Nonpolar Hydrocarbon Solvents Research Articles

Microfluidic fabrication using cyclic olefin copolymer and hydrocarbon solvents

Cyclic olefin copolymer (COC) is a promising material in microfluidic applications due to their unique physical, chemical, and optical properties. This study implements a new and versatile fabrication process to fabricate COC microchannels, combining the fabrication and bonding processes in a single step, taking advantage of COCs’ swelling behavior in linear non-polar hydrocarbon solvents and their chemical compatibility with photolithography. Dodecane was selected as the hydrocarbon solvent based on the degree of swelling and Flory-Huggins interaction parameter, which resulted in the highest degree of swelling and affinity to COC. The effect of dodecane immersion time on the COC microchannel height was investigated, achieving a maximum average height of 50 ± 3 µm after 180 min. Bonding quality was quantified by a leakage test (maximum flow rate of 1730 ± 205 µL/min (Re = 237)), and a tensile test (800 ± 90 kPa). Furthermore, the effectiveness of the implemented process was demonstrated through the successful execution of three highly diverse microfluidic applications. These applications included a serpentine microchannel featuring semicircular obstacles that facilitated passive mixing, pinched flow fractionation which enabled the separation of a system of three different sizes of microparticles, and droplet microfluidics that allowed for the efficient generation of water in oil droplets.

Complexes of aluminum, iron(III), and gallium(III) chlorides with ethers in synthesis of highly reactive polyisobutylene

In this review, the latest achievements in the field of cationic polymerization of isobutylene catalyzed by the complexes of conventional Lewis acids with ethers are presented. The experimental and computational data on the influence of steric structure and basicity of ether used for the preparation of the Lewis acid-ether complex on the catalyst activity and regioselectivity of β-H abstraction are discussed here. Complexes of metal halides with linear (Bu2O) and moderately branched (iPr2O) ethers of moderate basicity (pKa from –4.3 to –5.4) displayed the highest activity and regioselectivity in the cationic polymerization of isobutylene affording highly reactive polyisobutylene (HR PIB) – the key intermediate in the preparation of motor oil and fuel additives. The review is also focusing on the adaptation of the developed catalytic system to the industry, which consists in using non-polar hydrocarbon solvents, high temperatures and monomer concentrations.

Supramolecular self-assembly of oleylamide into organogels and hydrogels: a simple approach in phase selective gelation of oil spills

ABSTRACTA new gelator based of oleylamide has been introduced, which was gelled nonpolar hydrocarbon and CCl4 solvents through self-assembly. Also, the gelator formed a two-component hydrogel in combination with SDS, an anionic surfactant. UV-Vis studies revealed that the H-type and J-type aggregation of organogels in hexane and hydrogel in water, respectively. The xerogel, obtained by evaporating the solvent of organogel, selectively gelled and adsorbed oil spills on water surfaces. The effect of the various parameters, including temperature, water acidity and pH on the oil spill adsorption was studied, revealing the high ability of the xerogel to removing the oil contamination from water in up to 10 min. The novelty of this work is the ability of the xerogel to the phase selective gelation of oil without an extra auxiliary and/or heat. Simple synthesis of gelator started with oleic acid from natural resources is a main advantage of the present work.

Effect of Nature of Nonpolar Hydrocarbon Solvents on Adsorption Capacity of Synthetic Fatty Acids, Amines, and Amides

The sorption of surface-active substances (surfactants), namely, C18–C21 synthetic fatty carboxylic acids (distillation residues of their production), a number of amines, and amides from films of pure, normal paraffinic hydrocarbons such as heptane, octane, nonane, decane, and pentadecane deposited on St3 steel immersed in 0.5 M NaCl solution, has been studied. Concentrations have been obtained at which the degree of surface filling with surface-active substances approaches unity. It is shown that surfactant adsorption takes place on an energetically inhomogeneous surface, and it seems that in a number of cases it is realized by the donor-acceptor interaction mechanism.

Alternatives for Conventional Alkane Solvents.

