Alkylene Oxide Research Articles

Poly(ether-ester) multiblock copolymers based on poly(oxymethylene-alt-oxyalkylene) glycols

Alternating polyols of oxymethylene and oxyalkylene were synthesized and used as precursors for thermoplastic poly(ether-ester) elastomers (TPEs). The polyols were synthesized by reacting diols having different methylene units with dichloromethane in the presence of a phase transfer catalyst. The number of methylene units in the alkylene oxides was varied from 3 to 6. TPEs were prepared using the polyols as soft segments and poly(butylene terephthalate) units as hard segments. The polyols and TPEs synthesized were characterized using FTIR, NMR, GPC, DSC, and polarized optical microscopy. The polyols showed a profound odd-even effect on the melting(Tm) and glass transition temperatures(Tg). Polyols with odd numbers of methylene groups in the alkylene units have higher transition temperatures than polyols with odd number of methylene groups. The tendency is still kept in TPEs, even though theTg of soft segment in TPEs are slightly higher than those of corresponding neat polyols. TheTm andTg of soft segments are almost constant in the range of 20 to 60 wt % contents of soft segments. On the other hand, the normalized heat of fusion of hard segment decreased with increasing the content of soft segment.

Selective oxidation of alkylarenes in dry media with potassium permanganate supported on Montmorillonite K10

The solvent-free oxidation of alkylarenes with KMnO4 supported on Montmorillonite K10 is reported. The beneficial effects of microwave and ultrasound irradiation on the reactions is described.

Direct syntheses of ordered SBA-15 mesoporous materials containing arenesulfonic acid groups

SBA-15 mesoporous silica has been functionalized with arenesulfonic acid groups by means of a one-step simple synthesis approach involving co-condensation of tetraethoxysilane (TEOS) and 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane (CSPTMS) in the presence of a poly(alkylene oxide) block copolymer (Pluronic 123) under acid silica-based catalysis. The resultant materials show hexagonal mesoscopic order and pores sizes up to 60 A, with acid exchange capacities of ca. 1.3 mequiv. H+ per g SiO2 and surface areas up to 600 m2 g−1. The sulfonic groups anchored to the silica surface of the pore walls are thermally stable to temperatures up to 380 °C and resistant to leaching in organic and aqueous solutions under mild conditions. 31P MAS NMR measurements of chemically adsorbed triethylphosphine oxide and the catalytic properties confirm the presence of Bronsted acid centers in these mesoporous materials containing arenesulfonic acid groups that are stronger than those found in propanesulfonic-modified SBA-15 and Al-MCM-41.

Preparation of Isophorone Diisocyanate Terminated Star Polyethers

Reactive star shaped isocyanate prepolymers have been prepared by endcapping hydroxy functionalized poly(alkylene oxide)s with isophorone diisocyanate. Selective reaction conditions have been worked out to reduce the amount of chain extension and crosslinking due to reaction of both isocyanate groups of the IPDI moieties. By combining 1 H and 13 C NMR spectroscopy with size exclusion chromatography (SEC), the fractions of the monourethane isomers, and the extent of diurethane formation was determined. The effect of catalysis, of the excess of isocyanate, and of the type of poly(alkylene-oxide) on the product structure and composition were investigated.

Atom Transfer Radical Polymerization of Hydroxy-Functional Methacrylates at Ambient Temperature: Comparison of Glycerol Monomethacrylate with 2-Hydroxypropyl Methacrylate

The homopolymerization of two hydroxy-functional monomers, glycerol monomethacrylate [GMA] and 2-hydroxypropyl methacrylate [HPMA], has been investigated using ATRP chemistry in aqueous, methanolic, or water/methanol solution. In methanol, both monomers are polymerized to high conversion with reasonably good control (final polydispersities are 1.30 and 1.09 for GMA and HPMA, respectively) within a few hours at 20 °C. “Self-blocking” chain growth experiments indicate good living character under these conditions. Addition of water leads to much more rapid polymerizations in both cases, but high polydispersities (e.g., Mw/Mn = 1.90 for a 50/50 water/methanol mixture) were always obtained with GMA. With HPMA, relatively low polydispersities (Mw/Mn = 1.17) can be achieved under the same conditions. Several new diblock copolymers were synthesized using poly(alkylene oxide)-based macroinitiators. One of these hydrophilic−hydrophobic diblocks proved to be thermoresponsive and aggregated reversibly in aqueous media.

Adamantylation of Indazole and Its C-Nitro Derivatives

Adamantylation of indazole and its C-nitro derivatives with 1-hydroxyadamantane in mineral acids yields exclusively the corresponding 1-(1-adamantyl)indazoles via attack by 1-adamantyl cation on the protonated substrate. The oxidative alkylation with 1-iodoadamantane leads to formation of 1- and 2-(1-adamantyl)indazoles, the 2-isomer prevailing.

