Vinylacetic Acid Research Articles

Reactivity of osmium–rhodium mixed-metal cluster [Os 3Rh(μ-H) 3(CO) 12] towards vinyl containing ligands

Reaction of [Os 3Rh(μ-H) 3(CO) 12] ( 1) with an excess amount of vinylacetic acid gave two new clusters, [Os 5Rh 2(μ-CO)(η 6-C 6H 5CH 3)(CO) 16] ( 2) and [Os 2Rh 2(μ-CO) 2(η 3-CH 2CHCH 2COO) 2(CO) 7] ( 3) in 20 and 40% yields, respectively. Treatment of [Os 3Rh(μ-H) 3(CO) 12] with vinylacetate in refluxing toluene afforded the complexes [Os 3Rh(μ 3-CCH 3)(η 6-C 6H 5CH 3)(CO) 9] ( 4) and [Os 5Rh 2(μ-CO)(η 6-C 6H 5CH 3)(CO) 16] ( 2) in 40 and 20% yields, respectively. Thermolysis of [Os 3Rh(μ-H) 3(CO) 12] in refluxing toluene produced the known cluster compound, [Os 3Rh(μ-H) 3(η 6-C 6H 5CH 3)(CO) 9]. Treatment of 1-octene with [Os 3Rh(μ-H) 3(CO) 12] led to the isomerization to give all isomers of octenes. All the new clusters have been fully characterized by both spectroscopic and crystallographic techniques. The isomerization has been examined by GCMS technique.

Oxidation of olefins by palladium(II). 18. Effect of reaction conditions, substrate structure and chiral ligand on the bimetallic palladium(II) catalyzed asymmetric chlorohydrin synthesis

The effect of electronic factors, solvent composition, identity of the chiral bidentate, and olefin structure on the yields and enantioselectivities of the asymmetric chlorohydrin synthesis were investigated. Electronic effects on the chlorohydrin reaction were tested by oxidation of phenyl allyl ether p-substituted by H, Cl, CH 3O and CN. All species gave same similar yields and enantioselectivities indicating that electronic effects are not important. Varying the solvent composition of the THF–H 2O mixtures indicated that the optimal solvent mixture contains more than 85% THF. Variation of added [Cl −] indicated that the added chloride had to be greater than 0.2 M for high yields and %ee's. Under ideal conditions the enantioselectivities of the chlorohydrins from the phenyl allyl ethers were more than 90%ee. Vinylacetic acid, methyl acrylate and trans-cinnamaldehyde were unreactive under the usual reaction conditions while 2-hydroxy-3-butene and allyl acetate give lower %ee's than did the phenyl allyl ethers. Styrene and α-methylstyrene gives comparable rates of reactions but the %ee's were lower with the latter. (2,6-Diisopropyl)phenyl allyl ether and 2-hydroxy-3-butene give high %ee's indicating that steric hindrance was not a major factor. All of the chiral bridging ligands tested gave satisfactory results except for DACH. A strange case was BZOX which did not give any induction at all. Structural studies showed the ligands are not large enough to bridge both Pd(II) in the bimetallic catalyst so one Pd(II) contained both ligand groups of the bidentate ligand and was thus unreactive. The other Pd(II) of the dimer was reactive but did not contain any chiral ligands to induce optical activity.

Glucose binding to molecularly imprinted polymers

The main goal of this study was to prepare molecularly imprinted polymers (MIPs) with glucose recognition sites and to evaluate their glucose-binding properties for potential applications in glucose sensing and self-regulating insulin delivery devices. Tomimic glucose-binding sites of natural proteins, monomers possessing functional groups similar to amino acids were used. Vinyl acetic acid (VAA), acrylamide (AAm), 4-pentenoic acid (PA), and allyl benzene (AB) were copolymerized with a cross-linking agent (N,N′-methylenebisacrylamide, BIS) in the presence of glucose as a template. The binding affinity of glucose to MIPs was examined by using an equilibrium dialysis technique. The dissociation constants of the MIPs were determined by Scatchard analysis. MIPs showed glucose-binding affinity, while polymers synthesized in the absence of glucose template did not show a glucose-binding property. MIPs composed of VAA, AAm, PA, and AB at optimized mole ratios of monomers and cross-linker showed the highest glucose-binding affinity, K D = 1.66 mM, which is comparable to that of a well-known glucose binding protein, concanavalin A (K D = 1.84 mM). The affinity between monomer and glucose was in the order VAA > AAm > AB > PA.

