Reaction Mechanism and Kinetics of 1,8‐Diazabicyclo[5.4.0]undec‐7‐ene and Carbon Dioxide in Alkanol Solutions

Carbon dioxide‐binding organic liquids (CO₂BOL) are a new class of solvents with advantageous properties such as high boiling points, low specific heats, high absorption capacities, and easily reversible reactions. In order to implement these solvents in processes, the reaction characteristics must be determined a priori. This work presents an analysis of the rate constants and activation energies of the reaction between carbon dioxide and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in 1‐hexanol and 1‐propanol. The reactions were found to comply with a termolecular reaction mechanism and exhibited pseudo‐first‐order behavior in the presence of excess DBU and 1‐alkanol. It was concluded that DBU‐based CO₂BOL are environmentally friendly and easy‐to‐handle solvents that may provide great flexibility and improvements over conventional carbon dioxide absorption processes.     

High Resolution Optical Interference Measurements of Changes in Bond-Line Thickness—A Review

A novel moire optical interference method, originally developed¹ to measure the swelling displacement normal to the plane of a simple butt joint during water uptake at the joint edge, was subsequently used to investigate the unexpected occurrence of shrinkage and, at the same time, swelling during exposure to organic solvents. In later experiments, synergistic displacement fields generated during simultaneous exposure to water and organic solvents were studied. The same method has also been used to investigate the origin of adhesion failures at copper plated-through holes in thermally cycled multi-layer circuit boards.

The method employs a thin glass cover slip as one adherend. Changes in bondline thickness flex the cover slip thereby changing the gap between the latter and a nearby optical flat. By using monochromatic light to illuminate the specimen, interference between incident and reflected light is achieved. The small displacements of individual fringes associated with changes in gap size are used to generate moire patterns which bear a 1:1 relationship to the local changes in bondline thickness. Application of thin plate elasticity theory to the flexing of the cover slip yields the stress acting normal to the joint. The magnitude of this normal stress is strongly inhomogeneous, oscillating in sign and reaching compressive values as high as 50MNm^?2 for water uptake by a simple butt joint, and exceeding the yield strength of oxygen-free high conductivity copper (1MNm^?2) for the thermal expansion that accompanies simulated soldering of a multi-layer circuit board.

Attention is drawn to the high resolution achievable with the method. Changes in bond-line thickness of the order of Δ/10, where Δ is the wavelength of the light giving rise to the interference pattern, are readily resolved. It is pointed out that the method may well be sufficiently sensitive to detect the effects of different physical properties (thermal conductivity, specific heat capacity) of adherend surface on the nature of the cured adhesive and hence on the mechanical behaviour of the bond-line.     

The effect of asphaltene content on solvent selection for bitumen extraction by the SESA process

Bitumen is a complex mixture, containing a high proportion of poorly soluble asphaltenes. Unpredictable precipitation of this component can cause process problems during bitumen extraction. Consequently, the selection of an appropriate solvent is an important factor in the optimization of bitumen separation by solvent extraction. This aspect is discussed in the context of bitumen extraction from oil sands using the solvent extraction spherical agglomeration (SESA) process. The SESA process is a solvent extraction method which utilizes concurrent particle aggregation in order to overcome difficulties normally encountered in solid-liquid separation in the presence of fines.     

New melamine–formaldehyde–ketone polymers. III. Coatings from melamine and reactive solvents based on cyclohexanone

The conditions and methods of preparing novel melamine–formaldehyde–cyclohexanone coatings are presented. The coatings were prepared by dissolving melamine in reactive solvents based on formaldehyde and cyclohexanone. The latter were prepared at different molar ratios of the components. The water resistance of the resulting coatings was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1083–1092, 2006     

Chlorinated Solvents in UK Aquifers

The paper reviews background data on chlorinated solvents and all published data on chlorinated solvents in UK groundwaters. New data from an aquifer-wide survey of the organic water quality of the Birmingham aquifer (carried out by the University of Birmingham and the Water Research Centre (WRc)) show that contamination by chlorinated solvents is extensive and is greater than that observed in previously published UK studies. Trichloroethylene contamination is particularly apparent in the Birmingham aquifer, with 40% of the boreholes sampled containing waters above the new UK limit for this contaminant. Fortunately the Birmingham aquifer is not used for public supply. Land use and hydrogeological factors are shown to influence the contamination observed in particular boreholes. The difficulties associated with locating contaminated zones in aquifers, due to the immiscible flow of chlorinated solvents, are indicated. It is concluded that the occurrence of chlorinated solvents in groundwaters makes a significant contribution to the poor water quality of many UK aquifers that underlie, or are close to, urban and industrial areas.     

