A Convenient One-Step Synthesis of 5-(α-alkanonyl) and 5-(α-Cyclanonyl)-4-Pentanolides

The thermolysis of t-butyl perpent-4-enoate in ketones leads to the formation of 5-(α-alkanonyl) and 5-(α-cyclanonyl)-4-pentanolides with fairly good yields.     

Synthesis of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(arylamino)prop-2-en-1-one: advances in the mechanism of Combes 2-trifluoromethyl and 2-perfluoroalkyl quinolines synthesis

We report a new synthesis and our study of the mechanism of formation of substituted 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one starting from 3-(R-phenoxy)-3-perfluoroalkyl-prop-2-enals and arylamines. Reactivity study of the intermediates confirmed that 3-perfluoroalkyl-N,N′-diphenyl-1,5-diazapentadienes are the synthetic intermediates of the synthesis of 2-perfluoroalkylquinolines. The mechanism of the reaction of 1-trifluoromethyl and 1-perfluoroalkyl-3-(phenylamino)prop-2-en-1-one with POCl₃ was studied. To our knowledge this is the first detection and isolation of N,N′-diaryldiazapentadiene derivatives as intermediates in the Combes F-alkyl substituted quinoline synthesis starting from enaminoketones. Finally, we succeeded isolating and identifying unsymmetrically substituted 2-perfluorolakyldiazapentadiene.     

Pore-Scale Monitoring of Wettability Alteration by Silica Nanoparticles During Polymer Flooding to Heavy Oil in a Five-Spot Glass Micromodel

It is well known that the oil recovery is affected by wettability of porous medium; however, the role of nanoparticles on wettability alteration of medium surfaces has remained a topic of debate in the literature. Furthermore, there is a little information of the way dispersed silica nanoparticles affect the oil recovery efficiency during polymer flooding, especially, when heavy oil is used. In this study, a series of injection experiments were performed in a five-spot glass micromodel after saturation with the heavy oil. Polyacrylamide solution and dispersed silica nanoparticles in polyacrylamide (DSNP) solution were used as injected fluids. The oil recovery as well as fluid distribution in the pores and throats was measured with analysis of continuously provided pictures during the experiments. Sessile drop method was used for measuring the contact angles of the glass surface at different states of wettability after coating by heavy oil, distilled water, dispersed silica nanoparticles in water (DSNW), polyacrylamide solution, and DSNP solution. The results showed that the silica nanoparticles caused enhanced oil recovery during polymer flooding by a factor of 10%. The distribution of DSNP solution during flooding tests in pores and throats showed strong water-wetting of the medium after flooding with this solution. The results of sessile drop experiments showed that coating with heavy oil, could make an oil-wet surface. Coating with distilled water and polymer solution could partially alter the wettability of surface to water-wet and coating with DSNW and DSNP could make a strongly water-wet surface.     

Study of Microscopic and Macroscopic Displacement Behaviors of Polymer Solution in Water-Wet and Oil-Wet Media

Performance of a polymer flood process requires the knowledge of rheological behavior of the polymer solution and reservoir properties such as rock wettability. To provide a better understanding of effects of polymer chemistry and wettability on the performance of a polymer flood process, a comprehensive experimental study was conducted using a two-dimensional glass micromodel. A series of water and polymer flood processes were carried out at different polymer molecular weights, degrees of polymer hydrolysis, and polymer concentrations in both water-wet and oil-wet systems. Image processing technique was applied to analyze and compare microscopic and macroscopic displacement behaviors of polymer solution in each experiment. From micro-scale observations, the configuration of connate water film, polymer solution trapping, flow of continuous and discontinuous strings of polymer solution, piston-type displacement of oil, snap-off of polymer solution, distorted flow of polymer solution, emulsion formation, and microscopic pore-to-pore sweep of oil phase were observed and analyzed in the strongly oil-wet and water-wet media. Rheological experiments showed that a higher polymer molecular weight, degree of hydrolysis, and concentration result in a higher apparent viscosity for polymer solution and lower oil–polymer viscosity ratio. It is also shown that these parameters have different impacts on the oil recovery in different wettabilities. Moreover, a water-wet medium generally had higher recovery in contrast with an oil-wet medium. This experimental study illustrates the successful application of glass micromodel techniques for studying enhanced oil recovery (EOR) processes in five-spot pattern and provides a useful reference for understanding the displacement behaviors in a typical polymer flood process.     

