Dioxane Solution Research Articles

Extraction and characterization of lignins from maize stem and sugarcane bagasse

AbstractLignins were isolated from maize stem and sugarcane bagasse by using mild dioxane or acidic dioxane solution. The result of nitrobenzene oxidation of the isolated lignins shows that there is a high proportion of p‐hydroxyphenyl alcohol in the lignins of maize stem and sugarcane bagasse. The lignins isolated from maize stem and sugarcane bagasse have relatively same value of the weight‐average (Mw = 3405–3868 g mol−1) and number‐average (Mn = 1411–1612 g mol−1) molecular weights, and polydispersity (Mw/Mn = 2.24–2.51). Acidic dioxane treatment did attack the β‐aryl ether structures in lignins, in particular for β‐aryl syringyl ethers, and broke the ester bonds between arabinose and ferulic acid that etherified to lignins, and it also cleaved lots of bonds in hemicellulosic polymer. The proportion of β‐O‐4 (threo) guaiacyl units is higher than that of β‐O‐4 (erthreo) guaiacyl units. The phenyl glycoside and benzyl ether linkages between lignin and hemicelluloses are also demonstrated in NMR analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

HX Addition and Photochemical H2 Elimination by Ni NHC Complexes

Ni(H)(X)(IMes)(2) was prepared by the addition of HX to Ni(IMes)(2) (X = Cl, Br; IMes = 1,3-dimesitylimidazol-2-ylidene). Ni(H)(Cl)(IMes)(2) (1) was isolated from the reaction mixture of Ni(IMes)(2) and 2 equiv of 2,6-lutidine·HCl. Ni(H)(Br)(IMes)(2) was prepared in a similar way. Although treatment of Ni(IMes)(2) with a HCl·dioxane solution gives rise to a mixture of 1, NiCl(2)(IMes)(2), and NiCl(IMes)(2), 1 was not isolable from the mixture. All three complexes cocrystallized. Photolysis of these nickel hydrides activates their Ni-H bonds by populating Ni-H σ* orbitals, which results in the formation of H(2). Treatment of 1 with HCl·dioxane gives rise to H(2) and NiCl(2)(IMes)(2).

Novel linear fluoro-silicon-containing pentablock copolymers: synthesis and their properties as coating materials

A series of linear fluorosilicone pentablock copolymers consisting of poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA) and poly(dodecafluoroheptyl methacrylate) (PDFHM), named as PDMS-b-(PMMA-b-PDFHM)2, have been synthesized by ATRP and their thermal properties, self-assembly behavior in different solutions and surface features of films have been systematically investigated. TGA measurements reflect that the thermal stability of PDMS-b-(PMMA-b-PDFHM)2 is enhanced by the middle-block PDMS. TEM observation and DLS analysis reveal that PDMS-b-(PMMA-b-PDFHM)2 is able to self-assemble into unimers in both chloroform and dioxane solutions, and spherical micelles with a core–corona structure in chloroform, oblate spheroidal micelles with a multilayer core–corona structure in dioxane. The diameters of micelles in the dioxane solution are larger, while the concentrations of unimers in the chloroform solution are higher. SCA, QCM-D and XPS measurements have confirmed that the unimers play a dominant role in governing the surface properties of PDMS-b-(PMMA-b-PDFHM)2 films. In the case of PDMS-b-(PMMA-b-PDFHM)2 with a PMMA/PDMS weight ratio of 10 : 1 and 20%wt of DFHM content, the film cast from chloroform solution has a lower surface free energy of 16.8 mN m−1, lower adsorbed amounts of 8.6 × 104 ng cm−2 for water and 6.6 × 104 ng cm−2 for hexadecane, and higher surface stability. Such excellent thermal and surface properties demonstrate that this novel pentablock copolymer PDMS-b-(PMMA-b-PDFHM)2 is a promising candidate as a coating material.

Conformational, optical, and electrooptical properties of cellulose pelargonates in solutions

Newly prepared cellulose pelargonate samples of various molecular weights were studied in dioxane and chloroform solutions by isothermal translation diffusion, high-speed sedimentation, flow birefringence (Maxwell effect), electric birefringence (Kerr effect), and viscometry. The conformational, hydrodynamic, optical, electrooptical, and dynamic characteristics of the polymer were determined.

The Synthesis of Phenol–formaldehyde Copolymers Based on Phthalide-containing Monophenol

Phthalide-containing monophenol 3-phenyl-3-(41-hydroxyphenyl)phthalide (I) was synthesised by the interaction of o-benzoylbenzoic acid chloride with phenol in a dioxane solution in the presence of catalyst ZnCl2. Resol-type phenol-formaldehyde cooligomers and heat-resistant polymers based on them were obtained by the interaction of a mixture of the synthesised monophenol and phenol in different weight ratios (from 5:95 to 40:60).

