Oxirane Ring Opening Reactions Research Articles

Rapeseed Oil as Feedstock for High Functionality Polyol Synthesis

In this study, polyols with high average functionality were synthesized from a renewable resource, rapeseed oil, as raw material for rigid PU foam production. A well-known method of rapeseed oil fatty acid double bond epoxidation was used to introduce oxirane rings into rapeseed oil structure. The temperature influence on epoxidation reaction conversion rate was studied by volumetric and FTIR spectra analysis. After epoxidation of rapeseed oil, an oxirane ring-opening reaction was carried out to obtain high functionality polyols. Diethylene glycol, a conventional oxirane ring-opening reagent, was compared to amine-based polyfunctional alcohols, diethanolamine and triethanolamine. The introduction of tertiary amine groups into the polyol structure provided catalytical properties for obtained polyols, which will allow a reduction of the amount of catalysts in polyurethane foam formulations. Hydroxyl value, acid value, moisture content, viscosity and density of synthesized polyols were determined, and their structure and average functionality were analyzed by FTIR and MALDI-TOF spectroscopy and GPC analysis. Also, the main characteristics of rigid PU foam obtained from synthesized polyols were determined.

Liquid–Liquid–Solid Model for the Epoxidation of Soybean Oil Catalyzed by Amberlyst-16

The epoxidation of soybean oil is a hot topic for biorefinery. The process is nowadays performed in the presence of a strong mineral acid (H2SO4, H3PO4) that catalyzes both the epoxidation and the oxirane ring opening reactions, leading to high conversions and low selectivity. Moreover, the separation of such a catalyst needs neutralization steps, thus operation units. Previous studies revealed that Amberlyst-16, an acid exchange resin, is a stable and active catalyst in the epoxidation of soybean oil, showing high selectivity. In the present paper, a rigorous liquid–liquid–solid kinetic model has been proposed to interpret the kinetics of the soybean oil epoxidation reaction catalyzed by Amberlyst-16. The intrinsic kinetics of the overall reaction network has been investigated by taking into account all the occurring chemical and physical phenomena, overall dealing with the intraparticle diffusion limitations. From the data elaboration, it has been demonstrated that the unique role of the resin is to cat...

Blending of vegetable oils and chemical modification by epoxidation followed by oxirane ring-opening reaction

In this paper, vegetable oil as refined soybean oil, refined sunflower oil and their blends of different proportions have been investigated. The physicochemical properties such as viscosity, acidity value, iodine value and saponification value have been reported. From the result, the blend of vegetable oils with volume ratio at 20:80 has higher viscosity index than individual vegetable oil, as well as suitable acidity and saponification value. However, iodification of this blend is relatively high, indicating that this blend has a low oxidation stability. Hence, this mixture has been continually exposed to epoxidation reaction with the purpose of removing the presence of double bond C=C followed by oxirane-ring open reaction. The results indicate that temperature, time of reaction, molar ratio H2O2/C=C influence significantly on iodine value of obtained blend. The following conditions in epoxidation step: CH3COOH/C=C 1:1; time of reation 7h, temperature of reaction 60oC, stirring speed 500 rpm and H2O2/C=C 3:1 can reduce effectively iodine value, from 129.6 to 6.9. In the oxirane-ring open reaction, n-butanol is used as reagent and the final product has higher viscosity compared to epoxidized blend.

Controlling Nanodomain Morphology of Epoxy Thermosets Modified with Reactive Amine-Containing Epoxidized Poly(styrene-b-isoprene-b-styrene) Block Copolymer

