Acid Chloride Groups Research Articles

Composite nanofiltration membranes prepared by interfacial polymerization with natural material tannic acid and trimesoyl chloride

Natural material tannic acid was first selected as polyphenol monomer to fabricate the novel composite nanofitration membranes. There was chemical cross-linking reaction took place between the phenol groups of tannic acid and acyl chloride groups of trimesoyl chloride (TMC) in the water/oil interfacial zone. The polyester thin layers from tannic acid and TMC interfacial polymerization on porous ultrafiltration membrane support were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and water contact angle measurement. The effects of post treatment temperature and reaction time, and monomer concentrations in aqueous and organic solutions on water permeability, and rejection of dyes and inorganic salts of the nanofiltration membranes were studied, respectively. Tannic acid and TMC composite nanofiltration membranes had low flux decline ratios and high flux recovery ratios without chemical cleaning in the antifouling evaluation experiments. The excellent antifouling properties and chemical stability of tannic acid and TMC composite nanofiltration membranes made them have potential uses in wastewater treatment.

Synthesis and Reactivity of Mono‐, Di‐, and, Triiron Selenocarboxylate Complexes

AbstractTreatment of the iron selenide (μ‐Se)[CpFe(CO)2]2 with one equivalent of 1, 3, 5‐C6H3(COCl)3 gave the organoiron selenocarboxylate complex CpFe(CO)2SeCO‐3, 5‐C6H3(COCl)2 (1), which contains two free acid chloride groups. Complex 1 reacted with amines, thiols, and phenols to produce the corresponding amides CpFe(CO)2SeCO‐3, 5‐C6H3(CONR2)2 (2), thioesters CpFe(CO)2SeCO‐3, 5‐C6H3(COSR)2(3), and aromatic esters CpFe(CO)2SeCO‐3, 5‐C6H3(CO2Ar)2 (4), respectively. Complex 1 was converted into the diacid CpFe(CO)2SeCO‐3, 5‐C6H3(COOH)2 (5) or the diamide CpFe(CO)2SeCO‐3, 5‐C6H3(CONH2)2 (6) complexes by reactions with NaOH or NaNH2, respectively. The bis(seleno)‐1, 3‐(CpFe(CO)2SeCO)2‐5‐C6H3(COCl) (7) and tris(seleno)‐carboxylate 1, 3, 5‐(CpFe(CO)2SeCO)3C6H3 (8) complexes were also prepared by controlled reaction of 1, 3, 5‐C6H3(COCl)3 with the iron selenide (μ‐Se)[CpFe(CO)2]2. Complexes 1–8 were characterized by spectroscopic techniques (IR, 1H‐NMR) and by elemental analysis as well. The X‐ray structures of CpFe(CO)2SeCO‐3, 5‐C6H3(COCl)2 (1) and CpFe(CO)2SeCO‐3, 5‐C6H3(COSCH2Ph)2 (3b) were determined.

Fabrication of Conducting Poly(3-thiophene boronic acid)-Grafted Multi-Walled Carbon Nanotubes by Oxidative Polymerization

Composite materials of multi-walled carbon nanotubes (MWNTs) and a conducting polymer, poly(3-thiophene boronic acid) (PTBA) were prepared by in-situ oxidative polymerization of TBA in the presence of MWNTs and potassium dichromate. The MWNTs which were previously surface functionalized with acid chloride groups were reacted with TBA using a simple "chemical grafting" technique. It was observed that the nanotubes were dispersed uniformly in the pi-conjugated polymer matrix and entrapped by the polymer. The conductivity of the composites was higher than that of the pure polymer from a conventional four-probe technique, which indicates that the fabrication of MWNTs into the polymer matrix significantly improves the conductivity of the polymer due to the intrinsic properties of MWNTs.

