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Vinod K. Shahi - One of the best experts on this subject based on the ideXlab platform.
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Efficient bipolar membrane with protein interfacial layer for optimal water splitting
Journal of Industrial and Engineering Chemistry, 2017Co-Authors: Murli Manohar, Geetanjali Shukla, Ravi P. Pandey, Vinod K. ShahiAbstract:Abstract Herein, we are reporting bipolar membranes (BPMs) for water splitting. BPMs are sandwiched structure of anion-exchange layer (AEL) and cation-exchange layer (CEL) with a protein (lysozyme (LYS) or bovine serum albumin (BSA) as interfacial layer (IL). CEL and AEL were prepared by controlled sulphonation or ChloroMethylation (without ChloroMethyl Methyl Ether). Presence of acidic and basic groups in the IL facilitates the H+/OH− transport and act as proton/hydroxide buffer. Further, water dissociation efficiency of BPMs was also analysed by experimental results (I–V curves, chronopotentiometry, and electrodialysis). Data revealed high suitability of BPM-LYS for excellent catalytic activity and water dissociation. The experimental results (I–V) curves, chronopotentiometry, and electrodialysis) revealed high suitability of BPM-LYS for excellent catalytic activity and water dissociation.
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Alternative preparative route for efficient and stable anion-exchange membrane for water desalination by electrodialysis
Desalination, 2017Co-Authors: Murli Manohar, A. Das, Vinod K. ShahiAbstract:Abstract We disclosed an alternative method for controlled ChloroMethylation of poly(2,6-diMethyl-1,4-phenylene oxide) (PPO) in presence of paraformaldehyde, tri-Methyl chlorosilane and Lewis acid catalyst. About 35–74% degree of ChloroMethylation (DCM) of PPO was achieved under optimized conditions. Reported method avoids the use of hazardous chemicals (such as ChloroMethyl Methyl Ether, and bromine) during preparation of AEM. AEMs with varied DCM were extensively characterized by measuring their physicochemical and electrochemical properties. Reported AEM-3 (DCM: 74%), was designed to possess all the required properties such as good water uptake (26.2%), ion-exchange capacity (1.61 meq·g − 1 ), high permselectivity (0.98), and conductivity (7.67 × 10 − 2 S cm − 1 ) due to high molality of quaternary ammonium groups. Chronopotentiometry study of prepared membranes confirmed their homogeneous and alkaline nature suitable. Most optimized AEM-3 with splendid alkaline, oxidative and hydrolytic stabilities is a good candidate for electrodialysis.
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Multi-block poly(arylene Ether)s containing pre-choloroMethylated bisphenol: anion conductive ionomers
Journal of Materials Chemistry A, 2013Co-Authors: Amaranadh Jasti, Vinod K. ShahiAbstract:We report a simple method for the preparation of anion conductive ionomers (ACIs) using ChloroMethylated bisphenol A, without the use of ChloroMethyl Methyl Ether (CMME) (carcinogenic). Aminated multi-block poly(arylene Ether)s (AMBPEs) were obtained by nucleophilic aromatic substitution, followed by polymer condensation then amination. The reported ACIs exhibited a 2.74 milliequivalent per g ion-exchange capacity (IEC) and hydroxide ion conductivity of 56 mS cm−1.
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Cross-linked poly(vinyl alcohol)-poly(acrylonitrile-co-2-diMethylamino ethylmethacrylate) based anion-exchange membranes in aqueous media.
The journal of physical chemistry. B, 2010Co-Authors: Mahendra Kumar, Shalini Singh, Vinod K. ShahiAbstract:Hydroxide anion conducting polymer membranes also termed as anion exchange membranes (AEMs) are recently becoming important materials for electrochemical technology, alkaline fuel cells, and electrolyzers. In this work, the preparation procedure for AEMs based on poly(vinyl alcohol) (PVA) and copolymer of poly(acrylonitrile (PAN)-diMethylamino ethylmethacrylate) (DMAEMA) with strongly basic quaternary ammonium in aqueous media has been reported. This simplified procedure avoids the use of ChloroMethyl Methyl Ether (CME), a carcinogen that is harmful to human health, generally used for ChloroMethylation during AEM preparation. Developed AEMs were extensively characterized by studying physicochemical and electrochemical properties, to assess their suitability for electrodialytic ion separation. These membranes were designed to possess all the required properties of a highly anion conductive membrane such as reasonable water uptake, good ion-exchange capacity (1.18 mequiv g−1), high permselectivity (0.90), a...
Anthony W. Czarnik - One of the best experts on this subject based on the ideXlab platform.
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Merrifield MicroTubeTM reactors for solid phase synthesis
Tetrahedron Letters, 1998Co-Authors: Xiao Yi Xiao, Anthony W. CzarnikAbstract:Abstract Polystyrene grafted polypropylene MicroTubeTM reactors (length × OD, 25 × 5 mm) have been functionalized with ChloroMethyl groups (Merrifield-type) using ChloroMethyl Methyl Ether and Lewis acid catalysts. A potentiometric method using a chloride ion selective electrode has been developed to measure the loading of the Merrifield MicroTubeTM reactors. A typical loading of 25–35 μmol/tube for Merrifield MicroTubeTM reactors has been achieved. Several reactions performed on Merrifield MicroTubeTM reactors demonstrated that they are excellent supports for solid phase synthesis. As a result of the ease with which radiofrequency memory tags can be associated with and separated from the supports, these MicroTubeTM reactors can facilitate the synthesis of combinatorial libraries.
