Electrochemical synthesis of N-phenyltetrahydro-oxazinone—role of the solvent

The electrochemical synthesis of 2-phenyltetrahydro-2H-1,2-oxazin-3-one $\text{1}$ is performed by electroreduction in aprotic solvent of nitrosobenzene in the presence of an equivalent of 4-chlorobutyryl chloride $\text{2b}$. In DMF, the yield does not exceed 8% at 18°. In MeCN, it reaches 35% at 18° and 42% at ?18°. It is suggested that the lower yield obtained in DMF is due mainly to a higher reactivity of the dielectrophile which forms an immonium salt in this solvent. It is shown that the chemical reduction of nitrosobenzene (HMPT, Na) followed by the addition of $\text{2b}$, does not lead to $\text{1}$.     

Coal-derived asphaltenes: effect of phenol content and molecular weight on viscosity of solutions

Phenol contents and molecular weights of coal-derived asphaltenes are shown to affect the viscosity of their solutions. Phenol contents were determined by non-aqueous titrimetry. Intermolecular aggregation probably involving hydrogen bonding is a prime factor in the increase in viscosity found with increased asphaltene concentration in a reference solvent system composed of an $\text{88}\text{12}$ ($\text{wt}\text{wt}$) mixture of 1-methylnaphthalene and o-cresol. Aggregation effects are greater for those asphaltenes with relatively higher phenol contents. Asphaltenes were separated into fractions of different polarity by adsorption chromatography. The more polar subfraction was found to increase viscosity in the reference solvent to a greater extent than the less polar subfraction. The logarithmic viscosity numbers of solutions of the asphaltenes and their subfractions are correlated by a linear combination of molecular weights and phenol contents. It is concluded that an effective means of reducing the viscosity of coal-derived liquids would be to reduce the phenol content of the asphaltene fraction.     

Copoly(m,p-chloromethylstyrene-50% styrene): Copolymer molecular weights,fractionation and derivatization

Copolymerization of an equimolar mixture of m,p-chloromethylstyrene ($\text{M}$₁) and styrene ($\text{M}$₂) was carried out in chlorobenzene in the presence of AIBN at 80°C. Molecular weight analysis (by g.p.c.) of the resulting polymer samples was performed at various conversions. $\text{M}\text{?}{}_{\mathrm{<mtext>w</mtext>}}$, $\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}$, and ($\text{M}\text{?}{}_{\mathrm{<mtext>w</mtext>}}\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}$) value of 21 300, 13 800 and 1.54 were obtained at 8.9% conversion. At higher conversions, the value of $\text{M}\text{?}{}_{\mathrm{<mtext>w</mtext>}}$ remained effectively constant while $\text{M}\text{?}{}_{\mathrm{<mtext>n</mtext>}}$ decreased to 9200 at ca. 80% conversion, and then increased to 12 000 at about 100% conversion (16 h), and to 13 700 if the polymer solutions were maintained at 80°C for an additional 44 h. These results suggest that, although the termination step initially involves the combination of polymer radicals, at high conversions a large number of very low molecular weight, and unsaturated, polymer molecules are formed possibly by disproportionation involving polymer radicals and primary radicals. The unsaturated polymer molecules are subsequently polymerized by growing polymer radicals towards the end of the polymerization. It was noticed that further reaction occurred after complete depletion of monomer, involving radical attack on the unsaturated polymer molecules. Other reactions including chain transfer to polymer will also be important at high polymer concentrations. A copolymer of $\text{M}$₁ and $\text{M}$₂ was separated into four fractions on a preparative scale, and molecular weight analysis of the resulting polymer samples provided more evidence of the above interpretation. G.p.c. analysis of several derivatives of a copolymer of $\text{M}$₁ and $\text{M}$₂ showed that most molecular weights were much lower than that of the starting polymer. These results in some cases may reflect the chemical or dimensional changes introduced into the polymer molecules during derivatization.     

