Unsaturated Epoxides Research Articles

Novel elastic rubbers from CO2-based polycarbonates

We report the synthesis of novel elastic rubbers based on polycarbonates prepared by the terpolymerisation of CO2 with a long-alkyl-chain epoxide and an unsaturated epoxide.

Co2(CO)8 and unsaturated epoxides as unexpected partners in generating functionalized siloxane oils and cross-linked materials

The unexpected formation of cross-linked silicon materials was observed via hydrosilylation of unsaturated epoxides with polymethylhydrosiloxane using Co2(CO)8 as a catalyst.

Titanocenes as Photoredox Catalysts Using Green-Light Irradiation.

Irradiation of Cp2TiCl2 with green light leads to electronically excited [Cp2TiCl2]*. This complex constitutes an efficient photoredox catalyst for the reduction of epoxides and for 5‐exo cyclizations of suitably unsaturated epoxides. To the best of our knowledge, our system is the first example of a molecular titanium photoredox catalyst.

Titanocenes as Photoredox Catalysts Using Green‐Light Irradiation

AbstractIrradiation of Cp2TiCl2 with green light leads to electronically excited [Cp2TiCl2]*. This complex constitutes an efficient photoredox catalyst for the reduction of epoxides and for 5‐exo cyclizations of suitably unsaturated epoxides. To the best of our knowledge, our system is the first example of a molecular titanium photoredox catalyst.

Synthesis of acrylated cardanol diphenyl phosphate for UV curable flame-retardant coating application

Acrylated cardanol diphenyl phosphate (ACP) was synthesized via epoxidation of unsaturation in long side chains of cardanol, followed by acrylation of epoxidized cardanol and, phosphorylation of acrylated cardanol. The chemical structure of synthesized products was confirmed using Fourier transform infrared spectroscopy (FTIR), Nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR and, 31P NMR) and gel permeation chromatography technique (GPC) respectively. The effect of increasing content of ACP into UA oligomer on viscosity of coating formulations was studied using rheometer analysis. The properties of UV curable coatings were determined by differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD) and, thermogravimetric analysis (TGA). The flammability of UV cured coatings were analyzed by limiting oxygen index (LOI) and UL-94 vertical burning test. TGA result shows that the introduction of ACP into UA oligomer promotes degradation of UA oligomer and enhances the char formation. The structure of obtained char residues was further investigated from scanning electron microscopy (SEM), FTIR and Raman spectroscopy analysis. These cardanol based reactive diluent is promising candidates for UV flame retardant UV curable coatings because of their unique structure contains rigid benzene rings, phosphate moiety, polar hydroxyl groups, and long aliphatic chains.

ChemInform Abstract: Cross Metathesis of Unsaturated Epoxides for the Synthesis of Polyfunctional Building Blocks.

AbstractThe cross metathesis of unsaturated epoxide (II) with either methyl acrylate or acrylonitrile is the first step for the synthesis of polyfunctional compounds.

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks.

The cross metathesis of 1,2-epoxy-5-hexene (1) with methyl acrylate and acrylonitrile was investigated as an entry to the synthesis of polyfunctional compounds. The resulting cross metathesis products were hydrogenated in a tandem fashion employing the residual ruthenium from the metathesis step as the hydrogenation catalyst. Interestingly, the epoxide ring remained unreactive toward this hydrogenation method. The saturated compound resulting from the cross metathesis of 1 with methyl acrylate was transformed by means of nucleophilic ring-opening of the epoxide to furnish a diol, an alkoxy alcohol and an amino alcohol in high yields.

Oxidative dihydroxylation of alicyclic unsaturated hydrocarbons with vinyl- and norbornene fragments in pseudohomogenic system

Oxidation of alicyclic unsaturated hydrocarbons (4-vinylcyclohexene, 5-vinylnorbornene, 5-cyclohexenylnorbornene, and 5-vinylbicyclooctene) with 30% hydrogen peroxide solutions and percarbamide is studied. Reaction was carried out at 40–70°C in the presence of heterogenized peroxocomplex compounds of molybdenum and tungsten formed “in situ” in the reaction of metal oxohalides with H3PO4, nano-dimensional particles of carbon material, and hydrogen peroxide. Main oxidation products of alicyclic diene hydro-carbons are the corresponding unsaturated epoxides and diols. Depending on the reaction condition their ratio varies in a wide range.