Controlling nanodomain morphology of nanostructured epoxy thermosets is critical to modulate the mechanical properties of the cross-linked matrix. In this contribution, we demonstrate that this can be achieved by using a suitable block copolymer containing an epoxy soluble block with the ability to react toward the epoxy system during curing. For this purpose we designed an epoxidized poly(styrene-b-isoprene-b-styrene) block copolymer incorporating amine-reactive functionalities (eSIS-AEP) in the epoxidized block as modifier for an epoxy system, which allowed the formation of nanostructured thermosets with controlled spherelike nanodomain morphology. The eSIS-AEP was obtained in two steps from poly(styrene-b-isoprene-b-styrene) (SIS) block copolymer by controlled epoxidation of the olefinic block followed by partial oxirane ring-opening reaction using 1-(2-aminoethyl)piperazine as nucleophile. Before the curing reaction it was observed that poly(styrene) blocks self-assembled to form ordered spherelike nanostructures in blends of eSIS-AEP with epoxy precursors. Since the amine-reactive moiety was incorporated to the block copolymer so that it could react toward diglicidyl ether of bisphenol A (DGEBA) at a similar temperature than the DGEBA/hardener reaction, the epoxy miscible block of eSIS-AEP (ePI-AEP) was able to react with DGEBA during curing. Once the cross-linked network was formed, the initially obtained spherelike nanodomains were preserved, indicating that no reaction-induced microphase separation of ePI-AEP subchains occurred. A completely different scenario was ascertained for epoxidized SIS block copolymer, which conducted to nonspherical nanodomains due to the uncontrolled epoxidized poly(isoprene) demixing process during the curing reaction. These results demonstrate the importance of the epoxy soluble block being reactive toward the epoxy precursors to control the morphology of the obtained nanostructure.

Synthesis of 5-substituted derivatives of isophthalic acid as non-polymeric amphiphilic coating for metal oxide nanoparticles

In the course of development of novel capping ligands with variable steric factor, which will be used as an organic coating for metal oxide nanoparticles, a base-catalyzed nucleophilic oxirane ring-opening addition reaction between dimethyl 5-hydroxyisophthalate and allyl glycidyl ether was studied. The allyl-terminated 1-1, 1-2, and 1-3 adducts and dihydroxylated derivative of the 1-1 adduct, 5-diglyceroxy isophthalic acid, were synthesized. The latter binds to the surface of 5 nm γ-Fe2O3 nanoparticles in reaction with their surfactant-free diethylene glycol colloids.

Easy synthesis of dendrimer-like polymers through a divergent iterative “end-grafting” method

We report here an easy method for the synthesis of dendrimer-like polymers with high branching functionality (1 → 8). The synthetic process involves iterative grafting reactions in a divergent way. A multi-functional core containing short segments of polyisoprene (PI), either as a star-like block copolymer of isoprene and styrene or as a linear triblock copolymer of isoprene, styrene and isoprene (coded G1), is epoxidized on the double bonds and grafted with a living block copolymer, polyisoprene-b-polystyrenyllithium (PI-b-PSLi), again with a short PI segment, through the ring-opening reaction of oxirane by polymeric anions. The resulting graft polymer, G2, possesses a definite number of PI segments at the periphery. These PI segments are further epoxidized followed by the ring-opening addition of PI-b-PSLi, affording G3. Repeating the process leads to the synthesis of a dendrimer-like polystyrene up to 5th generation with a polydispersity lower than 1.21, as measured by SEC. A feature of the process is the easily accessible high chain density in the final product, although defects exist due to steric hindrance in the reactions of high generations. The solution properties of the dendritic products are investigated using viscometry and dynamic and static laser light scattering on the molecular conformation. The results support a compact globular conformation model for the dendrimer-like products. In addition, the chain density of the products from the star-like core is higher than that of products from a linear triblock core. AFM results show that the dendritic products adopt flattened conformations and tend to form lateral sphere-like aggregates on mica substrate.

The Structural Studies of Oxirane Ring Opening Reaction in Epoxidized Natural Rubber (ENR-50) by SnCl<sub>2</sub>.2H<sub>2</sub>O and the Formation of ENR/TiN Complex Hybrid

Oxirane ring opening reaction of epoxidized natural rubber (ENR-50) is a promising method to produce hybrids or introduce reactive fillers into the polymers through the covalent bond. This paper reports the reaction between ENR-50 and SnCl2.2H2O under CO2environment. The complex formation is characterized via FTIR,1H,13C and119Sn NMR.1H NMR which displays deduction of methine proton integrals at δ 2.71 ppm implies the occurrence ring opening reaction. While13C NMR reveals new peaks which corresponds to Sn-C bond. The119Sn NMR proves four-coordinates tin in ENR/Sn complex hybrid.

