Acyl Chloride Groups Research Articles

Effect of acyl chloride functionalized carbon black on mechanical and thermal properties of acrylonitrile butadiene styrene/polyaniline blend

Pristine Carbon Black (CB) has been first oxidised to introduce carboxylic acid functional group on the surface of CB, followed by treating with thionyl chloride. The presence of acyl chloride group in the resultant product has been ascertained by FTIR spectroscopy. The acyl chloride functionalized CB (CB-Ac) has been used as a filler in Acrylonitrile Butadiene Styrene (ABS)/Polyaniline (PANI) blend to improve the mechanical and thermal properties. Further addition of Nanoclay (NC) in the blend has improved the dispersion of fillers in the polymer matrix as confirmed by FESEM images and XRD pattern. The Ultimate Tensile Analysis (UTA) and Dynamic mechanical analysis (DMA) have been studied. The Young modulus has shown increment of 48% and 66% in case of CB-Ac and CB-Ac/NC filled blend, respectively. The ultimate tensile strength has also been found to be increased in CB-Ac and CB-Ac/NC filled blends. DMA has given the insight about the excellent improvement in damping properties of the composites due to filler addition. Themo gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) has been carried out to ascertain the thermal properties. TGA has revealed the excellent augmentation in the flame retardancy and heat resistance of the composites due to CB-Ac/NC loading. DSC study has further verified the improvement in degree of crystallinity due to interfacial attraction between fillers and polymer matrix.

Sugar-based membranes for nanofiltration

Sugar-based nanofiltration membranes were successfully developed through a facile interfacial polymerization reaction. Glucose, maltose and raffinose, representing the most classic mono-, di- and tri-saccharides, were used as the aqueous monomers to react with trimesoyl chloride. Importantly, NaOH was utilized to accelerate the reaction between acyl chloride groups and the lowly active hydroxyl groups, forming a dense polyester separation layer. The optimal sugar-based membrane shows a high water permeance of 33.7 ± 1.4 L m−2 h−1 bar−1 and a Na2SO4 rejection of ~95%, demonstrating the potential of rapid desalination. Systematic characterizations by chemical analyses and optical microscopy were carried out. The results revealed that the high separation performance of the sugar-based membrane mainly benefited from its negatively charged, hydrophilic surface and super thin polyester layer. Considering the sustainable and green nature of saccharides, the sugar-based membrane is promising to stand out in the next-generation membrane field. Our findings enlighten the development of sugar as bio-monomer in fabricating high-performance nanofiltration membranes.

Structure adjustment for enhancing the water permeability and separation selectivity of the thin film composite nanofiltration membrane based on a dendritic hyperbranched polymer

In this study, a dendritic amphiphilic hyperbranched polyester acyl chloride (HPE-COCl) with abundant terminal acyl chloride groups was proposed to incorporate into the polyamide skin layer via interfacial polymerization to adjust the structure and the separation performance of the thin film composite (TFC) nanofiltration (NF) membranes. The modified NF membranes based on HPE-COCl exhibit looser, more hydrophilic and negatively charged surface, thereby endowing TFC membranes with relatively higher water permeability and selectivity of monovalent/divalent salts, heavy metals/common monovalent salts, and dyes/common monovalent salts. Especially, the TFC-H2 membrane containing 0.07% w/v HPE-COCl significantly increases the water flux by 145% compared to the pristine membrane. Furthermore, the corresponding selectivity of Fe3+/Na+ increase about 5.09 times. The hypothesis on the basis of experimental results is that the HPE-COCl with alternating hydrophilic and hydrophobic units is prone to form a plurality of hydrophilic channels based on PEG units and hydrophobic microdomains based on benzoate units, which enhances the water permeation through capillary forces. Moreover, the strong negatively charged surface formed by high-density terminal carboxyl groups in HPE-COCl facilitates the passage of monovalent salts and retains the lager-sized heavy metal salts and dyes, thereby improving the selectivity of membranes. Thus, this work provides a new idea and method for the development of high performance nanofiltration membranes.

