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Julia V. Zaikina - One of the best experts on this subject based on the ideXlab platform.
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rapid phase screening via Hydride route a discovery of k8 xzn18 3xsb16
Chemistry of Materials, 2018Co-Authors: Tori Cox, Volodymyr Gvozdetskyi, Bryan Owensbaird, Julia V. ZaikinaAbstract:A new antimonide K8–xZn18+3xSb16 was synthesized using reactive Potassium Hydride KH as a precursor. Owing to intimate mixing of starting materials, the Hydride route allows rapid phase “screening” of ternary systems and is particularly suitable for the search of new antimonides. The crystal structure of K8–xZn18+3xSb16 (x = 1.12(8); P42/nmc (no. 137), a = 12.3042(5) A, c = 7.3031(3) A, V = 1105.6(1) A3, R1 = 0.029) has a [Zn18Sb16] framework with large channels alternately filled by K cations and Zn3 triangular units. The Zn3 triangles break the channels into finite cages by forming covalent bonds to the framework, preventing K migration along the channel. This structural feature is responsible for its stability in air, uncommon for this class of compounds, as well as for its low thermal conductivity. Transport property measurement and computational analysis of the electronic structure indicate that the title compound is a semimetal with properties highly dependent on the precise composition, i.e., the K...
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Rapid Phase Screening via Hydride Route: A Discovery of K8–xZn18+3xSb16
2018Co-Authors: Tori Cox, Volodymyr Gvozdetskyi, Bryan Owens-baird, Julia V. ZaikinaAbstract:A new antimonide K8–xZn18+3xSb16 was synthesized using reactive Potassium Hydride KH as a precursor. Owing to intimate mixing of starting materials, the Hydride route allows rapid phase “screening” of ternary systems and is particularly suitable for the search of new antimonides. The crystal structure of K8–xZn18+3xSb16 (x = 1.12(8); P42/nmc (no. 137), a = 12.3042(5) Å, c = 7.3031(3) Å, V = 1105.6(1) Å3, R1 = 0.029) has a [Zn18Sb16] framework with large channels alternately filled by K cations and Zn3 triangular units. The Zn3 triangles break the channels into finite cages by forming covalent bonds to the framework, preventing K migration along the channel. This structural feature is responsible for its stability in air, uncommon for this class of compounds, as well as for its low thermal conductivity. Transport property measurement and computational analysis of the electronic structure indicate that the title compound is a semimetal with properties highly dependent on the precise composition, i.e., the K/Zn3 ratio in the channels. The Hydride preparative route provides accurate control over the composition of the target phase, thereby facilitating transport properties tuning. This synthetic method will allow for the synthesis of novel alkali metal antimonides as well as for the development of functional materials via precise compositional control
Andrzej Stolarzewicz - One of the best experts on this subject based on the ideXlab platform.
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study of the structure of poly methyl methacrylate obtained in the presence of Potassium Hydride
Rapid Communications in Mass Spectrometry, 2000Co-Authors: Andrzej Stolarzewicz, Barbara Morejkobuz, Dorota NeugebauerAbstract:Electrospray ionization mass spectrometry (ESI-MS) in positive- and negative-ion mode and multi-step tandem mass spectrometry (ESI-MS ( n) ) were selected for the determination of the structure of poly(methyl methacrylate) obtained using Potassium Hydride as initiator. Macromolecules with methoxy and methyl starting groups, i. e. those situated at the beginning of the polymer backbone, were observed in this case. No other differences in the chain structure were found in the polymer.
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influence of substituent on the polymerization of oxiranes by Potassium Hydride
Macromolecular Chemistry and Physics, 1999Co-Authors: Andrzej Stolarzewicz, Dorota NeugebauerAbstract:The polymerization of butoxymethyl-, ethyl-, methyl-, phenoxymethyl-, phenyl- and 2-propen-1-yloxymethyloxirane in the presence of Potassium Hydride suspension in tetrahydrofuran with 18-crown-6 was studied. The influence of polar and steric effects of substituent on the reaction rate is described. The appropriate correlation equation is derived. The chain transfer reaction to the monomer, found to occur only in the polymerization of methyloxirane, results in lower molecular weight and higher polydispersity of poly(methyloxirane) as compared with other polymers obtained.
