- Preparation and thermal properties of poly[acrylonitrile-co-(β- methylhydrogen itaconate)] used as carbon fiber precursor
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In order to replace terpolymer with bipolymer, a bifunctional comonomer β-methylhydrogen itaconate (MHI) containing carboxyl group and ester group was synthesized to prepare poly[acrylonitrile-co-(β-methylhydrogen itaconate)] [P(AN-co-MHI)] bipolymers used as carbon fiber precursor for improving the stabilization and spinnability at the same time. The P(AN-co-MHI) bipolymers with different monomer feed ratios were characterized by elemental analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The results show that both the polymerization conversion and molecular mass of P(AN-co-MHI) reduce with the increasing MHI amounts in the feed due to the larger molecular volume of MHI than acrylonitrile (AN). The monomer reactivity ratios were calculated by Fineman-Ross and Kelen-Tuedos methods, the results show good agreement and MHI possesses higher reactivity than AN. Two parameters Es = A1, 629 cm-1 / A2, 244 cm 1 and SI = (I0 - I S) / I0 were defined to evaluate the extent of stabilization, and the activation energy (E a) of the cyclization was calculated by Kissinger method and Ozawa method. The FTIR, XRD, and DSC results show that P(AN-co-MHI) bipolymers exhibit significantly improved stabilization characteristics than PAN homopolymer, such as larger extent of stabilization, lower initiation temperature, and smaller E a of cyclization, which is attributed to the ionic initiation by MHI comonomer and it is beneficial to preparing high-performance carbon fiber.
- Ju, Anqi,Xu, Hongyao,Ge, Mingqiao
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- Short Enantioselective Total Syntheses of Cheloviolenes A and B and Dendrillolide C via Convergent Fragment Coupling Using a Tertiary Carbon Radical
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The development of a convergent fragment coupling strategy for the enantioselective total syntheses of a group of rearranged spongian diterpenoids that harbor the cis-2,8-dioxabicyclo[3.3.0]octan-3-one unit is described. The key bond disconnection relies on a late-stage fragment coupling between a tertiary carbon radical and an electron-deficient alkene to unite two ring systems and form two new stereocenters, one of which is quaternary, in a stereoselective and efficient manner. This strategy is applied toward scalable 14-15 step syntheses of three rearranged spongian diterpenoids, cheloviolenes A and B, and dendrillolide C.
- Garnsey, Michelle R.,Slutskyy, Yuriy,Jamison, Christopher R.,Zhao, Peng,Lee, Juyeol,Rhee, Young Ho,Overman, Larry E.
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- A novel poly[acrylonitrile-co-(3-ammoniumcarboxylate-butenoic acid-methylester)]copolymer for carbon fiber precursor
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A novel bifunctional comonomer 3-ammoniumcarboxylate-butenoic acid-methyl ester (ACBM) was synthesized for preparing poly[acrylonitrile-co-(3- ammoniumcarboxylate-butenoic acid-methyl ester)] [P(AN-co-ACBM)] copolymer as a carbon fiber precursor. Differential scanning calorimetry results show that the P(AN-co-ACBM) exhibits a significantly improved stabilization performance compared with polyacrylonitrile (PAN), such as lower cyclization temperature and smaller rate of heat release, which is mainly attributed to the initiation of ACBM through an ionic cyclization mechanism. Simultaneously, the rheological analysis shows that P(AN-co-ACBM) possesses better spinnability than PAN.
- Ju, An Qi,Guang, Shan Yi,Xu, Hong Yao
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- Poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester): A better precursor material for carbon fiber than acrylonitrile terpolymer
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In order to improve the stabilization and spinnability of polyacrylonitrile, a bifunctional comonomer containing both ester and amide groups was synthesized to prepare poly(acrylonitrile-co-3-aminocarbonyl-3-butenoic acid methyl ester) [P(AN-co-ABM)] copolymers used as the carbon fiber precursor instead of poly(acrylonitrile-acrylamide-methyl acrylate) [P(AN-AM-MA)] terpolymer. The differential scanning calorimetry and thermogravimetry results show that the stabilization of P(AN-co-ABM) have been remarkably improved by ABM compared with P(AN-AM-MA) terpolymer, such as lower initiation temperature, broadened exothermic peak and smaller activation energy. Moreover, the spinnability of P(AN-co-ABM) is also improved by ABM due to the lubrication of ester groups in ABM. This study clearly shows that P(AN-co-ABM) copolymer is a better material for use as a carbon fiber precursor than P(AN-AM-MA) terpolymer.