In-situ coating TiO2 surface by plant-inspired tannic acid for fabrication of thin film nanocomposite nanofiltration membranes toward enhanced separation and antibacterial performance

A major issue hindering development of thin film nanocomposite (TFN) nanofiltration (NF) membrane is the interfacial defects induced by nanomaterial aggregation in top layer. Although various nanomaterials surface modification strategies have been developed to eliminate the interfacial defects, they usually involve extra modification steps and complex post-treatments. Inspired by the substrate-independent coating ability of tannic acid (TA) and the fact that the phenolic hydroxyl groups in TA can react with acyl chloride group in trimesoyl chloride, a TA coating solution containing TiO2 nanoparticles was used as an aqueous phase of interfacial polymerization to prepare interfacial modified TFN NF membranes in this study. Surface modification of TiO2 nanoparticles and interfacial polymerization can be carried out in a single step without any extra pre-modification step. It was found that the TA coating on TiO2 nanoparticles surface could decrease TiO2 aggregations and enhance interfacial compatibility between TiO2 and polyester matrix. The TFN NF membrane prepared at a TiO2 loading of 0.020 wt% exhibited a pure water flux of 28.8 L m-2 h−1 (284% higher than that of the controlled TFC membrane), and possessed enhanced NaCl and Na2SO4 rejections of 57.9% and 94.6%, respectively, breaking through the trade-off between permeability and selectivity.

A novel nanofiltration membrane with [MimAP][Tf2N] ionic liquid for utilization of lithium from brines with high Mg2+/Li+ ratio

In order to utilize lithium from brines with high Mg2+/Li+ ratio, a positively charged nanofiltration (NF) membrane was prepared by grafting amine-functionalized ionic liquid 1-(3-aminopropyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([MimAP][Tf2N]) onto the surface of polyamide (PA) membrane. The effects of [MimAP][Tf2N] contents on the chemical composition, surface morphology, surface charges and separation properties of the modified PA membranes were discussed. The results of chemical composition analyses indicated reaction of the amine group of [MimAP][Tf2N] with the residual acyl chloride groups, which was existed on the surface of the nascent PA membrane. The surfaces of all the modified PA membranes were positively charged at pH = 6.4 due to the quaternary ammonium group of [MimAP][Tf2N]. In the separation process, the resulting membrane presented high water permeance (37.8 L/(m2⋅h)) and mono-/divalent cation selectivity (Li+ and Mg2+) with much higher MgCl2 rejection (83.8%) than LiCl rejection (24.4%). For a simulative brine with a Mg2+/Li+ ratio of 20, the rejections to Mg2+ and Li+ by the optimized membrane (NF-IL-2.0%) were around 81.9% and −45.2%, respectively, where the permeate with the Mg2+/Li+ ratio of 3.5 was obtained and the selectivity (SLi,Mg) was 8.12. Additionally, the optimized membrane exhibited a stable performance for Mg2+/Li+ separation. Therefore, there is a very possibility for utilization of lithium from brine with high Mg2+/Li+ ratio by using the optimized NF membrane.

PH-Responsive Copolymer Films Prepared by Surface-Initiated Polymerization and Simple Modification.

We report the preparation of pH-responsive, ester/carboxylic acid random copolymer films via simple modification of poly(norbornene diacyl chloride) (pNBDAC), prepared via surface-initiated ring-opening metathesis polymerization, with mixtures of water and ethanol to form carboxylic acid and ethyl ester side groups. The pNBDAC film serves as a compositionally versatile platform to controllably obtain copolymers with multiple functionalities. In modifying the pNBDAC to form the copolymer film, ethanol exhibits a significantly higher reactivity with acyl chloride groups within the film than does water. The magnitude and range of the pH-responsive performance are highly dependent on the carboxylic acid content in the copolymer films, which demonstrates the effect of film hydrophilicity on the pH-responsive switching of ionic barrier properties. The resistance of the film against ion transfer can be decreased by a factor of 104 through pH change, demonstrating pH-induced switching from hydrophobic and insulating to swollen and ion-permeable films. The interactions of the copolymer films with water at different pH values were also explored. When the copolymer contains 34% carboxylic acids, a 4× greater film thickness is obtained in high pH solution than in low pH solution due to ionically driven water swelling. The reversibility of the pH-responsive performance of these copolymer films is high based on measurements using quartz crystal microbalance with dissipation (QCM-D).

