Kinetics of Nonideal Hyperbranched Polymerizations. 2. Kinetic Analysis of the Polycondensation of 3,5-Bis(trimethylsiloxy)benzoyl chloride Using NMR Spectroscopy†

2003 ◽  
Vol 36 (1) ◽  
pp. 97-108 ◽  
Author(s):  
Dirk Schmaljohann ◽  
Hartmut Komber ◽  
Joshua G. Barratt ◽  
Dietmar Appelhans ◽  
Brigitte I. Voit
Keyword(s):  
Nmr Spectroscopy ◽  
Kinetic Analysis ◽  
Benzoyl Chloride ◽  
Kinetics Of

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

1980 ◽  
Vol 45 (8) ◽  
pp. 2219-2223 ◽  
Author(s):  
Marie Jakoubková ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Electron Density ◽  
Phosphorus Atom ◽  
Proton Acceptor ◽  
Trimethylsilyl Group ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

Kinetics of Alkali-Catalyzed Monomethylol Phenol Formation for F/P < 1 by 1H NMR Spectroscopy for Ablative Applications

2021 ◽  
Author(s):  
Praveen Kumar Solasa ◽  
Manu Saraswathi Kesava Pillai ◽  
Vijendra Kumar ◽  
Ancy Smitha Alex ◽  
Srinivas Chinthalapalli ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Kinetics Of

scholarly journals Effect of Pyridine and Tribenzylamine on the Hydrolysis Kinetics of Benzoyl Chloride in Water-Dioxane System

2017 ◽  
Vol 29 (9) ◽  
pp. 1888-1890
Author(s):  
Mohammad A. Batiha ◽  
Elena A. Chizhova ◽  
Marwan M. Batiha ◽  
Leema A. Al-Makhadmeh ◽  
Saleh Rawadieh ◽  
...  
Keyword(s):  
Benzoyl Chloride ◽  
Hydrolysis Kinetics ◽  
Kinetics Of

scholarly journals Biochemical elucidation of citrate accumulation in Synechocystis sp. PCC 6803 via kinetic analysis of aconitase

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maki Nishii ◽  
Shoki Ito ◽  
Noriaki Katayama ◽  
Takashi Osanai
Keyword(s):  
Kinetic Analysis ◽  
Chemical Equilibrium ◽  
Isocitrate Dehydrogenase ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Unicellular Cyanobacterium ◽  
Citrate Accumulation ◽  
Kinetics Of ◽  
Synechocystis Sp ◽  
Pcc 6803

AbstractA unicellular cyanobacterium Synechocystis sp. PCC 6803 possesses a unique tricarboxylic acid (TCA) cycle, wherein the intracellular citrate levels are approximately 1.5–10 times higher than the levels of other TCA cycle metabolite. Aconitase catalyses the reversible isomerisation of citrate and isocitrate. Herein, we biochemically analysed Synechocystis sp. PCC 6803 aconitase (SyAcnB), using citrate and isocitrate as the substrates. We observed that the activity of SyAcnB for citrate was highest at pH 7.7 and 45 °C and for isocitrate at pH 8.0 and 53 °C. The Km value of SyAcnB for citrate was higher than that for isocitrate under the same conditions. The Km value of SyAcnB for isocitrate was 3.6-fold higher than the reported Km values of isocitrate dehydrogenase for isocitrate. Therefore, we suggest that citrate accumulation depends on the enzyme kinetics of SyAcnB, and 2-oxoglutarate production depends on the chemical equilibrium in this cyanobacterium.

Kinetics of the Friedel—Crafts Reaction, and Activity of Mixed Catalysts in the Reaction of Benzoyl Chloride with Toluene

1935 ◽  
Vol 57 (12) ◽  
pp. 2584-2589 ◽  
Author(s):  
Lawrence F. Martin ◽  
Philip Pizzolato ◽  
Lynn S. McWaters
Keyword(s):  
Benzoyl Chloride ◽  
Kinetics Of

scholarly journals Perphenazine-macrocycle conjugates divert Aβ42 towards non-toxic aggregates by monomer sequestration

2020 ◽  
Author(s):  
Sarah R Ball ◽  
Julius S P Adamson ◽  
Michael A Sullivan ◽  
Manuela R Zimmermann ◽  
Victor Lo ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Nmr Spectroscopy ◽  
Kinetic Analysis ◽  
Amyloid Β ◽  
Dimensional Structure ◽  
Amyloid Β Peptide ◽  
Monomeric Form ◽  
Starting Point ◽  
The Impact

AbstractThe amyloid-β peptide, the main protein component of amyloid plaques in Alzheimer’s disease, plays a key role in the neurotoxicity associated with the condition through the formation of small toxic oligomer species which mediate the disruption of calcium and glutamate homeostasis. The lack of therapeutic benefit associated with removal of mature amyloid-β fibrils has focused attention on the toxic oligomeric species formed during the process of fibril assembly. Here, we present the design and synthesis of a family of perphenazine-macrocyle conjugates. We find that two-armed perphenazine-cyclam conjugates divert the monomeric form of the amyloid-β peptide away from the amyloidogenic pathway into amorphous aggregates that are not toxic to differentiated SH-SY5Y cells in vitro. This strategy prevents the formation of damaging amyloid oligomers. Kinetic analysis of the effects of these compounds on the assembly pathway, together with NMR spectroscopy, identifies rapid monomer sequestration as the underlying neuroprotective mechanism. The ability to specifically target the monomeric form of amyloid-β allows for further understanding of the impact of the multiple species formed between peptide biogenesis and plaque deposition. The modular, three-dimensional structure of these compounds provides a starting point for the design of more potent modulators of this amyloid-forming peptide, and can be adapted to probe the protein self-assembly pathways associated with other proteinopathies.Significance statementThe aggregation pathway of the amyloid-β (Aβ) peptide in Alzheimer’s disease is complex and involves multiple different species. An inability to isolate and study the impact of distinct Aβ species has undermined efforts to develop effective therapies. To address this issue, we have developed a series of molecules that specifically sequester the monomeric form of the highly aggregation-prone Aβ42 peptide. Interaction with these molecules diverts Aβ42 from the amyloidogenic pathway and prevents formation of toxic oligomeric species. We use kinetic analysis and NMR spectroscopy to identify rapid monomer sequestration as the underlying neuroprotective mechanism. Future rational development of these molecules and characterisation of their interactions with Aβ will delineate the impact of different Aβ oligomers on neurobiology and pathology.

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