Synthesis,Characterization and Texture Observations of Calamitic Liquid Crystalline Compounds

Several divinylic mesogenic monomers were synthesized based on coupling the monomer 4-(4-pentenyloxy)benzoic acid with chlorohydroquinone, 2,5-dihydroxy- acetophenone, methylhydroquinone or 2-methoxyhydroquinone. This resulted in novel mesogens of phenylene esters with different lateral substituent groups. The effect of the lateral substituent group on the thermotropic phase behavior for these liquid crystalline compounds was investigated using DSC and optical polarized microscopy. All the mesogens proved to have a wide nematic liquid crystalline range. Only the phenylene ester, which has a methoxy lateral substituent, exhibited both nematic and smectic phases. Structural confirmation of all new derivatives was accomplished by ¹H- and ¹³C-NMR spectroscopic analysis, along with CH elemental analysis.     

Conversion of benzoic acid during TiO2-mediated photocatalytic degradation in water

The photocatalytic degradation of benzoic acid in water over Degussa P-25 TiO₂ suspensions was studied. UVA irradiation at 365 nm was supplied by a medium pressure mercury lamp providing 25 mW cm⁻² light intensity. Experiments were conducted at benzoic acid initial concentrations between 25 and 150 mg L⁻¹, catalyst loadings between 0.2 and 1 g L⁻¹ and initial solution pH values between 2 and 10.6. Conversion increased with increasing catalyst loading up to about 0.6 g L⁻¹ and it was favored at alkaline or neutral conditions but impeded at extremely acidic conditions. Increasing initial substrate concentration led to decreased benzoic acid conversion, which was found to follow a Langmuir–Hinshelwood kinetic expression. High performance liquid chromatography (HPLC) was employed to follow benzoic acid concentration profiles as well as to identify reaction by-products, while chemical oxygen demand (COD) and total organic carbon (TOC) analyses were carried out to assess the extent of mineralization. Benzoic acid hydroxylation by-products, namely 2-, 3- and 4-hydroxybenzoic acids as well as phenol were identified as reaction intermediates, although these contributed only a small fraction of the residual organic content. Although benzoic acid at 50 mg L⁻¹ was not ecotoxic to marine photobacteria Vibrio fischeri, its photodegraded solution exhibited substantial toxicity, which, however, proved not to be due to the identified intermediates.     

On the acidity of liquid and solid acid catalysts. Part 3. Esterification of benzoic and mesitoic acids

Methyl esters of benzoic and mesitoic acid have been prepared with high yields (>98 wt%) from the corresponding carboxylic acids + methanol in aprotic solvents over samples of H₂SO₄/SiO₂ at 60°C. The results show a high catalytic efficiency of the solids but also suggest an acid strength comparable to that observed in concentrated aqueous H₂SO₄ (range >90 wt%) when the acid requirements for the esterification of analogous compounds in aqueous acid solutions are taken into account. Indeed, different reacting species, i.e., ArC(OH) ₂ ⁺ from benzoic acid and 2,4,6‐triMe‐ArC=O⁺ from mesitoic acid are involved in the esterification, but the mesitoyl cation can be formed and esterified in the acidity ranges between 92 and 98 wt% H₂SO₄. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analysis of molecular species of peroxide adducts of triacylglycerols following treatment of corn oil with tert-butyl hydroperoxide

We recently demonstrated that exposure of synthetic mono-and diunsaturated triacylglycerols to tert-butylhy-droperoxide (TBHP) leads to formation of stable adducts of the oxidizing agent and the unsaturated esters (Sjövall, O., Kuksis, A., and Kallio, H., Reversed Phase High-Performance Liquid Chromatographic Separation of tert-Butyl Hydroperoxide Oxidation Products of Unsaturated Triacylglycerols. J. Chromatogr. A 905, 119–132, 2001). In the present study we isolated and identified the TBHP adducts of corn oil triacylglycerols. The much wider range of molecular species available in the corn oil permitted us to demonstrate that the yield of the adducts varies with the degree of unsaturation of the triacylglycerol. The highest yields were obtained for the linoleate (20% of linoleoyl-containing residual triacylglycerols) and the lowest ones for the oleate (5% of oleoyl-containing residual triacylglycerols) tria-cylglycerols, whereas the saturated triacylglycerols did not give TBHP adducts in readily detectable amounts. Normal-phase thin-layer chromatography along with reversed-phase high-performance liquid chromatography/mass spectrometry (LC/MS) with electrospray ionization was used to isolate and separate the major molecular species of polyunsaturated triacylglycerols and corresponding TBHP adducts. As an extreme example, the dilinoleoylmonooleoylglycerol was identified as the mono-, di-, tri-, tetra-, and penta-TBHP adduct. LC/MS with electrospray ionization at elevated capillary exit voltage (pseudo tandem mass spectrometry) was used to confirm structures of the [M?RCOOH]⁺ ions and the absence of TBHP adducts of [M?RCOOH]⁺. It is concluded that stable adduct formation is an unavoidable complication of preparation of oxotriacylglycerols by oxidation with concentrated TBHP solutions and care must be taken to resolve the adducts from the desired oxidation product.     