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influence of the kind of crown ether on the heterogeneous polymerization of propylene oxide in the presence of Potassium Hydride
Macromolecular Chemistry and Physics, 1998Co-Authors: Andrzej Stolarzewicz, Dorota NeugebauerAbstract:The influence of 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6 and dicyclo-hexano-24-crown-8 on the propylene oxide polymerization with Potassium Hydride was studied. The highest reaction rate was obtained in the presence of 18-crown-6 or dicyclohexano-18-crown-6. The use of dicyclohexano-18-crown-6 was found to enhance the molecular mass of polymers more than other ligands. The observed effects were related to the heterogeneity of the reaction mixture and the structure of the crown ether complexes with the Potassium cation.
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Potassium Hydride the new initiator for anionic polymerization of oxiranes
Macromolecular Rapid Communications, 1996Co-Authors: Andrzej Stolarzewicz, Dorota Neugebauer, Janusz GrobelnyAbstract:Potassium Hydride with 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) was used in the anionic polymerization of (butoxymethyl)oxirane. Polymers with low ratio of mass- to number average molar masses (M w /M n < 1.1) were obtained, each macromolecule being terminated (after hydrolysis) with hydroxyl group on both of its ends. Chain transfer reactions to the monomer were not observed to operate in this system
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anionic polymerization of carbazolyl substituted oxiranes initiated by Potassium alkalide Potassium tert butoxide and Potassium Hydride
Macromolecular Chemistry and Physics, 1995Co-Authors: Gintaras Buika, Juozas Vidas Gražulevicius, Andrzej Stolarzewicz, Zbigniew GrobelnyAbstract:The influence of the kind of initiating system and the addition of a crown ether on the anionic polymerization of oxiranes with a carbazoyl substituent (9-carbazolylmethyloxirane, 2-(9-carbazolyl)ethoxymethyloxirane and 1,3-bis(9-carbazolyl)propan-2-yloxymethyloxirane) is described. Potassium alkalide, Potassium tert-butoxide and Potassium Hydride were used as initiators. Selecting a suitable initiator and crown ether concentration, carbazolyl-containing polymers with polymerization degrees from 4 to 60 can be produced. Using a suspension of Potassium Hydride in tetrahydrofuran, polymers with relatively high molar masses were obtained
Bryan Owensbaird - One of the best experts on this subject based on the ideXlab platform.
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rapid phase screening via Hydride route a discovery of k8 xzn18 3xsb16
Chemistry of Materials, 2018Co-Authors: Tori Cox, Volodymyr Gvozdetskyi, Bryan Owensbaird, Julia V. ZaikinaAbstract:A new antimonide K8–xZn18+3xSb16 was synthesized using reactive Potassium Hydride KH as a precursor. Owing to intimate mixing of starting materials, the Hydride route allows rapid phase “screening” of ternary systems and is particularly suitable for the search of new antimonides. The crystal structure of K8–xZn18+3xSb16 (x = 1.12(8); P42/nmc (no. 137), a = 12.3042(5) A, c = 7.3031(3) A, V = 1105.6(1) A3, R1 = 0.029) has a [Zn18Sb16] framework with large channels alternately filled by K cations and Zn3 triangular units. The Zn3 triangles break the channels into finite cages by forming covalent bonds to the framework, preventing K migration along the channel. This structural feature is responsible for its stability in air, uncommon for this class of compounds, as well as for its low thermal conductivity. Transport property measurement and computational analysis of the electronic structure indicate that the title compound is a semimetal with properties highly dependent on the precise composition, i.e., the K...
Douglass F. Taber - One of the best experts on this subject based on the ideXlab platform.