The studies described in this paper show that hydrocarbon oligomers are alternatives for low molecular weight alkane solvents. These oligomeric solvents are nontoxic, nonvolatile, and recyclable alternatives to heptane in thermomorphic solvent mixtures that use a polar solvent such as methanol, aqueous ethanol, or DMF or in biphasic mixtures that use acetonitrile. Regardless of which polar solvent is used, hydrocarbon oligomers like poly(α-olefin)s (PAOs) exhibit very low leaching into the polar phase. UV-visible spectroscopy studies show that these solvents have the solubility properties of heptane. For example, PAOs dissolve heptane soluble dyes and quantitatively separate them from polar phases in thermomorphic solvent mixtures. PAOs either as pure solvents or as additives in heptane act as antileaching agents, decreasing the already low leaching of such dyes into a polar phase in heptane/polar solvent mixtures. These oligomeric hydrocarbon solvents were also compared to heptane in studies of azo dye isomerization. The results show that thermal isomerization of an azo dye occurs at the same rate in heptane and a PAO. Further studies of carboxylic acid promoted dye isomerization in heptane and a PAO show that low molecular weight and oligomeric carboxylic acids are kinetically equivalent at accelerating this isomerization. The results suggest that these and other hydrocarbon oligomers behave as solvents like their low molecular weight nonpolar hydrocarbon solvents and that they can be substituted successfully for conventional solvents like heptane.

Synthesis of Telechelic Olefin Polymers via Catalyzed Chain Growth on Multinuclear Alkylene Zinc Compounds

Multinuclear alkylene zinc (MAZ) compounds of the type EtZn-(R″-Zn)n-Et (R″ = ethyl and propyl branched alkylene groups) were synthesized by a simple one-step procedure in nonpolar hydrocarbon solvents from α,ω-dienes (e.g., 1,7-octadiene or 1,9-decadiene) and diethylzinc using a bis(salicylaldiminato)Zr(IV) complex, [(2-methylcyclohexyl)N═CH(2-O-C6H3-3,5-di-tert-butyl)]2ZrMe2, as a catalyst. The MAZ serves as a divalent reversible chain-transfer agent for olefin polymerization, resulting in telechelic Zn-metalated polyolefins whose molecular weights are controllable over a wide range. The Zn-terminated telechelics serve as a polymer precursor for further reactions and can be converted into a variety of telechelic functionalized polyolefins in high yield.

Preparation of stable dispersions of layered double hydroxides (LDHs) in nonpolar hydrocarbons: new routes to polyolefin/LDH nanocomposites

We report a simple and cost effective solvent treatment method for the synthesis of a stable and transparent dispersion of the hydrophilic layered double hydroxide, [Mg(6)Al(2)(OH)(16)](CO(3)) in non-polar hydrocarbon solvents. This dispersion can be used to make polyolefin/LDH nanocomposites using a simple solvent mixing method.

Experimental and theoretical study of the reaction locus during the dispersion polymerization of methyl methacrylate in a nonpolar hydrocarbon solvent at low temperature

AbstractThe dispersion polymerization of methyl methacrylate (MMA) has been studied in a nonpolar hydrocarbon solvent at low temperature using N,N‐dimethylaniline (DMA) and lauroyl peroxide (LPO) as redox initiation system. To explain the heterogeneous kinetic characteristics of the polymerization process, the reaction locus has been experimentally and theoretically investigated. The evolutions of monomer conversion, polymer molecular weight distribution (MWD), and particle morphology were measured throughout the polymerization. It was found that the significant preferences of LPO and DMA to accumulate in the polymer‐rich phase after the system phase separation are mainly responsible for both the uniformity of particle sizes and the broad polymer MWDs. It was observed that particle agglomeration and breakup mechanisms were enhanced under agitation, thus promoting the formation of broader particle size distributions. The observed kinetics and thermodynamics of the low‐temperature polymerization were also examined through a mathematical model where the distributions of initiators, solvent, and monomer between phases were considered. A good agreement between the experimental and theoretical results was observed and the model was used to estimate the conditions that promote bimodal MWDs. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Synthesis, Characterization, and Photophysical Study of Fluorescent N-substituted Benzo[ghi]perylene “Swallow Tail” Monoimides

