Selective Si–O–Si Bond Cleavage as Synthetic Access to Functionalized, Hydrolysis-stable Zinc Silanolates

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1558-s1579 ◽  
Author(s):  
Christian Däschlein ◽  
Carsten Strohmann
Keyword(s):  
Solid State ◽  
High Stability ◽  
Bond Cleavage ◽  
Structural Studies ◽  
Nmr Studies ◽  
Molecular Systems ◽  
Simple Treatment ◽  
Mild Conditions ◽  
Long Time ◽  
Hydrolysis Of

The selective cleavage of the strong and poorly reactive Si-O-Si bond in functionalized siloxanes under mild conditions is a decisive task for modern synthetic chemistry. Simple treatment of the aminomethyl-functionalized disiloxanes 1, 6, (R,R)-7 and 8 ([R2(CH2NR')SiO]2, R =Me or Ph, NR'= NC5H10, NC5H8(CH3)2 or NC4H7(CH3)) with zinc(II) bromide and zinc(II) chloride, respectively, results in the formation of highly hydrolysis-stable, molecular zinc silanolates which were long time supposed to be unstable in the presence of water. Both, the selective cleavage of the Si-O-Si bond as well as the formation of the molecular zinc silanolates are independent of the substituents at silicon, the used zinc(II) salt or the aminomethyl side arm. Detailed structural studies showed that zwitterionic interactions are the reason for the high stability towards hydrolysis of the formed zinc silanolates 9, 10, (R,R)-11 and 12. NMR studies are indicative of the same structure of these molecular systems in solution as in the solid state

Raman and NMR Studies of Hydrous Sodium Titanates

1988 ◽  
Vol 121 ◽  
Author(s):  
B. C. Bunker ◽  
C.H.F. Peden ◽  
D. R. Tallant ◽  
S. L. Martinez ◽  
G. L. Turner
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Ion Exchange ◽  
Catalyst Support ◽  
Sodium Titanate ◽  
Titanium Isopropoxide ◽  
Nmr Studies ◽  
Support Materials ◽  
Hydrolysis Of

ABSTRACTRaman and solid state 17O NMR spectroscopies have been used to determine the molecular structure of amorphous hydrous sodium titanate catalyst support materials prepared by hydrolysis of titanium isopropoxide. Three types of oxygens have been identified: oxygens bridging three titanium atoms, oxygens bridging two titaniums, and non-bridging oxygens. Changes in the relative populations of the different oxygen types have been used to help understand the ion-exchange and polymerization properties of hydrous titanates.

scholarly journals Selective Partial Hydrolysis of 2-isopropyl-2-oxazoline Copolymers towards Decreasing the Ability to Crystallize

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3403
Author(s):  
Natalia Oleszko-Torbus ◽  
Barbara Mendrek ◽  
Agnieszka Kowalczuk ◽  
Alicja Utrata-Wesołek ◽  
Andrzej Dworak ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermal Properties ◽  
Solid State ◽  
Polymer Chain ◽  
Partial Hydrolysis ◽  
Selective Hydrolysis ◽  
Mild Conditions ◽  
Cytotoxicity Studies ◽  
Hydrolysis Of ◽  
Potential Use

Poly(2-isopropyl-2-oxazoline) (PiPrOx) is readily prone to crystallization both in solid and from solutions. This feature is detrimental for certain applications. Here, we examine whether the presence of unsubstituted ethyleneimine (EI) units, a gradient distributed within a polymer chain composed of 2-isopropyl-2-oxazoline (iPrOx) and 2-methyl-2-oxazoline (MOx) units, decreases the ability to crystallize the copolymer and affects thermal properties compared to the homopolymer of iPrOx. We assumed that the separation of stiff iPrOx units by the more flexible EI will affect the spatial arrangements of the ordered chains, slightly plasticize and, as a result, decrease their ability to crystallize. The selective hydrolysis of gradient iPrOx and 2-methyl-2-oxazoline (MOx) copolymers, carried out under mild conditions, led to iPrOx/MOx/EI copolymers. To the best of our knowledge, the selective hydrolysis of these copolymers has never been carried out before. Their thermal properties and crystallization abilities, both in a solid state and from an aqueous solution, were analyzed. Based on the analysis of polymer charge and cytotoxicity studies, the potential use of the copolymers obtained was indicated in some biological systems.

