Acetalization

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Karen L. Wooley - One of the best experts on this subject based on the ideXlab platform.

  • a vinyl ether functional polycarbonate as a template for multiple postpolymerization modifications
    Macromolecules, 2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis(hydroxymethyl)propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound ...

  • A Vinyl Ether-Functional Polycarbonate as a Template for Multiple Postpolymerization Modifications
    2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis­(hydroxymethyl)­propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly­(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound 4-methylbenzyl alcohol resulted in a maximum of 42% acetal and 58% hydroxyl side chain groups. Nonetheless, the amphiphilicity of the block polymer allowed for its self-assembly in water to afford nanostructures, as characterized via dynamic light scattering and transmission electron microscopy. The kinetics of acetal cleavage within the block polymer micelles were examined in acidic buffered solutions (pH 4 and 5). In addition, mPEG-b-PMVEC and its hydrolyzed polymer mPEG-b-PMHEC (i.e., after full cleavage of acetals) exhibited minimal cytotoxicity to RAW 264.7 mouse macrophages, indicating that this polymer system represents a biologically nonhazardous material with pH-responsive activity

  • Development of a Vinyl Ether-Functionalized Polyphosphoester as a Template for Multiple Postpolymerization Conjugation Chemistries and Study of Core Degradable Polymeric Nanoparticles.
    Macromolecules, 2014
    Co-Authors: Young H. Lim, Gyu Seong Heo, Mahmoud Elsabahy, Yohannes H. Rezenom, Stephanie F. Pollack, Jeffery E. Raymond, Karen L. Wooley
    Abstract:

    A novel polyphosphoester (PPE) with vinyl ether side chain functionality was developed as a versatile template for postpolymerization modifications, and its degradability and biocompatibility were evaluated. An organocatalyzed ring-opening polymerization of ethylene glycol vinyl ether-pendant cyclic phosphotriester monomer allowed for construction of poly(ethylene glycol vinyl ether phosphotriester) (PEVEP). This vinyl ether-functionalized PPE scaffold was coupled with hydroxyl- or thiol-containing model small molecules via three different types of conjugation chemistries—thiol–ene “click” reaction, Acetalization, or thio-Acetalization reaction—to afford modified polymers that accommodated either stable thio–ether or hydrolytically labile acetal or thio–acetal linkages. Amphiphilic diblock copolymers of poly(ethylene glycol) and PEVEP formed well-defined micelles with a narrow and monomodal size distribution in water, as confirmed by dynamic light scattering (DLS), transmission electron microscopy, and at...

Sangho Cho - One of the best experts on this subject based on the ideXlab platform.

  • a vinyl ether functional polycarbonate as a template for multiple postpolymerization modifications
    Macromolecules, 2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis(hydroxymethyl)propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound ...

  • A Vinyl Ether-Functional Polycarbonate as a Template for Multiple Postpolymerization Modifications
    2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis­(hydroxymethyl)­propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly­(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound 4-methylbenzyl alcohol resulted in a maximum of 42% acetal and 58% hydroxyl side chain groups. Nonetheless, the amphiphilicity of the block polymer allowed for its self-assembly in water to afford nanostructures, as characterized via dynamic light scattering and transmission electron microscopy. The kinetics of acetal cleavage within the block polymer micelles were examined in acidic buffered solutions (pH 4 and 5). In addition, mPEG-b-PMVEC and its hydrolyzed polymer mPEG-b-PMHEC (i.e., after full cleavage of acetals) exhibited minimal cytotoxicity to RAW 264.7 mouse macrophages, indicating that this polymer system represents a biologically nonhazardous material with pH-responsive activity

Rinaldo Marini Bettolo - One of the best experts on this subject based on the ideXlab platform.