Preparation of high molecular weight polybenzoxazine prepolymers containing siloxane unites and properties of their thermosets

AbstractHigh‐molecular‐weight polybenzoxazine prepolymers containing polydimethylsiloane unit in the main‐chain have been synthesized from α,ω‐bis(aminopropyl)polydimethylsiloxane (PDMS) (molecular weight = 248, 850, and 1622) and bisphenol‐A with formaldehyde. Moreover, another type of prepolymers was prepared using methylenedianiline (MDA) as codiamine with PDMS. The weight average molecular weight of the obtained prepolymers was estimated from size exclusion chromatography to be in the range of 8000–11,000. The chemical structures of the prepolymers were investigated by 1H NMR and IR analyses. The prepolymers gave transparent free standing films by casting their dioxane solution. The prepolymer films after thermally cured up to 240 °C gave brown colored transparent and flexible polybenzoxazine films. Tensile test of the films revealed that the elongation at break increased with increasing the molecular weight of PDMS unit. Dynamic mechanical analysis of the thermosets showed that the Tgs were as high as 238–270 °C. The thermosets also revealed high thermal stability as evidenced by the 5% weight loss temperatures in the range of 324–384 °C from thermogravimetic analysis. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

ChemInform Abstract: Kinetics of Aminolysis of Some Benzoyl Fluorides and Benzoic Anhydrides in Non-hydroxylic Solvents

The kinetic form of the spontaneous aminolysis of benzoyl fluorides in non-hydroxylic solvents is unlike that reported for the other benzoyl halides but is similar to that found for the aminolysis of esters. Variations on the mechanisms currently advocated for ester aminolysis are suggested for the benzoyl fluoride reactions. Tetrahedral intermediates are likely, but their rate-determining breakdown to products may involve a simultaneous proton transfer to the leaving fluoride ion. The kinetic behaviour differs from that found for aqueous solutions. The kinetics of the spontaneous aminolysis of benzoic anhydrides by primary amines, and by morpholine, in dioxane solution are first-order in each reagent over a wide amine concentration range, but the aminolysis by imidazoles involves also an important kinetic term second-order in amine. The mechanistic implications are discussed. Again the observations differ from some of those reported for aqueous solutions. For aminolyses of a variety of acylating agents, kinetic observations using non-hydroxylic solvents show that the easier it is for the leaving group to depart, owing to the structure of the acylating agent and/or that of the attacking amine, the less important become paths involving two or more amine molecules, but that such paths are generally more important than they are in hydroxylic solvents.

New method for preparation of hydrophobic interaction chromatographic stationary phases based on polymer‐grafted silica and their chromatographic properties

AbstractA new “grafting to” method for the preparation of polymer‐grafted silica hydrophobic interaction (HIC) packings was used in following steps. Firstly, 3‐mercaptopropyltrimethoxysilane was bonded on silica to obtain SH‐group modified silica. Secondly, glycidylmethacrylate (GMA) was coated on the surface of SH‐silica to obtain polymer‐grafted epoxide‐silica. Finally, the polymer‐grafted epoxide‐silica was dispersed in polyethylene glycol of dioxane solution to produce HIC stationary phase. The prepared HIC packings have advantages for biopolymer separation, high column efficiency and good resolution for proteins. The dynamic protein loading capacity of the synthesized packings was 36.0 mg/g. Six proteins were fast separated in less than 12.0 minutes using the synthesized HIC stationary phases. Then the stationary phase was evaluated in detail to determine the effects of pH of mobile phase, concentration of ammonium sulfate and the temperature on the retention of proteins. The thermodynamic parameters of these proteins are consistent with the entropically driven nature of hydrophobic interactions, The HIC column was used for purification of trypsin from a crude extract solution with only one step. The purity of the purified trypsin was more than 95%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Structure of the cobalt complexes with the Schiff base of salicylaldehyde and lysine according to the H NMR spectroscopic data

The Co(II) complex with the Schiff base of salicylaldehyde and lysine is studied by the 1H NMR method in dioxane and dimethyl sulfoxide (DMSO) solutions. In a dioxane solution, the complex is paramagnetic and dimeric. In the dimer, the cobalt ion coordinates two ligand molecules and each ligand is bound to two cobalt ions. In a water-containing DMSO solution, the complex is diamagnetic due to the oxidation of Co2+ to Co3+.