The Interaction of the [B10H10]2- Cage with Lewis Acids and the Formation of Decaborane Derivatives by Cage-Opening Reactions

1997 ◽  
Vol 62 (8) ◽  
pp. 1273-1278 ◽  
Author(s):  
Bernard Bonnetot ◽  
Philippe Miele ◽  
Daoud Naoufal ◽  
Henri Mongeot
Keyword(s):  
Solid State ◽  
Electron Donor ◽  
Lewis Acids ◽  
Preliminary Step ◽  
Mild Conditions ◽  
Reaction Proceeds ◽  
Stretching Vibrations ◽  
Hydrolysis Of

The interaction of hydroborates M2[B10H10] (M = NH4, Et4N, Bu4N, etc.) or Et4N[B10H9-NH2COCH3] with Lewis acids AlX3 (X = Cl, Br, I) in the solid state is sufficiently strong to produce an increase of more than 85 cm-1 of the BH stretching vibrations. A similar interaction was not observed for the hydroborate (NH4)2[B10H9I] owing to the electronegativity of the iodine substituent which hampers the electron donor properties of the cage. Hydrolysis of (AlX3)n-[B10H10]2- adducts under mild conditions results in opening of the boron cage with the formation of halodecaboranes 6-B10H13X. It seems that this reaction proceeds only when the above adducts can form in a preliminary step. Pure hexane solutions of 6-B10H13X were easily obtained with a 45% yield for X = Cl or Br and a 30% yield when X = I.

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

Electron Donation by Low-Crystalline Ba-La-Ce Oxygen-Deficient Composite Oxide Accumulating on Ru Nanoparticles for Ammonia Synthesis under Mild Conditions

2019 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Bond Cleavage ◽  
Synthesis Process ◽  
Strong Electron ◽  
Mild Conditions ◽  
Ru Nanoparticles ◽  
Rate Determining Step ◽  
Highly Active ◽  
Composite Oxides ◽  
Low Crystalline

<p>To mitigate global problems related to energy and global warming, it is helpful to develop an ammonia synthesis process using catalysts that are highly active under mild conditions. Here we show that the ammonia synthesis activity of Ru/Ba/LaCeO<i><sub>x</sub></i> pre-reduced at 700 °C is the highest reported among oxide-supported Ru catalysts. Our results indicate that low crystalline oxygen-deficient composite oxides, which include Ba<sup>2+</sup>, Ce<sup>3+</sup> and La<sup>3+</sup>, with strong electron-donating ability, accumulate on Ru particles and thus promote N≡N bond cleavage, which is the rate determining step for ammonia synthesis.</p>

New Copper Compounds with Antiplatelet Aggregation Activity

2019 ◽  
Vol 15 (8) ◽  
pp. 850-862
Author(s):  
Mirthala Flores-García ◽  
Juan Manuel Fernández-G. ◽  
Cristina Busqueta-Griera ◽  
Elizabeth Gómez ◽  
Simón Hernández-Ortega ◽  
...  
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Thrombotic Event ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Schiff Base Ligands ◽  
X Ray ◽  
Antiplatelet Aggregation ◽  
Aggregation Activity ◽  
L1 And L2

Background: Ischemic heart disease, cerebrovascular accident, and venous thromboembolism have the presence of a thrombotic event in common and represent the most common causes of death within the population. Objective: Since Schiff base copper(II) complexes are able to interact with polyphosphates (PolyP), a procoagulant and potentially prothrombotic platelet agent, we investigated the antiplatelet aggregating properties of two novel tridentate Schiff base ligands and their corresponding copper( II) complexes. Methods: The Schiff base ligands (L1) and (L2), as well as their corresponding copper(II) complexes (C1) and (C2), were synthesized and characterized by chemical analysis, X-ray diffraction, mass spectrometry, and UV-Visible, IR and far IR spectroscopy. In addition, EPR studies were carried out for (C1) and (C2), while (L1) and (L2) were further analyzed by 1H and 13C NMR. Tests for antiplatelet aggregation activities of all of the four compounds were conducted. Results: X-ray diffraction studies show that (L1) and (L2) exist in the enol-imine tautomeric form with a strong intramolecular hydrogen bond. NMR studies show that both ligands are found as enol-imine tautomers in CDCl3 solution. In the solid state, the geometry around the copper(II) ion in both (C1) and (C2) is square planar. EPR spectra suggest that the geometry of the complexes is similar to that observed in the solid state by X-ray crystallography. Compound (C2) exhibited the strongest antiplatelet aggregation activity. Conclusion: Schiff base copper(II) complexes, which are attracting increasing interest, could represent a new approach to treat thrombosis by blocking the activity of PolyP with a potential anticoagulant activity and, most importantly, demonstrating no adverse bleeding events.

Effect of removing hemicellulose and lignin synchronously under mild conditions on enzymatic hydrolysis of corn stover

2020 ◽  
Vol 204 ◽  
pp. 106407 ◽  
Author(s):  
Shengxin An ◽  
Wenzhi Li ◽  
Fengyang Xue ◽  
Xu Li ◽  
Ying Xia ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Corn Stover ◽  
Mild Conditions ◽  
Hydrolysis Of

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

ChemInform Abstract: HPLC and 1H NMR Studies of Alkaline Hydrolysis of Some 7-(Oxyiminoacyl) cephalosporins.

ChemInform ◽  
2010 ◽  
Vol 25 (11) ◽  
pp. no-no
Author(s):  
B. VILANOVA ◽  
F. MUNOZ ◽  
J. DONOSO ◽  
F. GARCIA BLANCO
Keyword(s):  
1H Nmr ◽  
Alkaline Hydrolysis ◽  
Nmr Studies ◽  
Hydrolysis Of
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