ESR study of the thermal decomposition of di-tert-butoxy-tert-butyl alumotrioxide formed in the reaction of tri-tert-butoxyaluminum with tert-butyl hydroperoxide

Tri-tert-butoxyaluminum reacts with tert-butyl hydroperoxide to produce di-tert-butoxy-tert-butyl alumotrioxide, which decomposes heterolytically to form singlet dioxygen and homolytically with the O—O bond cleavage. The ButOO·, (ButO)2AlOO·, ButO·, and (ButO)2AlO· radicals were identified by ESR using spin traps. These findings confirm the formation of aluminum-containing trioxide. The above radicals initiate alkylarene oxidation by the tri-tert-butoxyaluminum—tert-butyl hydroperoxide system. The carbon-centered and alkylperoxy radicals originated from the oxidized substrates were identified.

ChemInform Abstract: New Access to α‐Substituted (Z)‐Fluoroalkene Dipeptide Isosteres Utilizing Organocopper Reagents under “Reduction—Oxidative Alkylation (R—OA)” Conditions.

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.

New access to α-substituted ( Z)-fluoroalkene dipeptide isosteres utilizing organocopper reagents under ‘reduction–oxidative alkylation (R–OA)’ conditions

( Z)-Fluoroalkene dipeptide isosteres serve as potential dipeptide mimetics. The present paper reports a new access to α-substituted ( Z)-fluoroalkene isosteres utilizing an organocopper-mediated ‘reduction–oxidative alkylation (R–OA)’ reaction.

Concentrated CO2-in-Water Emulsions with Nonionic Polymeric Surfactants

Concentrated CO2-in-water (C/W) emulsions are reported for amphiphiles containing alkylene oxide-, siloxane-, and fluorocarbon-based tails as a function of temperature and salinity. Poly(ethylene oxide)–b–poly(butylene oxide) (EO15–b–BO12) can emulsify up to 70% CO2 with droplet sizes from 2 to 4 μm in diameter, as determined by video-enhanced microscopy. This emulsion is stable over 48 h against both flocculation and coalescence. In contrast, it is extremely difficult to form concentrated water-in-CO2 (W/C) emulsions with surfactants containing alkylene oxide moieties due to limited solvation of such tails by CO2. In several cases, C/W emulsions are formed even when the surfactant prefers CO2. This violation of Bancroft's rule may be attributed in part to the low viscosity of the compressed CO2, which governs several mass and momentum transport mechanisms relevant to emulsion formation and stabilization. For the first time, W/C microemulsions are observed in a system with a nonionic amphiphile, namely F(CF2CF2)3–8CH2CH2O(CH2CH2O)10–15H. For the same system, the emulsion morphology changes from C/W to W/C as the temperature increases. The electrical conductivity of C/W emulsions is predicted successfully as a function of the dispersed phase volume fraction of CO2 with Maxwell's theory for inhomogeneous systems.

Rheological properties of acid gel cleansers

Aqueous solutions based on alkyl dimethyl amine oxide surfactants were formulated and characterized by rheometry. Steady shear and oscillatory rheological measurements have been used to study the effect of added acids and salts. The influence of the amine oxide alkyl chain length was also investigated. The formulations were optimized in order to develop home care products, such as bathroom or toilet cleansers. The properties of the cleanser systems are explained by the balance of elastic and viscous components. Highly elastic, gel-like solutions could be obtained upon addition of nitric acid or nitrate salts together with strong acids. The viscosity profile is controlled by synergistic effects between the different ingredients. The rheological properties have been found to be strongly dependent on the surfactant and electrolyte concentrations. The viscoelastic behavoiur of the formulations is discussed with respect of the requirements of ready-to-use gel cleanser products.

Mesoporous thin film TiO2 electrodes

Thin layer electrodes (200–500 nm) of highly organized nanotextured anatase were prepared by hydrolysis of TiCl4 in the presence of poly(alkylene oxide) block copolymer, Pluronic P-123, acting as a structure-directing agent. Electrochemical insertion of Li was studied in LiN(CF3SO2)2 + ethylene carbonate + dimethoxyethane. Cyclic voltammograms of these electrodes showed unusual occurrence of two pairs of cathodic/anodic peaks at 1.5 and 1.6 V vs. Li/Li+. These peaks can serve as indicators of structural perfection of the mesoscopic skeleton; they diminish after mechanical or thermal destruction of the organized nanotexture.

Ring‐opening polymerization of epichlorohydrin and its copolymerization with other alkylene oxides by quaternary catalyst system

AbstractAn effective quaternary catalyst consisting of trialkyl aluminum, phosphoric acid, electron donor, and water for ring‐opening polymerization of epichlorohydrin (ECH), as well as its copolymerization with ethylene oxide (EO), propylene oxide (PO), and allyl glycidyl ether (AGE) to obtain elastomers, were studied. We investigated the optimum composition for the quaternary catalyst; the character of the catalyst; the reactivity of the four alkylene oxides during homopolymerization and copolymerization; the behavior of ECH, EO, and PO during terpolymerization; and glass transition temperatures of the copolymer and terpolymers. The results showed that the nitrogen‐containing electron donors are suitable as the third component, whereas oxygen‐containing electron donors are not. Water as the fourth component can increase the molecular weight of the homopolymer and copolymers of ECH. According to the polymerizability of tetrahydrofuran with the quaternary catalyst and the reactivity ratios of the four alkylene oxides, the quaternary catalyst was assumed to be of a coordinated anionic type. The reactivity ratios for these four alkylene oxides were determined to be EO > PO > AGE > ECH. They were verified by terpolymerization of ECH, EO, and PO. The glass transition temperature of the terpolymer exhibits a minimum value at nearly 3:1 molar ratio of PO to EO, when the molar ratio of ECH used is constant at the beginning of terpolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2446–2454, 2001