A Fully Nonlinear Nonhomogeneous Neumann Problem

Let Ω be an open bounded set in ℝ^N, N≥3, with connected Lipschitz boundary ∂Ω and let a(x,ξ) be an operator of Leray–Lions type (a(⋅,∇u) is of the same type as the operator |∇u|^p−2∇u, 1<p<N). If τ is the trace operator on ∂Ω, [φ] the jump across ∂Ω of a function φ defined on both sides of ∂Ω, the normal derivative ∂/∂ν_a related to the operator a is defined in some sense as 〈a(⋅,∇u),ν〉, the inner product in ℝ^N, of the trace of a(⋅,∇u) on ∂Ω with the outward normal vector field ν on ∂Ω. If β and γ are two nondecreasing continuous real functions everywhere defined in ℝ, with β(0)=γ(0)=0, f∈L¹(ℝ^N), g∈L¹(∂Ω), we prove the existence and the uniqueness of an entropy solution u for the following problem,

Novel Helmholtz-based photoacoustic sensor for trace gas detection at ppm level using GaInAsSb/GaAlAsSb DFB lasers

A new and compact photoacoustic sensor for trace gas detection in the 2-2.5 microm atmospheric window is reported. Both the development of antimonide-based DFB lasers with singlemode emission in this spectral range and a novel design of photoacoustic cell adapted to the characteristics of these lasers are discussed. The laser fabrication was made in two steps. The structure was firstly grown by molecular beam epitaxy then a metallic DFB grating was processed. The photoacoustic cell is based on a Helmholtz resonator that was designed in order to fully benefit from the highly divergent emission of the antimonide laser. An optimized modulation scheme based on wavelength modulation of the laser source combined with second harmonic detection has been implemented for efficient suppression of wall noise. Using a 2211 nm laser, sub-ppm detection limit has been demonstrated for ammonia.     

Global Stabilization of a Class of Bilinear Systems in $${\mathbb{R}^3}$$

In this paper, we consider a class of bilinear systems in dimension three which can be an extension of another one in \({\mathbbm{R}^{2}}\). We prove that there exists some homogeneous feedback of degree zero stabilizing the considered class if and only if these feedbacks are constants.     

Novel synthesis, reactivity, and stereochemistry of substituted 3-trifluoromethyl- and 3-perfluoroalkyl-3-phenoxyprop-2-enal

Substituted 3-phenoxy-3-perfluoroalkylprop-2-enals 3a-s are synthesized in high yields starting from a gem-iodoacetoxy derivative 1 and phenoxides 2. Then efficient syntheses of push-pull derivatives 4, 5,8a,b, and nonconjugated analogues 6 and 7 illustrate the synthetic potentialities of 3. Stereochemical studies of these perfluoroalkyl-containing trisubstituted olefinic derivatives 3-8b revealed that the (4)J(CF) coupling constant observed in the (13)C NMR spectra was crucial in the determination of their configurations and conformations in solution. The solvent polarity effect on the stereochemistry of push-pull compounds 3-5 and 8a,b was studied. Unusual significant medium polarity effect on the stereochemistry of imino enol ether derivative 4 was observed.     

Pore-Level Observation of Free Gravity Drainage of Oil in Fractured Porous Media

This work presents results from two sets of experiments conducted to study, in pore level, the role of fracture aperture and tilt angle on the stability of liquid bridges and the shape of a front during free gravity drainage process. Glass micromodels of two different aperture sizes were used to monitor the mechanism of gravity drainage of air?Ccrude oil system, rotating around a bottom corner to create different tilting angles. Oil content within the matrix blocks was determined as a function of time using a series of images obtained during the experiments, from which net drainage rate from the upper and lower matrix blocks is calculated. Liquid bridges are more frequent but less stable at early time of drainage. The liquid bridges, which have widths as thin as 50 ??m, can resist instability to maintain continuity. Liquid bridges formed in stacks with higher tilt angles are more stable, enhancing oil drainage from the upper matrix block and causing higher recoveries. Quantitative analysis of the results shows that a wider fracture aperture increases the oil production rate, but reduces the ultimate recovery. Furthermore, stacks with higher tilt angles present larger ultimate recoveries and smaller production rates. The front geometry in the lower block deviates from linearity due to formation of liquid bridges in the middle fracture. The results of this work can be helpful to better understand the interaction between fractures and matrix blocks.