Monochlorodimethyl Ether Research Articles

Attempts to Optimizing the Synthesis of Hypercrosslinked Polystyrene. Reactions with in situ Formed Monochlorodimethyl Ether

Attempts to Optimizing the Synthesis of Hypercrosslinked Polystyrene. Reactions with in situ Formed Monochlorodimethyl Ether

Attempts to Optimizing the Synthesis of Hypercrosslinked Polystyrene. 1. Crosslinking with Monochlorodimethyl Ether

Attempts to Optimizing the Synthesis of Hypercrosslinked Polystyrene. 1. Crosslinking with Monochlorodimethyl Ether

On the Mechanism of Swelling of Gel-Type, Macroporous and Hypercrosslinked Copolymers of Styrene

Gel type polymers, polymers of expanded structure and macroporous polymers of styrene mostly with 6 mole% of divinylbenzene have been obtained by suspension polymerization, expanded and macroporous structures being prepared in the presence of 1.5 volumes of toluene or iso-octane, respectively. All three types of copolymers were further converted into highly porous hypercrosslinked products by their intensive post-crosslinking with monochlorodimethyl ether. For all samples obtained, the inner specific surface area, total pore volume, apparent density, and uptake of toluene, methanol and water have been measured. It was found that the swelling of macroporous and hypercrosslinked porous polymers results in an increase in the volume of the polymeric phase and decrease in the volume of large pores with insignificant rise in the total size of the polymeric beads. Swelling of porous polymers thus mainly proceeds at the expense of space of internal voids.

Optical Properties and Model of the Electronic and Spatial Structure of Hypercrosslinked Polystyrene

A number of hypercrosslinked polystyrene networks are studied. The networks are obtained via additional crosslinking of granules of styrene copolymer with 0.5% divinylbenzene (0.3–0.5 mm) and microgranules with 1% divinylbenzene (3.5 µm) using monochlorodimethyl ether to densities of crosslinking from 60 to 500%. It is found that as the degree of crosslinking grows, the absorption in the electronic spectrum of the polymer extends to the visible region, and the granules change color (toward as dark as black); this phenomenon is much less expressed for microgranules and milled materials. For a consistent explanation of these two observations, assumptions are made about the appearance and increase in the contrast of density fluctuations of a tracery hypercrosslinked network and light scattering on such micro-inhomogeneities in the volume of particles of the compared series of polymers.

Synthesis and Physicochemical Properties of Hypercrosslinked Polysterene Restricted-Access Materials

With a view to simplifying and reducing the cost of the synthesis of novel selective restricted-access materials based on microporous hypercrosslinked polystyrene for solid-phase extraction, various polystyrene crosslinking agents and Friedel–Crafts catalysts in various combinations have been studied. It has been found that the most effective crosslinking agent is monochlorodimethyl ether; in addition, expensive tin chloride has been effectively replaced with a smaller amount of cheap ferric chloride. Under special conditions for the suspension copolymerization of styrene with 1, 2, and 3% of divinylbenzene, copolymers with a bead size of 30–70 μm have been synthesized. Each of the copolymers has been further crosslinked with monochlorodimethyl ether to a degree of crosslinking of 100, 150, and 200%. These polymers are porous materials swellable in water and any organic solvents. The hypercrosslinked polymer network is not accessible to large molecules of proteins (Cytochrome C and albumin) and does not cause protein adsorption; owing to this feature, the sorbents can be classified as novel selective restricted-access materials.

Hypercrosslinked polymeric restricted access materials for analysis of biological fluids.

New restricted access materials based on microporous hypercrosslinked polystyrene have been developed. The materials are aimed to use as packings for solid-phase extraction cartridges to isolate low-molecular-weight analytes from biological fluids (for instance, blood plasma or serum). Two features distinguish these polymers from all known restricted access materials. The first one consists of the microporous hypercrosslinked polystyrene that not only exclude proteins from the sorbent phase but also do not adsorb them on the bead outer surface, and so they do not cause coagulation of blood protein components. Therefore, these materials do not require any chemical modification. The second distinguishing feature is the ability of hypercrosslinked sorbents to take up a wide variety of polar and nonpolar organic compounds. The sorbents were obtained in the form of beads of 60-70μm in diameter by cross-linking styrene copolymers with 1, 2, and 3% divinylbenzene with monochlorodimethyl ether to 100, 150, and 200% cross-linking degree. The sorbents exhibit all typical properties of hypercrosslinked networks. They do not take up albumin, the major blood protein, and cytochrome C, representative of smaller protein molecules, but are capable of adsorbing drugs, vitamins, and phenyl carboxylic acids (markers of sepsis) from model aqueous solutions.