Copper containing TUD-1: synthesis, characterization and catalytic behavior in liquid-phase oxidation of ethylbenzene

Three dimensional amorphous mesoporous material, TUD-1 with different Cu-loading were prepared by using triethanolamine (TEA) as cheap, small, bi-functional template which acts as a mesoporous directing agent as well as an anchoring agent for copper active sites on the mesoporous wall. The materials thus prepared have been characterized by X-ray diffraction, N₂ sorption, FT-IR, TEM, DR-UV–Vis and ICP-OES. The catalytic activities of the prepared material (CuTUD-1) were tested in liquid phase oxidation of ethylbenzene with tert-butyl hydroperoxide (TBHP) as an oxidant. Influence of various reaction parameters such as time, temperature, Si to Cu ratio, oxidant and solvent were studied. Isolated framework substituted Cu sites are active for ethylbenzene conversion (35.2%) with 67% selectivity towards acetophenone.     

Synthesis and water absorbency of polyampholytic hydrogels with antibacterial activity

Amphoteric terpolymers of acrylic acid (AA), acrylamide (AM), and N,N′‐dimethyl‐N‐ethylmeth‐acryloxylethylammoniumbromide (DMAEA‐EB) with varied compositions P[AA‐AM‐(DMAEA‐EB)] were synthesized by inverse suspension polymerization. The components of P[AA‐AM‐(DMAEA‐EB)] were verified by FTIR spectroscopy. The water absorption ability and antibacterial activity of the copolymer against Escherichia coli(E. coli) and Staphylococcus hyicus(S. hyicus) suspended in sterilized physiological saline were investigated. The introduction of  N⁺R₄ may increase the water absorbency of P[AA‐AM‐(DMAEA‐EB)] in some degree because of the excellent hydrophilicity of  N⁺R₄. The AA‐AM‐(DMAEA‐EB) hydrogels exhibited high antibacterial activity against bacteria tested. The process of adsorption between live bacteria cells and resins was at least partially reversible. A peak of antibacterial efficiency existed with increasing contact time. The resin killed 96.6% E. coli organisms and 90.3% S. hyicus organisms, respectively, within 30 min of contact at dosage of 0.1g. The concentration of DMAEA‐EB has a special effect on the antibacterial activity of the polyampholytic hydrogels, which is different from polycation. It was observed that the antibacterial activity of the resin with 2 mol % of DMAEA‐EB is superior to the copolymers tested with other compositions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

On the acidity of liquid and solid acid catalysts. Part 2. A thermodynamic and kinetic study for acid-catalysed nitrations

Solid acids prepared by adding sulfuric acid on silica gel have been used as catalysts in the nitration of nitrobenzenes and their properties have been tested by kinetic studies at 25°C. Nitration rates in concentrated aqueous solutions of sulfuric acid were also analysed and the catalytic efficiencies of sulfuric acid in liquid and solid phase were compared by using kinetic data of analogous compounds. The results show that the solid acid samples exhibit nitrating properties very similar to those observed in concentrated aqueous solutions of sulfuric acid (range of 90 wt%). The relationship between nitration rates and effective concentration of electrophilic species [NO ₂ ⁺ ], determined by studying the protonation–dehydration equilibrium of nitric acid in strong acids (HNO₃ + H⁺ ⇌ H₂O + NO ₂ ⁺ ), was tested to better understand the acidity properties of medium. This revised version was published online in November 2006 with corrections to the Cover Date.     