Controlled selectivity for palladium catalysts using self-assembled monolayers

The selective reaction of one part of a bifunctional molecule is a fundamental challenge in heterogeneous catalysis and for many processes including the conversion of biomass-derived intermediates. Selective hydrogenation of unsaturated epoxides to saturated epoxides is particularly difficult given the reactivity of the strained epoxide ring, and traditional platinum group catalysts show low selectivities. We describe the preparation of highly selective Pd catalysts involving the deposition of n-alkanethiol self-assembled monolayer (SAM) coatings. These coatings improve the selectivity of 1-epoxybutane formation from 1-epoxy-3-butene on palladium catalysts from 11 to 94% at equivalent reaction conditions and conversions. Although sulphur species are generally considered to be indiscriminate catalyst poisons, the reaction rate to the desired product on a catalyst coated with a thiol was 40% of the rate on an uncoated catalyst. Interestingly the activity decreased for less-ordered SAMs with shorter chains. The behaviour of SAM-coated catalysts was compared with catalysts where surface sites were modified by carbon monoxide, hydrocarbons or sulphur atoms. The results suggest that the SAMs restrict sulphur coverage to enhance selectivity without significantly poisoning the activity of the desired reaction.

New macromonomers: Commercially available polycarbonate and polyarylate grafted with unsaturated and alkoxysilyl group pendants

AbstractThe insertion reaction of commercially available polycarbonate (PC) and polyarylate (PAR) with unsaturated epoxides produced new macromonomers grafted with many unsaturated group pendants in the middle of the polymer chain in fair to good yields. The insertion reaction readily occurred not only in solvents but also in solid PC. The unsaturated group was hydrosilylated with triethoxysilane to produce triethoxysilyl group pendant PC and PAR, which are expected to be useful for sol–gel precursors for organic–inorganic hybrid materials, in good yields. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Epoxidation of karanja (Pongamia glabra) oil by H2O2

AbstractEpoxidation of karanja oil (KO), a nondrying vegetable oil, was carried out with peroxyacetic acid that was generated in situ from aqueous hydrogen peroxide and glacial acetic acid. KO contained 61.65% oleic acid and 18.52% linoleic acid, respectively, and had an iodine value of 89 g/100 g. Unsaturated bonds in the oil were converted to oxirane by epoxidation. Almost complete epoxidation of ethylenic unsaturation was achieved. For example, the iodine value of the oil could be reduced from 89 to 19 by epoxidation at 30°C. The effects of temperature, hydrogen peroxide‐to‐ethylenic unsaturation ratio, acetic acid‐to‐ethylenic unsaturation ratio, and stirring speed on the epoxidation rate and on oxirane ring stability were studied. The rate constant and activation energy for epoxidation of KO were 10−6 L·mol−1·s−1 and 14.9 kcal·mol−1, respectively. Enthalpy, entropy, and free energy of activation were 14.2 kcal·mol−1, −51.2 cal·mol−1·K−1, and 31.1 kcal·mol−1, respectively. The present study revealed that epoxides can be developed from locally available natural renewable resources such as KO.

Titanocene Catalysed 5-exoCyclisations of Unsaturated Epoxides- Reagent Control in Radical Chemistry

Titanocene Catalysed 5-<b><i>exo</i></b>Cyclisations of Unsaturated Epoxides- Reagent Control in Radical Chemistry

Synthesis of terminal Si–H irregular tetra-branched star polysiloxanes. Pt-catalyzed hydrosilylation with unsaturated epoxides. Polysiloxane films by photo-acid catalyzed crosslinking