Flash pyrolysis of coals: behaviour of three coals in a 20 kg h−1 fluidized-bed pyrolyser

Flash pyrolysis of Loy Yang brown coal, and Liddell and Millmerran bituminous coals has been studied using a fluidized-bed reactor with a nominal throughput of 20 kg h^?1. The apparatus and its performance are described. The yields of tar and hydrocarbon gases are reported for each coal in relation to pyrolysis temperature, as also are analytical data on the pyrolysis products. The peak tar yields for the dry, ash-free Loy Yang and Millmerran coals were respectively 23% wt/wt (at ≈ 580 °C) and 35% wt/wt (at $\text{\$}\text{?}$600 °C). The tar yield from Liddell coal was 31% wt/wt at ≈ 580 °C. Hydro-carbon gases were produced in notable quantities during flash pyrolysis; e.g. Millmerran coal at 810 °C gave 6% wt/wt (daf) methane, 0.9% wt/wt ethane, 6% wt/wt ethylene, and 2.5% wt/wt propylene. The atomic $\text{H}\text{C}$ ratios and the absolute levels of hydrogen in product tars and chars decreased steadily with increasing pyrolysis temperature.     

Electrochemical synthesis of heterocyclic compounds—XIII. (1) Anodic synthesis of 1, 3-imidazoles and 1, 3-oxazoles derivatives

Anodic oxidation of a series of structurally different Schiff bases ($\text{1a}$–$\text{15a}$), prepared from o-phenylendiamine, o-aminophenol, 3-amino-4-hydroxycoumarine or 3,4-diaminocoumarine and corresponding aromatic aldehyde, were performed in acetonitrile-tetraethylammonium perchlorate electrolyte solution at platinum using controlled potentials. As a result of two-electron oxidative cyclodehydrogenations several 1,3-oxazoles derivatives (1b–10b) and 1,3-imidazoles derivatives (11b–15b) were prepared in the yields ranging from 60 to 90%. A mechanism rationalizing the formation of 2-anisylbenzimidazole, $\text{11b}$, and 2-anisylbenzoxazole, $\text{3b}$, has been studied by lsv, cpsv, rde, coulommetry and preparative scale electrolysis.     

Reduction of coal in hexamethylphosphoramide-Na-t-BuOH and the molecular weight distribution of pyridine-soluble material

Eight coals were reduced by hexamethylphosphoramide (HMPA)-Na-t-BuOH at room temperature and atmospheric pressure. More than 70 wt % of the coal is soluble in pyridine after this reduction. Coals having ≈88 wt% of carbon content show a maximum solubility in pyridine after reduction. The pyridine-soluble material has a higher $\text{H}\text{C}$ ratio after reduction. l.r. and n.m.r. spectra show that the reaction product is richer in aliphatic and olefinic structures and that the aromatic ring systems are extensively saturated. From g.p.c. separations and molecular weight measurements, it is found that the molecular weight distribution has a maximum at lower and higher molecular weight values. The average molecular weight of the reduced pyridine-soluble material decreases with increase in rank of the coal. Coking properties of these coals can be related to proportions of material in the two modes of distribution of molecular weight.     

盐碱与冻融耦合作用下再生混凝土耐久性试验研究

通过再生混凝土在3.5%NaCl、3.5%Na2SO4、3.5%NaCl+3.5%Na2SO4和水四种溶液中的冻融循环试验,分析再生混凝土在同浓度不同种类盐碱溶液中经过不同冻融次数后(N)的质量变化(△m)和动弹性模量变化(△E) ,绘制N-△m和N-△E的曲线.同时,设置单掺10%、20%粉煤灰和2%、4%硅灰为对照组,研究粉煤灰和硅灰组分别在3.5%NaCl和3.5%Na2SO4环境下混凝土的抗冻性能规律.结果表明:氯盐环境中,随冻融次数的增加,混凝土表面剥削、开裂现象明显,质量和动弹性模量损失严重,而硫酸盐环境中,冻融前期混凝土内部生成水化产物使质量增加,表面膨胀开裂,后期质量和动弹性模量急剧下降,与浓度3.5%氯盐盐冻相比,硫酸盐盐冻动弹性模量损失更大.冻融破坏强度由强到弱排序为氯盐冻、硫酸盐冻、复合盐冻、水冻;掺入粉煤灰后,氯盐环境下的混凝土抗冻性反而下降,10%掺量优于20%掺量.掺入硅灰后,硫酸盐环境下再生混凝土抗冻性提高,破坏程度要比水冻小,4%掺量优于2%掺量;最后分析了混凝土腐蚀机理.     