An unexpected ring carboxylation in the electrocarboxylation of aromatic ketones

The electrocarboxylation of various aromatic ketones, carried out in N-methyl-2-pyrrolidone (NMP) in a diaphragmless cell equipped with a carbon cathode and an aluminium sacrificial anode, yielded, among the products, the target hydroxy acids, the corresponding alcohols and pinacols and, quite surprisingly, detectable amounts of substituted benzoic acids and cycloexene carboxylic acids. These compounds arise from a never reported before electrocarboxylation on the aromatic ring, respectively, for substitution of an aromatic hydrogen and from an addition reaction. For example, the electrocarboxylation of acetophenone gave rise to the substituted benzoic acids in ortho, para and meta positions, while for 2,2-dimethylpropiophenone the substituted benzoic acid in meta position and the cyclohex-5en-1,3-dicarboxylic acid derivative were detected among the products.     

Structure and mechanical properties of blends of two thermotropic copolyesters

Blends of two thermotropic copolyesters, poly(ethylene terephthalate/p‐hydroxy benzoic acid) (20/80), EB, and poly(p‐hydroxy benzoic acid/2,6‐hydroxy naphthoic acid) (73/27), BN, were obtained in the melt state by direct mixing in an injection machine throughout the full composition range. They comprised an almost pure EB phase and a BN‐rich phase that contained some reacted EB. Important synergisms with most of the values above those of the two pure blend components were found at most compositions in the modulus of elasticity and the tensile strength. The synergisms appeared to be due to the concomitant effect mainly of an orientation of the components higher in the blends than in the pure components, and to a lesser extent, of a blending‐induced specific volume decrease.     

Separation of ethylbenzene from C7+‐cut naphtha

A fractional distillation process for separating ethylbenzene (EB) from a feed mixture C7⁺‐cut naphtha, comprising nonaromatics, BTX, EB, styrene, and C8⁺ fraction, was used. Primarily, 29.63 wt % EB in the bottom was obtained. Redistillation of the bottom component produced 63.98 wt % EB in the 2nd cut; finally, this cut was used as a feed to distillation process and 83.21 wt % EB was obtained in distillate, and this feed was used directly for dehydrogenation process to produce styrene monomer. All of the distilled fractions were analyzed by gas chromatography instrument. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2795–2798, 2006     

异丙苯液相催化氧化

在500 mL钛制间歇釜中,以异丙苯为原料,醋酸为溶剂,醋酸钴、醋酸锰和溴化氢为催化剂,空气为氧化剂,考察催化剂浓度和反应温度对产物组成和反应速率的影响,并分析异丙基氧化产物结构.结果表明,比较适宜的反应条件为180℃,催化剂Co和Mn与反应物异丙苯物质的量之比为0.05,该条件下,异丙苯可以完全转化,苯甲酸的收率为95%.异丙苯氧化产物主要为α-甲基苯乙烯、苯乙酮、α-甲基苯乙烯的聚过氧化物以及苯甲酸;整个氧化过程中,α-甲基苯乙烯与氧气作用形成聚过氧化物的反应是影响苯甲酸收率的关键因素;提高反应温度和增加催化剂浓度都能改变口-甲基苯乙烯的聚过氧化物的稳定性,使其开裂并最终转化为苯甲酸.     

Redox behavior and oxidation catalysis of HnXW12O40 (X = Co2 +, B3 +, Si4 +, and P5 +) Keggin heteropolyacid catalysts

Redox behavior and oxidation catalysis of H_nXW₁₂O₄₀ (X = Co^2 +, B^3 +, Si^4 +, and P^5 +) Keggin heteropolyacid catalysts were investigated. Successful formation of H_nXW₁₂O₄₀ catalysts was confirmed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Reduction potentials of H_nXW₁₂O₄₀ catalysts were determined by electrochemical measurements. First electron reduction potential of H_nXW₁₂O₄₀ catalysts decreased with increasing overall negative charge of heteropolyanion. H_nXW₁₂O₄₀ catalysts were then applied to the liquid-phase oxidation of benzaldehyde to benzoic acid. Yield for benzoic acid increased with increasing first electron reduction potential.     

