Alkyl Type Research Articles

Alkyl substituents of P,S,N-containing organic ligands influencing the uptake of Au3+ and Pt2+ ions over a hydrophobic hypercrosslinked polymeric sorbent

To increase the uptake efficiency towards Au3+ and Pt2+ ions, a hydrophobic hypercrosslinked polymeric sorbent (Purosorb™ PAD600, Purolite®) was impregnated with P,S,N-containing organic ligands: diethyldithiophosphoric acid (DEDTP), diisopropyldithiophosphoric acid (DIPDTP), diisobutyldithiophosphoric acid (DIBDTP), and 2-amine-1-methylbenzimidazole (MAB). Two stable polymorphs of 2-amino-1-methylbenzoazolium chloride monohydrate were formed and structurally analyzed by X-ray diffraction. The successful impregnation of organic ligands on the polymeric sorbent was confirmed by SEM, EDS and FTIR spectroscopy. The impregnation of the selected organic ligands significantly increased the uptake efficiency for Au3+ and Pt2+ ions of the polymeric sorbent. The uptake of Au3+ and Pt2+ ions is spontaneous, exothermic and obeys a pseudo-second-order kinetics, suggesting a complex uptake mechanism that includes a precipitation process dominating over both physical adsorption and strong chemical interaction. The highest uptake rates for Au3+ and Pt2+ ions were observed with PAD600-DIPDTP (3.71 mmol g−1) and PAD600-MAB (1.57 mmol g−1), respectively. The uptake ability of the selected organic ligands is discussed based on their electronic structure and type of alkyl groups, number and nature of donor atoms, hydrophobic and stereochemical parameters, chelate formation, possibility of the formation of poorly soluble compounds, dissociation constant, acid-base properties and synthesis conditions (pH, temperature, concentration, etc.). A complete desorption (>99%) of Au3+ and Pt2+ ions was achieved by introducing 60 mg L−1 of SC(NH2)2 solution (0.3 M H2SO4). The uptake efficiency of the Au3+ and Pt2+ ion was decreased by 10% in six successive adsorption–desorption cyclic runs due to the release of the impregnated organic ligands into the aqueous solution. The inexpensive, efficient and recyclable sorbents could be used for the uptake of various noble metals.

Imidazolium-based polymer hydrogels with microdomains as carriers of hydrophobic molecules

Alkyl imidazolium-based polymer hydrogels were prepared by copolymerizing N-allylimidazolium chloride monomers (AlImCls) bearing four types of alkyl groups with N-isopropylacrylamide and N, N′-methylenebisacrylamide. The conditions for preparing the anion-responsive hydrogels were screened by gelation test before and after the addition of tetrafluoroborate anions. The sol-gel phase transition was observed in N-dodecyl and N-octadecyl AlImCls-based copolymer solutions. Considering the anion selectivity in the gelation test, this phase transition was assumed to be derived from the formation of water-immiscible ion pairs of N-allylimidazolium cations and large anions on the polymers. Microscopic observations revealed that spherical domains with micro-sized diameters were formed in the hydrogels. A hydrophobized fluorescent dye was localized to the microdomains. Observations using time-lapse confocal microscopy and electron microscopy indicated that large microdomains were captured by the gel meshes consisting of thin sub-micron fibers. Based on the data collected during the analysis of the copolymer solutions, the spherical microdomains and the thin gel meshes were presumably formed through the anion-induced aggregation of small copolymer assemblies. Furthermore, the high fluidity of the microdomains was confirmed by measuring fluorescence recovery after photobleaching. In summary, anion-responsive hydrogels with hydrophobic microdomains were developed using ionic salt-based copolymers. These hydrogels are promising as a unique carriers for the use in biotechnology. Alkyl imidazolium-based polymer hydrogels produced by copolymerizing N-allylimidazolium chloride (AlImCl) bearing a long alkyl chain exerted a sol-gel phase transition in response to the addition of specific anions. Microscopic observation indicates that spherical microdomains of the polymer assembly were formed in the hydrogels. A hydrophobized fluorescent dye spontaneously accumulated and freely moved in the microdomains due to their high hydrophobicity and fluidity. The hydrogels with the unique domains are promising supports that can be used for multiple functional molecules in biosensing, bioproduction and a new type of drug delivery system.

