Alkyl Vinyl Ethers Research Articles

Synthesis of Clickable Isotactic Poly(vinyl ether)s through Organocatalytic Stereoselective Cationic Copolymerization.

By virtue of the high reliability of click chemistry, polymers with clickable groups provide a useful platform for the rapid synthesis of polymer materials with diverse functionalities and architectures. However, the polymerization of clickable vinyl monomers with a concurrent regulation on tacticity remains underdeveloped. Herein, we report the successful development of a stereoselective cationic copolymerization of C-C triple bond-containing vinyl ethers with simple alkyl vinyl ethers by employing confined Brønsted acid as catalyst, which allows for the synthesis of alkyne-functionalized vinyl ether copolymers with high isotacticity (up to 90% m), controlled molecular weight, and variable content of C-C triple bonds. Further transformation of the pendant clickable alkyne groups via thiol-yne click reactions and copper(I)-catalyzed alkyne-azide cycloaddition reaction enables a modular access to isotactic polymers with various functional groups.

Design of sec-Benzyl Vinyl Ethers toward the Synthesis of Alternating Copolymers Composed of Vinyl Alcohol and Vinyl Ether Units.

In this work, we designed benzyl vinyl ethers carrying alkyl substituents at the benzyl position (i.e., sec-BnVEs) as bulky, reactive, and transformable monomers to realize the alternating cationic copolymerization with an alkyl vinyl ether (VE). In particular, the isopropyl substitution caused not only the bulkiness to suppress the successive propagation but also an enhancement of the vinyl group reactivity to promote crossover propagation with a less bulky VE comonomer. The isopropyl-substituted BnVE (iPr-BnVE) underwent living cationic alternating copolymerization with n-butyl VE (nBVE), and the alternating propagation was strongly suggested by the reactivity ratios. The subsequent deprotection of the sec-benzyl pendant afforded the vinyl alcohol (VA)-nBVE alternating copolymer, and the corresponding statistical copolymer was also synthesized by using the nonsubstituted monomer (BnVE) instead of iPr-BnVE. The alternating copolymer exhibited a higher glass transition temperature, which likely stems from the uniform and efficient hydrogen-bonding formation due to the periodic sequence.

Modular Synthesis of Fully‐Substituted and Configuration‐Defined Alkyl Vinyl Ethers Enabled by Dual‐Functional Copper Catalysis

AbstractHere we present a modular, chemo‐, regio‐, and stereoselective synthesis of fully‐substituted and configuration‐defined alkyl vinyl ethers (AVEs) using simple chemical feedstocks. The distinctive approach involves the chemo‐ and regioselective functionalization of the CF2 unit in gem‐difluorinated cyclopropanes with O−H and C−H nucleophiles in a specific order. The resulting highly functionalized cyclopropanyl ethers then undergo a stereoselective ring‐opening process to produce fully‐substituted and configuration‐defined AVEs. These AVEs are rarely accessible through conventional methods and are easily transformable. Mechanistic experiments indicate that the success of this method relies on the use of dual‐functional copper catalysis, which is involved in both the functionalization of the CF2 unit and the subsequent ring‐opening process.

Modular Synthesis of Fully-Substituted and Configuration-Defined Alkyl Vinyl Ethers Enabled by Dual-Functional Copper Catalysis.

Here we present a modular, chemo-, regio-, and stereoselective synthesis of fully-substituted and configuration-defined alkyl vinyl ethers (AVEs) using simple chemical feedstocks. The distinctive approach involves the chemo- and regioselective functionalization of the CF2 unit in gem-difluorinated cyclopropanes with O-H and C-H nucleophiles in a specific order. The resulting highly functionalized cyclopropanyl ethers then undergo a stereoselective ring-opening process to produce fully-substituted and configuration-defined AVEs. These AVEs are rarely accessible through conventional methods and are easily transformable. Mechanistic experiments indicate that the success of this method relies on the use of dual-functional copper catalysis, which is involved in both the functionalization of the CF2 unit and the subsequent ring-opening process.