Hypercrosslinked polystyrene networks: An atomistic molecular dynamics simulation combined with a mapping/reverse mapping procedure

An algorithm involving classical molecular dynamics simulations with mapping and reverse mapping procedure is here suggested to simulate the crosslinking of the polystyrene dissolved in dichloroethane by monochlorodimethyl ether. The algorithm comprises consecutive stages: molecular dynamics atomistic simulation of a polystyrene solution, the mapping of atomistic structure onto coarse-grained model, the crosslink formation, the reverse mapping, and finally relaxation of the structure dissolved in dichloroethane and in dry state. The calculated values of the specific volume and the elastic modulus are in reasonable quantitative correspondence with experimental data.

On the nature of “functional groups” in non-functionalized hypercrosslinked polystyrenes

The paper discusses the assignment of the absorbance band at 1700cm−1 in FTIR spectra of hypercrosslinked polystyrenes. This band is exceptionally intensive in the spectra of networks obtained by post-crosslinking styrene-0.5% DVB copolymer, swollen in ethylene dichloride, with monochlorodimethyl ether up to the maximum possible crosslinking degrees of 300%, 400% and 500% in the presence of non-oxidizing catalyst SnCl4. Theoretically, in these networks each phenyl ring binds to neighboring phenyls through three, four or five methylene groups, respectively. Elemental analysis of the products seems to be deficient in C and H, thus allowing expectation of a surprisingly high percentage of oxygen. However, the traditional attribution of both the suspected high content of oxygen and the band at 1700cm−1 to aromatic carbonyl groups is incorrect. Treatment of hypercrosslinked polystyrenes with hydroxylamine, sodium bisulfite, ethyl orthoformiate or LiAlH4 do not result in disappearance of the absorbance at 1700cm−1 in FTIR spectra and emergence of corresponding characteristic new bands. Solid state 13C NMR spectroscopy also confirms the absence of CO moieties in the above hypercrosslinked polystyrenes. The absorbance at 1700cm−1 disappears, while new bands in the range of 1670–1650cm−1 emerge, in the spectrum of the sample with 500% crosslinking degree after the reduction of its benzene rings via Birch reaction. This allows suggesting that the band at 1700cm−1 and its shoulders are caused by hindered vibrations of carbon–carbon bonds and valence angles in the aromatic fragments composing the rigid network with extremely high extent of mutual connectivity.

Hypercrosslinked polystyrene networks with ultimate degrees of crosslinking and their sorption activity

Hypercrosslinked networks with 43, 100, 200, 300, 400, and 500% nominal crosslinking, respectively, were prepared by crosslinking the dichloroethane-swollen styrene copolymer with 0.5% divinylbenzene by Friedel-Crafts reaction using 0.3, 0.5, 1.0, 1.5, 2.0, and 2.5 mol of a bifunctional reagent (monochlorodimethyl ether), respectively. The dependences of the free (pore) volume of networks and their equilibrium swelling in water on the degree of crosslinking are extrema with the maximum parameters 0.63 cm3/g and 1.31 ml/g corresponding to the polymer with 300% crosslinking. The apparent specific surfaces of samples with 43–400% bridges are comparable, 1300–1500 m2/g. The ability of water-swollen hypercrosslinked polymers to extract synthetic organic dyes from aqueous solutions is independent of their specific surface measured for dry samples, but depends on the volume of absorbed water.