Synthesis of Azanucleosides through Regioselective Ring-Opening of Epoxides Catalyzed by Sulphated Zirconia under Microwave and Solvent-Free Conditions

New azanucleosides were obtained using sulphated zirconia (ZS) as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl)pyrimidine-2,4(1H,3H)-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl)-pyrimidine-2,4(1H,3H)-dione, with (S)-prolinol. The new templates were obtained with good yields following a route which exploits the reactivity of epoxides in the presence of sulphated zirconia as catalyst. The key step was carried out using microwave and solvent-free conditions and proceeds with high selectivity.

Synthesis of Azido-, Hydroxy- and Nitro-, Hydroxy-Functionalized Spherosilicates via Oxirane Ring-Opening Reactions

Azido functional silsesquioxanes are the natural extension of click chemistry and a convenient starting material for further synthesis of new POSS compounds as well as modification of other materials in 1,3-dipolar cycloaddition processes. Increasing demand for these compounds has stimulated the search for new and efficient methods for their synthesis. In this paper, we present characterization and methodology of synthesis of new POSS compounds bearing azido groups via epoxy ring-opening reaction in epoxy functional POSS compounds with sodium azide. Two new POSS derivatives with azido and hydroxy functionalities were obtained­ with a high selectivity and yield. Also two new nitro- and hydroxy-functionalized POSS derivatives were obtained in the reaction of epoxy-functionalized POSS compounds with 4-nitrophenol.

Optimization of the oxirane ring opening reaction in biolubricant base oil production

This study has successfully optimized the conversion of monoepoxide linoleic acid (MEOA) into biolubricant via oxirane ring opening reaction using oleic acid (OA) with p-toluene sulfonic acid (PTSA) as a catalyst. The four main factors were studied according to a D-optimal design at three levels. These factors were OA/MEOA ratio, PTSA/MEOA ratio, temperature and reaction time. This analysis evidenced the best operating conditions of the oxirane ring opening reaction performed at the following condition; OA/MEOA ratio of 0.30:1 (w/w), PTSA/MEOA ratio of 0.50:1 (w/w), reaction temperature at 110°C and reaction time at 4.5h, an optimum yield of 84.61% and OOC of 0.05%. This model results showed a good agreement with the predict value, demonstrating that this methodology may be useful for industrial process optimization.

The physicochemical and tribological properties of oleic acid based triester biolubricants

Currently, increasing pollutants in the environment lead to an increase in the use of plant oil based biolubricants. These products could lead to a significant reduction in environmental pollution and thus contribute to the discovery of a replacement for petroleum-based lubricants. Plant oils are advantageous because they are rapidly biodegradable, renewable, excellent lubricants and inexpensive to produce. However, these oils show poor stability to oxidation and unfavorable properties at low temperatures. Thus, this work outlines modifications in the epoxidation, oxirane ring opening, esterification and acylation reactions used to produce oleic acid based triester derivatives. These products have improved physicochemical and tribological properties that make them good biolubricant base stock candidates. Octyl 9-(lauroyloxy)-10-(behenoxy)octadecanoate 22 has the lowest pour point (−45 °C) while octyl 9-(lauroyloxy)-10-(octyloxy)octadecanoate 16 has the highest onset temperature. Based on the results, an increase in mid chain substituent length improves the pour point and anti-wear properties but conversely lowers the onset temperature.

Synthetic biolubricant basestocks based on environmentally friendly raw materials

This work outlines modifications in the epoxidation, oxirane ring opening, estrification and acylation reactions to produce oleic acid based triester derivatives. Measuring of pour point (PP), flash point (FP), viscosity index (VI), oxidation onset temperature (OT) and signal maximum temperature (SMT) was carried out for each compound. The resulting product structures were confirmed by NMR and FTIR spectroscopic analysis. The results showed that butyl 9-(decanoyloxy)-10-(behenoxy)octadecanoate with bulky ester behenyl mid chain exhibited the most favorable low-temperature performance (PP −47°C). On the other hand, butyl 9-(decanoyloxy)-10-(octyloxy)octadecanoate exhibited higher oxidation stability (OT 173°C) than the other synthetic esters. In conclusion, an increase in mid chain substituent length improves the PP and conversely lowers the OT.