Facile access to redox responsive self-healing coating materials via living cationic block copolymerization of styrene and 2-chloroethyl vinyl ether

Poly(alkyl vinyl ether)-based functional copolymers have wide applications in many high-tech areas. However, their synthesis is still challenging which limits their applications. This article describes the synthesis of an unprecedented redox-responsive polystyrene-block-poly(2-thioethyl vinyl ether) (PSt-b-PTEVE) diblock copolymers via sequential “water tolerant” cationic polymerization of St and CEVE, followed by post-polymerization transformation of the pendant -CH2CH2Cl functionalities of PCEVE segment to -CH2CH2SH functionalities. The initiating system enabled controlled cationic polymerization of styrene (St), yielding well-defined PSt (at least up to 22500 g/mol) with relatively low dispersity (Đ ≤ 1.36) and polystyrene-block-poly(2-chloroethyl vinyl ether) (PSt-b-PCEVE) diblock copolymers with acceptable dispersity values (Đ ≤ 1.38) thereof, demonstrating high chain-end fidelity. The controlled character of the cationic polymerization reaction was confirmed by linear kinetic plots, linear increase of Mns (with low Đs) and synthesis of PSts of changing Mns simply by varying initial [St]0/[Initiator]0 feed ratio. The synthesized PSt-b-PTEVE diblock copolymers exhibited redox responsivity and self-healing behaviour. The self-healing property of the PSt-b-PTEVE diblock copolymer was studied by optical microscopy. For this, first, a mechanical cut was introduced in the cross-linked PSt-b-PTEVE thin films and then images were taken at regular intervals to investigate the healing. These promising PSt-b-PTEVE diblock copolymers might have potential applications in many emerging areas, including functional coating.

Organocatalytic stereoselective cationic polymerization of alkenyl vinyl ethers and post-functionalization via click chemistry

Vinyl polymer tacticity is critical for regulating the thermal and physical properties of materials. Stereoselective cationic polymerization of vinyl ethers has gained significant progress in recent years, while monomer scope beyond simple alkyl vinyl ethers to access functionalized isotactic polymer materials remains to be explored but highly desirable. Herein, we report the successful development of a stereoselective cationic polymerization of alkenyl vinyl ethers by employing confined Brønsted acid organocatalysis. This organocatalytic system shows high efficiency and stereoselectivity in the polymerization of several alkenyl vinyl ethers, as well as good compatibility to the diolefinic monomers without touching the C=C bonds in the alkenyl part during the cationic polymerization, thus allowing for further modification on these C-C double bonds after polymerization to construct functionalized, isotactic polymer materials. Further, a series of thermoplastic copolymers with tunable properties and variable and predictable contents of side-chain C=C bonds can be synthesized through the corresponding stereoselective copolymerization. Sequential post-polymerization modification of both isotactic homopolymers and copolymers by combining thiol-ene and sulfur(VI) fluoride exchange (SuFEx) click reactions is also demonstrated.

FTIR screening of phytocompounds in plant Spermacoce hispida L. of Vallimalai Hills at Vellore district

The objective of this study is to detect the FTIR fingerprints of phytocompounds in the plant Spermacoce hispida L. The FTIR analysis of methanol leaf extract of plant Spermacoce hispida L. revealed the presence of 19 bioactive phytocompounds such as aliphatic primary amine, alkene, alkanes, amine salt, aldehydes, aromatic compound, α, β-unsaturated ester, conjugated alkene, nitro compound, sulfonyl chloride, phenol, aromatic amine, alkyl aryl ether, vinyl ether, ester, tertiary alcohol, primary alcohol, carboxylic acids and halo compound.