  • Unexpected Racemization in the Course of the Acetalization of (+)-(S)-5-Methyl-Wieland–Miescher Ketone with 1,2-Ethanediol and TsOH under Classical Experimental Conditions
    International journal of molecular sciences, 2019
    Co-Authors: Francesca Leonelli, Irene Piergentili, Giulio Lucarelli, Luisa Maria Migneco, Rinaldo Marini Bettolo
    Abstract:

    (+)-(S) and (-)-(R)-5-methyl-Wieland-Miescher ketone (+)-1 and (-)-1, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O Acetalization to (+)-5 and (-)-5, respectively. Various procedures for this transformation have been described in the literature. Among them, the classical procedure based on the use of 1,2-ethanediol and TsOH in refluxing benzene in the presence of a Dean-Stark apparatus. Within our work on bioactive natural products, it occurred to us to observe the partial racemization of (+)-5 in the course of the Acetalization of (+)-1 by means of the latter methodology. Aiming to investigate this drawback, which, to our best knowledge, has no precedents in the literature, we acetalized with 1,2-ethanediol and TsOH in refluxing benzene and in the presence of a Dean-Stark apparatus under various experimental conditions, enantiomerically pure (+)-1. It was found that the extent of racemization depends on the TsOH/(+)-1 and 1,2-ethanediol/(+)-1 ratios. Mechanism hypotheses for this partial and unexpected racemization are provided.

  • unexpected racemization in the course of the Acetalization of s 5 methyl wieland miescher ketone with 1 2 ethanediol and tsoh under classical experimental conditions
    International Journal of Molecular Sciences, 2019
    Co-Authors: Francesca Leonelli, Irene Piergentili, Giulio Lucarelli, Luisa Maria Migneco, Rinaldo Marini Bettolo
    Abstract:

    (+)-(S) and (-)-(R)-5-methyl-Wieland-Miescher ketone (+)-1 and (-)-1, are important synthons in the diastereo and enantioselective syntheses of biological and/or pharmacological interesting compounds. A key step in these syntheses is the chemoselective C(1)O Acetalization to (+)-5 and (-)-5, respectively. Various procedures for this transformation have been described in the literature. Among them, the classical procedure based on the use of 1,2-ethanediol and TsOH in refluxing benzene in the presence of a Dean-Stark apparatus. Within our work on bioactive natural products, it occurred to us to observe the partial racemization of (+)-5 in the course of the Acetalization of (+)-1 by means of the latter methodology. Aiming to investigate this drawback, which, to our best knowledge, has no precedents in the literature, we acetalized with 1,2-ethanediol and TsOH in refluxing benzene and in the presence of a Dean-Stark apparatus under various experimental conditions, enantiomerically pure (+)-1. It was found that the extent of racemization depends on the TsOH/(+)-1 and 1,2-ethanediol/(+)-1 ratios. Mechanism hypotheses for this partial and unexpected racemization are provided.

Mahmoud Elsabahy - One of the best experts on this subject based on the ideXlab platform.

  • a vinyl ether functional polycarbonate as a template for multiple postpolymerization modifications
    Macromolecules, 2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis(hydroxymethyl)propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound ...

  • A Vinyl Ether-Functional Polycarbonate as a Template for Multiple Postpolymerization Modifications
    2018
    Co-Authors: Sangho Cho, Gyu Seong Heo, Sarosh Khan, Jessica Huang, David A Hunstad, Mahmoud Elsabahy, Karen L. Wooley
    Abstract:

    A highly reactive vinyl ether-functionalized aliphatic polycarbonate and its block copolymer were developed as templates for multiple postpolymerization conjugation chemistries. The vinyl ether-functional six-membered cyclic carbonate monomer was synthesized by a well-established two-step procedure starting from 2,2-bis­(hydroxymethyl)­propionic acid. An organobase-catalyzed ring-opening polymerization of the synthesized monomer afforded polycarbonates with pendant vinyl ether functionalities (PMVEC). The vinyl ether moieties on the resulting polymers were readily conjugated with hydroxyl- or thiol-containing compounds via three different postpolymerization modification chemistries: Acetalization, thio-Acetalization, and thiol–ene reaction. Acetal-functionalized polycarbonates were studied in depth to exploit their acid-labile acetal functionalities. Acetalization of the amphiphilic diblock copolymer of poly­(ethylene glycol) methyl ether (mPEG) and PMVEC, mPEG113-b-PMVEC13, with the model hydroxyl compound 4-methylbenzyl alcohol resulted in a maximum of 42% acetal and 58% hydroxyl side chain groups. Nonetheless, the amphiphilicity of the block polymer allowed for its self-assembly in water to afford nanostructures, as characterized via dynamic light scattering and transmission electron microscopy. The kinetics of acetal cleavage within the block polymer micelles were examined in acidic buffered solutions (pH 4 and 5). In addition, mPEG-b-PMVEC and its hydrolyzed polymer mPEG-b-PMHEC (i.e., after full cleavage of acetals) exhibited minimal cytotoxicity to RAW 264.7 mouse macrophages, indicating that this polymer system represents a biologically nonhazardous material with pH-responsive activity