Mechanism of acetic acid transfer from aqueous sodium chloride solutions to some orgranic solvents

Salting out of acetic acid from aqueous solutions containing various concentrations of sodium chloride into some organic solvents has been studied at various temperatures. The solvents include cyclohexane, carbon tetrachloride, 1,2-dichloroethane, isopropyl ether, 2-pentanone and 1-heptanol. The results are consistent with a transfer mechanism involving monomer partitioning, dimerization and dimer return to the aqueous phase. Factors favoring monomer partitioning such as rise in both temperature and salt level retard dimer return, a process which is found to be significant in dimerization-enhancing solvents. The sensitivity of various solvents towards salt effect increases in the order 1-heptanol < isopropylether < 1,2-dichloroethane < 2-pentanone < cyclohexane < carbon tetrachloride which generally parallels in the reverse order the extent of stabilization of the acid by various solvent interactions.     

CL-20转晶废剂的处理研究

采用烃油及正辛醇对六硝基六氮杂异伍兹烷(CL-20)转晶废剂进行预处理,回收CL-20固体,再利用废剂中各溶剂的沸点不同,通过共沸蒸馏分离出乙酸乙酯和氯仿等溶剂。利用高效液相色谱(HPLC)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)对转晶废剂组分和析出的固体进行了表征。结果表明,转晶废剂主要含有氯仿、乙酸乙酯、α-CL-20;用烃油处理废剂回收到的α-CL-20的纯度为99.1%,回收率为79.5%。     

Recovering Bioactive Compounds from Olive Oil Filter Cake by Advanced Extraction Techniques

The potential of by-products generated during extra-virgin olive oil (EVOO) filtration as a natural source of phenolic compounds (with demonstrated bioactivity) has been evaluated using pressurized liquid extraction (PLE) and considering mixtures of two GRAS (generally recognized as safe) solvents (ethanol and water) at temperatures ranging from 40 to 175 °C. The extracts were characterized by high-performance liquid chromatography (HPLC) coupled to diode array detection (DAD) and electrospray time-of-flight mass spectrometry (HPLC-DAD-ESI-TOF/MS) to determine the phenolic-composition of the filter cake. The best isolation procedure to extract the phenolic fraction from the filter cake was accomplished using ethanol and water (50:50, v/v) at 120 °C. The main phenolic compounds identified in the samples were characterized as phenolic alcohols or derivatives (hydroxytyrosol and its oxidation product), secoiridoids (decarboxymethylated and hydroxylated forms of oleuropein and ligstroside aglycones), flavones (luteolin and apigenin) and elenolic acid derivatives. The PLE extraction process can be applied to produce enriched extracts with applications as bioactive food ingredients, as well as nutraceuticals.     

Comparative Study of Excited State Dipole Moment of Coumarin Laser Dyes： Solvent and Substituent Effect

In the present work, an array of novel substituted 2H-chromen-2-one （coumarin derivatives abbreviated as C-337, C-480, C-540A） has been subjected to photophysical analysis. Although the influence of the electron donating groups such as amino, substituted amino, hydroxyl, alkoxy groups at position 7 of the coumarin ring system has been extensively studied, However, coumarin moieties with substituent at position 3 have not been explored much. Attempt is made to explain the effect of electron donating and electron accepting substituent on excited state and ground state dipole moment. The ground state （μ） and excited state （μ＊） dipole moment of C-337, C-480, C-540A coumarins are estimated from solvatochromic shift of absorption and fluorescence spectra as a function of the dielectric constant and refractive index using Bakhshiev and Kwaski-Chamma Vialletequ. μ＊ and μ for all the reported coumarin are also calculated using Reichardt correlation method. The small angle is also reported between the ground and excited state dipole moment suggesting that they are almost parallel to each other. Excited state dipole moment is observed larger than ground state dipole moment for all the coumarins studied indicating substantial n-electron density redistribution.