Multi-stimuli responsive amphiphilic diblock copolymers by a combination of ionic liquid-mediated cationic polymerization and recyclable alloy nanoparticle-mediated photoRDRP

Poly(alkyl vinyl ether)-containing multifunctional block copolymers (BCPs) are challenging to synthesize and still limited in numbers despite their possible applications in high-tech areas. This article presents the synthesis of unprecedented amphiphilic poly(2-thioethyl vinyl ether)-block-poly(poly(ethylene glycol) methacrylate) (PTEVE-b-PPEGMA) BCPs via sequential ionic liquid-mediated cationic polymerization of CEVE and recyclable alloy-mediated photoRDRP of PEGMA, followed by post-polymerization modification of the pendant -CH2CH2Cl functionality to -CH2CH2SH. Controlled nature of both the cationic polymerization and photoRDRP was demonstrated by the first-order kinetic and linear increase of molecular weight with increase of monomer conversion, keeping low dispersity values. The synthesized PTEVE-b-PPEGMA BCP exhibited a dual (redox and temperature) stimuli-response. The cloud point of PTEVE-b-PPEGMA BCP can be tuned by changing the PEGMA mol% in the BCP. Amphiphilic PTEVE-b-PPEGMA diblock copolymer undergoes self-aggregation forming spherical nano-objects. These promising PTEVE-b-PPEGMA diblock copolymers could be used for many applications, including dual stimuli-responsive materials, materials with tunable hydrophobicity, and contaminant removal.

Radical homopolymerization of vinyl ethers activated by Li+-π complexation in the presence of CH3OLi and LiI

The radical polymerization activity of both hydroxyl and alkyl vinyl ether monomers is significantly activated by Li+-π complexation with CH3OLi or LiI.

Phytochemical screening by FTIR spectroscopic analysis of methanol leaf extract of herb Andrographis echioides

The plant Andrographis echioidesis play a vital role in curing various human diseases. According to traditional siddha medicinal system till date it is accountable as to cure 81 diseases. The cost of fresh leaves is Rs 1750/Kg in Medicinal live, a largest online medicinal supplier in India. This much of cost may be due to its demand in siddha medicine to prepare various medicine is so high. Even though, this much of demand is exists but no any scientific validation and documentation for this plant possessing phytocompounds to cure the disease. Hence the present study was aimed to evaluate the possible bioactive functional group present in the methanol leaf extract of Andrographis echioides. The major functional group present in this plant was determined by FTIR analysis showed the existence of functional groups such as alkanes, aromatic compound, conjugated alkene, cyclic alkene, nitro compound, aromatics, carboxylic acid, phenol, aromatics ester, alkyl aryl ether, vinyl ether, ester, tertiary alcohol, primary alcohol, alkyl halides, alkene and halo compounds.

Structure-specific, accurate quantitation of plasmalogen glycerophosphoethanolamine

Changes in plasmalogen glycerophosphoethanolamine (PE-P) composition (structure and abundance) are a key indicator of altered lipid metabolism. Differential changes in the levels of PE-P have been reported in different disease states, including neurodegenerative diseases. Of particular interest, traumatic brain injury (TBI) has resulted in altered expression of glycerophospholipid profiles, including PE-P. To date, most analytical assays assessing PE-P have focused on general lipidomic workflows to evaluate the relative, semi-quantitative abundance of PE-P during disease progression. This approach provides a broad evaluation of PE-P, yet often lacks specificity and sensitivity for individual PE-P structures which is a necessity for robust quantitative data. The present study highlights the development of a targeted, quantitative method using a HILIC separation and selective reaction monitoring mass spectrometry for the confident identification and accurate quantitation of PE-P. Our innovative method incorporates both the sn-1 alkyl vinyl ether and sn-2 acyl chain as product ion transitions, for specific and sensitive quantitation of 100 PE-P structures. Our method also uniquely allowed for the unambiguous assignment and quantitation of di-unsaturated sn-1 PE-P structures, which to date have not been conclusively quantified. Application of this assay to a TBI mouse model resulted in distinct temporal profiles for plasma PE-P up to 28 days post injury. Plasma PE-P were significantly increased 24 h after induced TBI, followed by a gradual reduction to sham concentrations by day 28. Overall, we established a structure-specific, quantitative assay for identification and quantitation of a comprehensive set of PE-P structures with demonstrated relevance to brain injury.

