Alkyl Vinyl Ethers Research Articles

Development of a highly efficient catalytic method for synthesis of vinyl ethers.

A new method for the preparation of alkyl vinyl ethers has been developed. Thus, various types of alkyl vinyl ethers were synthesized by the reaction of alcohols with vinyl acetate under the influence of a catalytic amount of [Ir(cod)Cl]2 combined with Na2CO3 in good to excellent yields.

Effect of Fluoric Resin Coating on Bending Strength of Ceramics.

The stress distribution characteristics at the edge of pores of sintered ceramics with fluoric resin coating were investigated by paying attention to the effect of Young's modulus and the thermal expansion coefficient on the stress concentration factor. The residual stress characteristics of ceramic composite, induced by the infiltration of fluoric resin into sintered ceramic pores, were clarified by using the finite element analysis. As a result, it was confirmed that a high compressive residual stress could be induced around the ceramic pores by the mismatch of the thermal expansion coefficients between the ceramics and the fluoric resin. It was also confirmed that the bending strength of sintered 20 mass% alumina and sintered 95 mass% alumina with tetra fluoro ethylene-perfluoro alkylvinyl ether copolymer (PFA) coating was markedly improved in comparison with each as-sintered alumina samples.

Photocurable positive photoresist-comprising copolymers having pendant alkoxy ethyl moieties

A series of copolymers based on methacrylic acid (MAA), methyl methacrylate (MMA), n-butyl methacrylate (BM), and bornyl methacrylate (BMA) with various feed molar ratios were synthesized. To introduce the protecting alkoxy ethyl moieties onto copolymers, the pendant carboxyl groups were further reacted with alkyl vinyl ether. The pendant alkoxy ethyl groups on copolymers could be deprotected by acid catalyst. Characterization of positive-tone photoresist-comprising copolymers having pendant alkoxy ethyl groups was carried out. Effects of alicyclic bornyl groups on the sensitivity and thermal properties of copolymers were investigated. It was found that the existence of bornyl groups in polymer might interfere with the hydrogen bonding produced by pendant carboxyl groups, leading to the decrease of thermal resistance. Acid-catalyzed dehydration crosslinking of pendant carboxyl groups of copolymers was also investigated. The exposure characteristic curves and the lithographic evaluation of the positive-tone photoresist were all investigated. Effects of alicyclic bornyl groups on the plasma etching resist of copolymers were also evaluated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 889–897, 2002

ChemInform Abstract: Acetonyltriphenylphosphonium Bromide and Its Polymer‐Supported Analogues as Catalysts in Protection and Deprotection of Alcohols as Alkyl Vinyl Ethers.

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.

Highly regioselective, sequential, and multiple palladium-catalyzed arylations of vinyl ethers carrying a coordinating auxiliary: an example of a Heck triarylation process.

This article describes the development of new auxiliary-accelerated Heck multiarylations by intramolecular presentation of the oxidative addition complex. The introduction of a specific, palladium-coordinating dimethylamino group allows for the desired chelation-accelerated and chelation-controlled tri- and diarylation reactions. We report (a) the first example of a Heck triarylation process, (b) highly selective palladium-catalyzed diarylations of alkyl vinyl ethers, and (c) a very rapid two-phase protocol for the microwave-assisted hydrolysis of amino-substituted, arylated vinyl ethers constituting an entry to diarylated ethanals and substituted desoxybenzoins. X-ray structures and product patterns support the suggested substrate-controlled Heck reaction pathway. The catalyst-directing alkyl dimethylamino functionality was rapidly (1-2 min) and efficiently released by microwave hydrolysis after Heck multiarylation reactions. The liberated aromatic carbonyl compounds were thereafter isolated and fully characterized.

The formation of peroxides from vinyl ethers in the presence of silica-gel

Silica-gel containing H 2O 2 or ROOH transforms vinyl alkyl or vinyl aryl ethers into the corresponding α-alkoxy hydroperoxides and dialkyl peroxides under very mild reaction conditions.