Synthesis of ω-mercapto-poly(alkylene oxide) by the Mitsunobu reaction

An efficient way to transform ω-hydroxy-poly(alkylene oxide) in ω-mercapto-poly(alkylene oxide) in two steps is described : the Mitsunobu reaction with thiolacetic acid followed by the reduction of the thiol ester. Yields are quantitative with water soluble polymers.

ChemInform Abstract: A Novel Oxidative Alkylation—Nitration of 1,3‐Dicarbonyl Compounds to Dicyclopentadiene and Norbornene.

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.

Supramolecular Dissociation of Polymeric Inclusion Complexes Containing Cyclodextrins as a Method of Preparing New Columnar Structures

Polymeric inclusion complexes formed from cyclodextrins (CDs) and linear polymers are molecular necklaces (MNs), structures in which dozens of CD molecules are tightly thread onto a polymer chain [1]. These systems clearly exemplify the significance of the geometric match between the size of the CD cavity and the cross section of the polymer. For example, α -CD forms complexes with poly(ethylene oxide) (PEO) but not with poly(propylene oxide) (PPO); β -CD forms complexes with PPO but not with PEO; and γ -CD interacts either with one PPO molecule or with two PEO molecules [2]. In crystals of MNs, CD molecules are arranged in channels, forming a columnar structure. The question arises as to whether this structure will survive after removal of the thread polymer. Similar structures are of interest as new crystalline CD modifications with a common extended channel and, hence, exhibiting new properties. The resolution of the problem calls for a method of removing the polymer from the MN cavity that would leave the type of crystal lattice unaltered. In this paper, we describe a new property of MNs, namely, their ability to dissociate under the action of an organic solvent, selective to the thread polymer but inert to the macrocycle, to produce a new ordered CD form, a columnar CD structure (CD column ). The synthesis of complexes and their properties are described elsewhere [3‐5]. Previously, we studied the formation, composition, and structure of MNs based on α -, β - , and γ -CDs. These MNs are precipitated on mixing water solutions of a CD and a poly(alkylene oxide) (PAO) complementary in size to the CD. The complexes contain one macrocyclic molecule per two monomeric units of PAO (except the γ -CD‐PEO, which contains a double amount of the polymer). As a third component, MNs also include water, which is involved in the formation of intermolecular hydrogen bonds between hydroxyls of neighboring CD molecules. Therefore, we obtained the complexes α - CD‐PEO, γ -CD‐PEO, and β -CD‐PPO, composed of macrocycles threaded on polymer chains and characterized by a lack of covalent bonds between cyclic and thread molecules. To selectively extract the polymers from MNs, we used both polar (acetone, THF) and nonpolar (chloroform, carbon tetrachloride, benzene, tert -butylbenzene, Tetralin) organic solvents inert to CDs. A solvent was added to a MN powder, stirred for several hours, and then the organic phase was separated. For all three types of complexes, the corresponding polymer was identified in the solution within several hours. The polymer content of the β -CD‐PPO-3500 complexes was quantitatively assessed by IR spectroscopy [6].

Coal solubilization through ‘ionic’ oxidation and base-promoted alkylation

Coal solubilization through ‘ionic’ oxidation and base-promoted alkylation

Effects of Block Copolymers of Alkylene Oxides on the Permeability of Lipid Membranes: Possible Origins of Biological Activity

Effects of Block Copolymers of Alkylene Oxides on the Permeability of Lipid Membranes: Possible Origins of Biological Activity

OZONOLYSIS OF CINNAMIC ACID IN WATER MEDIUM

The ozonolysis of trans-cinnamic acid (trans-3-phenyl-acrylic acid) in aqueous medium is studied in this paper. In acid medium, benzaldehyde was formed in a 1:1 ratio with respect to both cinnamic acid and ozone consumption throughout the reaction. Simultaneously, significant amounts of organic peroxides were measured in the reaction mixture, which proved to be stable during one hour or more. These facts suggest that in the reaction mechanism, the carbonyl group is preferentially formed in the aryl side of the former double bond, while the Criegee's carbonyl oxide (zwittenon) is formed in the alkyl moiety. An explanation based on die stabilization of the carbonyl oxide alkyl moiety by the influence of the neighbor carboxyl group, reinforced by water solvation, is advanced.

Oxidative Alkylation of Azoles: VII. Adamantylation of Azoles via Oxidative Generation of 1-Adamantyl Cations

A procedure has been developed for oxidative N-adamantylation of azoles with 1-iodoadamantane in the presence of chromium(IV) oxide or iodine(V) oxide. The procedure is applicable to azoles whose pK B H + value does not exceed 2.26.