POCl3-mediated H-bonding-directed one-pot synthesis of macrocyclic pentamers, strained hexamers and highly strained heptamers

Previously we have shown that POCl3-mediated H-bonding-directed one-pot macrocyclization allows for the highly selective preparation of five-residue macrocycles as the predominant product with low yields of hexamers and an undetectable occurrence of both tetramers and heptamers. Replacing the interiorly arrayed methyl groups with ethyl groups in these 4–7 residue macrocycles alters the relative stability order among them. Specifically, ethoxy-substituted six-residue macrocycle, rather than pentamer, turns out to be computationally the most stable, suggesting that ethoxy-containing hexamer possibly can be formed as the major product under suitable conditions. We have investigated this possibility by varying reaction temperatures and concentrations, invariably affording pentamer as the major macrocycle with strained circular hexamers and highly strained circular heptamers produced in substantial amounts. This discrepancy can be reasonably explained on the basis of bimolecular reactions between two oligomers higher than monomers via kinetic simulations. In this scenario, the acyclic pentamer is kinetically “trapped” to undergo an intramolecular cyclization to yield circular pentamer, rather than to produce acyclic hexamer. As a result, acyclic hexamer precursor is generated largely from sterically demanding bimolecular reactions between a dimer and a tetramer, or between two trimers that are kinetically slower than the pentamer-producing chain-growth reactions. We additionally found that one-pot macrocyclization proceeds to the largest extent at 40 °C, an intriguing finding that highlights the low reactivities of acid chloride and amine groups in these H-bond-enforced acyclic oligomeric intermediates.

Syntheses and reactivities of non-symmetrical “active ester” bi-dentate cross-linking reagents having a phthalimidoyl and acid chloride, 2-benzothiazole, or 1-benzotriazole group

We have newly synthesized the non-symmetrical "phthalimidoyl active ester" bi-dentate cross-linking reagents having an acid chloride, 2-benzothiazole, or 1-benzotriazole group (i.e., 9, 15, and 16) on the basis of the reactivity study of the "active ester" model compounds, 11-14, toward the various nucleophiles and examined their reaction selectivity towards the same nucleophiles. Then, we applied for the modification of cholesterol at the more reactive site of the bi-dentate linkers to give 3β-cholesteryl 4-(phthalimidoyloxycarbonyl)butyrate (39), and the subsequent reaction of 39 with several amines, such as benzylamine, 4-chlorobenzylamine, 2-phenylethylamine, L-phenylalanine methyl ester, or diphenylalanine benzyl ester as a protein model of the cholesterol antigen.

Study on a novel polyester composite nanofiltration membrane by interfacial polymerization. II. The role of lithium bromide in the performance and formation of composite membrane

Composite membranes were prepared by interfacial polymerization of trimesoyl chloride (TMC) with (i) triethanolamine (TEOA), and (ii) N-methyl-diethanolamine (MDEOA) on addition of various contents of LiBr in aqueous phase. The influence of LiBr in aqueous phase on the composite membrane performance and surface morphologies was investigated. For monomer TEOA, the pure water flux of composite membrane enhanced as the LiBr content increased and it reached a maximum at 3% of LiBr, then decreased. However, the extreme value of the salt rejection functioned with the content of LiBr changed to 1% (a turning point), at which the membrane displayed a lowest salt rejection. The change in performance of the composite membrane with the content of LiBr was due to the competition of two factors. One was the interaction of Li + ion with the hydroxyl oxygen atom of alcohol amine, which could induce an increase in the density and reactivity of OH groups in the aqueous phase, forming a dense skin layer of the composite membrane as a result. The other factor was the complexation of Li + ion with the carbonyl in TMC, causing the acid chloride group of TMC preferring to hydrolyze which could induce to construct a hydrophilic and loose surface layer. The role of LiBr in the formation of the composite membrane was further testified by investigating another monomer MDEOA. The analysis of the composite membrane formation in the presence of LiBr was validated by reaction coefficient, contact angle, streaming potential, SEM, and AFM.

Reactions of nonsymmetrical bidentate linkers having a phthalimidoyl and acid chloride group or a 2-benzothiazole group with α- d-glucoside derivatives and their application for the modification of cellulose

The reaction of ‘active ester’ bidentate cross-linking reagents, phthalimido 4-chloroformylbutanoate ( 1) and phthalimido 4-(2-benzothiazolyloxycarbonyl)butanoate ( 2) with several protected d-glucose derivatives is described. These reactions are used to introduce the reactive group into cellulose (filter paper) with the aim of linking proteins and cellulose.