- Ju, An-Qi,Li, Meng-Juan,Luo, Miao,Ge, Ming-Qiao
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- A high molecular weight acrylonitrile copolymer prepared by mixed solvent polymerization: I. effect of monomer feed ratios on polymerization and stabilization
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A bifunctional comonomer β-methylhydrogen itaconate (MHI) was employed to prepare high molecular weight poly[acrylonitrile-co-(β-methylhydrogen itaconate)] [P(AN-co-MHI)] copolymers by radical polymerization in a mixed solvent of dimethyl sulfoxide/deionized water = 60/40 (wt/wt), which was used as a carbon fiber precursor instead of acrylonitrile terpolymers for improving the stabilization and spinnability simultaneously. The structure and stabilization of P(AN-co-MHI) copolymers with different monomer feed ratios were characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results show that both the polymerization conversion and molecular weight reduce with the increase of MHI content in the feed due to the larger molecular volume of MHI. The monomer reactivity ratios were calculated by Fineman-Ross and Kelen-Tüds methods and the reactivity of MHI is higher than that of AN. Two parameters Es = A1618 cm-1/A2244 cm-1 and SI = (I0 - Is)/I0 were defined to evaluate the extent of stabilization and the activation energy (Ea) of the cyclization. The FTIR, XRD and DSC results show that P(AN-co-MHI) copolymers exhibit significantly improved stabilization characteristics than the PAN homopolymer and poly(acrlonitrile-methyl acrylate-acrylic acid) terpolymer, such as a larger extent of stabilization, lower initiation temperature and smaller Ea of cyclization, which is attributed to the ionic initiation of the MHI comonomer and is beneficial for preparing high performance carbon fiber.
- Ju, Anqi,Yan, Yafeng,Wang, Dawei,Luo, Jun,Ge, Mingqiao,Li, Mengjuan
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- Biobased Spiroimides from Itaconic Acid and Formamides: Molecular Targets for a Novel Synthetic Application of Renewable Chemicals
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Spiroimides exhibit a wide range of biological activities, such as anticonvulsant, antiarrhythmic, and antihyperglycemic activities. Herein, a novel synthetic application of renewable chemicals, itaconic acid and formamides, is described. Proper exploitation of the reactivity of itaconic acid and formamide allows for the development of an efficient synthetic approach for the production of several new biobased spiroimides, spiro[dihydroquinolin-2-one-succinimides] and spiro[indolin-2-one-glutarimides], in excellent overall yields (up to 98%).
- Hornink, Milene Macedo,Lopes, Alice Uva,Andrade, Leandro Helgueira
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supporting information
p. 296 - 308
(2020/11/09)
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- A Br?nsted acidic, ionic liquid containing, heteropolyacid functionalized polysiloxane network as a highly selective catalyst for the esterification of dicarboxylic acids
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A Br?nsted acidic, ionic liquid containing, heteropolyanion functionalized polysiloxane network was formed by self-condensation of dodecatungstophosphoric acid and a zwitterionic organosilane precursor containing both imidazolinium and sulfonate groups. The resulting hybrid material POS-HPA-IL was investigated as a catalyst for the selective esterification of dicarboxylic acids.
- Rajabi, Fatemeh,Wilhelm, Christian,Thiel, Werner R.