A set of N-substituted benzoperylene monoimide (BPI) fluorophores was synthesized and characterized structurally and photophysically. Condensation of benzo[ghi]perylene-1,2-dicarboxylic anhydride in the presence of "swallow tail" alkyl amines produced fluorophores that are soluble in a range of organic solvents, highly absorbing in the near-UV (ε(334) = 79,000 M(-1) cm(-1)), and fluorescent in the visible range. Photophysical behavior of the compounds was studied with steady-state and time-correlated single photon counting. The synthesized BPIs exhibit positive solvachromatic emission (λ(em) (hexane) = 469 nm; λ(em) (ethanol) = 550 nm) as a function of solvent polarity with little change in their excited-state lifetime (9.6-6.5 ns) and fluorescence quantum yield (0.27-0.44) over the polarity range studied. Solvachromatic shifts were analyzed using the Lippert-Mataga approach. In nonpolar hydrocarbon solvents evidence of dual emission from closely spaced (562 cm(-1)) S(1) and S(2) excited states is observed. Preliminary peak assignments for the anomalous S(2) emission are made.

Enforced liquid crystalline properties of dibenzo[a,c]phenazine dimer and self assembly

Dibenzo[a,c]phenazine dimers with the following features: (i) short spacer, (ii) peripheral chains shorter and longer than the spacers, and (iii) reduced symmetrical structure of the disc were synthesized. The dibenzo[a,c]phenazine disc has enforced the self-assembly of discotic dimers connected through six methylene spacers to form mesophases through a folded conformation in the mesophase. An X-ray diffraction study pinpoints the preferential intra-molecular bridging conformation of these dimers at the mesophase. These new discotic dimers showed polymesomorphism and glass formation. Interestingly, these discotic dimers form organogels with non-polar hydrocarbon solvents and long chain aliphatic alcohols. A superstructure arising from association of the nanofibers was observed with transmission electron microscopy.

Densities, viscosities and ultrasound velocities for binary mixtures of isopropylethanoate and non-polar hydrocarbon solvents

Densities (ρ), viscosities (η), and ultrasound velocities(u) for binary mixtures of isopropylethanoate and non-polar hydrocarbon solvents viz cyclohexane, benzene,1,4-dimethylbenzene and 1,3,5-trimethylbenzene have been measured at 308.15 K.Adiabatic compressibilities(β ad), available volume(V a) and acoustical impedance(Z) for the binary mixtures are evaluated from the ultrasound velocity and density data. Deviations in viscosity (Δη), in ultrasound velocity (Δu) and in compressibility (Δβ ad) from their additive values for all the systems studied are evaluated from the experimental values for the mixtures and their components at experimental temperature. ∆η and ∆u values are negative and ∆β ad are positive for cyclohexane + isopropylethanoate binary mixture. Several models for mixture viscosity are analysed. The strength of interactions are discussed in terms of Grunberg and Nissan interaction parameter (d). Hind–McLaughlin–Ubbelohde viscosity equation is found to be most suitable for the viscosities of the binary mixtures studied. Results are discussed in terms of interactions between components of the mixtures.

Nucleophilic Substitution Reactions of meso‐5,10,15‐Tris(pentafluorophenyl)corrole; Synthesis of ABC‐Type Corroles and Corrole‐Based Organogels

AbstractNucleophilic substitution reactions of 5,10,15‐tris(pentafluorophenyl)corrole (1) with amines were examined as a post‐modification route to functional corroles. Reaction of 1 with an excess of amine nucleophiles led to exclusive formation of 5,10,15‐tris(4‐amino‐2,3,5,6‐tetrafluorophenyl)‐substituted corroles. In this nucleophilic reaction, 5‐ and 15‐pentafluorophenyl substituents were found to be more reactive than the substituent at the 10‐position. This substitution reaction was applied for the preparation of ABC‐type corroles and corrole‐based organogels. The latter exhibited a blue‐shifted Soret band and small fluorescence quantum yields in nonpolar hydrocarbon solvents due to the formation of H‐type aggregates.