Vibrational state distribution and relaxation of vinoxy radicals

The vinoxy radical ⋅CH2CHO is a product of the reaction of O(3P) atoms with terminal alkenes and can also be made by photodissociation of an alkyl vinyl ether. In either case it is formed in a vibrationally excited state. The nascent radical displays a rich electronic spectrum to the red of its X→B band origin consisting of bands originating from vibrationally excited states. Some transitions, true “hot bands,” terminate on the vibrationless B state; others, sequence bands, terminate on vibrationally excited B states. The spectra become unobservably weak at a certain energy. The difference between that energy and the energy of the band origin is roughly the maximum vibrational energy in the radical. This is 5600 cm−1 for the vinoxy produced by photodissociation of ethyl vinyl ether at 193 nm and 3200 cm−1 for the product of the reaction of O(3P) with ethylene, propene, 1-butene, and 1-pentene. There is a remarkable cooling of the vibrations as the hydrocarbon chain lengthens. The average vibrational energy of the vinoxy product of the reaction O(3P) with ethylene, propene, 1-butene, and 1-pentene is 2100, 1800, 1570, and 1180 cm−1, respectively. This cooling implies that the reaction complex lives long enough for internal vibrational relaxation to occur. The average vibrational energy in the reaction-produced vinoxy is small, which implies that there is considerable kinetic energy. The time dependence of the intensity of the hot bands measures the relaxation rates of different energies, some of which are the energies of a single vibrational state. The ground-state population increases monotonically to an asymptote. The population of most states grows with time and then decays. The growth is due to a cascading from upper states. The populations of the highest energy states decay monotonically; the still higher energy states are almost unpopulated. These results prove that the relaxation proceeds stepwise. The magnitude of the step, ∼200–300 cm−1, can be inferred from the growth rate of the ground-state population.

Acetonyltriphenylphosphonium bromide and its polymer-supported analogues as catalysts in protection and deprotection of alcohols as alkyl vinyl ethers

Both acetonyltriphenylphosphonium bromide (ATPB, 1) and poly- p-styryldiphenylacetonylphosphonium bromide ( A) were effective catalysts in the protection of alcohols as THP, THF, and EE ethers as well as the cleavage of THP, THF, and EE ethers to the corresponding alcohols. They could be applied to 1°, 2° and 3° alcohols, phenol and acid-labile alcohols. Both ATPB and catalyst A are excellent catalysts in the present study. It needed only 1×10 −2–1.25×10 −2 mol equiv. of the polymer-supported catalyst A in the reactions.

ChemInform Abstract: Asymmetric Methoxyselenenylation of Alkyl Vinyl Ethers: A New Route to Chiral Acetals.

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.

Aqueous DMF-potassium carbonate as a substitute for thallium and silver additives in the palladium-catalyzed conversion of aryl bromides to acetyl arenes.

Highly selective palladium-catalyzed internal alpha-arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.

Improvement in adhesive strength of fluorinated polymer films by atmospheric pressure glow plasma

We tried to treat poly (vinyl fluoride) (PVF), poly(tetrafluoroethylene- co-hexafluoropropylene) (FEP) and poly(tetrafluoroethylene- co-perfluoro [alkyl vinyl ether]) (PFA) films by atmospheric pressure glow plasma to increase their adhesive strength with an epoxy resin. Their adhesive strength could be improved; the maximum peel force values obtained from a 180° peel test were over 2.00, 0.90 and 0.62kgf 20 mm −1, respectively. These values were near or higher than those of the control sample films treated by a surfactant: 1.06, 0.47 and 0.70kgf 20 mm −1, respectively. In this study, we found that the O 2/He plasma-treated films had the highest peel forces although their contact angles were highest and their amounts of incorporated oxygen or nitrogen atoms were least; He plasma treatment also showed better effects on the overall results.

Asymmetric methoxyselenenylation of alkyl vinyl ethers: a new route to chiral acetals

The asymmetric methoxyselenenylation of alkyl vinyl ethers afforded the corresponding chiral acetals with moderate to good diastereoselectivity. This reaction and subsequent deselenenylation provided a new method of preparing enantiomerically enriched acetals in which the acetal carbon was the only stereogenic center.

ChemInform Abstract: Cross‐Metathesis vs. Silylative Coupling of Vinyl Alkyl Ethers with Vinylsilanes Catalyzed by a Ruthenium—Carbene Complex (Grubbs Catalyst).