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supporting information
p. 4438 - 4444
(2020/08/10)
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- Synthesis and Bioactivity of Polymer-Based Synthetic Mimics of Antimicrobial Peptides (SMAMPs) Made from Asymmetrically Disubstituted Itaconates
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A series of asymmetrically disubstituted diitaconate monomers is presented. Starting from itaconic anhydride, functional groups could be placed selectively at the two nonequivalent carbonyl groups. By using 2D NMR spectroscopy, it was shown that the first functionalization step occurred at the carbonyl group in the β position to the double bond. These monomers were copolymerized with N,N-dimethylacrylamide (DMAA) to yield polymer-based synthetic mimics of antimicrobial peptides (SMAMPs). They were obtained by free radical polymerization, a metal-free process, and still maintained facial amphiphilicity at the repeat unit level. This eliminates the need for laborious metal removal and is advantageous from a regulatory and product safety perspective. The poly(diitaconate-co-DMAA) copolymers obtained were statistical to alternating, and the monomer feed ratio roughly matched that of the repeat unit content of the copolymers. Investigations of varied R group hydrophobicity, repeat unit ratio, and molecular mass on antimicrobial activity against Escherichia coli and on compatibility with human keratinocytes showed that the polymers with the longest R groups and lowest DMAA content were the most antimicrobial and hemolytic. This is in agreement with the biological activity of previously reported SMAMPs. Thus, the design concept of facial amphiphilicity has successfully been transferred, but the selectivity of these polymers for bacteria over mammalian cells still needs to be optimized.
- Boschert, David,Schneider-Chaabane, Alexandra,Himmelsbach, Andreas,Eickenscheidt, Alice,Lienkamp, Karen
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p. 8217 - 8227
(2018/05/30)
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- Rh(III)-catalyzed halogenation of vinylic C-H bonds: Rapid and general access to Z-halo acrylamides
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Herein, the regio- and stereoselective iodination, along with some examples for the bromination, of readily available acrylamides to access a variety of differently substituted Z-haloacrylic acid derivatives is reported. The reaction proceeds under mild conditions via a Rh(III)-catalyzed C-H-activation/ halogenation mechanism and represents a rare example of a direct halogenation of electron-poor acrylic acid derivatives.
- Kuhl, Nadine,Schroeder, Nils,Glorius, Frank
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supporting information
p. 3860 - 3863
(2013/09/02)
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- HETEROARYL COMPOUNDS AND METHODS OF USE THEREOF
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Provided herein are heteroaryl compounds, methods of their synthesis, pharmaceutical compositions comprising the compounds, and methods of their use. In one embodiment, the compounds provided herein are useful for the treatment, prevention, and/or management of various disorders, such as CNS disorders and metabolic disorders, including, but not limited to, e.g., neurological disorders, psychosis, schizophrenia, obesity, and diabetes.
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Page/Page column 53
(2012/07/27)
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- Process for the production of sitagliptin
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The present invention is directed to a process for the preparation of Sitagliptin, having formula (I)
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Page/Page column 6-7
(2012/03/26)
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- A convergent approach to (-)-callystatin a based on local symmetry
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The key is symmetry! A convergent synthetic approach of the highly cytotoxic natural product (-)-callystatin A was developed assembling three fragments through Julia-Kocienski olefination and Stille cross-coupling. The new strategy relies on a pivotal local symmetry of the target molecule. In this preliminary study, particular attention was devoted to facilitate the catalytic enantiocontrol of strategic stereogenic centers present in each of the fragments (see scheme). Copyright
- Candy, Mathieu,Tomas, Lo?c,Parat, Sabrina,Heran, Virginie,Bienaymé, Hugues,Pons, Jean-Marc,Bressy, Cyril
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supporting information
p. 14267 - 14271
(2013/01/15)
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- 2-PYRROLIDONE DERIVATIVES FUNCTIONALIZED WITH AN ESTER, ACID OR AMIDE RADICAL, COSMETIC COMPOSITION COMPRISING THEM AND USE THEREOF FOR CONDITIONING KERATIN MATERIALS
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The invention relates to the use of compounds derived from 2-pyrrolidone functionalized in position 4 with an ester, carboxylic acid or amide radical, for cosmetically treating keratin materials, especially for conditioning keratin materials, and in particular in terms of the disentangling, straightening, combability and manageability of human keratin fibres such as the hair. The invention also relates to novel cationic monopyrrolidone derivatives and to a cosmetic composition comprising them. Besides the suppleness of the keratin fibre, the compounds of formula (I) as defined previously also make it possible to improve the disentangling, straightening, combability and manageability of the head of hair; the shaping of the head of hair is easier, and the hair has a very pleasant, fluid feel.