Improvement of Physicochemical Characteristics of Monoepoxide Linoleic Acid Ring Opening for Biolubricant Base Oil

For environmental reasons, a new class of environmentally acceptable and renewable biolubricant based on vegetable oils is available. In this study, oxirane ring opening reaction of monoepoxide linoleic acid (MEOA) was done by nucleophilic addition of oleic acid (OA) with using p-toluene sulfonic acid (PTSA) as a catalyst for synthesis of 9(12)-hydroxy-10(13)-oleoxy-12(9)-octadecanoic acid (HYOOA) and the physicochemical properties of the resulted HYOOA are reported to be used as biolubricant base oils. Optimum conditions of the experiment using D-optimal design to obtain high yield% of HYOOA and lowest OOC% were predicted at OA/MEOA ratio of 0.30 : 1 (w/w), PTSA/MEOA ratio of 0.50 : 1 (w/w), reaction temperature at 110°C, and reaction time at 4.5 h. The results showed that an increase in the chain length of the midchain ester resulted in the decrease of pour point (PP) −51°C, increase of viscosity index (VI) up to 153, and improvement in oxidative stability (OT) to 180.94°C.

Modification of epoxidised canola oil

AbstractEpoxidation of canola oil was carried out using a peroxyacid generated in situ from hydrogen peroxide and a carboxylic acid (acetic or formic acid) in the presence of liquid inorganic acid, H2SO4, as catalyst. Acetic acid was found to be a better oxygen carrier than formic acid as it gave about 11% more conversion of ethylenic unsaturation to oxirane than that given by formic acid under otherwise identical conditions. A high temperature of above 65 °C is significantly unfavourable for achieving high oxirane numbers, as the selectivity to oxirane ring opening reaction increases. Higher concentrations (above 0.5 mol/mol of ethylenic unsaturation) of acetic acid, formic acid or hydrogen peroxide are also detrimental (mainly, the carboxylic acids) but much less than that of the temperature effect. From a detailed process developmental study, the parameters optimised were a temperature of 65 °C, acetic acid‐to‐ethylenic unsaturation molar ratio of 0.5, hydrogen peroxide‐to‐ethylenic unsaturation molar ratio of 1.5 and sulphuric acid loading of 2%. A relative conversion to oxirane of 81% and an iodine value conversion of 86.5% were obtained under the optimum reaction conditions. The formation of the epoxide as well as ring‐opened product of canola was confirmed by FTIR and 1H NMR spectral analysis. From a kinetic analysis, the activation energy of this commercially important reaction was determined to be 10.7 kcal/mol. The findings of this study show that hydroxylated canola oil can be used as a starting material for the lubricant formulations. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Tris(hydroxymethyl)aminomethane‐functionalized silica particles and their application for hydrophilic interaction chromatography

A new method is presented for synthesizing a highly hydrophilic silica-based material for use in hydrophilic interaction chromatography. Porous silica particles used as a starting substrate were modified with 3-bromopropyl trichlorosilane and grafted with glycidyl methacrylate by controlled ("living") atom transfer radical polymerization in order to introduce an oxirane-carrying reactive tentacle layer on the silica surface. The grafted material was thereafter subject to an oxirane ring opening reaction with tris(hydroxy-methyl)aminomethane in dimethylformamide to yield a polymer-bound equivalent of the well known and highly hydrophilic "TRIS" buffering substance. Chemical characterization was done by diffuse reflectance FT-IR, X-ray photoelectron spectroscopy, elemental analysis, and (1)H NMR. Porosity and surface area examination was done with Brunauer-Emmett-Teller. Chromatographic application of the material was evaluated by separations of nucleic bases, small organic acids, and common nucleotides under mixed hydrophilic interaction chromatography and weak anion exchange conditions.

ChemInform Abstract: A Facile One Pot Conversion of Chalcones to Pyrimidine Thione Derivatives. Ring Opening Reactions of Oxiranes Derived from Chalcones.