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.

Stereoregulation in cationic polymerization by designed Lewis acids. II. Effects of alkyl vinyl ether structure

Stereoregulation in the cationic polymerization of various alkyl vinyl ethers was investigated with bis[(2,6-diisopropyl)phenoxy]titanium dichloride (1; catalyst) in conjunction with the HCl adduct of isobutyl vinyl ether as an initiator in n-hexane at -78 °C. The tacticities depended on the substituents of the monomers. Isobutyl and isopropyl vinyl ethers gave highly isotactic polymers (mm = 83%), whereas tert-butyl and n-butyl vinyl ethers resulted in lower isotactic contents (mm ∼ 50%) similar to those for TiCl 4 , a conventional Lewis acid, thus indicating that the steric bulkiness of the substituents was not the critical factor in stereoregulation. A statistical analysis revealed that the high isospecificity was achieved not by the chain end but by the catalyst 1 or the counteranion derived therefrom.

New Materials from poly(vinyl ethers)

This paper gives an overview of the synthesis and properties of various kinds of amphiphilic segmented copolymers in which at least one of the segments is a poly(alkyl vinyl ether). Copyright © 2001 John Wiley & Sons, Ltd.

New thermosetting coatings using blocked carboxyl groups

Characteristics of blocked carboxylic acid compounds obtained by blocking carboxyl groups with alkyl vinyl ethers were studied, and new thermosetting coatings using blocked carboxyl groups and epoxide were also studied. Polybasic carboxylic acids were esterified with alkyl vinyl ethers to obtain blocked carboxylic acids having the hemiacetal ester moieties. Most of blocked carboxylic acids obtained were liquids and showed an excellent solubility in organic solvents and a good compatibility with epoxy resins. Although the blocked carboxylic acids were stable under ambient conditions, they could regenerate the corresponding carboxylic acids accompanied by the elimination of alkyl vinyl ethers by the thermal dissociation. They could be used as noble thermal latent hardeners. Curing of the blocked carboxyl groups and epoxide in the presence of relatively weak Lewis acid proceeded through a sequence of three-step reactions consisting of deblocking of alkyl vinyl ethers, esterification of epoxide, and the addition of alkyl vinyl ether to 2-hydroxyalkyl ester. The main product of the curing system was 2-acetalalkyl ester, but not 2-hydroxylalkyl ester. The new one-package thermosetting coatings using blocked carboxyl groups have been evaluated for use in the practical automotive and coil coatings line production. VOCs reduction, low-toxicity, and cost saving are satisfactory for the application of the systems. And the cured films of the coatings offered advantages in the high durability, the acid resistance and the soil resistance.

Catalytic Enantioselective 1,3-Dipolar Cycloaddition Reactions of Cyclic Nitrones: A Simple Approach for the Formation of Optically Active Isoquinoline Derivatives

The first highly diastereo- and enantioselective catalytic 1, 3-dipolar cycloaddition reaction of cyclic nitrones activated by chiral Lewis acids with electron-rich alkenes has been developed. The nitrones, mainly 3,4-dihydroisoquinoline N-oxides, are activated by chiral 3,3'-aryl BINOL-AlMe complexes and undergo a regio-, diastereo-, and enantioselective 1,3-dipolar cycloaddition reaction with especially alkyl vinyl ethers, giving the exo diastereomer of the cycloaddition products in high yield, >90% de and up to 85% ee. The reaction has been investigated under various conditions, and it is demonstrated that the reaction is an attractive synthetic procedure for the introduction of a chiral center in the 1-position of the isoquinoline skeleton. The mechanism of the reaction is discussed on the basis of the assignment of the absolute configuration of the cycloaddition product and theoretical calculations.