Computational investigation on the effect of [Bmim][BF4] ionic liquid addition to MEA alkanolamine absorbent for enhancing CO2 mass transfer inside membranes

Nowadays, various types of liquid solutions have been applied to remove acidic contaminants such as CO2 with the aim of mitigating their pernicious emission to atmosphere. Ionic liquids are recently of tremendous attention as promising solutions for CO2 molecular removal from disparate gaseous mixtures due to their superior characteristics such as regeneration simplicity, low volatility and negligible environmental toxicity. The main objective of this paper is to mathematically implement a model based on finite element approach (FEA) to analyze the governing mass and momentum partial differential equations inside the domains of polytetrafluoroethylene-co-perfluorinated alkyl vinyl ether membrane contactor (PFAMC). Also, a computational fluid dynamics (CFD) simulation is carried out to analyze the CO2 molecular removal percentage using MEA absorbent and a mixed solution containing 30% 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) ionic liquid and 70% MEA amine solution. The results show that although MEA has been able to remove only 18% of CO2 from the inlet gas, the addition of 30% [Bmim][BF4] ionic liquid to MEA significantly improved the CO2 mass transfer performance and consequently its removal efficiency to 79%. Study on the effect of some operational parameters such as inlet feed gas flow rate, packing density and number of hollow fibers on removing the CO2 molecules is another objective of this paper.

Metal-Free Living Cationic Polymerization Using Diaryliodonium Salts as Organic Lewis Acid Catalysts

A metal-free initiating system for the living cationic polymerization of alkyl vinyl ethers (VEs) and styrene derivatives was developed using diaryliodonium salts as an organic Lewis acid catalyst....

Chiral Fe(ii) complex catalyzed enantioselective [1,3] O-to-C rearrangement of alkyl vinyl ethers and synthesis of chromanols and beyond.

A highly efficient enantioselective [1,3] O-to-C rearrangement of racemic vinyl ethers that operates under mild conditions was developed. This method with chiral ferrous complex catalyst provided an efficient access to a wide range of chromanols with high yields and excellent enantioselectivities. In addition, an important urological drug (R)-tolterodine and others were easily obtained after simple transformations.

Polar Thermoplastics with Tunable Physical Properties Enabled by the Stereoselective Copolymerization of Vinyl Ethers

A series of isotactic, semicrystalline vinyl ether copolymers (up to 94% meso diads) were synthesized using a chiral BINOL-based phosphoric acid in combination with a titanium Lewis acid. This stereoselective cationic polymerization enabled the systematic tuning of both glass transition (Tg) and melting temperature (Tm) in copolymers derived from alkyl vinyl ethers (i.e., ethyl, butyl, isobutyl). Additionally, a vinyl ether comonomer bearing an acyl-protected alcohol was utilized as a platform for postfunctionalization. Copolymers containing the masked alcohols were shown to undergo deprotection and subsequent coupling with a desired acid chloride. Collectively, these results highlight the diverse material properties and expanded chemical space accessible through stereoselective cationic polymerization mediated by a chiral anion.

Structure–property relationship of phenoxyimine ligands/metal chloride initiating systems for controlled cationic polymerizations of alkyl vinyl ethers

ABSTRACTThe catalyst structure–property relationships of the phenoxyimine complexes in controlled cationic polymerization of vinyl ethers were investigated based on the Hammett correlation. The correlation analyses of a series of experiments using the phenoxyimine ligands/TiCl4 initiating systems indicated that the substituents on the N‐aryl phenoxyimine ligands affected the polymerization rate and stereoselectivity. Importantly, a linear correlation was observed between the Hammett substituent constants and the polymerization rates, which indicates that the Lewis acidity of the complex is affected by the electron‐withdrawing and ‐donating effects of the substituents. The tacticity of product polymers correlated to the Hammett substituent constants. Unlike the relationship with the polymerization rates, the σ– values, which account for the enhanced resonance effects, were more appropriate for the relationship with the tacticity than the normal σ values. In contrast, the polymerization behavior using o‐substituted ligands exhibited a trend different from those using p‐ or m‐substituted ligands. The structural change, which was caused by the rotation of the CN bonding, most likely triggered the acceleration effect in the case of the o‐substituents. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2021–2029

Impacts of SO2, Relative Humidity, and Seed Acidity on Secondary Organic Aerosol Formation in the Ozonolysis of Butyl Vinyl Ether.