Acid catalyzed insertion of octamethylcyclotetrasiloxane (D 4) into the Si–O bonds of tetrakis(dimethylsiloxy)silane leads to irregular tetra-branched star polymers—tetrakis(ω-dimethylsiloxy)poly(dimethylsiloxy)silane ( I). The terminal Si–H bonds of I have been modified by Pt-catalyzed hydrosilylation with 4-vinylcyclohexane-1,2-epoxide to yield a tetra-branched star polydimethylsiloxanes (PDMS) with terminal 2′-ethyl-4-cyclohexanyl-1,2-epoxide groups (II). Solutions of this material and a catalytic amounts of diaryl iodonium hexafluoroantimonate, a photo-acid catalyst, were cast onto glass slides and subsequently irradiated. This results in formation of crosslinked PDMS films ( V). The soluble tetra-branched PDMS stars have been characterized by 1H, 13C, and 29Si NMR as well as by IR spectroscopy. Their molecular weight distributions have been determined by gel permeation chromatography (GPC), multi-angle laser light scattering (MALLS), and end groups analysis. Their viscosities were measured with a Brookfield viscometer. The thermal stability of the polymers and the crosslinked films were determined by TGA. The glass transition temperatures ( T g)s of the polymers were determined by DSC. The loss ( G″) and storage ( G′) shear moduli of the films were determined by DMTA. Surface properties of the films were determined by measurement of static contact angles. Similar star polymers, tetrakis(dimethylsiloxy)poly[3′,3′,3′-trifluoropropylmethylsiloxyl]silanes ( III) were prepared by acid catalyzed equilibration of tetrakis(dimethylsiloxy)silane with 1,3,5-trimethyl-1,3,5-tris(3′,3′,3′-trifluoropropyl)cyclotrisiloxanes (D 3 F). These were, likewise, modified by Pt-catalyzed hydrosilylation with 4-vinylcyclohexane-1,2-epoxide. Films ( VI) of this material were similarly prepared by photo-acid catalyzed crosslinking.

CH3ReO3-catalyzed oxidation of cholesta-5,7-dien-3β-yl acetate with the urea-hydrogen peroxide adduct under various conditions. Synthesis of the natural epoxy sterol 9α,11α-epoxy-5α-cholest-7-en-3β,5,6β-triol

This article describes the oxidation of cholesta-5,7-dien-3beta-yl acetate (4) with the urea-hydrogen peroxide adduct (UHP) using methyltrioxorhenium (MTO) as catalyst, under various conditions. Specifically, the effects of using different solvents (CHCl(3) and ethers) and additives (EtOH and pyridine) on the course of the MTO-catalyzed oxidation of 4 were investigated. Some new steroids (6, 9, 10 and 11), obtained from this oxidation, were isolated and characterized on the basis of chemical evidence and interpretation of spectroscopic data including H-H COSY and HMBC experiments. The optimal solvent for the oxidation of 4 with MTO/UHP oxidizing system was diethyl ether. In this solvent the reaction is clean and gave as the main product 5,6beta-dihydroxy-5alpha-cholest-7-en-3beta-yl acetate (8, 65% yield), obtained with a more simple procedure and with a higher yield than that reported in literature. Sterol 8 is a key intermediate compound in the synthesis of many steroids of marine origin, biologically active, oxygenated at the B/C rings. In fact, starting from diol 8, we performed the synthesis of the natural cytotoxic epoxy sterol 9alpha,11alpha-epoxy-5alpha-cholest-7-en-3beta,5,6beta-triol (15, 21% yield) with an improvement in yield and number of steps over a synthesis of the same natural product previously reported. When the oxidation of 4 with the MTO/UHP system in diethyl ether was performed in the presence of pyridine as ligand, the unsaturated epoxide 5,6alpha-epoxy-5alpha-cholest-7-en-3beta-yl acetate (10, 90% yield) was obtained after only 5 min in good yield. In fact, pyridine, besides having beneficial effect on the reaction rate, shuts down the ring opening reactions, as reported in literature.