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Page/Page column 34
(2012/01/04)
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- The first kinetic enzymatic resolution of methyl ester of C75
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Enantioselective hydrolysis of methyl ester of (±)-C75 was successfully accomplished by means of Acylase I from Aspergillus to afford (2,R,3S)-(+)-C75 with 96% e.e. The unreacted methyl ester was recovered with >99% e.e. This latter compound was either chemically or enzymatically hydrolyzed to furnish (2S,3,R)-(-)-C75 with >99% e.e.
- Chakrabarty, Kuheli,Forzato, Cristina,Nitti, Patrizia,Pitacco, Giuliana,Valentin, Ennio
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scheme or table
p. 245 - 248
(2011/06/28)
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- Synthesis of versatile building blocks through asymmetric hydrogenation of functionalized itaconic acid mono-esters
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The rhodium-catalyzed asymmetric hydrogenation of several β-substituted itaconic acid monoesters, using a library of monodentate phosphoramidite and phosphite ligands is described. Two β-alkylsubstituted substrates were readily hydrogenated by the rhodium complex Rh(COD) 2BF4 in combination with (S)-PipPhos as a ligand resulting in ees of 99 %. In contrast, the corresponding more hindered β-arylsubstituted substrates did not exhibit acceptable enantioselectivities under these conditions. However, the use of a 48-membered ligand library led to the identification of several suitable ligands for these substrates, resulting in ees of 89-99%. The resulting optically active succinic acid derivatives are potentially useful building blocks for more elaborate compounds, because of the ability to differentiate between the carboxylic acid and the ester groups on either side of the molecule.
- Hekking, Koen F. W.,Lefort, Laurent,De Vries, Andre H. M.,Van Delft, Floris L.,Schoemaker, Hans E.,De Vries, Johannes G.,Rutjes, Floris P. J. T.
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experimental part
p. 85 - 94
(2009/04/07)
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- Catalytic asymmetric alkynylation and arylation of aldehydes by an H 8-binaphthyl-based amino alcohol ligand
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A novel chiral H8-1,1'-binaphthyl-based amino alcohol ligand (1Ra,2S,3R)-2 has been synthesized and applied in the direct nucleophilic addition of organozincs (alkynylzinc and arylzinc prepared in situ) to aldehydes, yielding the corresponding optically active propargylic alcohols and diarylmethanols in high yields and good to excellent enantioselectivities. For the asymmetric arylation reaction, one catalyst (1Ra,2S,3R)-2 can afford both enantiomers of many pharmaceutically interesting diarylmethanols by a proper combination of various arylzinc reagents and aldehydes.
- Ruan, Jiwu,Lu, Gui,Xu, Lijing,Li, Yue-Ming,Chan, Albert S. C.
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experimental part
p. 76 - 84
(2009/04/11)
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- Chemo-enzymatic synthesis of a series of 2,4-syn-functionalized (S)-glutamate analogues: New insight into the structure-activity relation of ionotropic glutamate receptor subtypes 5, 6, and 7
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(S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the central nervous system (CNS) activating the plethora of ionotropic Glu receptors (iGluRs) and metabotropic Glu receptors (mGluRs). In this paper, we present a chemo-enzymatic strategy for the enantioselective synthesis of five new Glu analogues 2a-f (2d is exempt) holding a functionalized substituent in the 4-position. Nine Glu analogues 2a-j are characterized pharmacologically at native 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA), kainic acid (KA), and N-methyl-D-aspartic acid (NMDA) receptors in rat synaptosomes as well as in binding assays at cloned rat iGluR5-7 subtypes. A detailed in silico study address as to why 2h is a high-affinity ligand at iGluR57 (Ki = 3.81, 123, 57.3 nM, respectively), while 2e is only a high affinity ligand at iGluR5 (Ki = 42.8 nM). Furthermore, a small series of commercially available iGluR ligands are characterized in iGluR5-7 binding.