Polymerization of methyl methacrylate in the presence of a nonpolar hydrocarbon solvent. I. Construction of a complete ternary phase diagram through an in situ polymerization

AbstractThis article presents the ternary phase diagram for methyl methacrylate (MMA), poly(methyl methacrylate) (PMMA), and n‐hexane system at 70°C. It was constructed by both theoretical calculations and online laser light scattering (LLS) technique. In situ polymerization of MMA in a nonpolar nonsolvent carried out in a LLS cell provides a new means for the accurate detection of the cloud points of highly viscous polymer mixtures, with polymer weight fractions over 0.6. The ternary phase diagram measured in this study can be used to design the reaction conditions for the precipitation and/or dispersion polymerization in a nonpolar nonsolvent medium where polymerization kinetics as well as polymer particle morphologies are strongly affected by thermodynamic phase separation phenomena. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Potential for Misidentification of Environmentally Persistent Free Radicals as Molecular Pollutants in Particulate Matter

Environmentally persistent free radicals (EPFRs) have been shown to form on the surfaces of various types of transition metal-containing particulate matter (PM), and it has been demonstrated they are capable of initiating adverse health impacts. Following sonification and solvent extraction for chemical analysis, they are partially converted to molecular species. Alcoholic solvents extracted the EPFRs with near 100% efficiency, while nonpolar hydrocarbon solvents exhibited <20% efficiency and dichloromethane exhibited 20-55% efficiency. The extracted radicals reacted in solution to form multiple molecular reaction products including catechol, hydroquinone, phenol, chlorinated phenols, dibenzo-p-dioxin, and dibenzofuran. This suggests that EPFRs in environmental samples are indistinguishable from molecular pollutants and are subject to misidentification as molecular adsorbates when traditional extraction and chemical analysis methods are employed. On the basis of these findings, the origin of the toxicity of particulate matter contaminated with toxic organic compounds should be considered for re-evaluation to include the possibility that EPFRs may be a significant contributor, and the impact of some molecular pollutants may have been overestimated.

Excess Molar Volumes and Viscosities of Binary Mixture Between n-Butylethanoate and Several Non Polar Hydrocarbons

Abstract The densities (ρmix) and viscosities (ηmix) of binary mixtures between n-butylethanoate and several non-polar hydrocarbon solvents viz; cyclohexane, benzene, 1,4-dimethylbenzene and 1,3,5-trimethylbenzene have been measured at 308.15 K for the whole composition range. From the experimental densities values, excess molar volumes(VE) have been estimated. VE values are found to be large positive for mixtures with cyclohexane for entire range of concentration while small positive for benzene and 1,3,5-trimethylbenzene except a negative value at lower concentration of both hydrocarbons and at higher concentration of latter hydrocarbon only. Almost all the VE values are negative for mixtures with 1,4-dimethylbenzene. Deviations in viscosities (Δη) from ideal behaviour have been calculated from the experimental viscosities values. Δη values are large negative for mixtures with cyclohexane. The negative Δη values gradually decreases from benzene, 1,4-dimethylbenzene to 1,3,5-trimethylbenzene respectively. Experimental viscosities values have been analysed on the basis of several viscosities models. The results have been discussed in terms of molecular interactions between unlike molecules.

Solvent‐Assisted Organized Structures Based on Amphiphilic Anion‐Responsive π‐Conjugated Systems

The synthesis of amphiphilic pi-conjugated acyclic oligopyrroles and the formation of solvent-assisted aggregates are reported. We have prepared various types of BF(2) complexes of 1,3-dipyrrolylpropane-1,3-diones bearing aryl rings substituted with hydrophilic polyethyleneglycol (PEG) chains, both as acyclic anion receptors and as building subunits for organized architectures based on pi-pi stacking. The formation of supramolecular H-type assemblies of these "amphiphilic" derivatives in aqueous solution was suggested by UV/Vis and fluorescence spectroscopy and further supported by (1)H NMR and dynamic light scattering (DLS) analyses. Cryogenic transmission electron microscopy (cryo-TEM) analyses of the aqueous solutions suggest that the fabrication of nanoscale network structures and vesicles depends on the peripheral substituents. The H-aggregates in aqueous solution are sensitive to the conditions required for transformation into monomers through replacement with miscible solvents such as alcohols and into J-type aggregates by water evaporation and freeze-drying procedures. However, they are fairly stable and sustainable to anion binding, whereas on CH(2)Cl(2) extraction they are transformed into other assembled modes but remain in the aqueous solution. The metastable states of affairs for distributions between two immiscible solvents are controlled by the orders of solution preparation; this also suggests that the formation of stable assemblies is assisted by water molecules. Furthermore, assemblies in which the stacking modes depend on the aliphatic side chains are also observed in a nonpolar hydrocarbon solvent.