Development of layered porous poly(l-lactide) for bone regeneration

Biodegradable porous materials called scaffold have been used for cell culture in tissue engineering. Poly(L-lactide) (PLLA) and poly(e-caprolactone) (PCL), typical biodegradable polymers, have been considered as the candidates for polymeric scaffolds [1–7]. These scaffolds should have proper mechanical properties comparative to target tissues to be regenerated. For example, scaffolds for bone tissue may need to have much higher mechanical properties than for softer tissues. However, such polymeric scaffolds have much lower mechanical properties than bone tissue, and may easily be collapsed when implanted into damaged part of bone tissue. In this study, therefore, layered structure was introduced to improve the mechanical properties of porous PLLA scaffold. In this newly developed structure, a porous core region is surrounded by a solid layer that works as load bearing structure. This kind of layered structure is very similar to the bone structure in which porous cancellous bone is surrounded by cortical bone. Porous structure of PLLA was fabricated by the solid– liquid phase separation and freeze-drying methods [6, 8]. In the first process, PLLA pellets were dissolved in 1,4-dioxane to make 3 and 7 wt% solutions. These solutions were then filled into a test tube in which a PLLA film with a thickness of 250 lm was inserted. The PLLA dioxane solutions in test tubes were cooled from the bottom surfaces at a constant rate by using liquid nitrogen to induce solid–liquid phase separation. The phase-separated samples were then dried under vacuum at -5 C for about 1 week to remove the solvent completely. Cylindrical samples were obtained and then trimmed to be a cylinder with 8.5 mm diameter and 11 mm length. For each of the samples, the diameter and length were measured at three different positions and averaged values were then used to estimate the volume of the cylinder. The density of the sample was evaluated from the volume and weight. Porosity (volume fraction of pores) of the scaffold was then estimated from the densities of PLLA solid and the scaffold. Compression tests of the scaffolds were performed using a conventional mechanical testing machine at a loading rate of 1 mm/min. Five specimens were tested for each of the samples. Elastic moduli were then estimated from the initial slope of the stress–strain curves. Compressive strength values were also evaluated at the critical points where the stress–strain curves reached the first inflection points that corresponded to the end of elastic deformation behavior. A field-emission scanning electron microscope (FE-SEM) was also used to observe the microstructures of the porous samples and the deformation behavior of the porous samples at the critical point. FE-SEM microphotographs of the monoand layeredstructural scaffolds made from 3 wt% solution are shown in Fig. 1. The mono-structure shows homogeneous distribution of pores with larger holes that are produced by solvent exhaust. It is seen that the solid layer is firmly connected to the porous core region. For the 3 wt% scaffolds, the range of pore size is about 10–100 lm, and for the 7 wt%, the range is 10–55lm. The size of solvent exhaust hole is 90–120 lm. The porosity values of the scaffolds are shown in Fig. 2. The porosities tend to decrease with increase of PLLA concentration. The porosities of both mono-scaffolds are much higher than J.-E. Park Interdisciprinary Graduate School of Engineering and Sciences, Kyushu University, 6-1 Kasuga-koen, Kasuga 816-8580, Japan

Macromol. Biosci. 2/2010

Cover: Highly perfusive 3D scaffolds were prepared by thermally induced phase separation starting from poly(L-lactic acid)/dioxane solutions. Mesenchymal stem cells were vacuum seeded deeply and uniformly into the bio-support taking advantage of the remarkably interconnected branched porosity, allowing for the development of a thick proto-tissue after 14 days in vitro. Further details can be found in the article by C. Mandoli, B. Mecheri, G. Forte, F. Pagliari, S. Pagliari, F. Carotenuto, R. Fiaccavento, A. Rinaldi, P. Di Nardo, S. Licoccia, and E. Traversa* on page 127.

Complexation of metal ions with double-armed diazadithia lariat ether carrying anthracene moieties in acetonitrile–dioxane

A new 14-membered crown ether with nitrogen–sulfur donor atom carrying two anthryl groups was designed and synthesized by the reaction of the corresponding macrocyclic compound and 9-(chloromethyl) anthracene. The influence of metal cations such as Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ on the spectroscopic properties of the ligand was investigated in acetonitrile–dioxane solution (1/1) by means of absorption and emission spectrometry. The results of spectrophotometric titration experiments disclosed the complexation stoichiometry and complex stability constant of the novel ligand with Fe2+, Fe3+, Al3+, Cd2+, Cu2+, Zn2+, Pb2+ and Hg2+ cations. Absorption spectra show isobestic points in the spectrophotometric titration of these cations. The presence of excess of Al3+, Zn2+, Fe2+, Fe3+, Co2+, Ni2+, Mn2+, Cu2+, Cd2+, Hg2+ and Pb2+ cations caused an enhancement of anthryl fluorescence. Especially, the enhancement in case of the interaction of Hg2+ and Al3+ cations with the ligand was pronounced.