Anodic oxidations—I. The Kolbe oxidation of unsymmetrical half-esters derived from stobbe condensation

The Kolbe oxidation of some partially neutralized half-ester, viz., 3-carbethoxy-4,4-diphenyl but-3-enoic acid ($\text{1}$), 3-carbethoxy-4,4-dimethyl but-3-enoic acid ($\text{2}$), 3-carbethoxy-3-cyclopent-1′-en-propionic acid ($\text{3}$) and 3-carbethoxy-3-cyclohex-1′-en-propionic acid ($\text{4}$), has been investigated in an undivided cell at smooth platinum foil anode in methanol. In order to optimize the yield of the dimer, the anodic oxidation of $\text{1}$ has been studied in detail by varying different parameters, like current density, degree of partial neutralization of the half-ester and electrode material. Besides the dimerized product, affoded by all these half-ester, two stereoisometric ethers, viz., ethyl 2-methoxymethyl-3,3-diphenyl prop-2-enoate ($\text{1b}$) and ethyl 2-[methoxy (diphenyl)] methyl prop-2-enoate ($\text{1c}$) have been isolated in 69% and 11% respectively from $\text{1}$ in a typical experiment. The probable mechanism for the process has been presented.     

Studies of a CuY zeolite as a redox catalyst

The stability and behavior of CuY in the redox cycles with $\text{CO}\text{O}{}_2$, $\text{H}{}_2\text{O}{}_2$, and $\text{CO}\text{NO}$ have been studied using a microbalance operating in the flow mode and with a standard (BET) volumetric system. When CO was used as a reducing agent CO₂ was produced, thus removing oxygen from the zeolite lattice, but when H₂ was used only some of the H₂ consumed was evolved as H₂O. The rest was retained as lattice OH groups, but this was minimal when H₂ was used after treating the sample with CO. Oxidation with NO produced only N₂. At 500 °C the sample was stable and could be reversibly oxidized and reduced through many cycles using either $\text{CO}\text{O}{}_2$ or $\text{NO}\text{CO}$. In all cases the ratio $\text{O}\text{Cu}$ was close to 0.5, i.e., $\text{1e}\text{Cu}$. Treatment in CO at higher temperatures did not affect the reversible nature of the oxidation, but now the valence change was substantially larger; it approached $\text{2e}\text{Cu}$. The crystallinity of the exchanged zeolite was studied using X-ray diffraction and by measurement of the pore filling with liquid N₂. No significant changes could be detected after the different treatments, even those performed at 750 °C. Temperature-programmed reduction, temperature-programmed oxidation, and X-ray diffraction studies were made and the different maxima are reported. CuO and Cu ^o appeared in the oxidized and reduced samples, respectively, after treatment at 750 °C in CO but not at lower temperatures. Subsequent redox cycles at 500 °C did not appear to affect the size or amount of Cu ^o crystallites. CuY was active in the oxidation of CO with O₂ or NO. Its activity was lower than that of FeY zeolite when it exhibited an oxygen-carrying capacity of 0.5 $\text{O}\text{Cu}$. Treatment with CO at 750 °C, however, reversed the situation. Kinetic results showed that the fresh CuY catalyst was close to zero order in CO and fractional order in O₂ with an activation energy of 15 kcal/mole. After treatment at 750 °C in CO, the rate law became dependent upon the $\text{CO}\text{O}{}_2$ ratio. It was close to first order in CO and zero order in O₂ under oxidizing conditions ($\text{CO}\text{O}{}_2\text{≤ 2}$), but the orders were reversed under reducing conditions ($\text{CO}\text{O}{}_2\text{> 2}$). The activation energies were 12 and 15 kcal/mole, respectively. The data suggested that the Cu²⁺ with bound oxygen are the species active in the oxidation reaction.     

