large Available Brazilian Biomass

Citrus biomass is a source of biobased products and presents extensive chemical diversity. Among the structural macromolecules, lignins have been used in resins, bioplastics, and nanoencapsulation. Brazil has a large source of lignins, which are orange trees removed from groves that need to be renewed. However, the knowledge about these lignins is limited and little explored. Thus, this work aimed to evaluate the lignins from Citrus sinensis and to provide information on the interesting use of orange trees as a source of macromolecules. The lignins were isolated from the trunk, central and secondary roots from the orange tree by Technical Association of the Pulp and Paper Industry (TAPPI)-methods. The lignin contents for the extractive-free samples were 19.8 ± 0.19, 21.9 ± 0.36, and 19.5 ± 0.41% (m/m) in the trunk, central and secondary roots, respectively. Infrared (IR) and 13C nuclear magnetic resonance (NMR) analyses confirmed typical bands and chemical shifts to syringyl and guaiacyl units. These results are consistent with the features of lignins previously reported for orange tree branches and hardwood roots. The greatest amount of lignin in the orange tree was found in the central root. The lignins extractive-free by TAPPI-T264 cm-97 presented low solubility in organic solvents, due to their compaction and folding, which was confirmed by 13C NMR in the solid-state, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

Synthesis and characterization of 5(6)-carboxyfluorescein-conjugated F127 and 10R5 copolymers as potential water-soluble fluorescence probes

Abstract In this work, a chemical data collections is regarding the synthesis, purification and characterization of water-soluble fluorescent probes based on (5)6-carboxyfluorescein (CF)-conjugated with normal and reverse triblock copolymers (F127 and 10R5). Due to the fact that F127 shows low solubility in organic solvents, most studies involve the removal of dicyclohexylurea (side product) using ether solution, resulting in an unclean material for to medicinal applications. In our study, cleaner purification protocols were performed by using dialysis and size-exclusion column chromatography (SEC) in a water medium for obtaining F127-CF and 10R5-CF copolymers with in good yields (80–85%). Proton nuclear magnetic resonance (1H NMR) was employed to confirm the chemical structures of the final products.

Optical and morphological properties and in silico studies on metallophthalocyanines containing pyridyloxy moieties

Metallophthalocyanines (M = zinc (II) and cobalt (II)) containing four 4-pyridyloxy -terminal groups were prepared by cyclotetramerization of 4-(4-pyridyloxy)phthalonitrile. The optimized geometry, electronic properties (chemical hardness, electron affinity, electronegativity), linear and nonlinear optical features of the phthalocyanine derivatives were investigated using density functional theory (DFT). The energy of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were calculated. The excitation features of electrons in the ultraviolet–visible (UV) region were computed with time-dependent density functional theory (TD-DFT). Thin films of these metallophthalocyanines which have low solubility in organic solvents have been prepared by spin coating after solution preparation by both magnetic stirring and ultrasonic treatment. Results showed that ultrasonic treatment increased the solubility of the compounds and better thin films were obtained.

Kinetics and Thermodynamics of Thermal Degradation of Different Starches and Estimation the OH Group and H2O Content on the Surface by TG/DTG-DTA.

The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats–Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The study also shows a proposed method for reactive hydroxyl groups content on the starch surface determination, and values were in range of 960.21–1078.76 mg OH per 1 g of starch. Thermal processing revealed the thermophysical properties of biomass for the kinetics of decomposition estimation. Activation energies reached the values in range of approximately 66.5–167 kJ·mol−1. This research also enables the determination of the temperature conditions required for becoming the desired form of material. Therefore, it is necessary to achieve the requested compact porous structure in an activation process, because in the native state, the polymer exhibits limited applications as a result of thermal decomposition, low shear stress, retrogradation, and syneresis, hence the low solubility in organic solvents. Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature.

Controlled Synthesis of Linear Polyamidoamino Acids.

Polyamidoamino acids (PAACs) are synthetic polymers prepared by the polyaddition of bisacrylamides with natural α-amino acids, which in the process maintain both their chirality and their amphoteric nature. This polymerization process is slow, but has the merits of taking place in water and of neither involving protection/de-protection steps nor releasing by-products. However, it leads to polydisperse polymers and, using α-amino acids mixtures, random copolymers. This paper presents a step-by-step polyaddition process leading to homo- and copolymeric PAACs with controlled sequences and controlled molecular weights. It exploits the much different rates of the two Michael addition steps of NH2 of α-amino acids with acrylamides, and the low solubility in organic solvents of the α-amino acid addition products. As a proof of principle, the controlled synthesis of the PAAC from l-arginine and N,N′-methylenebisacrylamide was performed up to a monodisperse product with 11 monomeric units and molecular weight 1840. This synthetic procedure was also tested with l-alanine. All intermediates were isolated and characterized. Noticeably, all of them were α,ω-difunctionalized with either acrylamides or sec-amines and were, in fact, building blocks with potential for preparing complex macromolecular architectures. In a first instance, copolymers with controlled sequences of amidoamine- and amidoamino acid units were prepared.