Migratory Aptitudes of Alkyl Groups on Boron: A Computational Study of Halomethyllithium-Induced Migration Reactions

For reactions of alkyldioxaborolanes with halomethyllithium reagents, migrations of tertiary alkyl groups and benzylic groups often give lower yields of migrated products. The only published computational study calculated the barriers to tert-alkyl migration to be lower than for other types of simple alkyl groups. In contrast to this, the present work shows that, when detailed conformational analysis is carried out, tert-alkyl and benzylic groups have significantly higher gas phase barriers to migration than for other types of alkyl groups, such that for tertiary alkyl groups, oxygen migration of the ethylenedioxy group could compete. The barriers are reduced when a solvent model is included, which reduces the importance of oxygen migration.

Synthesis, local anaesthetic and antiarrhythmic activities of N-alkyl derivatives of proline anilides

We describe here the design, synthesis and evaluation of in vivo local anaesthetic and antiarrhythmic activities of a series of N-alkylproline anilides. Most of the compounds demonstrated surface anaesthetic activity higher than that of lidocaine, ropivacaine and bupivacaine. We established that the local anaesthetic activity was sensitive to structural variations in the substitution pattern at the aromatic ring and the type of alkyl group at the proline nitrogen atom. Some of the prepared N-alkylproline anilides possessed significant antiarrhythmic activity with higher therapeutic indexes than the reference drugs.

Shear behaviour of polyalkylmethacrylate solutions under thin film lubrication

Film-forming properties and traction were determined for the oils containing polyalkylmethacrylates (PAMAs) under a temperature of 40 °C and a rolling speed between 0.001 and 1 m/s with the disc-on-roller tester. Oil film thickness measurements were made under a pure rolling condition and traction measurements were made under the slide/roll ratio of 50 per cent. All the copolymers were synthesized in the base oil by a random copolymerization method. Difference in oil film thickness between polymer solutions became significant under the rolling speed below 0.1 m/s. Among non-functionalized homopolymers, PAMAs with branched alkyl group were superior to those with linear alkyl group in film-forming performance. In functionalized PAMAs, film-forming performance was affected by the functional group as well as the coexisting alkyl group. High-mole-concentration of functional group produced a greater oil film thickness than the corresponding low-mole-concentration PAMAs. This tendency was more marked for high-molecular-weight PAMAs. Among all the polymer solutions, high-molecular-weight PAMA with methyl group as a main component showed the thickest oil film, followed by high-molecular-weight PAMA containing branched alkyl group and dimethylaminoethyl group. In the low speeds of the traction–speed curves, most PAMA solutions showed the effect of friction reduction, whose extent depended upon the type of alkyl group and functional group. It was inferred that the friction behaviour in the partial elastohydrodynamic lubrication (EHL) regime was considerably affected by the friction in the thin film lubrication based on the mutual interaction between polymer molecules.

Highly ordered bilayer structures of gold(I)–alkanethiolates having two types of alkyl groups

The luminescent gold(I)–alkanethiolates containing two types of alkyl groups, Au(I)–(SR) x (SR′) y s, were synthesized by mixing HAuCl 4 with two n-alkanethiols in tetrahydrofuran. Au(I)–(SR) x (SR′) y s have highly ordered bilayer structures and the dominant conformations of the alkyl groups were found to be all-trans from X-ray diffraction and FT-IR spectroscopy studies. The gold nanoparticles stabilized by two types of alkanethiolates could be prepared by reducing the Au(I)–(SR) x (SR′) y s using tetrabutylammonium borohydride (TBABH) as a reducing agent. Elemental analysis results of Au(I)–(SR) x (SR′) y s and gold nanoparticles prepared from Au(I)–(SR) x (SR′) y s indicated that the longer alkanethiols are more reactive for the formation of Au(I)–(SR) x (SR′) y s and also the longer alkylthiolates are preferentially absorbed on the gold particles compared with the shorter ones.

Helix‐Sense‐Selective Polymerization of Achiral Bis(hydroxymethyl)phenylacetylenes Bearing Alkyl Groups of Different Lengths

Abstract4‐Alkyloxy‐3,5‐bis(hydroxymethyl)phenylacetylenes with eight types of alkyl groups were synthesized and polymerized with a chiral catalytic system. We found that the length of the alkyl groups played a very important role in achieving helix‐sense‐selective polymerization. Five helix‐sense‐selective polymerizations were achieved resulting in polymers with alkyl groups whose chain length was longer than six. We think that the longer‐chain alkyl groups prevented the polymers from becoming insoluble by forming intermolecular hydrogen bonds between the hydroxyl groups, and stabilized their one‐handed helical structure by promoting the formation of intramolecular hydrogen bonds.magnified image

A 31P CP/MAS NMR study of PbS surface [formula omitted]-dialkyldithiophosphate lead(II) complexes