Liquefaction of coal and related materials

Bituminous coal, lignite, peat and more recent biogenic materials were reacted as water slurries at 380 °C for short periods with hydrogen, directly and from the water-gas shift reaction, without organic solvents or catalysts. Conversion increases with $\text{H}\text{C}$ and $\text{O}\text{C}$ ratio of the input material and reaches 90%. For benzene-soluble products $\text{O}\text{C}$ is always lower and $\text{H}\text{C}$ usually higher than for the original material.     

Osmotic concentration of salt solutions in a countercurrent multiplier system

Analysing the principles of performance of the human kidney, in about 1940, Kuhn and co-workers established the theoretical and physical model of concentrating solutions without the use of substantial differences of pressure (the so-called loop of Henle). p]Continuing this idea, a system of double channel asymmetrical capillaries made of cellulose 2$\text{1}\text{2}$ acetate was constructed and sodium and potassium chloride solutions were concentrated. The degree of concentration increased for higher feed concentrations. In experiments with one metre loop longitudinal apparatus 20 gl^-1 NaCl feed solution, the final concentration was 25 gl^-1 NaCl. To obtain 1 m³day concentrated solution with 10% recovery, about 1m² of membrane area was required.     

Mass transfer in packed liquid—liquid extraction columns

The mass transfer characteristics of 3·5, 7·3, 10·16 and 15·6 cm i.d. packed liquid—liquid extraction columns were studied with a variety of packings such as, $\text{3}\text{8}$, $\text{1}\text{2}$ and 1 in. ceramic Raschig rings, $\text{5}\text{8}$ in. stainless steel Raschig rings, $\text{1}\text{2}$ and 1 in. ceramic Intalox saddles, $\text{5}\text{8}$ and 1 in. stainless steel Pall rings, and 1 in. polypropylene Intalox saddles and Pall rings. Some data were also obtained for the co-current mode of operation (up-flow) for packed columns, and without packings. In addition the mass transfer charactersitics of a packed extraction column with film flow were studied.The theory of extraction accompanied by a fast pseudo-first order reaction was employed to measure the values of effective interfacial area. The values of overall (continuous and/or dispersed phase) mass transfer coefficient were measured by the Colburn—Welsh technique. A fairly wide range of physical properties of the two phases was covered.The values of overall (continuous phase) mass transfer coefficient and effective interfacial area for new packings such as Pall rings and Intalox saddles, under otherwise similar conditions, are only about 10 and 35 per cent higher, respectively, than those provided by the conventional packings of the same nominal size. However, the flooding velocities for the newer packings are as much as 80 per cent higher than those for the conventional packings of the same nominal size.     

A study of the heat treating cycle for internally sealed concrete containing montan-paraffin wax beads

Cylindrical concrete specimens, with 2 ft. ³/yd.³ (0.074 m³/m³) of fine aggregate replaced by montan-paraffin wax beads, were placed in a heating chamber designed to heat only their top surface. The heating cycle was varied to determine the optimum for the equipment used. After cooling, the specimens were cut longitudinally and subjected to an acid etching process to determine the depth of sealing. The maximum allowable surface temperature was found to be 425° F. (218° C.) if the deterioration of the wax due to heating was to be limited to a depth of $\text{1}\text{32}$ in. (0.8 mm.). The maximum depth of complete sealing was $\text{1?1}\text{16}$ in. (27 mm.). No significant reduction in the total duration of the heat treating process was found.     

Solution properties and chain flexibility of polythiolmethacrylates: 1. Poly(phenyl thiolmethacrylate) and poly(O-methyl phenyl thiolmethacrylate)

Dilute solution properties of poly(phenyl thiolmethacrylate) (PTPh) and poly(o-methylphenyl-thiolmethacrylate) (PTMPh) were studied by gel permeation chromatography, light scattering, osmotic pressure and viscosity measurements in different solvents. Relations between intrinsic viscosity [η], z-average root-mean-square end-to-end distance $\text{(}\text{r}\text{?}{}^2\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and molecular weight $\text{M}\text{?}{}_{\mathrm{w}}$ were established. The unperturbed dimensions were calculated by different methods using $\text{M}\text{?}{}_{\mathrm{w}}$ and [η]. PTPh (σ = 2.26) and PTMPh (σ = 2.27) have practically the same flexibility, but both are more flexible than poly(phenyl methacrylate) (σ = 2.50). In our opinion, this is due to the change in the local intramolecular interaction and the higher flexibility of the sulphur-containing side group.     