Experimental correlation of nitroxide recollision spin exchange with free volume and compressibility in alkane and aromatic compounds

Diffusion of perdeuterated tempone (PDT) in various nonpolar hydrocarbon solvents on both the large and microscopic scales is examined through electron paramagnetic resonance spectroscopy. Spectral line broadening and hyperfine spacing are measured in order to extract both the Heisenberg spin-exchange rate as well as the average recollision times between spin-probe pairs. Probe recollision is responsible for a linear component to the dependence of the line shift on spectral broadening which has been identified in recent years. The present study extends the work of a previous paper by Kurban et al. [J. Chem. Phys. 129, 064501 (2008)], in which it was reported that recollision rates for PDT formed a common curve across n-alkanes when plotted with respect to free volume and to isothermal compressibility. It is now found that such common curves occur within distinct chemical families, in particular, the alkane and aromatic groups. Within each chemical family, the spin probe recollision rate correlates with free volume and compressibility independently of the geometry of the particular solvent. All solvents show significantly enhanced recollisional diffusion over the Stokes-Einstein (SE) prediction at high temperatures. The spin-exchange rate forms a common curve with respect to T/eta for all alkanes except cyclohexane and another common curve in all three aromatic compounds. It is reasoned that although all spin-exchange rates are near to the SE prediction, the semblance of hydrodynamic behavior is superficial and arises incidentally from mathematical cancellation of terms in a generalized diffusion coefficient. As a collision pair coexists for a time within a solvation shell, the recollision time places a lower limit on the lifetime of the solvent cage. Although molecular dynamics simulations conducted thus far have yielded cage lifetimes lower than the measured recollision times, this is attributable to the fact that such simulations have mostly examined cage configurations too small to harbor a spin-exchange encounter, and is also likely due to restrictive mathematical definitions of cage lifetimes that are employed in such simulations.

Noncovalent Macromolecular Architectures of Oligo(p‐phenylenevinylene)s (OPVs): Role of End Functional Groups on the Gelation of Organic Solvents

AbstractSummary: Self‐assembly of a few OPV derivatives having different end functional groups to aggregates, fibrous networks and organogels are discussed. OPV1 and OPV2 functionalized with ester moieties form gels in nonpolar hydrocarbon solvents whereas OPV3 with carboxylic acid groups form gel from THF and dichloromethane. OPV4 with dicyano moieties form aggregates but could not gelate solvents. AFM and TEM studies revealed considerable difference in the morphology of the self‐assembled structures of OPV1‐4. From the optical, morphological and gelation data it is concluded that the nature of the end functional groups strongly influences upon the self‐assembly and gelation properties of OPVs.

Helical Supramolecular Architectures of Self-Assembled Linear π-Systems

Abstract The present account describes the summary of the recent developments to the design of helical self-assemblies of linear π-conjugated molecules, particularly of oligo(p-phenylenevinylenes) (OPVs) and oligo(p-phenyleneethynylenes) (OPEs). The design strategy involves functionalization of π-conjugated backbones with achiral and chiral alkoxy side chains and hydroxymethyl end groups. Self-organization of these molecules in nonpolar hydrocarbon solvents resulted in a variety of supramolecular architectures such as tapes, helices, vesicles, and tubules. These supramolecular structures eventually lead to the formation of entangled networks resulting in gelation of solvents. It has been observed that OPVs in nonpolar solvents prefer to form supramolecular tapes whereas the corresponding OPEs form nano- to microsized vesicles and bundled fibers. Attachment of chiral motifs to OPVs and OPEs resulted in the formation of helical structures with a preferred handedness. The “sergeants and soldiers” co-assembly approach to chirality induction and amplification is efficient in these systems in the gel state. These results highlight the importance of the subtle difference in the strength of π–π interaction in gel forming linear π-systems to the creation of hierarchical architectures with different size and shape, particularly helical structures.

Polyyne Synthesis Using Carbene—Carbenoid Rearrangements

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.