Internal stresses in hypercrosslinked polystyrene: Polarized optical studies

Polarized optical microscopy is used for studying the hypercrosslinked PS network prepared by the crosslinking of DC swollen spherical beads of styrene copolymer containing 0.5% of divinylbenzene by monochlorodimethyl ether up to 100% crosslinking. The removal of the solvent decreases the volume of the sample and leads to the development of internal stresses, which manifest themselves as strong optical anisotropy of dry beads. On the contrary, upon swelling in toluene, the network is expanded and shows anisotropy. When the network swells in any thermodynamically good solvent, existing stresses invert their sign and this network appears to be free of any internal stresses. This state of the network should be treated as the ϑ state, in which beads are optically isotropic. This state can also be achieved by swelling of a hypercrosslinked polymer in methanol, which eliminates compressive stresses in the hypercrosslinked network via increase in volume but cannot extend it like toluene. Conventional gel copolymers of styrene with divinylbenzene prepared without any toluene or in the presence of minor amounts of toluene are fully isotropic only in their dry state. These copolymers are inert to methanol but swell in hexane and cyclohexane, and their swelling is accompanied by the development of internal stresses.

Sorption of ions of heavy metals by neutral hypercrosslinked polystyrene

Sorption of acetates and nitrates of mercury, lead, silver and bismuth from acetate buffers or nitric acid solutions by three types of neutral hypercrosslinked polystyrene materials has been studied. The sorbents were prepared by crosslinking either linear polystyrene or a styrene-0.7% DVB copolymer with monochlorodimethyl ether or p-xylylene dichloride, the degree of crosslinking amounting to 100% and more. The commercial hypercrosslinked sorbent, Macronet Hypersol MN-200 (Purolite), was used in the study, as well. The sorption of the above salts appears to be caused by the formation of ~ -complexes between the metal cations and two (or more) benzene rings of the hypercrosslinked polystyrene. The formation of the complexes was found to proceed slowly at room temperature with the rate depending on the network mobility and "pore" size. The sorption isotherms for mercury proved to be characterized by strong hysteresis, but, the mercury absorbed can be easily removed by washing the sorbent with HC1 or EDTA solutions. At a concentration of less than 20 mg/ml, MN-200 exhibits the largest capacity for mercury ions, up to 200 mg/g. At higher concentrations, the sorption capacity of the polymer based on styrene-DVB copolymer rises to 400 mg (or 2 mmol Hg) per 1 g of the polymer. The sorption of the other aforementioned ions is markedly lower and reversible.

Hypercrosslinked polystyrene: A polymer in a non-classical physical state

Deformation and relaxation properties of hypercrosslinked polystyrene networks have been studied by thermomechanical method at a uniaxial compression using individual spherical beads of the polymer. The networks examined were prepared by postcrosslinking of highly swollen beads of a styrene-0.3% DVB copolymer with 0.3–0.75 mole of monochlorodimethyl ether, which results in the introduction of 0.6–1.5 methylene bridges between each two polystyrene phenyl rings. The polymers obtained are shown to belong neither to typical glassy materials, nor to typical elastomers. Though no characteristic plateau of rubberlike elasticity was observed on the deformation curves of the beads, the polymers exhibit two fundamentally important features of the rubberlike state: The deformations are large (up to 30–40% of the initial diameter) and reversible. Relaxation of residual deformations, however, requires prolonged heating of the sample, or a cycle of swelling and drying. The deformation can start in the temperature range from −70 to +150°C depending on pressure applied. The crosslinking degree in the range from 40–100% and higher does not affect noticeably the behavior of the hypercrosslinked polystyrene. Nature of the high mobility of the hypercrosslinked network is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2324–2333, 1999

Ortho-phosphorylated phenols and their methoxymethyl ethers, phosphines, and phosphine oxides

1. By reaction of o-methoxymethoxyphenyllithium with P(III) acid chlorides and with phosphinyl chlorides o-methoxymethoxyphenylphosphines and methoxymethyl ethers of o-phosphinyl-substituted phenols were obtained, and by hydrolysis transformed into the corresponding o-phosphinyl-substituted phenols. 2. A method for obtaining phenol methoxymethyl ethers was developed by alkylation of phenols with monochlorodimethyl ether in two steps.

Substitution reactions with the participation of organoaluminum compounds. 7. Reaction of organoaluminum compounds with monochlorodimethyl ether

The reaction of monochlorodimethyl ether with different organoaluminum compounds is only a convenient method for the isolation of alkyl methyl ethers in the case of trialkylalanes.