Improved dielectric,nonlinear and magnetic properties of cobalt-doped CaCu3Ti4O12 ceramics

The dielectric properties and voltage–current nonlinearity of the pure and various cobalt-doped CaCu₃Ti₄O₁₂ (Co-doped CCTO) prepared by solid-state reactions were investigated. The improved dielectric properties in the Co-doped CCTO, with a dielectric constant $\text{ε'}$ ≈7.4?×?10⁴ and dielectric loss $\text{tan}\text{δ}$?≈?0.034, were observed in the sample with a Co doping of 5% (CCTO05) at room temperature and 1?kHz. The related multi-relaxations, RII (?20 to 40?°C) and RIII (100–150?°C), were demonstrated to be a Debye-like relaxation and a Maxwell–Wagner relaxation related to oxygen vacancies. The low dielectric loss of CCTO05 was associated with the high grain boundary resistance and the increase in cation vacancies. The improved nonlinear electrical properties (CCTO05, with nonlinear coefficients $\text{α}$?≈?5.22 and breakdown electric field ${\text{E}}_{\text{b}}$?≈?300.46?V/cm) and the ferromagnetism in Co-doped CCTO were also discussed.     

Effect of impeller geometry on drop break-up in a stirred liquid—liquid contactor

Drop size measurements were made in the break-up zone at the tip of three 6 bladed disc turbines of different geometries in a 0·30 m dia. vessl. Three systems kerosene, methyl iso-butyl ketone (MIBK) and n-butanol at a volumetric fractional hold-up of 0·05 in water were examined. Power input and circulation time characteristics were determined and a new dimensionless group (?^{?$\text{1}\text{3}$}t_c/T^{$\text{2}\text{3}$}) is proposed to account for the effect of geometric parameters in the correlation of the drop size.     

Inhalability of large solid particles

Large particles (10–$\text{150}\text{μm}\text{)}$ with systemic toxicity pose a health risk if inhaled regardless of where they deposit. This research seeks to better define particle inhalability, the fraction of airborne particles that are inhaled as a function of particle size.Measurements of inhalability were made for solid particles using a 1.6×1.6×5-m wind tunnel. Tunnel air velocities were 0.4, 1.0, and $\text{1.6}\text{m}\text{/}\text{s}$. A full-size, full-torso mannequin was used to collect dust entering either the mouth or nose for breathing at minute volumes of 14.2, 20.8, and $\text{37.3}\text{l}$. The mannequin either faced the oncoming wind or rotated slowly $\text{(0.06}\text{rpm}\text{)}$ during sample collection. At the test section, air velocity was uniform to within 10% and aerosol concentration was uniform to within 15% over the central 80% of the cross section.Orientation-averaged inhalability for mouth breathing was higher than the inhalable particulate mass (IPM) sampling criterion for particles smaller than $\text{35}\text{μm}$ and lower than the criterion for larger particles, leveling off at about 30% for particles $\text{>70}\text{μm}$. Facing-the-wind mouth inhalability showed the same trend as the IPM sampling criterion, but the measured values were 25% higher. Wind velocity and breathing pattern had little effect on inhalability for the range of conditions examined here. Orientation-averaged inhalability for nose breathing dropped quickly with particle size reaching less than 10% at $\text{60}\text{μm}$. Facing-the-wind nose inhalability was slightly increased for particles smaller than $\text{60}\text{μm}$ compared to orientation averaged inhalability for nose breathing.     

Effect of micropore structure on cellular concrete shrinkage

This paper presents the results of studies on the effect of micropore structure on the shrinkage of autoclaved cellular concrete with sand aggregate. It has been found that the shrinkage of cellular concrete is the function of volume and specific surface of micropores of radii $\text{75 <}\text{r}\text{< 625}\text{A}\text{?}$. On the base of mathematical analysis the requirements concerning the micropore structure of cellular concrete have been proposed to ensure the proper shrinkage characteristic of this material.