N. Ramanathan - One of the best experts on this subject based on the ideXlab platform.
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Dimethoxymethane–Hydrogen Chloride Interaction: Gas Phase versus Low-Temperature Behavior Studied Using Matrix Isolation Infrared and Density Functional Theory Methods
2016Co-Authors: K. Sundararajan, N. RamanathanAbstract:Premixing of dimethoxy methane (DMM) and hydrogen chloride (HCl) with Ar/N2 in the gas phase resulted in a nucleophilic substitution reaction and yielded products, cis-ChloroMethyl Methyl Ether (cis-CMME) and methanol. On the contrary, when DMM and HCl were separately codeposited in a low-temperature Ar matrix produced hydrogen-bonded alkoxy adduct, probably the intermediate in the gas phase nucleophilic substitution reaction. The formation of the alkoxy adduct was evidenced by the shifts in the vibrational frequencies of the DMM and HCl submolecules. The structure and energy of the alkoxy adduct were computed at the B3LYP/6-311++G** level of theory. The computations indicated only one minimum for the DMM–HCl adduct. The nucleophilic substitution reaction between DMM and HCl is prevented in the low-temperature matrix probably due to the cage effect in the matrix
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Dimethoxymethane–Hydrogen Chloride Interaction: Gas Phase versus Low-Temperature Behavior Studied Using Matrix Isolation Infrared and Density Functional Theory Methods
The journal of physical chemistry. A, 2013Co-Authors: K. Sundararajan, N. RamanathanAbstract:Premixing of dimethoxy methane (DMM) and hydrogen chloride (HCl) with Ar/N2 in the gas phase resulted in a nucleophilic substitution reaction and yielded products, cis-ChloroMethyl Methyl Ether (cis-CMME) and methanol. On the contrary, when DMM and HCl were separately codeposited in a low-temperature Ar matrix produced hydrogen-bonded alkoxy adduct, probably the intermediate in the gas phase nucleophilic substitution reaction. The formation of the alkoxy adduct was evidenced by the shifts in the vibrational frequencies of the DMM and HCl submolecules. The structure and energy of the alkoxy adduct were computed at the B3LYP/6-311++G** level of theory. The computations indicated only one minimum for the DMM–HCl adduct. The nucleophilic substitution reaction between DMM and HCl is prevented in the low-temperature matrix probably due to the cage effect in the matrix.
Zhi-tang Huang - One of the best experts on this subject based on the ideXlab platform.
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Macrocyclic, linear and starlike assemblies of calix[4]arenes covalently bridged by Methylenes at the upper rims: simple route to novel receptors with defined polycavities
Tetrahedron, 2002Co-Authors: Jun-min Liu, Yan-song Zheng, Qi-yu Zheng, Jian Xie, Mei-xiang Wang, Zhi-tang HuangAbstract:Abstract ChloroMethylation of 5,17-di- tert -butyl-25,27-dihydroxy-26,28-dimethoxycalix[4]arene with ChloroMethyl Methyl Ether in the presence of zinc chloride led to the formation of macrocyclic and linear oligomers containing three to five calix[4]arenes bridged via Methylenes at the upper rims. Under the identical conditions, however, 5,17-di- tert -amyl-25,27-dihydroxy-26,28-dimethoxycalix[4]arene was converted into a mixture of linear dimer and trimer in yields of 39.5 and 34%, respectively. Only dimer was obtained as the sole product in 41% yield when 25,27-dihydroxy-26,28-diethoxycalix[4]arene was used. Efficient synthesis of linear or starlike polycalixarenes was achieved utilizing the Friedel–Crafts reaction of debutylated or partially debutylated calix[4]arenes with ChloroMethylated calix[4]arene promoted by anhydrous zinc chloride.
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Synthesis of oligomers of calix[4]arene with Methylene bridge at the upper rims
Tetrahedron Letters, 1998Co-Authors: Yan-song Zheng, Zhi-tang HuangAbstract:Abstract Oligomeric mixture of calix[4]arene with Methylene bridge at the upper rims was synthesized by the reaction of 5,17-di-tert-butyl-25,27-dihydroxy-26,28-dimethoxycalix[4]arene with ChloroMethyl Methyl Ether, and the major product is cyclic trimer.
Katherine Belecki - One of the best experts on this subject based on the ideXlab platform.
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Organic Syntheses - Synthesis of Alpha‐Halo Ethers from Symmetric Acetals and in Situ MethoxyMethylation of an Alcohol
Organic Syntheses, 2006Co-Authors: Martin A. Berliner, Katherine BeleckiAbstract:Dimethoxymethane Zinc bromide Acetyl chloride ChloroMethyl Methyl Ether Alpha-Phenethyl alcohol Diisopropylethylamine 1-Methoxy-1-phenylethane Keywords: alpha halo Ethers; methoxyMethylation; acetals; OSHA carcinogen; exchange reactions; zinc catalyst; acid halides; alkylation; aliphatic acetals; waste disposal
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Simple, rapid procedure for the synthesis of ChloroMethyl Methyl Ether and other chloro alkyl Ethers.
The Journal of organic chemistry, 2005Co-Authors: Martin A. Berliner, Katherine BeleckiAbstract:Zinc(II) salts catalyze the reaction between acetals and acid halides to provide haloalkyl Ethers in near-quantitative yield. Reactions from millimole to mole scale are typically complete in 1−4 h with 0.01 mol % catalyst. The solutions of haloalkyl Ethers thus obtained can be utilized directly in reactions in which the presence of the ester byproduct does not interfere. Excess haloalkyl Ether is destroyed on workup, thereby minimizing exposure to this class of carcinogenic compounds.