Synthesis and characterization of a new discotic columnar side-chain liquid crystalline polymer deuterated for NMR analysis

As part of our attempt to prepare molecular spinning machine, we synthesized a new discotic liquid crystalline polymethacrylate based on the taper-shaped monoester of triethylene glycol with 3,4,5-tris(p-dodecyloxylbenzyloxy-m-methoxybenzyloxy)benzoic acid. The polymethacrylate was deuterated in the benzoic ring for subsequent solid-echo ²H NMR spectroscopy. The m-methoxy group was proposed to prevent the rotation of the benzene ring, thereby inducing the cooperative rotational motion of the polymer.     

Fast switching ferroelectric liquid crystal side chain polymer

Two products were isolated at a result of esterification of acrylic acid with 4-[4-(n-hydroxyundecanyloxy)phenyl] benzoic acid (5) One is 4-[4-(n-acryloloxy-undecanyloxy)phenyl] benzoic acid (6), and the other is 4-{4-[n-(3-acryloloxy-propionyloxy)undecanyloxy]phenyl}benzoic acid (7) which containts two molecules of acrylic acid. Compound7 is obtained unexpectedly and still unknown in the literature. Its identification is confirmed by the isolation and characterization of the monomer9. The mesogenic monomers8 and9 which were synthesized from 4-hydroxyphenyl 2(S)-[2(S)-methylbutoxylpropionate (4) and the corresponding acrylates6 and7 exhibit the enentiotropic Sc* and S_A phases. The Sc^* phase temperature range is up to 31 °C. The spontaneous polarization and response time for the monomers8 and9 is 97 and 16 nC/cm² as well as 90 and 64 µs respectively. It us the liquid crystal side chain polymer11, not10, which is switchable in the presence of an electric field. The spontaneous polarization of 36 nC/cm² and the response time of 3.1 ms is obtain from the new polyacrylate.     

Vanadia supported on ceria: Characterization and activity in liquid-phase oxidation of ethylbenzene

Vanadia/ceria catalysts (2–10 wt% of V₂O₅) were prepared by wet impregnation of ammonium metavanadate in oxalic acid solution. Structural characterization was done with energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), BET surface area measurements, FT-IR spectroscopy and nuclear magnetic spectral analysis (⁵¹V MASNMR). XRD and ⁵¹V MASNMR results show highly dispersed vanadia species at lower loadings and the formation of CeVO₄ phase at higher V₂O₅ loading. The catalytic activity of catalysts was conducted in liquid phase oxidation of ethylbenzene with H₂O₂ as oxidant. The oxidation activity is increased with loading up to 8 wt% V₂O₅ and then decreased with further increase in V₂O₅ content to 10 wt%. Different vanadia species evidenced by various techniques were found to be selective towards ethylbenzene oxidation. The CeVO₄ formation associated with increased concentration of vanadia on ceria results the production of acetophenone along with 2-hydroxyacetophenone.     

Liquid phase reactions catalyzed by Fe- and Mn-sulphated ZrO2

Fe- and Mn-promoted ZrO₂–SO₄ (ZS) powders were prepared both by a single step sol–gel reaction and by impregnation of the zirconia hydrous precursor. The samples were calcined at 890 K and characterized for the structural (XRD) and morphological features (BET method). Surface functionalities were investigated by XPS, ¹H MAS NMR and FTIR analyses. The liquid medium catalytic activity was tested with respect to both the esterification of benzoic acid to methylbenzoate and the benzylation of toluene. The acidity features appeared not to be significantly different among the various samples while all surface characterizations showed a lower affinity to retain water by the metal-promoted samples with respect to ZS, the more so in the case of iron-containing samples. The presence of Mn reduced the surface area and depressed the catalytic activity. Iron-doped catalysts appeared, instead, to be more efficient than ZS especially for the benzylation of toluene.     

Protection by multiple antioxidants against lipid peroxidation in rat liver homogenate