31P CP/MAS NMR spectroscopy was used to study the adsorption of six different O , O ′ -dialkyldithiophosphate ions on the surface of synthetic galena (PbS). The 31P CP/MAS NMR spectra of the surface lead(II) dithiophosphates were compared with the 31P CP/MAS NMR spectra of polycrystalline lead(II) dithiophosphate complexes of the same ligands. Surface complexation of the dialkyldithiophosphate ions was established on the surface of PbS. A terminal S , S ′ -chelating coordination is suggested for the surface complexes. The bulkier alkyl groups lead to surface precipitation in addition to the surface adsorption. Derivatives of monothiophosphoric and phosphoric acids were displayed as hydrolysis products of dialkyldithiophosphates on the synthetic PbS, the amount of which depends on the type of alkyl group.

Investigation of Tribochemical Reactions by Organic Sulfides on Nascent Metal Surfaces

Under conditions of boundary lubrication, there is direct contact and surface films such as metal oxides and organic contaminants are mechanically removed by mechanical contacts. This causes to form a chemically active nascent surface. It is essential to understand the reaction between lubricant additives and the nascent metal surface. In this research, the well known organic sulfides were selected as the model compounds of extreme pressure additives (EP additives). The catalytic effect of a nascent metal surface without thermal effect was studied using cutting method with a ceramic tip and the reaction was monitored with a quadrupole mass spectrometer. The main result is that the type of alkyl group and the number of sulfur atoms in the central chain (for instance, mono-sulfide or disulfide) have a strong influence on the adsorption and reaction of the sulfide compounds.

Thermodynamic study of N-trifluoroacetyl-O-alkyl nipecotic acid ester enantiomers on diluted permethylated β-cyclodextrin stationary phase

Thermodynamic studies were performed on 12 pairs of N-trifluoroacetyl-O-alkyl nipecotic acid ester enantiomers on diluted permethylated beta-cyclodextrin stationary phase (CP Chirasil-Dex CB). The influence of ester alkyl group structure on interaction with permethylated beta-cyclodextrin (Me-CD) and enantioselectivity was studied. The types of alkyl groups studied included n-alkyl (C1-C5) and groups containing branching at differing locations relative to the chiral center of the molecule. The results show that for a given molecular weight, the n-alkyl esters have stronger interactions with Me-CD than esters containing branched alkyl groups. However, although having weaker interactions with Me-CD, esters containing alpha-branched alkyl groups exhibit higher enantioselectivity than the corresponding n-alkyl or beta-branched isobutyl esters. From the retention data, thermodynamic parameters were estimated using the retention increment method and enthalpy-entropy compensation plots (ln R' versus deltaH) were constructed. The results suggest that ester enantiomers with branching at the alpha-carbon of the ester alkyl group have additional and/or different types of enantioselective interactions with Me-CD than the C1-C5 n-alkyl esters or beta-branched isobutyl ester. In order to obtain a qualitative sense of the interaction with Me-CD, structures of the diastereomeric complexes formed between Me-CD and some of the ester enantiomers were modeled using simulated annealing molecular dynamics.

The properties of epoxy-imide resin cured by phosphorylated diamines containing different alkyl groups on phosphorus

Cured networks of epoxy–imide resin cured with four types of phosphorylated diamine curing agents that contained different alkyl groups on phosphorus were studied. The structures of these novel phosphorus-containing curing agents were confirmed by Mass, EA, IR, and 1H-NMR and 13C-NMR spectra characterization. The reactivities were measured by differential scanning calorimetry (DSC). It is found that the reactivities were not affected by the types of alkyl groups in the curing agents. In thermal gravimetric analysis (TGA), those polymers that were obtained through the curing reactions between epoxy–imide resin and four curing agents (BAMP, BAEP, BAPP, and BABP) also demonstrated excellent thermal properties as well as a high char yield. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 141–147, 2002

Effects of Nonionic Surfactants on Oxide-to-Polysilicon Selectivity during Chemical Mechanical Polishing