Lipase-catalyzed synthesis of 6-O-vinylacetyl glucose in acetonitrile

6-O-Vinylacetyl glucose was synthesized with an immobilized lipase using vinylacetic acid and glucose in water-miscible organic solvents, of which acetonitrile gave the highest conversion of 35% at 50 mM glucose and 600 mM vinylacetic acid. The addition of 3A molecular sieves at 60 mg ml−1 increased the conversion to 74%. The product, 6-O-vinylacetyl glucose, was polymerized to yield a water-soluble polymer with a molecular mass of about 5000.

Studies of Peptide Binding to Allyl Amine and Vinyl Acetic Acid-Modified Polymers Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

Previous studies have shown that increases in surface–peptide binding affinity result in decreases in peptide matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) ion signals. The present work demonstrates that, with appropriate corrections for peptide ionization efficiency under MALDI conditions, relative surface–peptide binding affinities can be assayed using the MALDI MS methodology. Peptides with a range of pI values are allowed to interact with amine-modified and carboxylic acid-modified polymer surfaces (produced by pulsed radio-frequency plasma polymerization of allyl amine and vinyl acetic acid) in buffered solutions of neutral pH. Because of the net positive and negative charges associated with the peptides and surfaces in solution, both electrostatic and hydrophilic interactions play a role in the surface–peptide interaction. Consistent with expectations, the peptide MALDI ion signals for peptides with net negative charges in solution are smaller than those for peptides with net positive charges in solution when the peptides are allowed to interact with positively charged surfaces. A reversal of the relative peptide MALDI ion signal intensities is observed when the same peptides are allowed to interact with negatively charged surfaces. Cumulatively, the results demonstrate that even modest changes in surface–peptide interactions can be comparatively probed by MALDI mass spectrometry.

Structopendant unsaturated cellulose esters via acylation in homogeneous lithium chloride/N,N‐dimethylacetamide solutions

Novel acylation reactions of cellulose were accomplished with a series of unsaturated carboxylic acids or their respective anhydrides including crotonic acid (CRA), methacrylic acid (MAA), vinyl acetic acid (VAA), fumaric acid monoethyl ester (FAME), and cinnamic acid (CINA) in lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solutions. The acylation reactions were conducted at room temperature using dicyclohexylcarbodiimide (DCC) as a condensation agent and 4-dialkyl-aminopyridine (4-[N,N-dimethylamino-] or 4-pyrrolidino-pyridine, DMAP or PP) as a catalyst. A reaction mechanism is proposed based on experimental evidence. The acylated cellulose derivatives obtained from CRA, MAA, or their anhydrides exhibit poor solubility in organic solvents. Side reactions, e.g., the Michael addition, likely occur at the high temperatures required for reaction of these acyl groups. However, acylation of cellulose with VAA, FAME, and CINA is facile with derivatives readily soluble in DMSO. The structures of these derivatized celluloses were characterized with FTIR and 1H-NMR spectroscopy and degrees of substitution were calculated. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 293–305, 1997

Structopendant unsaturated cellulose esters via acylation in homogeneous lithium chloride/ N,N ‐dimethylacetamide solutions

Novel acylation reactions of cellulose were accomplished with a series of unsaturated carboxylic acids or their respective anhydrides including crotonic acid (CRA), methacrylic acid (MAA), vinyl acetic acid (VAA), fumaric acid monoethyl ester (FAME), and cinnamic acid (CINA) in lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solutions. The acylation reactions were conducted at room temperature using dicyclohexylcarbodiimide (DCC) as a condensation agent and 4-dialkylaminopyridine (4-[N,N-dimethylamino-] or 4-pyrrolidino-pyridine, DMAP or PP) as a catalyst. A reaction mechanism is proposed based on experimental evidence. The acylated cellulose derivatives obtained from CRA, MAA, or their anhydrides exhibit poor solubility in organic solvents. Side reactions, e.g., the Michael addition, likely occur at the high temperatures required for reaction of these acyl groups. However, acylation of cellulose with VAA, FAME, and CINA is facile with derivatives readily soluble in DMSO. The structures of these derivatized celluloses were characterized with FTIR and 1 H-NMR spectroscopy and degrees of substitution were calculated.