Synthesis and characterization of graft copolymers based on poly(p-phenylene terephthalamide) backbone and well-defined polystyrene side chains

A novel dualfunctional monomer, 2-(2′,2′,6′,6′-tetramethyl-piperidinyl-1′-oxy)methylbenzene-1,4-dioyl chloride hydrochloride, with two acid chloride groups for step-growth polymerization and a nitroxide group for the mediation of living radical polymerization was synthesized. It was first copolymerized with terephthaloyl chloride and p-phenylenediamine at a feed molar ratio of 1:3:4 in N-methyl-2-pyrrolidone containing 10 wt% calcium chloride at −10°C to yield a poly(p-phenylene terephthalamide) based macroinitiator, which initiated radical polymerization of styrene at 125°C to obtain a series of poly(p-phenylene terephthalamide)-g-polystyrenes. A combinatory analysis of proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, elementary analysis, thermogravimetry and gel permeation chromatography indicated that the macroinitiator induced the radical polymerization of styrene to proceed in a well-controlled way. The molecular weight of side-chains increased with an increase of monomer conversion, and the molecular weight distribution index remained lower than 1.5. The graft copolymers showed a remarkably improved solubility in N-methyl-2-pyrrolidone and much depressed crystallinity in bulk.

Chemical transformations of poly(arylene ether ketones) containing side functional groups

Conditions for chemical transformations of poly(arylene ether ketones) containing side carboxyl and phthalimidine functional groups have been investigated. The reason why the chemical modification of poly(arylene ether ketones) with side acid chloride groups leads in some cases to the formation of insoluble products is established. Ionogenic and comb-shaped poly(arylene ether ketones) with hydrophobic fragments in side branches are obtained through chemical transformations of previously synthesized polymers containing side carboxyl, hydroxyl (alcohol), and phthalimidine groups. The properties of poly(arylene ether ketones) can be varied in a wide range via chemical reactions of side reactive groups.

Chemically modified porous silicon for laser desorption/ionization mass spectrometry of ionic dyes

Desorption/ionization on silicon (DIOS) mass spectra of model ionic dyes methylene blue (MB+Cl-) and methyl orange (Na+MO-) were studied using p+ type-derived porous silicon (PS) free layers. As-prepared PS (PS-H), the PS thermally oxidized at 300 degrees C (PS-OX), PS with chemically grafted cation-exchanging alkylsulfonic acid (PS-SO(3)H) and anion-exchanging propyl-octadecyldimethylammonium chloride (PS-ODMA+Cl-) groups was tested as ionization platforms. Two mechanisms of the methylene blue desorption/ionization were found: (1) the formation of [MB + H]+* ion due to the reduction/protonation of MB+, which is predominant for PS-H and PS-OX platforms and (2) direct thermal desorption of the MB+ cation, prevailing for PS-SO3H. The fragmentation of the cation is significantly suppressed in the latter case. The samples of PS-SO3H and PS-ODMA+ Cl- efficiently adsorb the dyes of the opposite charge from their solutions via the ion-exchange. Consequent DIOS MS studies allow to detect only low fragmented ions (MB+ and MO-, respectively), demonstrating the potential of the ion-exchange adsorption combined with DIOS MS for the analysis of ionic organic compounds in solutions.

Fabrication of patterned single-walled carbon nanotube films using electrophoretic deposition

Thin films of chemically functionalized single-walled carbon nanotubes (SWNTs) were fabricated by using a direct current (dc) electrophoretic deposition method. SWNTs were shortened and then functionalized with acid chloride group to combine with the amine group-terminated gold substrate. Silica nanospheres with a diameter of about 190 nm were arrayed on gold substrate to pattern a thin SWNT film. Periodically patterned SWNT film was eventually produced and would be used in potential applications like electron emitters and large surface area electrodes.

Study on the Functionalization of Multi‐Walled Carbon Nanotube with Monoamine Terminated Poly(ethylene oxide)

AbstractThrough the introduction of carboxylic acid or thionyl chloride groups in multi‐walled carbon nanotubes (MWNT‐COOH or MWNT‐COCl) and amine group in poly(ethylene oxide) (PEO‐NH2), complexation of MWNT with PEO was successfully performed, yielding MWNT/PEO complex having approximately 40 wt.% of PEO. The MWNT/PEO complexes exhibited excellent dispersibility in solvents including water, ethanol and DMF. From SEM observation, the increases in the diameter of the nanotubes were observed. The presence of PEO on the nanotube surface was also confirmed through EDX and FT‐IR. The effects of different functionality on MWNTs (COOH vs. COCl) and different molecular weight of PEOs (1000 g/mol vs. 2000 g/mol) were not so prominent.