Surface modification of polyetheretherketone by grafting amino groups to improve its hydrophilicity and cytocompatibility

Although special engineering plastics polyether ether ketone (PEEK) have many excellent properties, its hydrophobicity and biological inertia limit its application in the field of implant materials. In this study, amino modification of PEEK was conducted to endow it with good hydrophilicity and bioactivity. PEEK was sulfonated with concentrated sulfuric acid, and reacted with sulfoxide chloride to obtain aromatic sulfonyl chloride. Finally, amino (–NH2) was introduced onto the surface of PEEK by acylation reaction between acyl chloride group and ethylenediamine (EDA) to improve its hydrophilicity and cell compatibility. The PEEKs before and after modification were characterized by FTIR, XPS and WCA. The cell compatibility was evaluated by human umbilical vein endothelial cells (HUVEC). The results showed that –NH had been successfully introduced onto the surface of PEEK, and the hydrophilicity of the aminated PEEK was significantly improved. Compared with the PEEK before amino modification, the aminated PEEK significantly promoted adhesion and spread of cells, indicating good cell compatibility. This study breaks through the limitations of traditional wet chemical methods and provides a new way for further modification of PEEK.

Metal Chelating Polymer Thin Films by Surface-Initiated ROMP and Modification

We report the surface-initiated ring-opening metathesis polymerization (SiROMP) of hydroxamic acid-containing, metal-chelating polymer thin films. SiROMP of trans-5-norbornene-2,3-dicarbonyl chloride (NBDAC) is introduced as a versatile platform to achieve many functional polymer films via simple exposure of pNBDAC films to reagents. This modification strategy owes its success to the fast and high-yield reaction of acyl chlorides with alcohols, amines, water, and other molecules. The polymerization of NBDAC is performed with monomer in the vapor phase and exhibits rapid kinetics, producing ∼400 nm thick films within 5 min. Because of the high reactivity of the acyl chloride groups in the film, the pNBDAC films are easily modified to produce side chains of carboxylic acids, esters, and amides via the reaction of the acyl group with water, alcohols, and amines, respectively. Exposure of the pNBDAC film to hydroxylamine results in a film with hydroxamic acid functionality that is capable of chelating various metal ions. The chelation process effectively cross-links the polymer chains to greatly improve the thermal and pH stability of the film in solution, elevate resistance against water and ion transfer, and alter the mechanical properties to a more solid-like film.

Tip and Inner Wall Modification of 4.9 nm Diameter Multi-Walled Carbon Nanotubes and Its Nanocomposite Polyamide Reverse Osmosis Membrane.

The tip and inner surface of large diameter multi-walled carbon nanotubes (MWCNTs) (4.9 nm diameter) were functionalized on the tip and inner surface to improve the rate of desalination and maintain high water flux. The modified MWCNTs-doped reverse osmosis membranes were fabricated by interfacial polymerization using trimesoyl chloride (TMC) solution in n-hexane and aqueous solutions of m-phenylenediamine (MPD) containing functionalized MWCNTs. The functionalized MWCNTs were analyzed by X-ray photoelectron spectroscopy (XPS), thermal gravity analysis (TGA), high resolution transmission electron microscopy (HRTEM), UV-Vis spectroscopy and other techniques. The obtained results showed that changes occurred in the structure of the carbon nanotubes with the inner diameter becoming smaller, and the dispersibility and stability were improved. Carboxyl, acyl chloride, amide and amino groups were successfully grafted on the tip and interior of MWCNTs. The surface characteristics of the prepared membranes were studied by scanning electron microscopy (SEM) and contact angle analysis. The desalination performance of the membranes was investigated in terms of water flux and salt rejection. The experimental results revealed that the incorporation of the modified MWCNTs (especially containing hydrophilic groups such as carboxyl groups) into the polyamide layer of RO membranes led to a significantly increase of the water flux and salt rejection.

Surface modified polyamide nanofiltration membranes with high permeability and stability

High performance membranes circumventing the global water scarcity are emerging from exquisite nanofabrication but the materials preparation complexity and permeability stability remain challenges. We report here that both the permeability and antibacterial property of piperzine-trimesoyl chloride (PIP-TMC) polyamide nanofiltration membranes were improved through simple surface modification by a strong electrolyte monomer bearing a multiple of amines and quaternary ammonium (Quaternized diaminoethylpiperzine, QAEP). The new monomer reacts effectively with residual acyl chloride groups on pristine membranes, bringing about the synergy of improved hydrophilicity with surface microstructures that facilitates high way path for transmembrane transportation of water molecules. The PIP-TMC-QAEP membrane exhibit high salt rejection (RNa2SO4 = 97.8%, RMgSO4 = 94.2%), coupled with high permeate flux (96 L m-2 h-1, feed: 1 g L-1 Na2SO4, 6 bar) that is 3 times as high as that of the PIP-TMC membranes. Meanwhile the membrane features a high salt selectivity (30) in processing NaCl/Na2SO4 mixed solution (10 g L-1), coupled with satisfactory performances against fouling and biofouling and elongated continuous operation time (12 days).