Arylidene 2,5-dimethylacetophenones (1) reacted with thiourea and hydrogen peroxide to give pyrimidinethione (2) and oxirane derivatives (7), respectively. The behaviour of pyrimidinethione (2) towards hydrazine, acetylhydrazines, secondary amines under Michael reaction conditions, and phenylisocyanate has been investigated. The reaction of oxirane derivative (7) with aqueous sodium hydroxide, glacial acetic acid and p-xylene under Friedel Crafts reaction conditions is also described

Assessment of noncollinear spin-flip Tamm–Dancoff approximation time-dependent density-functional theory for the photochemical ring-opening of oxirane

Under the usual assumption of noninteracting v-representability, density-functional theory (DFT) together with time-dependent DFT (TDDFT) provide a formally exact single-reference method suitable for the theoretical description of the electronic excited-states of large molecules, and hence for the description of excited-state potential energy surfaces important for photochemistry. The quality of this single-reference description is limited in practice by the need to use approximate exchange-correlation functionals. In particular it is far from clear how well approximations used in contemporary practical TDDFT calculations can describe funnel regions such as avoided crossings and conical intersections. These regions typically involve biradical-like structures associated with bond breaking and conventional wisdom would seem to suggest the need to introduce explicit double excitation character to describe these structures. Although this is lacking in ordinary spin-preserving (SP) TDDFT, it is present to some extent in spin-flip (SF) TDDFT. We report our tests of Wang-Ziegler noncollinear SF-TDDFT within the Tamm-Dancoff approximation for describing the avoided crossing in the C(2v) CC ring-opening reaction of oxirane and for describing the conical intersection relevant for the more physical asymmetric CO ring-opening reaction of oxirane. Comparisons are made with complete active space self-consistent field and quantum Monte Carlo benchmark results from two previous papers on the subject [J. Chem. Phys., 2007, 127, 164111; ibid 129, 2008, 124108]. While the avoided crossing in the C(2v) pathway is found to be reasonably well described, the method was found to be only partially successful for the conical intersection (CX) associated with the physically more important asymmetric pathway. The origin of the difficulties preventing the noncollinear SF-TDDFT method from giving a completely satisfactory description of the CX was traced back to the inability of SF-TDDFT based upon a single triplet reference state to correlate all potentially relevant configurations involving not just two but three nearly degenerate orbitals (n, σ(CO), and σ(CO)(*)). This article is also the first report of our implementation of SF-TDDFT within the deMon2k program.

Cobalt Complex as Building Blocks: Synthesis, Characterization, and Catalytic Applications of {Cd2+−Co3+−Cd2+} and {Hg2+−Co3+−Hg2+} Heterobimetallic Complexes

The present work demonstrates the utilization of the Co(3+) complex of pyridine-amide ligand as building blocks for the assembly of heterobimetallic complexes. These Co(3+)-centered building blocks orient the tethered pyridine groups to a preorganized cleft that successively coordinates to the Cd(2+) and Hg(2+) ions in the periphery. Both {Cd(2+)-Co(3+)-Cd(2+)} and {Hg(2+)-Co(3+)-Hg(2+)} heterobimetallic complexes have been thoroughly characterized, including crystal structures depicting interesting weak interactions in the solid state. The {Cd(2+)-Co(3+)-Cd(2+)} and {Hg(2+)-Co(3+)-Hg(2+)} heterobimetallic complexes have been further used for the catalytic cyanosilylation of imines and ring-opening reactions of oxiranes and thiiranes. The results suggest peripheral metal-selective catalytic reactions.

Synthesis of Novel Cyclopropyl Nucleoside Analogues as Potential Antiherpetic Agent

Synthesis of novel cyclopropyl pyrimidine and purine nucleoside derivatives was successfully achieved using one pot reactions including an alkylation, an oxirane-ring opening reaction and a lactonization and a hydroboration-oxidation as the key steps in order to find new antiherpetic agent.

Synthesis of diverse 6-(1,2-disubstituted ethyl)purine bases and nucleosides via 6-(oxiran-2-yl)purines

Dihydroxylation of 6-vinylpurines with t-BuOOH and OsO 4 gave 6-(1,2-dihydroxyethyl)purines 2, while the epoxidation with H 2WO 4 and t-BuOOH afforded 6-(oxiran-2-yl)purines 3. Oxirane ring-opening reactions of 3 with diverse nucleophiles gave a series of title 6-(1,2-disubstituted ethyl)purine bases and nucleosides, which were tested for cytostatic and antiviral activities.