The purpose of this study was to test the hypothesis that multiple antioxygenic nutrients provide increased protection against lipid peroxidative damage to rat liver. Rats were fed diets (i) deficient in vitamin E and selenium (Diet 1), (ii) supplemented with vitamin E and selenium (Diet 2), (iii) supplemented with (ii) and in addition trolox C,N-acetylcysteine, coenzyme Q₀, and (+)-catechin (Diet 3), or (iv) supplemented with (iii) and in addition β-carotene, ascorbic acid palmitate, canthaxanthin, and coenzyme Q₁₀ (Diet 4). Liver homogenates were obtained from three rats fed each of the diets for six weeks and were incubated at 37°C up to two hours with and without exogenous tertiary-butyl hydroperoxide (TBHP) or Cu²⁺. Lipid peroxidation was determined by measurement of thiobarbituric acid substances. Diets 2 and 3 significantly protected againstin vivo hepatic lipid peroxidation, and this protection was augmented by Diet 4. Diets 2, 3, and 4 were protective against mild oxidation induced by TBHP or Cu²⁺. During incubations with exogenous TBHP and Cu²⁺, there were only small differences between diets supplemented with antioxidants in inhibition of lipid peroxidation, indicating that diets supplemented with vitamin E and selenium (Diet 2) may have provided the maximal protection for liver. The possible mechanisms of protection provided by multiple antioxidants in diets were discussed. Protection by multiple antioxidants against lipid peroxidation may translate to prevention of peroxidative damage to human tissue, a factor in human disease.     

Highly Efficient and Selective Transport of Cu(II) with a Cooperative Carrier Composed of Tetraaza-14-Crown-4 and Oleic Acid through a Bulk Liquid Membrane

Tetraaza-14-crown-4 and oleic acid was successfully applied for transport of Cu(II) in chloroform bulk liquid membrane. The uphill moving of Cu(II) during the liquid membrane transport process has occurred. The main effective variable such as the type of the metal ion acceptor in the receiving phase and its concentration, tetraaza-14-crown-4 and oleic acid concentration in the organic phase on the efficiency of the ion-transport system were examined. By using L-cysteine as a metal ion acceptor in the receiving phase, the maximum amount of copper (II) transported across the liquid membrane was achieved to 96 ± 1.5% after 140 minutes. The selectivity of copper ion transport from the aqueous solutions containing Pb²⁺, Tl⁺, Ag⁺, Co²⁺, Ni²⁺, Mg²⁺, Zn²⁺, Hg²⁺, Cd²⁺ and Ca²⁺ ions were investigated. In the presence of CH₃COONH₄ and Na₄P₂O₇ as suitable masking agents in the source phase, the interfering effects of Pb⁺² and Cd²⁺ were diminished drastically.     

Study of the Alkylation of Phenol with Methanol on Zn(H)-Exchanged NaY Zeolites

Abstract  

The gas-phase alkylation of phenol with methanol was studied at 473 K on zeolite NaY exchanged with Zn⁺² (samples Zn(x)NaY) or H⁺ (samples Na(x)HY) cations. Zeolite NaY contained only weak and medium Lewis acid sites. The addition of Zn⁺² formed essentially strong Lewis acid sites. In contrast, the exchange of NaY with H⁺ generated Br?nsted acid sites and decreased the density of Lewis acid sites. Zeolite NaY was inactive at 473 K, but after its exchange with Zn²⁺ efficiently promoted the phenol methylation reaction. Phenol conversion and the selectivities to o- and p-cresols increased with the Zn content in the sample. The exchange of Na⁺ with H⁺ also activated the parent NaY zeolite. At similar phenol conversion levels, Na(x)HY samples formed more anisole and less cresols than Zn(x)NaY. All the Zn(x)NaY and Na(x)HY samples deactivated on stream, but the catalyst activity decay increased with the exchange degree.     

Synthesis of electrically conducting copolymers of aniline with o/m-amino benzoic acid by an inverse emulsion pathway

Copolymers of aniline and ortho/meta-amino benzoic acid were synthesized by chemical polymerization using an inverse emulsion pathway. The copolymers are soluble in organic solvents, and the solubility increases with the amino benzoic acid content in the feed. The reaction conditions were optimized with emphasis on high yield and relatively good conductivity (2.5×10⁻¹ S cm⁻¹). The copolymers were characterized by a number of techniques including UV-vis, FT-IR, FT-Raman, EPR and NMR spectroscopy, thermal analysis, SEM and conductivity. The influence of the carboxylic acid group ring substituent on the copolymers is investigated. The spectral studies reveal that the amino benzoic acid groups restrict the conjugation along the polymer chain. The SEM micrographs of the copolymers reveal regions of amorphous and crystalline domain. Thermal studies indicate a marginally higher thermal stability for poly(aniline-co-m-amino benzoic acid) compared to poly(aniline-co-o-amino benzoic acid).