Alkyl vinyl ethers are widely used as fuel additives. Despite this, their atmospheric chemistry and secondary organic aerosol (SOA) formation potentials are still not well-known under complex pollution conditions. In this work, we examined the impact of SO2, relative humidity (RH), and particle acidity on the formation and oxidation state (OSc) of SOA from butyl vinyl ether (BVE) ozonolysis. Increasing SO2 concentration produced a notable promotion of SOA formation and OSc due to the significant increase in H2SO4 particles and formation of more highly oxidized components. Increased RH in the presence of SO2 appeared to promote, suppress, and dominate the formation and OSc of SOA in the dry range (1-10%), low RH range (10-42%), and moderate RH range (42-64%), respectively. This highlights the importance of competition between H2O and SO2 in reacting with the stabilized Criegee intermediate in BVE ozonolysis at ambient RH. Increased particle acidity mainly contributed to the change in chemical composition of BVE-dominated SOA but not to SOA formation. The results presented here extend previous analysis of BVE-derived SOA and further aid our understanding of SOA formation potential of BVE ozonolysis under highly complex pollution conditions.

Visible-Light Photocatalytic Preparation of 1,4-Ketoaldehydes and 1,4-Diketones from α-Bromoketones and Alkyl Enol Ethers.

A Ru2+-photocatalyzed, visible-light-mediated ATRA reaction for the straightforward preparation of 1,4-ketoaldehydes, 1,4-diketones, and 1,4-ketoesters, which are of difficult access by other means, is reported herein. This method employs readily accessible α-bromoketones and alkyl vinyl ethers as starting materials, allowing the construction of secondary, tertiary, and challenging quaternary centers. In addition, the synthetic usefulness of this method is illustrated by applying it to the construction of substituted pyrroles.

Experimental and modeling of CO2 removal from gas mixtures using membrane contactors packed with glass beads

The efficiency of gas removal using hollow fiber membrane (HFM) contactors and liquid solvents is determined by several factors. The liquid film resistance has been identified as one of the important factors affecting the overall mass transfer coefficient. The present work describes the use of spherical glass beads as additional packing in the shell (solvent) side to act as solid baffles which should impart stirring effect in the flowing solvent and increase its velocity. These two effects should decrease the liquid film resistance and consequently enhance the gas removal efficiency. Two types of custom-made hollow fiber membrane contactors (HFMC) were constructed from thick-walled acrylic tube (20 mm ID, OD 30 mm) and equipped with the commercially available poly(tetrafluoroethylene-co-perfluorinated alkyl vinyl ether) (PFA) hollow fibers. In one type of the contactors, glass beads were introduced in the shell side. The two types of contactors (with and without beads) were tested and compared in terms of CO2 removal efficiency from gas mixtures (5% CO2 − 95% CH4) using aqueous sodium hydroxide and several amine solutions. Different parameters were studied to evaluate the performance of the membrane contactors at feed gas pressures up to 25 bars. The obtained results indicated an increase of up to 21% enhancement in CO2 removal efficiency when the shell compartment was packed with the glass beads. The results obtained from the overall mass transfer coefficient model showed good agreement with those of the experimental data.

Exceptional copolymerizability of o-phthalaldehyde in cationic copolymerization with vinyl monomers

o-Phthalaldehyde is copolymerized via the unique active species, which allows the controlled copolymerization with alkyl vinyl ethers, alternating copolymerization, and copolymerization with sterically hindered nonhomopolymerizable vinyl monomers.