C2-Symmetric Chiral Squaramide, Recyclable Organocatalyst for Asymmetric Michael Reactions.

A very simple and highly efficient C2-symmetric tertiary amine-squaramide organocatalyst for asymmetric Michael reactions has been elaborated. In the presence of only 1 mol % of this catalyst, kojic acid derivatives and β-dicarbonyl compounds reacted with nitroolefins, affording the corresponding adducts in a nearly quantitative yield with an enantioselectivity up to 99% ee. The kojic acid-derived adducts could be efficiently produced under "green" conditions (in 96% EtOH or pure water). Moreover, due to the very low solubility in organic solvents, the developed nonsupported catalyst could be readily recovered and reused in catalytic reactions up to 7 times. Utmost availability (one-step synthesis without chromatographic purification), high level of stereoinduction, low efficient loading, and recyclability make it attractive for industrial application in the pharmaceutical industry.

Synthesis and Physical Characterization of β-Alkyl Oligoselenophenes

α-Conjugated oligoselenophenes are characterized by very low solubility in organic solvents. Their higher solubility may be achieved by introducing alkyl side chains into the β-positions of selenophene moieties. For the first time, β,β′-dihexyl sexiselenophene is synthesized according to the conventional approach. Physical and electrochemical studies of β,β′-dialkyl oligomers are analyzed and compared with corresponding thienyl oligomers.

NEW AROMATIC DINITRODERIVATIVES OF CHLORAL AS MONOMER FOR SYNTHESYS OF POLYESTER AND POLYHETERO-ARYLENE

The synthesis of aromatic dinitroderivatives of chloral effectively used in production of soluble, heat and fire resistant polyester and polyhetero arylenes using in the reaction of aromatic nucleophilic replacement was studied. The groups of new aromatic dinitroderivatives containing chloral as central groups between the phenyl nuclei: dichlorethelyne, carbonyl, acetylene and methylene groups were considered. The synthesis conditions were improved for polyester polyesterketones, polyesteretherketones, poliftalimides and polynaphtalamids without substantially affecting the thermal and solid characteristics achieved under relatively mild conditions using nucleophilic polynitro substitution. The search of new functional groups used in the condensation reactions, is an urgent task of polymer chemistry. Such groups must be determined by enough high reactivity of the monomers, without reducing their availability and without increasing their toxicity. It has decisive importance in the structure of initial monomers, which would be determined by the properties of polymers and the solubility of the target. In this aspect, dinitro compounds containing diphenyl, phthalimide and naftalimidnye cycles are presented their unique structures. It is known that improvement in meltability and solubility of the polymers without significant effect on the thermal and strength properties achieved by the introduction of these "carded" groups bulky substituents or phenyl phenoxide, flexible "bridge" fragments and introduced into the aromatic nuclei of the starting compounds bulk chlorine atoms. As part of this review it was made an attempt to describe methods of synthesis and properties of aromatic dinitropro- derivatives containing combinations of bulky substituents and flexible "bridged" groups using as initial compounds the simplest derivatives of chloral. The mostly known polyimides and polyetherimides prepared by reacting dianhydrides of aromatic tetracarboxylic acids with aromatic diamines with two-staged process where the first stage, a poly (o-carboxy) imides, and the second, due to thermal or catalytic imidization of polyamides with low solubility in organic solvents. It should be noted that the second stage -thermal or catalytic imidization not always results in a totally cycling polyamides that reduces the possibility of a relatively high molecular weight of polymers. At using aromatic dinitro- compounds containing a phthalimide and naftalimide cycles as comonomers bis-phenols, the problem of the extent of cyclization is absent. It was noted that an important determinant of obtaining high molecular weight of polymers is using nucleophilic polinitro-substitution in a process flow on the first stage under relatively mild conditions in a medium of DMSO or DMSO / toluene at 70 °C for 2 h in a completely dry environment. The review deals with some aspects of activation mechanism of nitro groups in nucleophilic polynitro-substitution. The processes of synthesis of condensation monomers of dinitro-derivatives using chloral were considered in detail. The methods of preparation and some properties of aromatic dinitroarilene, dinitroftalimide and dinitronaftalimide with dichlorethylenes, ketones, acetylene and methylene "bridged" groups between the phenyl nuclei are given. Forcitation:Kumykov R.M., Vologirov A.K. New aromatic dinitroderivatives of chloral as monomer for synthesys of polyester and polyhetero- arylene. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 4-14