Syntheses and characterization of coordination compounds of N-(2-mercaptoethyl)-4-(3' -carboxy-2' -hydroxyphenyl)·2·azetidinone

A dioxane solution of N-(2-mercaptoethyl)-3-carboxy-2-hydroxybenzylideneimine, LH 3 (I) on reacting with chloroacetyl chloride in the presence of triethylamine, undergoes cyclization to form N-(2-mercaptoethyl)-4-(3'-carboxy-2'-hydroxyphenyl)-2-azetidinone, L'H 3 (II). A MeOH solution of L'H 3 reacts with Mn, Co II , Ni II , Cu II , II , II , Zr IV , MoO 2 2+ and UO 2 2+ ions to form the complexes [M(L'H).MeOH] 2 (where M = Mn, Co II or Ni II ), [Cu(L'H)] 2 , [M'(L'H)] (where M' = II , Cd, MoO 2 2+ or UO 2 2+ ) and [Zr(OH) 2 (L'H)] 2 . The compounds have been characterized on the basis of elemental analyses, molar conductance, molecular weight, spectral (IR, UV-Visible) studies and magnetic susceptibility measurements. L'H 3 behaves as a dibasic tridentate OON donor ligand in [Cu(L'H)] 2 , while it acts as a dibasic tetradentate OONS donor ligand in rest of the compounds. The complexes [M(L'H).MeOH] 2 (where M = Mn, Co II or Ni II ), [Cu(L'H)] 2 and [Zr(OH) 2 (L'H)] 2 are dimers, and the complexes [M'(L'H)] (where M' = Zn, Cd, MoO 2 2+ or UO 2 2+ ) are monomers. The dimeric complex [Cu(L'H)] 2 exhibits subnormal magnetic moment and is involved in antiferromagnetic exchange, while all other complexes are magnetically dilute. The octahedral structure for Mn II , Co, Ni II. MoO 2 2+ and UO 2 2+ complexes, square planar structure for Cu II complex, tetrahedral structure for Zn and Cd complexes, and pentagonal bipyramidal structure for Zr IV complex have been suggested.

Study Reactions of acetylenic amine N-Oxidewith reactive Halides

new acetylenic amine derived from cyclic secondary amines such as piperidine were synthesized , these amine were oxidized with m-chloroper benzoic acid to the corresponding N-Oxides. The acetylenic amine and its oxide were investigated through the study of their physical and chemical properties ,spectral analysis (IR and UV) in addition to the micro analysis of the elements(C.H.N). Aqueous hydrochloric and hydrobromic acids ethanolic hydrogen chloride from the monomeric halides(II) of the amine oxide. dioxan solutions of hydrogen chloride, hydrogen bromide and hydrogen iodide or aqueous hydro iodic acid yield the dimiric hydrohalides(III).The monomeric hydrochloride and hydro bromide are converted to the dimiric hydro iodide (IV) by treated with sodium iodide. Reaction of the amine oxide which is readily split by picric acid. A mechanism for the formation of all complexes (II-V) as well as an explanation for the formation of all types of hydro halides were presented .

Studies of viscosities of dilute solutions of alkylamines in non-electrolyte solvents: IV. Alkylamines in 1,4-dioxane and oxolane at 303.15 K

Viscosities η of dilute solutions of n-propylamine, n-butylamine, di-n-propylamine, di-n-butylamine, triethylamine, tri-n-propylamine, and tri-n-butylamine in 1,4-dioxane and oxolane (tetrahydrofuran) have been measured at 303.15 K. The specific viscosities ( η − η S o ) / η S o and viscosity deviations Δ η have been calculated. The values of ( η − η S o ) / η S o and Δ η for alkylamine solutions are negative in dioxane while positive in oxolane, and their magnitude increases with the increase in concentration of alkylamine. The values of excess Gibbs energy of activation Δ G* E of viscous flow, based on Eyring's theory of absolute reaction rates, are negative for alkylamine solutions in 1,4-dioxane, while positive for alkylamine solutions in oxolane solutions. The results have been analyzed in terms of Herskovits and Kelly equation and Nakagawa equation. The values of viscosity increment ν in Herskovits and Kelly equation and the coefficient B ′ int in Nakagawa equation are negative for the investigated alkylamine solutions in dioxane, while opposite is the case for oxolane.