  • Development of a Vinyl Ether-Functionalized Polyphosphoester as a Template for Multiple Postpolymerization Conjugation Chemistries and Study of Core Degradable Polymeric Nanoparticles.
    Macromolecules, 2014
    Co-Authors: Young H. Lim, Gyu Seong Heo, Mahmoud Elsabahy, Yohannes H. Rezenom, Stephanie F. Pollack, Jeffery E. Raymond, Karen L. Wooley
    Abstract:

    A novel polyphosphoester (PPE) with vinyl ether side chain functionality was developed as a versatile template for postpolymerization modifications, and its degradability and biocompatibility were evaluated. An organocatalyzed ring-opening polymerization of ethylene glycol vinyl ether-pendant cyclic phosphotriester monomer allowed for construction of poly(ethylene glycol vinyl ether phosphotriester) (PEVEP). This vinyl ether-functionalized PPE scaffold was coupled with hydroxyl- or thiol-containing model small molecules via three different types of conjugation chemistries—thiol–ene “click” reaction, Acetalization, or thio-Acetalization reaction—to afford modified polymers that accommodated either stable thio–ether or hydrolytically labile acetal or thio–acetal linkages. Amphiphilic diblock copolymers of poly(ethylene glycol) and PEVEP formed well-defined micelles with a narrow and monomodal size distribution in water, as confirmed by dynamic light scattering (DLS), transmission electron microscopy, and at...

Fumin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • polyoxometalates confined in the mesoporous cages of metal organic framework mil 100 fe efficient heterogeneous catalysts for esterification and Acetalization reactions
    Chemical Engineering Journal, 2015
    Co-Authors: Fumin Zhang, Jing Shi, Yan Jin, Yijun Zhong, Weidong Zhu, Samy M Elshall
    Abstract:

    Abstract 12-Tungstophosphoric heteropolyacid (HPW) has been encapsulated in a mesoporous metal–organic framework (MOF), MIL-100(Fe), by a simple low-temperature ( 2 adsorption, FT-IR, acid–base titration, 31 P MAS NMR, TEM, SEM, TGA, XPS techniques and elemental analysis, and then used as a heterogeneous catalyst in acid-catalyzed esterification and Acetalization. The characterization results indicate that the HPW molecules were successfully incorporated within the mesoporous cages of the MIL-100(Fe) matrix as noncoordinating guests, thus maintaining the integrity of the protonic acidity of HPW. The resulting HPW@MIL-100(Fe) catalyst exhibits high activity and excellent reusability in the esterification reactions with no evidence for agglomeration, leaching, or deactivation of the HPW during several repeated uses of the catalyst. Similarly, the HPW@MIL-100(Fe) catalyst also shows excellent catalytic properties in the Acetalization of benzaldehyde and ethanediol. The unique characteristics of MIL-100(Fe) and the uniform dispersion of HPW molecules within the mesoporous cages of the MIL-100(Fe) matrix may account for the high catalytic activity and recyclability of the HPW@MIL-100(Fe) catalyst.

  • facile synthesis of mil 100 fe under hf free conditions and its application in the Acetalization of aldehydes with diols
    Chemical Engineering Journal, 2015
    Co-Authors: Fumin Zhang, Jing Shi, Yan Jin, Yijun Zhong, Weidong Zhu
    Abstract:

    Abstract Mesoporous iron(III) carboxylate [MIL-100(Fe)] has been successfully synthesized by a simple unappreciated low-temperature ( 3 BTC) under HF-free conditions. The synthesized MIL-100(Fe) was systematically characterized by XRD, N 2 adsorption, XPS, TGA, FT-IR, and SEM and used as a catalyst in the liquid-phase Acetalization of various aldehydes with diols. In comparison with other methods commonly used for the preparation of MIL-100(Fe), the current synthesis strategy has merits such as mild and environmentally benign synthesis conditions. Additionally, the synthesized MIL-100(Fe) shows some excellent catalytic properties in the Acetalization of aldehydes with diols, due to the Lewis acidity of the available unsaturated metal sites, accompanied with abundant mesoporous cages in the framework of MIL-100(Fe), superior to commercial resin and zeolite catalysts.