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Potassium Hydride in paraffin a useful base for williamson ether synthesis
ChemInform, 2010Co-Authors: Haihong Huang, Christopher G Nelson, Douglass F. TaberAbstract:A procedure for the preparation of KH in paraffin from Potassium metal and hydrogen is developed.
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Potassium Hydride in paraffin a useful base for williamson ether synthesis
Tetrahedron Letters, 2010Co-Authors: Haihong Huang, Christopher G Nelson, Douglass F. TaberAbstract:Abstract A procedure for the preparation of Potassium Hydride in paraffin from Potassium metal has been developed. The KH (P) so produced proved to be an efficient base for the Williamson ether synthesis.
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Potassium Hydride in paraffin a useful base for organic synthesis
ChemInform, 2007Co-Authors: Douglass F. Taber, Christopher G NelsonAbstract:The preparation of Potassium Hydride as a 1:1 homogenate with paraffin, termed KH(P), is reported. KH(P), a solid at room temperature, is stable without special handling. On suspension in THF with a phosphonium salt, KH(P) rapidly generates the ylide. Wittig condensation with aromatic, aliphatic, and α,β-unsaturated aldehydes proceeds with high Z selectivity. KH(P) should be a generally useful base for organic synthesis.
Dorota Neugebauer - One of the best experts on this subject based on the ideXlab platform.
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study of the structure of poly methyl methacrylate obtained in the presence of Potassium Hydride
Rapid Communications in Mass Spectrometry, 2000Co-Authors: Andrzej Stolarzewicz, Barbara Morejkobuz, Dorota NeugebauerAbstract:Electrospray ionization mass spectrometry (ESI-MS) in positive- and negative-ion mode and multi-step tandem mass spectrometry (ESI-MS ( n) ) were selected for the determination of the structure of poly(methyl methacrylate) obtained using Potassium Hydride as initiator. Macromolecules with methoxy and methyl starting groups, i. e. those situated at the beginning of the polymer backbone, were observed in this case. No other differences in the chain structure were found in the polymer.
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influence of substituent on the polymerization of oxiranes by Potassium Hydride
Macromolecular Chemistry and Physics, 1999Co-Authors: Andrzej Stolarzewicz, Dorota NeugebauerAbstract:The polymerization of butoxymethyl-, ethyl-, methyl-, phenoxymethyl-, phenyl- and 2-propen-1-yloxymethyloxirane in the presence of Potassium Hydride suspension in tetrahydrofuran with 18-crown-6 was studied. The influence of polar and steric effects of substituent on the reaction rate is described. The appropriate correlation equation is derived. The chain transfer reaction to the monomer, found to occur only in the polymerization of methyloxirane, results in lower molecular weight and higher polydispersity of poly(methyloxirane) as compared with other polymers obtained.
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influence of the kind of crown ether on the heterogeneous polymerization of propylene oxide in the presence of Potassium Hydride
Macromolecular Chemistry and Physics, 1998Co-Authors: Andrzej Stolarzewicz, Dorota NeugebauerAbstract:The influence of 12-crown-4, 15-crown-5, 18-crown-6, dicyclohexano-18-crown-6 and dicyclo-hexano-24-crown-8 on the propylene oxide polymerization with Potassium Hydride was studied. The highest reaction rate was obtained in the presence of 18-crown-6 or dicyclohexano-18-crown-6. The use of dicyclohexano-18-crown-6 was found to enhance the molecular mass of polymers more than other ligands. The observed effects were related to the heterogeneity of the reaction mixture and the structure of the crown ether complexes with the Potassium cation.
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Potassium Hydride the new initiator for anionic polymerization of oxiranes
Macromolecular Rapid Communications, 1996Co-Authors: Andrzej Stolarzewicz, Dorota Neugebauer, Janusz GrobelnyAbstract:Potassium Hydride with 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) was used in the anionic polymerization of (butoxymethyl)oxirane. Polymers with low ratio of mass- to number average molar masses (M w /M n < 1.1) were obtained, each macromolecule being terminated (after hydrolysis) with hydroxyl group on both of its ends. Chain transfer reactions to the monomer were not observed to operate in this system