(Invited) Modification of Lithium-Ion-Containing [60]Fullerene: Synthesis and Successful Preparation of Each [5,6]- and [6,6]-Isomer

Lithium-ion-containing [60]fullerene, Li+@C60, is a highly electron accepting material, which have been utilized in electron transfer chemistry, supramolecular chemistry, photovoltaics, singlet oxygen generation, and so on. Considering what chemical modification of fullerene has played in, that for Li+@C60 would be a significant step for further functionalization of this compound.[1-7] In addition, chemical modification of Li+@C60 can solve this compound's drawback of low solubility in organic solvents due to rock salt packing of [Li+@C60][PF6 –]. Li+@C60 was modified with diphenyl(diazo)methane as an easily available diazoalkane to obtain lithium-ion-encapsulated [5,6]- and [6,6]-diphenylmethano[60]fullerenes, Li+@C61Ph2. Successful separation of each [5,6]- and [6,6]-isomer was performed with a positive-ion exchange columns. Both [5,6]-open and [6,6]-closed structures of Li+@C61Ph2 were determined with X-ray crystallographic analysis. Figure 1

Poly(ionic liquid)-Mediated Morphogenesis of Bismuth Sulfide with a Tunable Band Gap and Enhanced Electrocatalytic Properties.

Conventional polymer additives have a substantial impact on synthetic inorganic chemistry, but critical shortcomings remain; for example, low solubility in organic solvents and potential thermodynamic aggregates. Poly(ionic liquid)s have now been used as efficient additives that enable a high level control of bismuth sulfide crystals with significant size and morphological diversities. The bismuth sulfides exhibit tunable band structure as a result of the quantum size effects. Moreover, poly(ionic liquid)s are able to couple with as-synthesized bismuth sulfides chemically and endow a modified surface electronic structure, which allows resultant products to possess outstanding electrocatalytic performance for water oxidation, although its commercial counterpart is catalytically inert.

Hydrodynamic properties and conformation of poly(3-hexylthiophene) in dilute solutions

Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb-shaped poly(3-hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm-like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain λ = 0.37 nm was determined experimentally. The following parameters of poly(3-hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) А = 6.7 nm and hydrodynamic diameter of a polymer chain d = 0.6 nm. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 875–883

Pd/PdO nanoparticles supported on carbon nanotubes: A highly effective catalyst for promoting Suzuki reaction in water

We report that the presence of PdO nanoparticles can enhance the catalytic performance of Pd catalyst for the Suzuki reaction in water. Heterogeneous Pd/PdO nanoparticles supported on multi-walled carbon nanotubes (CNTs), weakly oxidized multi-walled carbon nanotubes (WCNTs) and strongly oxidized multi-walled carbon nanotubes (SCNTs) catalysts are synthesized by a one-pot gas–liquid interfacial plasma (GLIP) method using Pd(NO3)2·2H2O as precursor. Among these synthesized catalysts, the Pd/PdO supported on WCNTs (Pd/PdO/WCNTs) catalyst exhibits the highest catalytic activity during the Suzuki reaction in water. Moreover, the Pd/PdO catalyst shows higher catalytic activity during the Suzuki reaction than Pd catalyst. The as-prepared catalyst displayed remarkable activity toward challenging substrates such as heteroaryl halides and ortho-substituted aryl halides as well as aryl chlorides using low Pd loading in good yields. Since the catalyst exhibits extremely low solubility in organic solvent, the product can be simply extracted with ethyl acetate while the catalyst remained in the aqueous phase. The catalyst can be simply and efficiently used for ten consecutive runs without significant decrease in activity.

A highly water-dispersible/magnetically separable palladium catalyst based on a Fe3O4@SiO2 anchored TEG-imidazolium ionic liquid for the Suzuki–Miyaura coupling reaction in water

A novel ionic liquid functionalized magnetic nanoparticle was prepared by anchoring an imidazolium ionic liquid bearing triethylene glycol moieties on the surface of silica-coated iron oxide nanoparticles. The material proved to be an effective host for the immobilization of a Pd catalyst through a subsequent simple ion-exchange process giving a highly water dispersible, active and yet magnetically recoverable Pd catalyst (Mag-IL-Pd) in the Suzuki–Miyaura coupling reaction in water. The as-prepared catalyst displayed remarkable activity toward challenging substrates such as heteroaryl halides and ortho-substituted aryl halides as well as aryl chlorides using very low Pd loading in excellent yields and demonstrating high TONs. Since the catalyst exhibited extremely low solubility in organic solvent, the recovered aqueous phase containing the catalyst can be simply and efficiently used in ten consecutive runs without significant decrease in activity and at the end of the process can be easily separated from the aqueous phase by applying an external magnetic field. This novel double-separation strategy with negligible leaching makes Mag-IL-Pd an eco-friendly and economical catalyst to perform this transformation.