High-performance functionalized polymer of intrinsic microporosity (PIM) composite membranes with thin and stable interconnected layer for organic solvent nanofiltration

A novel polymer of intrinsic microporosity, acyl chloride-functionalized polymer of intrinsic microporosity (PIM-COCl), was obtained by hydrolysis under alkaline conditions and acylation in thionyl chloride of PIM-1. PIM-COCl is soluble in common organic solvents, and it is used for the first time for organic solvent nanofiltration (OSN). The acyl chloride groups in PIM-COCl can be further cross-linked with an amine-functionalized polyacrylonitrile (APAN) ultrafiltration membrane to form an interconnected layer, which shrinks pore size and provides better structural stability and selectivity. The PIM-COCl composite membranes exhibit high rejection and alcohol flux during OSN. Compared with the reported PIM OSN membranes, APAN-90-3@PIM-0.1 exhibits higher rejection for crystal violet (408 g mol−1, over 94%) in ethanol and several times higher alcohol flux. The membrane shows outstanding stability in ethanol for 14 days. PIM provides a microporous structure, while the interconnected layer maintains this structure in organic solvents via hydrogen bonding, electrostatic interactions and covalent cross-linking. Other PIMs can readily undergo acyl chloride functionalization, which provides them with high reactivity towards amine groups to form stable interconnected layers. This work offers new strategies for the design and preparation of high performance OSN membranes.

A comprehensive understanding of co-solvent effects on interfacial polymerization: Interaction with trimesoyl chloride

Co-solvent assisted interfacial polymerization (CAIP) has been widely used to increase the water permeability of thin-film composite (TFC) reverse osmosis (RO) membranes. However, its outcomes are often poorly understood or unpredictable. To bridge the gap between conventional wisdom and the real effects of the co-solvent, we report—for the first time, to the best of our knowledge—empirical evidence in terms of the actual interfacial tension between two immiscible solutions used in CAIP. According to our results, dimethyl sulfoxide (DMSO), which is frequently used as a co-solvent, influences IP by interacting with trimesoyl chloride (TMC). The dipole-dipole interaction between DMSO and TMC was estimated to increase the TMC concentration at the interface and, thereby, the reaction rate. Due to the fast reaction, the diffusion barrier forms quickly, reducing the thickness and roughness of the active layer. The cross-linking degree was also determined to decrease due to the incomplete reaction that occurs when one of three acyl chloride groups interacts with Sδ+−Oδ− electrostatic dipoles of DMSO at the interface, as evidenced by the variation in unreacted acyl chloride groups in the active layer and by the nitrogen/oxygen ratio. Such morphological changes were consistent with the trend in the performances of the RO membranes prepared with different amounts of DMSO, and were used to interpret the possible transport phenomena.

Immobilization of MoO2(acac)2 on Multiwall Carbon Nano Tube and Epoxidation of Alkenes

The acidic group (-CO2H) of MultiWall Carbon Nanotube (MWCNT) converted to acyl chloride group (-COCl) producing of MVCNT@COCl. Then the reaction of MVCNT@COCl and MoO2(acac)2 resulted in direct immobilization of the MoO2(acac)2 and the formation of MVCNT@CO(acac)MoO2(acac) catalyst. In addition, the MVCNT@COCl was esterified by NaOC2H5 and formed the esteric MVCNT@COC2H5 reagent. In a subsequent reaction of MVCNT@COC2H5 by ethylene diamine, the MVCNT@CONHCH2CH2NH2 was produced. It was reacted with MoO2(acac)2 and immobilized the MoO2(acac)2 via imine bond formation and produced the MVCNT@CONHCH2CH2N(acac)MoO2(acac) catalyst. The functionalized MVCNT reagents were characterized by FT-IR spectra and elemental analysis. The molybdenum loading on MVCNT was determined by ICP analysis. The catalytic activity of the two molybdenum immobilized catalysts (MVCNT@COMoO2(acac)2 and MVCNT@CONHCH2CH2N(acac)MoO2(acac)) was investigated in the epoxidation of cyclooctene and different reaction parameters such as solvent, oxidant, amount of catalyst and oxidant were optimized and the epoxidation of different alkenes was investigated in these optimized conditions. The obtained results showed that the supported catalysts of MVCNT@CO(acac)MoO2(acac)2 and MVCNT@CONHCH2CH2N(acac)MoO2(acac) were highly active and selective in the epoxidation of a wide range of alkenes. The reusability of the supported catalysts was also studied. The results showed that they had good reusability in the epoxidation of alkenes.