The effects of surfactants on oxide-to-polysilicon selectivity during chemical mechanical polishing have been investigated. Slurries with nonionic surfactants such as Brij surfactants, polyethylene oxide (PEO), and ethylene oxide-propylene oxide-ethylene oxide triblock copolymer enhanced oxide-to-polysilicon polishing selectivity. Although a current conventional oxide slurry has a low oxide-to-polysilicon selectivity of 0.5:1, slurries with nonionic surfactants show a higher selectivity due to a combined effect of adsorption and interfacial adhesion of added nonionic surfactant molecules on the polysilicon surface. The oxide-to-polysilicon selectivity of the Brij surfactant added slurry displayed a stronger dependency on the hydrophile-lipophile-balance (HLB) value than the type of alkyl group or the chain length of surfactants. Especially, Brij52 with low HLB value gave an oxide-to-polysilicon selectivity of 9.3, which is 17 times higher than the selectivity of a commercial oxide slurry. A high molecular weight polymeric surfactant such as PEO also gave a greater selectivity than a low molecular weight surfactant. In addition, slurries with nonionic surfactants reduce the final thickness variation effectively in damascene structure having a polysilicon stopping layer. The final thickness variation polished with the Brij52 added slurry was decreased to one fourth of that with the conventional oxide slurry only. © 2002 The Electrochemical Society. All rights reserved.

The influence of polychromatic UV-irradiation on new thiophene copolymers

Abstract Three new thiophene-based copolymers, characterising the electrical conductivity and photosensitivity, were obtained in a four-step reaction. The acrylic or methacrylic substituents as well as nonyl or pentyl side groups were incorporated into thiophene rings. All thiophene copolymers were then exposed to UV-irradiation in air atmosphere and in room temperature using polychromatic high-pressure mercury lamp. The process of photooxidative degradation was monitored by FT-IR and UV–VIS spectroscopy. It was found that these polymers undergo chain scission, oxidation and decomposition in side groups with different efficiency. The decrease of conjugated double bonds amount, influencing the conducting properties, was also observed. It was concluded that copolymer containing methacrylic substituent was less photostable than that with acrylic one. The type of alkyl group (pentyl or nonyl) in copolymers has no significant influence on their photodegradation.

Preparation and properties of silica films with higher-alkyl groups

Silica films with various types of alkyl groups were grown from the liquid phase, at room temperature, using alkyl tri-alkoxy silane compounds. From Fourier transform infrared (FTIR) absorption measurements, a majority of Si-alkyl bonds in the source molecules were found to remain in the grown film, while Si-alkoxy bonds were completely removed. Electrical and thermal properties have been measured comparatively for various films having dense alkyl groups. The films with the methyl group are promising for silicon production in ultra large-scale integrated circuits (Si-ULSIs) and the film having the vinyl group for non-heat-tolerant compound-semiconductor large-scale integrated circuits (LSIs).

Oxidative polymerization ofp-alkylphenols catalyzed by horseradish peroxidase

Enzymatic oxidative polymerization of p-alkylphenols using horseradish peroxidase as catalyst has been carried out in two polymerization solvent systems: a mixture of phosphate buffer (pH 7) and 1,4-dioxane, and a reverse micellar solution, yielding powdery polymeric materials. The polymer yield was much dependent upon the type of alkyl group in the monomer as well as the solvent type. In case of the polymerization of umbranched alkylphenols in the aqueous 1,4-dioxane, the polymer yield increased with increasing chain length of the alkyl group from 1 to 5, and the yield of the polymer from hexyl or heptylphenol was almost the same as that of the pentyl derivative. The relationship between the type of substituent and the polymer yield in the reverse micellar system was different from that in the aqueous 1,4-dioxane; the highest yield was achieved from ethylphenol. The resulting polymers had molecular weight of several thousands. The polymer was estimated to be composed from a mixture of phenylene and oxyphenylene units from IR analyses. TG measurement exhibited that the polymer had relatively high thermal stability. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1453–1459, 1997

Soluble polymer‐supported catalysts containing pendant quaternary onium salts for the addition reaction of oxiranes with carbon dioxide

AbstractThe addition reaction of oxiranes (15a‐d) with carbon dioxide (CO2) was carried out using 1 mol % of soluble polymer‐supported quaternary onium salts as catalysts under atmospheric pressure. The reaction of 15a‐d with CO2 proceeded very smoothly to give the corresponding five‐membered cyclic carbonates (16a‐d) in high yields at 90‐100°C. The catalytic activity of the soluble polymer‐supported quaternary onium salts was strongly affected by the following factors: kind of reaction solvent, degree of introduction of the pendant onium salt residues in the polymer chain, and type of alkyl group on the onium salts due to the balance between lipophilicity and steric hindrance of the onium salt residue. Furthermore, these soluble polymer‐supported quaternary onium salts were found ordinarily to have higher catalytic activity than low molecular weight quaternary onium salts under the same reaction conditions. It was also found that the rate of reaction was proportional both to catalyst concentration and to oxirane concentration. © 1995 John Wiley & Sons, Inc.