ChemInform Abstract: Stereocontrolled Synthesis of Unsaturated Halohydrins from Unsaturated Epoxides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Titanocene Catalyzed 5‐exo Cyclizations of Unsaturated Epoxides—Reagent Control in Radical Chemistry

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and reactions of self-crosslinkable epoxy- and anhydride-containing macromolecules

Synthesis of ternary copolymers of some unsaturated electron-donor epoxide monomers (UEM) such as 4-methyl-4,5-epoxypentene-1 (MEP), vinyl- (VGE), allyl- (AGE) and p-isopropenyl-phenyl (PhGE) glycidyl ethers, maleic anhydride (MA) and styrene (St) was carried out in methylethyl ketone (MEK) in the presence of benzoyl peroxide as an initiator at 50–80 °C. Constants of charge-transfer complex (CTC) formation (Kc) for MEP…MA (Kc = 0.10 L mol−1), VGE…MA (Kc = 0.17 L mol−1), AGE…MA (Kc = 0.09 L mol−1), PhGE…MA (Kc = 0.14 L mol−1) and St…MA (Kc = 0.29 L mol−1) donor–acceptor complexes in deuterated acetone at 37 °C were determined by 1H NMR spectroscopy. Constants of copolymerization for monomer and complexed monomer pairs were determined by the Kelen–Tudos and Seiner–Litt methods. Kinetic parameters together with ratios of chain growth rates for the participation of monomer CTC and free monomers were obtained for all monomer systems studied. The results showed that terpolymerization was carried out through a primary ‘complex’ mechanism in the state close to binary copolymerization of UEM…MA and MA…St complexes. The synthesized terpolymers with free anhydride and epoxide reactive groups easily underwent crosslinking by thermotreatment and by UV-irradiation, as confirmed by DTA and FTIR analyses. © 2001 Society of Chemical Industry

Sex Pheromone Components of Pink Gypsy Moth, Lymantria mathura

Pheromone extract of female pink gypsy moth, Lymantria mathura, was analyzed by coupled gas chromatographic-electroantennographic detection (GC-EAD) and coupled GC-mass spectrometry (MS), employing fused silica columns coated with DB-5, DB-210, or DB-23 and a custom-made GC column that separated enantiomers of unsaturated epoxides. These analyses revealed (9R,10S)-cis–9,10-epoxy-Z3,Z6-nonadecadiene [termed here (+)-mathuralure] and (9S,10R)-cis–9,10-epoxy-Z3,Z6-nonadecadiene [termed here (–)-mathuralure] at a 1 : 4 ratio as major candidate pheromone components. In field experiments in northern Japan (Morioka, Iwate Prefecture and Bibai, Hokkaido Prefecture), (+)- and (–)-mathuralure at a ratio of 1 : 4, but not 1 : 1 or singly, were attractive to male L. mathura. This is the first demonstration that attraction of male moths required the very same ratio of pheromone enantiomers as produced by conspecific females. Whether L. mathura employ different blend ratios in different geographic areas, and the role of five additional candidate pheromone components identified in this study remains to be investigated.

Remarkably complex and unpredictable cyclization and rearrangement reactions of cations derived from unsaturated oxiranes

Lewis-acid catalyzed reactions of unsaturated epoxides 1 and 2 afford the unprecedented products 3 and 5, respectively. Mechanistic pathways for these reactions are presented (Schemes 2 and 4) along with a more fundamental analysis.

Samarium(II) Iodide-Mediated Reductive Annulations of Ketones Bearing a Distal Vinyl Epoxide Moiety

Samarium(II) iodide in the presence of hexamethylphosphoramide (HMPA) efficiently promotes the intramolecular coupling of ketones with distal epoxy olefins. The reaction appears to proceed by a mechanism wherein a ketyl couples with the unsaturated epoxide. Subsequent fragmentation of the epoxide ring in compounds 1a−k yields carbocycles 2a−k with an allyl alcohol side chain in good yields, and often with high diastereoselectivity. When tetramethylguanidine was used as an additive instead of HMPA, the desired carbocycle was obtained in good yield, but the diastereoselectivity was diminished. A palladium(0)-catalyzed SmI2 reaction provided the expected product in modest yield, but the sense of diastereoselectivity was reversed. In the latter case, a different reaction mechanism may be involved. Thus, formation of an allylsamarium species may be invoked, with nucleophilic carbonyl addition leading to the observed facial selectivity.