- Sagot, Emanuelle,Pickering, Darryl S.,Pu, Xiaosui,Umberti, Michelle,Stensb?l, Tine B.,Nielsen, Birgitte,Chapelet, Marion,Bolte, Jean,Gefflaut, Thierry,Bunch, Lennart
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experimental part
p. 4093 - 4103
(2009/05/30)
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- Highly efficient esterification of carboxylic acids with alcohols by montmorillonite enwrapped titanium as a heterogeneous acid catalyst
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Montmorillonite-enwrapped titanium catalyst was found to efficiently promote the esterification of carboxylic acids with alcohols. In comparison to other catalysts reported to date, this heterogeneous catalyst offers a remarkably simple workup procedure, and is reusable without any appreciable loss in its activity and selectivity.
- Kawabata, Tomonori,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 9205 - 9208
(2007/10/03)
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- Solid-phase synthesis of α-substituted 3-bisarylthio N-hydroxy propionamides as specific MMP Inhibitors
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A novel series of potent and specific MMP-2,3,9,13 inhibitors has been obtained by modulation on solid phase by α and aryl substitutions on 3-arylthio-N-hydroxy-propionamides starting from itaconic acid.
- Chollet, Anne-Marie,Le Diguarher, Thierry,Kucharczyk, Nathalie,Loynel, Armelle,Bertrand, Marc,Tucker, Gordon,Guilbaud, Nicolas,Burbridge, Mike,Pastoureau, Philippe,Fradin, Armel,Sabatini, Massimo,Fauchère, Jean-Luc,Casara, Patrick
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p. 531 - 544
(2007/10/03)
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- A simple method for the preparation of monomethyl esters of dicarboxylic acids by selective esterification of the nonconjugated carboxyl group in the presence of an aromatic or conjugated carboxyl group
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Various dicarboxylic acids have been converted selectively into monomethyl esters in which the nonconjugated carboxyl group is selectively esterified in the presence of an aromatic or conjugated carboxyl group at room temperature (~ 25-27°C) in methanol using a catalytic amount of thionyl chloride.
- Ram, Ram N.,Meher, Nabin Kumar
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p. 282 - 283
(2007/10/03)
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- An efficient and regiospecific esterification of dioic acids using PTSA
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Regiospecific mono alkyl esters of dioic acids have been obtained in excellent yield using PTSA as a catalyst. This method is mild and simpler than the previous methods.
- Rama Devi,Rajaram
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p. 294 - 296
(2007/10/03)
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- Selective esterification of nonconjugated carboxylic acids in the presence of conjugated or aromatic carboxylic acids under mild conditions
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Nonconjugated carboxylic acids are selectively esterified in good yields in the presence of conjugated or aromatic carboxylic acids by stirring over Amberlyst-15 in alcohol at room temperature.
- Anand, Ramesh C.,Vimal,Milhotra, Archana
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p. 378 - 379
(2007/10/03)
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- Selective esterification of aliphatic nonconjugated carboxylic acids in the presence of aromatic or conjugated carboxylic acids catalysed by NiCl2.6H2O
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Unhindered aliphatic nonconjugated carboxylic acids were esterified selectively in the presence of aromatic or conjugated acids on heating in the corresponding alcoholic solutions at reflux for 3-13 hr with 10 mol% of NiCl2.6H2O catalyst.
- Ram, Ram N.,Charles
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p. 7335 - 7340
(2007/10/03)
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- Synthetic cephalotaxine esters having antileukemic activity
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Six acyl esters of cephalotaxine have been synthesized by ordinary and standard procedures, and all have demonstrated chemotherapeutic activity against leukemia in animals.
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