Graft copolymerization of cellulose with structopendant unsaturated ester moieties in homogeneous solution

Cellulose esters of cinnamic acid, vinyl acetic acid, and fumaric acid monoethyl ester with moderate degrees of substitution were copolymerized with styrene, butyl methacrylate, and acrylic acid, respectively. Although high grafting ratios were obtained, crosslinked systems were formed despite attempts to manipulate pendant group reactivity vs. that of the grafting comonomer or the polymerization time and temperature. However, addition of a simple thiol chain-transfer agent resulted in soluble, noncrosslinked graft copolymers with moderate conversion (>40%) and grafting ratios to 170%. Structural elucidation of the graft copolymers was accomplished by FTIR and NMR spectroscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 307–317, 1997

Automated analysis of low-molecular weight organic acids in ambient air by a microporous tube diffusion scrubber system coupled to ion chromatography

A method for the automatic analysis of low-molecular weight organic acids (C < 5) in the atmosphere was developed using a microporous tube coupled to an ion chromatograph. A 220 cm long microporous polytetrafluoroethylene (PTFE) tube provided high collection efficiencies of alkanoic acids (formic acid: 97%, acetic acid: 94%, propionic acid: 92%) and alkenoic acids (vinylacetic acid: 98% and methacrylic acid: 96%). A 20 min cycle analysis could be continuously repeated. The coefficient of variation for repeated measurements was less than 5% for concentrations higher than 1 ppbv and 5–10% for concentrations lower than 1 ppbv. The detection limits of formic acid, acetic acid and propionic acid were 0.20, 0.29 and 0.32 ppbv, respectively. The concentration in gas samples was calculated using a good linear gas-solution curve (calibration curve). Formic acid, acetic acid and propionic acid in the urban atmosphere were determined in the concentration range of 1.5–5.5, 1.0–2.8 and < 0.32–1.25 ppbv, respectively.

Co-polymerised peptide particles (CPP) I: synthesis, characterisation and in vitro studies on a novel oral nanoparticulate delivery system

A novel co-polymeric nanoparticulate drug delivery system (Co-polymerised Peptide Particles: CPP) has been developed as a carrier for the oral uptake of therapeutic peptides. The system was based on the co-polymerisation of the active peptide derivative with n-butylcyanoacrylate ( n-BCA), the resulting co-polymer being formulated as nanoparticles. The peptide luteinizing hormone releasing hormone (LHRH) was used as a model drug to investigate the viability of the approach. LHRH was covalently bound to vinylacetic acid and the resulting LHRH-vinylacetate conjugate ( 3e) and a radiolabel ( 3c∗) were subsequently co-polymerised with n-BCA. The polymerisation reaction conditions were manipulated to exploit the particle-forming properties of n-BCA, so that the co-polymer was prepared as particles of average diameter 100 nm, containing LHRH molecules covalently bound as constituents of the oligomeric chains which formed the particles, rather than physically entrapped or adsorbed. The vinylacetic acid functions as a ‘linking acid’, allowing the formation of a polymerizable derivative of the peptide; also, the stability of the covalent bond between LHRH and vinylacetic acid ensures that the LHRH remains entrapped, and therefore protected, within the carrier in vivo. The co-polymeric particles were found to be stable in vitro when incubated over a 3 h period in gut luminal contents and mucosal scrapings. Their stability was also demonstrated in fetal calf serum and rat serum. In vitro transport studies using the Caco-2 cell line suggested that absorption in vivo was possible.

Dilithiated ( E)- N-isobutyl-4-tosyl-2-butenamide: An allyl sulfone dianion for the regiospecific γ-functionalization of crotonamide dianion

( E)- N-Isobutyl-4-tosyl-2-butenamide ( 5) (prepared from vinylacetic acid by stereoselective iodosulfonylation-dehydroiodination and further amidation) has been lithiated with two equiv of n-butyllithium at −78°C in the presence of DMPU leading to the corresponding allyl dianion 6. This intermediate reacts with electrophiles (alkyl bromides, aldehydes and electrophilic olefins) regiospecific and stereoselectively at the γ-position to afford γ-substituted ( E)- N-isobutyl-4-tosyl-2-butenamides 7. Desulfonylation of compounds 7 occurs stereoselectively to provide ( E)- β, γ-unsaturated amides 9. This methodology has been applied to the synthesis of dienamides such as naturally occurring N-isobutyl-(2 E,4 E)-decadienamide (pellitorine).

Photo-decarboxylation of substituted alkylcarboxylic acids brought about by visible light and iron(III) tetra(2-N-methylpyridyl)porphyrin in aqueous solution

The complexes of iron(III) tetra(2-N-methylpyridyl)porphyrin with vinyl acetic acid and a selection of α-halo and α-hydroxycarboxylic acids, α-,β- and γ-ketoacids, β-dicarboxylic acids and polyacrylic acid have been photolysed (λ > 390 nm) in anaerobic aqueous solution. UV–VIS spectroscopy shows that the primary reaction is photoreduction of the iron(III) atom by the axial carboxylate ligand to give a solvent-caged carboxyl radical and iron(II) porphyrin.