Immobilization of BINOL by cross-linking copolymerization of styryl derivatives with styrene, and applications in enantioselective Ti and Al Lewis acid mediated additions of Et2Zn and Me3SiCN to aldehydes and of diphenyl nitrone to enol ethers

The chiral ligand 1,1'-bi-2-naphthol (BINOL) has been succesfully immobilized on polystyrene. Several dendritic and non-dendritic BINOL derivatives (3, and 13-17), bearing at least two polymerizable styryl groups, were prepared and fully characterized. Suspension copolymerization of the MOM- or TIPS-protected cross-linking BINOL ligands (MOM = methyloxymethyl, TIPS = triisopropylsilyl) with styrene, cleavage of the protecting-groups, and loading with a Lewis-acid afforded catalytically active polystyrene-supported BINOLates. The polymer-bound BINOLs p-3, and p-13-p-16 were tested in the Ti-BINOLate-mediated addition of Et2Zn to PhCHO. The enantioselectivities (up to 93%) and conversions obtained with the polymer-bound catalysts were in most cases identical (within experimental error) to those obtained with the unsubstituted 1,1'-bi-2-naphthol and with the non-polymerized BINOL cross-linkers under homogeneous conditions. Special focus was put on the reusability of the supported catalyst: the polymer-beads were used in up to 20 consecutive catalytic runs, with the best polymers showing no or only minor loss of selectivity. BINOL-polymers p-17, obtained by copolymerization of a 3,3'-distyryl-substituted BINOL 17a with styrene, were used in the BINOL. AlMe-mediated cycloaddition of diphenyl nitrone with alkyl vinyl ethers. In all cases the exo/endo selectivity (> or =92:8) and the enantioselectivities with which the exo-cycloadducts were formed (> or =95%) correspond to those observed in the homogeneous reactions. A dendritically cross-linked BINOL-polymer was also employed in the Ti-BINOLate-mediated cyanosilylation of pivalaldehyde. The enantiopurity of the cyanohydrine obtained in the first run was as high as in the homogeneous reaction (72%); surprisingly the catalytic performance of the supported catalyst increased steadily during the first catalytic cycles to reach 83%. Thus, cross-linking BINOLs can be succesfully incorporated into a polystyrene matrix (without racemization!) to give polymer-bound BINOL ligands that give excellent performance over many catalytic cycles with catalytic activities comparable with those of soluble analogues.

Mechanistic study of the light-induced copolymerization of maleimide/vinyl ether systems

Real-time infrared spectroscopy was used to monitor the high-speed copolymerization of N-subsituted alkyl maleimide (MI) and vinyl ether (VE) mixtures upon UV exposure, with or without photoinitiator. The monomer feed composition was shown to play a decisive role on the polymerization kinetics of each monomer. When VE is in excess, the two monomers disappear at similar rates to yield an alternating copolymer. When MI is in excess, the copolymerization and the MI homopolymerization occur simultaneously to yield a copolymer with isolated VE units. The reaction scheme proposed to account for the kinetic data is based on the homopolymerization of donor-acceptor complex, with the VE . radicals acting as the main propagating species. The kinetic chain length was evaluated from quantum yield measurements performed under controlled initiation conditions and found to be on the order of 10 3 . The propagation rate constant of the VE/MI copolymerization was calculated to be twice that of the MI homopolymerization.

Silylative Coupling of Vinyl Alkyl Ethers with Vinylsilanes Catalyzed by Ruthenium Complexes

Ruthenium complexes such as RuHCl(CO)(PPh3)3 (I), RuCl(SiMe3)(CO)(PPh3)2 (II), RuCl2(PPh3)3 (III), and Ru(CO)3(PPh3)2 (IV) appear to be very effective catalysts of cross-disproportionation of vinyl-trisubstituted silanes CH2CHSiR3 (where R3 = Me3, PhMe2, (OEt)3) with vinyl alkyl ethers CH2CHOR‘ (where R‘ = ethyl, n-propyl, n-butyl, tert-butyl, tert-pentyl, 2-ethylhexyl, cyclohexyl, trimethylsilyl) to yield a mixture (E+Z) of 1-silyl-2-alkoxyethenes. Stoichiometric insertion of vinyl n-propyl ether into Ru−Si bonds of II and MS study of the products of the deuterated vinyltrimethylsilane with vinyl ethyl ether indicate that the mechanism of cross-disproportionation involves a migratory insertion of the vinyl ether into the Ru−Si bond (and vinylsilane into the Ru−H bond) followed by β-H (and β-Si) transfer to eliminate 1-triorganosilyl-2-alkoxyethenes (and ethene).