Photochemical Grafting and Activation of Organic Layers on Glassy Carbon and Pyrolyzed Photoresist Films

Organic films have been grafted to polished glassy carbon (GC) and as-prepared pyrolyzed photoresist film (PPF) by photolysis of alkenes and an alkyne. The alkene or alkyne is spin-coated onto the carbon surface and photolyzed in air at 254 nm. Characterization by water contact angle measurements, depth profiling and surface roughness measurements using atomic force microscopy (AFM), and electrochemistry reveal that for most modifiers a loosely packed monolayer is grafted to the surface. Grafted layers of 1-decene were further reacted by drop-coating with oxalyl chloride and photolyzing at 254 nm in air. The procedure adds acid chloride groups to the film. Amines were attached to these films via amide bond formation, and were characterized by electrochemistry and assembly of citrate-capped gold nanoparticles. Amines were also coupled to photografted 1-undecylenic acid layers and to carboxyphenyl layers prepared by electroreduction of the corresponding diazonium salt. Quantitative analysis using electrochemistry established that the highest concentration of amines was attached to the oxalyl chloride treated film, and that a higher concentration of amines was attached via reaction with the photografted 1-undecylenic acid layer than the electrografted carboxyphenyl layer. Thus photografting and photoreaction with oxalyl chloride are simple methods for generating amine-reactive tethers on GC and PPF surfaces.

Graft polymerization of styrene initiated by covalently bonded peroxide groups on silica

The graft polymerization of styrene initiated by immobilized peroxide groups was investigated. Three different types of modification reactions were used to introduce peroxide groups which are directly attached onto the surface of two different silica supports. Silanol groups were chlorinated using thionyl chloride or tetrachlorosilane. In another reaction pathway 1,3,5-benzenetricarbonyl chloride enabled the introduction of free acid chloride residues bonded onto the surface of silica. tert-Butyl hydroperoxide (TBHP) was used to transform the chlorosilyl and the acid chloride groups into peroxide residues. In a further reaction step the covalently bonded peroxides initiated the polymerization of styrene to form grafted polystyrene directly attached onto the silica support. Solid-state 13C CP/MAS NMR spectroscopy, and thermogravimetric and scanning electron microscope measurements enabled a clear structure and property elucidation of the different bonded phases. The highest amount of grafted polystyrene was achieved employing the acid chloride synthesis pathway with silica–gel, whereas modification of spherical silica only led to minor amounts of grafted polymer. The results contribute to the evolving need to understand particle surface modifications and may have positive impact on development of new HPLC stationary phases for improved elutant resolution.

α-Amylase immobilization on functionalized glass beads by covalent attachment

In this study, α-amylase was covalently immobilized onto phthaloyl chloride-containing amino group functionalized glass beads. In this procedure, amide bonds were formed between amino groups on the protein and acid chloride groups on the glass surface. The surface modified beads were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersion spectrum (EDS) and UV–Vis spectroscopy. Immobilization was successfully performed under very mild conditions (15 °C, 4 h). The amount of covalently bound α-amylase was found 25.2 ± 3.1 mg/g glass support. The optimum pH value for the free amylase was at pH 6.5. The optimum pH of the immobilized enzyme was shifted 1.0 pH unit to the acidic region. The immobilized α-amylase exhibited better thermostability than the free one. The free enzyme lost all its activity with in 15 days. Covalently bound amylase was stable up to 5 days and lost only 20% of activity in 25 days. The covalently bound enzyme demonstrated more than 98% activity after 6 runs and 81.4% activity after 25 runs.