The study of macronet isoporous styrene polymers by gel permeation chromatography

AbstractGel permeation chromatography was used for studying the structure of macronet isoporous styrene polymers swollen in chloroform. The polymers were obtained by crosslinking polystyrene either in a solution or in a swollen state using monochlorodimethyl ether and p‐xylylenedichloride via the Friedel–Crafts reaction. It is shown that the networks obtained by structurization of concentrated polystyrene solution in a good solvent are characterized by loose structure, fine pores (ca. 10 Å), and narrow pore distribution. In poor solvents or in strong dilution of polystyrene and at the instant of net formation, the polymers that are obtained contain, in addition to fine pores, large pores with diameters up to 300 Å.

The properties of sulphur cation-exchange resins based on bulk and granular, macro-crosslinked, isoporous styrene copolymers

Macro-mesh, isoporous styrene copolymers were produced by crosslinking polystyrene solutions and granules of the styrene copolymer with 1% butadiene using monochlorodimethyl ether as crosslinking agent, and this was followed by sulphonation. The properties of the resulting ion-exchange resins (exchange capacity, % swelling, permeability for tetrabutyl ammonium ions, volume changes due to composition changes of the external solution) have been compared with those of the standard sulphocation-exchange resins (S-CER). The rigidity of the macro-mesh, isoporous resins, combined with the high penetrability makes them suitable for use in non-aqueous media.

On factors determining the swelling ability of crosslinked polymers

AbstractMacronet isoporous styrene polymers were obtained by a cross‐linking process (using monochlorodimethyl ether as the cross‐linking agent) applied to both dissolved linear polystyrene and swollen styrene copolymers with 0.3–1.0% divinylbenzene at the same polymer‐solvent weight ratio for all the systems. The lower equilibrium swelling capacity of copolymer‐based three‐dimensional structures as compared to that of linear polystyrene cross‐linked to an equal extent is explained by the presence in the initial swollen styrenedivinylbenzene copolymers of internal strains inhibiting an increase in the volume of the final polymer network. Cross‐linking of the linear polystyrene by means of a partially chloromethylated polystyrene shows that irregularity in the distribution of cross‐linking bridges enhances the equilibrium swelling capacity of the final gels.

Polyfunctional anionites prepared from oligomers based on diphenyl ether and formaldehyde

The optimum conditions have been determined for the synthesis of oligomers based on diphenyl ether, and their structure has been investigated. Reactions of chloromethylation of the oligomers with monochlorodimethyl ether, and by the method of Blahn, have been analyzed. It was found that in contrast to diphenyloxide chloromethylation of the oligomers is accompanied by the formation of chloromethyl derivatives containing 19–22% chlorine, which corresponds on average to 1·2–1·4 chloromethyl groups per diphenyloxide unit. From the kinetic results it appears that the chloromethylation reaction is a second order process. Novel polycondensation anionites have been prepared from chloromethylated oligomers with polyethylenepolyamine, polyethyleneimine, polyxylylenepolyamine and hexamethylenediamine. A kinetic study has been made of reactions of the chloromethylated diphenyloxide-formaldehyde oligomer with the polyamines. Apart from the initial stages these reactions do not obey regularities of second order processes. The obtained anionites are satisfactory from the point of view of their chemical and thermal stability, and have good mechanical strength. The feasibility of employing the ionites for sorption of some non-ferrous metal ions has been demostrated.

NQR spectra of Cl35 in complexes of stannic chloride with monochlorodimethyl ether and benzyl chloride

The NQR spectra of Cl35 of complexes (1:2) of stannic chloride with monochlorodimethyl ether and benzyl chloride were investigated. Both complexes have an octahedral structure with a cis-arrangement of the donor molecules.

Electron diffraction by gases the molecular structure of monochlorodimethyl ether

AbstractThe structure of monochlorodimethyl ether has been reinvestigated by means of electron diffraction of the vapour. The rotation of both the chloromethyl group and the methyl group is restricted; the chlorine atom is approximately in the gauche position with respect to the O‐C bond. The carbon‐chlorine bond length is 1.813 Å, significantly larger than in chloroalkanes. The bond between the chloromethyl carbon atom and the oxygen atom is shorter than the carbonoxygen bond in aliphatic ethers.