Fabrication and Properties of Nanofiltration Membranes Assembled with Chitosan on Poly(Ether Sulfone) Membranes Surface-Functionalized with Acyl Chloride Groups

Composite membranes with a cross-linked chitosan active layer (CS-membrane) on a poly(ether sulfone) (PES) support layer surface-functionalized with acyl chloride groups were fabricated as nanofilters. The support layers composed of PES and PES functionalized with amine groups (PES-Am) were surface-functionalized with acyl chloride groups (membrane-COCl). The membrane-COCl reacted further with amine groups in chitosan to form CS-membrane. The CS-membrane exhibited increased salt removal rates, antibacterial activity, and a decrease in water flux with increasing PES-Am content up to 20 wt % in the support layer. The CS-membrane formed on the support layers containing 20 wt % PES-Am and a commercial NF membrane showed almost the same MgSO₄ rejection (97.5%), whereas the former had about 1.4 times higher water flux than the latter. Consequently, NF membranes having better water flux, fouling resistance, and antibacterial activity than commercial NF membrane were fabricated without reducing salt rejection by assembling a cross-linked chitosan layer on a PES support layer surface-functionalized with acyl chloride groups.

Amide-based covalent organic frameworks materials for efficient and recyclable removal of heavy metal lead (II)

Covalent organic frameworks (COFs) materials with designed skeleton structure and controlled pore size are a new class of adsorbent materials for environment remediation. Here, we synthesize two amide-based COFs materials via a polymerization reaction of acyl chloride and amino groups by mechanical ball milling at room temperature for Pb2+ removal as adsorbents. Two types of diamine monomers are selected to construct COFs with different framework structure and functional groups contents, i.e. COF-TP from aromatic diamine and COF-TE from linear diamine. The as-prepared COFs materials display typical lamellar structure, and the amide groups on COFs skeleton are confirmed to behave as active adsorption sites for Pb2+ capture via multi-coordination. COF-TE exhibits superior Pb2+ adsorption capacity to COF-TP, because that less aromatic skeleton and weak π-π stacking of COF-TE facilitate higher internal diffusion of Pb2+ adsorption. Meanwhile, the higher amide group content on COF-TE leads to its higher saturated adsorption capacity of 185.7 mg/g than COF-TP of 140.0 mg/g. Finally, great recycling stability of Pb2+adsorption allows the amide-based COFs materials to be promising adsorbents for heavy metal Pb2+ removal or recovery.

Homogeneous hydrogels made with acrylic acid, acrylamide and chemically functionalized carbon nanotubes

Carbon nanotubes (CNTs) chemically functionalized were used to synthesize a series of novel nanocomposite hydrogels by in situ polymerization with acrylic acid (AA) and acrylamide (AM). A novel strategy was developed to prepare these hydrogels. CNTs were functionalized following a three-step chemical procedure: (i) purified carbon nanotubes (CNTsp) were partially surface oxidized to obtain CNTs with hydroxyl, carbonyl and carboxyl groups on their sidewalls (CNTsoxi), (ii) CNTsoxi were reacted with oxalyl chloride to obtain CNTs functionalized with acyl chloride groups (CNTsOCl), and (iii) CNTsOCl were reacted with acrylic acid (AA). The product, AA modified CNTsOCl (CNTsOCl-AA) was used to prepare the (CNTsOCl-AA-AM) nanocomposite hydrogels, where anhydride groups were tethered to the surface of the CNTsOCl-AA. The swelling process in water was evaluated as a consequence of the anhydride group hydrolysis, which broke some chemical links between CNTsOCl-AA and crosslinked AA-AM network. Equilibrium-swelling values of all hydrogels increased as the content of AA increased and were larger for AA-AM hydrogels than for CNTsOCl-AA-AM nanocomposite hydrogels. Young’s moduli of CNTsOCl-AA-AM nanocomposite hydrogels prepared with 1 or 2 wt.% AA, reached larger values than those measured for AA-AM hydrogels. This tendency was reversed when the AA content was raised to 3 wt.%.