PH-Responsive Random Copolymer Films with Amine Side Chains

We have designed pH-responsive copolymer films that consist of polymethylene (PM) with dilute randomly distributed side chains terminated with dimethylamine groups. The films are grown on gold surfaces by (1) exposure to an ether solution of diazomethane and ethyl diazoacetate to produce a random copolymer Au-[(CH2)A-(CHCO2Et)B] (denoted as PM-CO2Et, A ≫ B), (2) hydrolysis of the ester groups to carboxylic acids (PM-CO2H), (3) complete conversion of the acids to acid chlorides (PM-COCl), and (4) quantitative reaction of the acid chlorides with N,N-dimethylethylenediamine (DMEDA) to yield a film (PM-CONHR, R represents −-CH2CH2N(CH3)2) with amide-linked, amine-terminated side groups that are pH active. The effect of polymer composition on pH response was investigated by electrochemical impedance spectroscopy (EIS). PM-CONHR films are more hydrophilic in their uncharged state than PM-CO2H films and thereby exhibit lower resistance against ion transfer. When the pH is decreased, the amine groups become protonated or charged, dramatically increasing their hydrophilicity and reducing the resistance of the film against ion transfer by around 2 orders of magnitude over the pH range of 7 to 4. In contrast, PM-CO2H films become protonated or neutralized as the pH is decreased and exhibit a 5 order of magnitude increase in resistance over a similar range of pH. The hydrophobicity of the PM-CONHR films can be enhanced by capping the acid chloride groups with a mixture of DMEDA and n-butylamine to yield a film with some pH inert groups that boost film resistance in the uncharged state and increase the magnitude of the change in film resistance. The resistance of the film against ion transfer correlates well with the hydrophobicity of its dilute side chain component, as quantified by the octanol−water partition coefficient (Kow).

Characteristics of Electrodeposited Single-Walled Carbon Nanotube Films

Thin films of chemically-functionalized single walled carbon nanotubes (SWNTs) were fabricated by using a direct current (DC) electrodeposition method. SWNTs were shortened and then functionalized with acid chloride group to combine with amine group-terminated gold substrate. The electrodeposited SWNT films were characterized by using Raman spectroscopy, attenuated total reflectance infrared (ATR/IR) spectrometry and atomic force microscopy. We demonstrated that the SWNT film was well distributed on an electrode with robust adhesion.

On SOCl 2 hydrolysis at carbon nanotubes

The experimentally observed oxygen content increase in SOCl 2 treated single-wall carbon nanotubes (SWCNTs) may be explained by the air moisture hydrolysis of the acid-chloride groups created at the structure defects as well as of SOCl 2 molecules adsorbed at SWCNT sidewalls. The adsorption of SOCl 2, and its hydrolysis products ( HOSO 2 - , HSO 3 - and SO 2 ) on coronene C 24H 12 as the simple SWCNT model has been studied at B3LYP/6-31+G ∗∗ level of theory (with relevant hydrogen atoms augmented by diffusion functions as well). Whereas the adducts with neutral molecules exhibit weak interactions of sulphur (SOCl 2 and SO 2) or oxygen (SOCl 2) atoms with π electron system of coronene, these interactions with cations are mediated via hydrogen bonds only. The optimal geometries indicate high affinity of all the adsorbed species to the structure defects (edges). The physisorption (especially of SOCl 2 and SO 2) produces a small gap, i.e. a tendency towards metallic character as seen in graphene sheets.

Model studies of SOCl 2 adsorption on carbon nanotubes

The experimentally observed oxygen content increase in SOCl 2 treated single-wall carbon nanotubes (SWCNTs) may be explained by the air moisture hydrolysis of the acid–chloride groups created at the structure defects as well as of SOCl 2 molecules adsorbed at SWCNT sidewalls. The first step of this process, thionylchloride adsorption on pyrene C 16H 10 and coronene C 24H 12 as simple models of the graphene sheet, has been studied at B3LYP/6-31+G** level of theory. The pyrene molecule is too small to be a suitable model for SOCl 2 adsorption. Non-planar thionylchloride molecules are physisorbed preferably with sulphur atoms oriented to the carbon sheet with high affinity to the structure defects (edges). The SOCl 2 physisorption supports the metallic character of graphene sheets.

Liquid/Liquid Interface Polymerized Porphyrin Membranes Displaying Size-Selective Molecular and Ionic Permeability

Thin polymeric membranes have been formed by liquid/liquid interfacial copolymerization of a sterically demanding tetraphenylporphyrin derivative having reactive phenol substituents and a second porphyrin having reactive acid chloride groups. The out-of-plane steric demand is created by 3,5-hexoxyphenyl groups positioned at two of the four meso carbons of the porphyrin ring. The bulky substituents were designed to create local pockets and extended pores within the resulting ester-linked copolymer. Quantitative measures of molecular and ionic transport were obtained by placing membranes over microelectrodes and recording voltammetric responses from redox-active probes. The membranes were found to be permeable to small molecules and ions, but blocking toward larger ones, displaying a sharp size cutoff at a probe diameter of ca. 3.5 A. Molecular transport can be modulated by axially ligating pore-blocking moieties to available porphyrin metal centers.