Electrochemical behaviour of ( N-R-4-cyanopyridinium)pentaammineruthenium(II) derivatives in acidic medium. Hydrolysis of coordinated nitriles

The electrochemical behaviour of N-R-4-cyanopyridinium (4-rcp) (R = methyl, decyl, dodecyl, or benzyl) coordinated to pentaammineruthenium(II) in CF 3COOH-CF 3COONa (μ = 0.1 M, pH 3) aqueous medium was studied by means of cyclic voltammetry and constant potential electrolysis. The electrochemical oxidation of the metallic centre ( E p ca 0.51 V/SCE) can be described as a reversible monoelectronic charge-transfer followed by an irreversible chemical reaction, which is the hydrolysis of N-R-4-cyanopyridiniumpentaammineruthenium(III) ( A) to N-R-4-carboxamidepyridiniumruthenium (III) ( B) with the k f1 values depending on the type of alkyl group. The E 1 2 values are not significantly influenced by the nature of the alkyl group. At more negative potential ( ca −0.5 V/SCE), B undergoes an electrochemical reduction followed by an aquation reaction to produce aquopentaammineruthenium(II) and free N-R-4-carboxamidepyridinium. The amide was identified by comparison of its cyclic voltammogram and UV-vis spectrum with that of a sample prepared by chemical reaction. The results were also discussed by comparison with other systems, and show that nitrile-amide conversion catalysed by pentaammineruthenium(II) complexes is possible.

Steric effects of alkyl groups: A ‘cone angle’ approach

AbstractA ‘cone angle’, θR, is defined for an alkyl group (R), which is proposed as a measure of the steric effect exerted by the group. The θR values for some 57 groups have been calculated mathematically by constructing the corresponding Corey—Pauling—Koltun molecular models. The variation in θR with the bulk of a group is satisfactory. However not all types of alkyl groups can be accommodated in this cone angle approach. In the case of the groups for which the cone angle can be measured, correspondences between θR and the two existing steric parameters (Taft's Es scale and Dubois' E′s scale) have been established. For some 23 alkyl groups θR has been used to explain the variation in the rate constant of the base‐catalysed hydrolysis of RCOOEt with the nature of R. Our studies independently substantiate the basic assumptions of the Taft—Ingold hypothesis that, while the base‐catalysed ester hydrolysis is mostly controlled by the steric and electronic effects of the R group, the acid‐catalysed one is controlled almost solely be the steric effect.

Zirconium oxides formed by hydrolytic condensation of alkoxides and parameters that affect their morphology

When zirconium oxides are formed via hydrolytic condensation of zirconium alkoxides, the particle size and morphology of the resultant zirconia is strongly affected by certain parameters during the condensation. These parameters include: the type of alkyl group in the alkoxide, water/alkoxide ratio, molecular separation of species, and the reaction temperature. The particle size and the morphology in turn affect the sintering behaviour and crystalline transformation of ZrO2, In this work the parameters that affect the formation of ZrO2 from zirconium alkoxides are investigated. It has been shown that the alkyl groups and molecular separations during the hydrolytic polycondensation have particular significance in the modification of monoclinic → tetragonal transformation of the resultant ZrO2. Tetragonal phase can also be stabilized by copolymerization of ZrO2 with SiO2 producing tough ceramic materials.

Surface free energy of poly(vinyl alcohol) modified with alkyl groups

The dispersive component of surface free energy γ S d and the nondispersive interactions with polar liquids I SW were determined for poly(vinyl alcohol) (PVA) copolymers having various types of alkyl groups, i.e., four kinds of partly alkyl acetalized PVA's (AIPVA), butyl vinyl ether — vinyl alcohol copolymers (BuVA), ethylene — vinyl alcohol copolymers (EtVA) and BuPVAPVA mixtures. γ S d and I SW were estimated from the measurements of contact angles by means of a two-liquid method proposed by Matsunaga and Ikada. γ S d and I SW for AIPVA, which were smaller than those for PVA itself, decreased with increases in either content or chain-length of the alkyl side group, while γ S d for EtVA was virtually independent of ethylene content. The dependences of γ S d and I SW on the alkyl side chain content per vinyl repeating unit for BuPVA were smaller than those for BuVA. The result for the polymer blends of PVA and BuPVA showed that both γ S d and I SW fell rapidly even at very small addition of BuPVA. The surface free energy γ S (= γ post|staggered|S d + γ S d) was found to decrease with increasing alkyl group content except for EtVA.