3- exo- tet Cyclization of 2,2-disubstituted 1,3-dihalopropanes with indium in aqueous and ionic liquid solvent system

The 3- exo- tet cyclization of 2,2-disubstituted 1,3-dihalopropanes with In powder in THF solution of 20% H 2O, dioxane solution of 20% H 2O, and ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF 4, respectively, was efficiently carried out to form the corresponding 1,1-disubstituted cyclopropanes in good yields. The cyclopropanation of 2,2-disubstituted 1,3-dihalopropanes with In powder in ionic liquids, such as [bmim]Br, [bmim]Cl, and [bmin]BF 4, was markedly accelerated compared with that in a THF solution of 20% H 2O and a dioxane solution of 20% H 2O. The mechanism was proposed to involve the radical 3- exo- tet cyclization of the formed 3-halopropyl radical.

Pd-catalyzed amination in the synthesis of a new family of polyazamacrocycles containing 1,3-disubstituted adamantane moieties

Pd-catalyzed amination of a number of dihaloarenes with equimolar amounts of 1,3-bis(2-aminoethyl)adamantane in dilute dioxane solution provided one-step route to a new family of polyazamacrocycles with various cavity sizes containing one or several adamantane and aromatic fragments.

High quantum yield photoluminescence of new polyamides containing oligo‐PPV amino derivatives and related oligomers

AbstractThe synthesis and the chemical physical characterization of new photoluminescent (PL) chromophores and polymers are reported. Chromophores (oligo‐PPV symmetric derivatives ending with amino groups) are strong blue emitters with a PL quantum yield of ∼70% in dioxane solution. They have been used to prepare polyamides by reaction with aliphatic acyl dichlorides in which emitting and non emitting units are alternated. PL properties of the synthesized polyamides have been evaluated in solution and reveal a strong blue emission (PL quantum yield ∼60%), To increase the solubility of these systems, oligomers have been purposely prepared and then characterized. They show a peculiar white emission when excited in DMF solution; to get insight into this interesting behavior, asymmetric monoacetylated chromophores have been prepared as model compounds for the chromophoric end groups of the polyamide chains. The emission spectra of these compounds reveal a broad excimeric yellow emission which is responsible, along with the blue emission of the inner chromophoric units, of the overall white emission of the oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2677–2689, 2009

Inactivation Kinetics of β-N-Acetyl-D-glucosaminidase from Green Crab (Scylla serrata) in Dioxane Solution

β-N-Acetyl-D-glucosaminidase (NAGase, EC.3.2.1.52), which catalyzes the cleavage of N-acetylglucosamine polymers, is a composition of chitinase and cooperates with endo- chitinase and exo-chitinase to disintegrate chitin into N-acetylglucosamine (NAG). In this investigation, A NAGase from green crab (Scylla serrata) was purified and the effects of dioxane on the enzyme activity for the hydrolysis of p-Nitrophenyl-N-acetyl-β-D- glucosamin- ide (pNP-NAG) were studied. The results show that appropriate concentrations of dioxane can lead to reversible inactivation of the enzyme and the inactivation is classified as mixed type. The value of IC50, the dioxane (inactivator) concentration leading to 50% activity lost, is estimated to be 0.68%. The kinetics of inactivation of NAGase in the appropriate concentrations of dioxane solution has been studied using the kinetic method of the substrate reaction. The rate constants of inactivation have been determined. The results showed that k +o is much larger than k′ +o, indicating the free enzyme molecule is more fragile than the enzyme- substrate complex in the dioxane solution. It is suggested that the presence of the substrate offers marked protection of this enzyme against inactivation by dioxane.

A Contactless Impedance Probe for Simple and Rapid Determination of the Ratio of Liquids with Different Permittivities in Binary Mixtures

AbstractSimple contactless cells with planar or tubular electrodes have been designed for measurement of the permittivity of solutions. The cells, connected to an integrated circuit of astable multivibrator, respond primarily to the capacitance component of the cell impedance, the multivibrator frequency depends in a defined manner on the solution permittivity and is readily used as the analytical signal in determinations of the ratios of components in binary liquid mixtures; water solution of methanol, ethanol and dioxane have been tested. The response of the cell with planar electrodes satisfies well the simple theoretical model and both the cells provide results with a sufficient sensitivity, a low LOD value (units of %vol) and a good precision (around 1%rel). The cell simplicity, small dimensions, long‐term stability and the possibility of powering them from a battery make them suitable for hand‐held meters. As an example of application in practice, the content of ethanol was determined in the car fuel petrol.