Preparation and thermal characterisation of some new liquid crystalline copolymers involving a spacer unit based on vinylacetic acid

Three series of new liquid crystalline (LC) copolymers having a polysiloxane backbone and two different mesogenic pendant groups, one involving a vinylacetic acid moiety in the spacer, have been synthesised. Thermal characterisation of these polymeers has allowed comparison of behaviour between a number of different copolymer systems. It was found that increasing amounts of the vinylacetic acid moiety lowered the clearing points (Ti) of the copolymers in an almost linear fashion whilst also inhibiting crystallinity in these polymers.

The effect of the spacer group on side-chain liquid crystal polymer dielectric mobility

Dielectric relaxation spectra have been measured for a series of siloxane based side-chain liquid crystal polymers and the effect of the spacer group chemical structure (alkyl and vinylacetic acid) on dielectric motion is presented, as is the effect of spacer length for each polymer with a given spacer type. The effect of increased spacer length is to increase the frequency of motion due to greater mesogen mobility. The materials containing vinylacetic acid spacer units show a biomodal dielectric frequency spectrum due to greater decoupling of the constituent motions of the side chains. The effect of spacer length on the cross-over frequency (which determines the nature of the liquid crystalline alignment by a.c. electric fields of various frequencies) is also discussed.

Photoinitiators with Functional Groups. Part II. Silicon-Containing Photoinitiators

Abstract The new photoinitiators (PIs) 1-(4-dimethylsilyl)phenyl-2-hydroxy-2-methyl-propan-1-one (8a) and 1-(4-dimethylsilyl)phenyl-2-methoxy-2-methyl-propan-1-one (8b) have been synthesized by Grignard reaction of 4-dimethylsilylphenylmagnesium chloride (5) with protected acetone cyanohydrins. The photoactivity of 8a was similar to the most efficient commercial hydroxyalkylphenone 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173) whereas 8b exhibits even higher efficiency. 8a and 8b were reacted with allyl alcohol, allyl amine, vinyl acetic acid, 3-allyloxypropane-1,2-diol, allyl glycidyl ether, polybutadiene, and a vinyl polysiloxane to yield new functional PIs of high activity. Thus, hydrosilation reactions of the new PIs enable the preparation of a variety of functional derivatives usable in different UV-curable systems.

Preparation, structural characterisation and thermal analysis studies of vinylacetic acid compounds of some first row transition metals

Compounds of vinylacetic acid with cobalt(II), nickel(II), copper(II) and zinc(II) have been prepared in aqueous solution. The cobalt, nickel and copper compounds have stoichiometry M(C 4H 5O 2) 2H 2O while the zinc compound has stoichiometry Zn(C 4H 5O 2) 2. The compounds have polymeric structures. Thermal decomposition studies on the compounds show that those compounds which are hydrated lose a water molecule followed by the organic ligand to give the metal oxide. The zinc compound forms an intermediate compound before decomposing to the metal oxide.

Electrophilic activation of carbon dioxide. Preparation of vinylacetic acid from CO2 and allyltrimethylsilane

The search for fundamentally new methods to activate the carbon dioxide molecule and involve it in various reactions attracts special attention. In this respect, the problem of the possible use of Lewis acids and protic superacids has been repeatedly discussed in the literature. However, no actual results in this field have been obtained until recently. Now the authors can report the first example of direct electrophilic activation of the CO{sub 2} molecule by aprotic Lewis acids under mild conditions.

Analogues of Butyric Acid that Increase the Expression of Transfected DNAs

Butyric acid has many strong effects on gene expression in mammalian and viral systems, as well as in increasing the expression of recombinant DNAs artificially introduced into cultured cells. We screened 14 analogues of butyric acid for their ability to upregulate expression from 3 different recombinant chloramphenicol acetyltransferase expression vectors stably integrated into NIH 3T3 cells that had been transformed by calcium phosphate transfection or electroporation. Butyric acid, 2-bromobutyric acid, 3-bromopropionic acid, 3-mercaptopropionic acid, vinylacetic acid, and butyraldehyde were found to upregulate human immunodeficiency viral long terminal repeat-, SV40 early gene promoter-, and glucocerebrosidase promoter-directed expression of heterologous genes in cultured cells. Three other analogues had lesser effects; and 6 additional analogues had very little, if any, effect.

Solubility of carbon dioxide in vinyl acetate and in a mixture of vinyl acetate and acetic acid

Solubility of carbon dioxide in vinyl acetate and in a mixture of vinyl acetate and acetic acid

Preparation of thermotrophic liquid crystalline polymers involving a novel spacer unit based on vinylacetic acid

Liquid crystaline polymers (LCPs) involving a polysiloxane backbone and a novel vinylacetic acid unit in the spacer have been synthesised, These polymers all show dramatically lower clearing points (Tcl) than polymers with similar chain lengths but involving established polymethylene spacer groups.