The effect of Schiff base network on the separation performance of thin film nanocomposite forward osmosis membranes

In this study, Schiff base network-1 (SNW-1) nanoparticles, which are covalent organic frameworks (COFs), were used as fillers in the polyamide (PA) active layer to elevate the performance of thin-film nanocomposite (TFN) forward osmosis (FO) membranes. The TFN membranes were prepared by interfacial polymerization (IP) of m-phenylenediamine (MPD) and trimesoyl chloride (TMC), and the SNW-1 nanoparticles were dispersed in the MPD aqueous solution at various concentrations. The secondary amine groups of SNW-1 nanoparticles reacted with the acyl chloride groups of TMC during the IP reaction to form strong covalent/amide bonds, which facilitated better interface integration of SNW-1 nanoparticles in the PA layer. Additionally, the incorporation of amine-rich SNW-1 nanoparticles into the TFN membranes improved their surface hydrophilicity, and the porous structure of SNW-1 nanoparticles offered additional channels for transport of water molecules. The TFN0.005 membrane with a SNW-1 nanoparticle loading of 0.005 wt% demonstrated a higher water flux than that of pristine TFC membrane in both AL-FS (12.0 vs. 9.3 L m−2 h−1) and AL-DS (25.2 vs. 19.4 L m−2 h−1) orientations when they were tested with deionized water and 0.5 M NaCl as feed and draw solution, respectively.

Evaluation of the resistance to bacterial growth of star-shaped poly(ε-caprolactone)-co-poly(ethylene glycol) grafted onto functionalized carbon nanotubes nanocomposites

Nanocomposites of functionalized carbon nanotubes (CNTsf) as nanofillers, and a copolymer of star-shaped poly(ε-caprolactone) (stPCL) and poly(ethylene glycol) (PEG) as a polymeric matrix were synthesized, characterized, and their resistance to the growth of Staphylococcus aureus and Pseudomonas aeruginosa was evaluated. CNTsf contain hydroxyl, carboxyl and acyl chloride groups attached to their surface. Nanocomposites were prepared by mixing CNTsf to a solution of stPCL-PEG copolymer. Raman and FT-IR spectroscopies confirm the functionalization of carbon nanotubes (CNTs). Star-shaped PCL-PEG copolymer was characterized by Gel permeation chromatography (GPC), and 1H-NMR and 13C-NMR spectroscopies. X-ray photoelectron spectroscopy (XPS) shows that CNTsf are grafted to the stPCL-PEG copolymer. Crystallization behavior of the nanocomposites depends on the amount of CNTsf used in their preparation, detecting nucleation (nanocomposites prepared with 0.5 wt.% of CNTsf) or anti-nucleation (nanocomposites prepared with 1.0 wt.% of CNTsf) effects. Young’s Moduli and thermal stability of nanocomposites were higher, but their resistence to the proliferation of Staphylococcus aureus and Pseudomonas aeruginosa was lower than the observed for their pure polymer matrix.

The use of a star-shaped trifunctional acyl chloride for the preparation of polyamide thin film composite membranes

A star-shaped trifunctional acyl chloride bearing ether linkages was synthesized as an alternative to the commonly used trimesoyl chloride (TMC) in the preparation of polyamide thin film composite membranes (TFC). Although this star-shaped acyl chloride has the same functionality as TMC, it is larger in size and its acyl chloride groups are less reactive due to the electron donating ether linkages. In this work, we prepared TFC membranes by the interfacial polymerization of both this star-shaped acyl chloride and TMC with either one of the two structural isomers: m-phenylenediamine (MPD) or p-phenylenediamine (PPD). No strong effect was observed of the substitution pattern of the aromatic diamine on the membrane formation with TMC, due to the high reactivity of the acyl chloride groups of TMC. In contrast, the use of this star-shaped acyl chloride results in significant differences in the properties of the formed TFC membrane depending on the use of MPD or PPD. Where TMC-MPD membranes are well-known for their excellent retention, we could not obtain defect-free membranes prepared from MPD and this star-shaped triacyl chloride (Rrosebengal<77%). The use of PPD instead of MPD, however, did result in defect-free membranes (Rrosebengal>97%) with an acceptable clean water permeance (2.5 L m−2 h−1 bar−1).

Catalytic hydroboration of aldehydes and ketones with sodium hydride: Application to chemoselective reduction of aldehydes over ketones

Sodium hydride-promoted catalytic hydroboration of aldehydes and ketones with pinacolborane (HBpin) was examined, and 10 mol% of NaH was found to cause the HBpin to participate in hydroboration in a convenient and efficient manner at mild reaction conditions. Further chemoselective hydroboration of aldehyde over ketone functionality was also analyzed. In addition, no hydroboration was observed form ester, acyl chloride, amide, nitrile, alkene, alkyne, alkyl halide and epoxide functional groups indicate that present system (HBpin, NaH) is highly selective for aldehydes and ketones.