Skeletal Rearrangements of Deprotonated Organosilanes in the Gas Phase. Silicon-Oxygen Bond Formation

1990 ◽  
Vol 43 (3) ◽  
pp. 511 ◽  
Author(s):  
KM Downard ◽  
JH Bowie ◽  
RN Hayes
Keyword(s):  
Carboxylic Acid ◽  
Gas Phase ◽  
Collisional Activation ◽  
Bond Formation ◽  
Rearrangement Reactions ◽  
Skeletal Rearrangements ◽  
Oxygen Bond ◽  
Silicon Oxygen

Trimethylsilyl anions containing additional alkoxy, ketone or carboxylic acid funtionality undergo a variety of rearrangement reactions upon collisional activation. The most common are those which involve production of Si -O bonds, either by formation of Me3SiO- or by elimination of Me3SiOH.

scholarly journals Experimental Determination of Activation Energies for Covalent Bond Formation via Ion/Ion Reactions and Competing Processes

2021 ◽  
Author(s):  
Melanie Cheung See Kit ◽  
Samantha O. Shepherd ◽  
James Prell ◽  
Ian Webb
Keyword(s):  
Gas Phase ◽  
Collisional Activation ◽  
Collision Cross Section ◽  
Bond Formation ◽  
Protein Structures ◽  
Covalent Bond ◽  
Activation Energies ◽  
Supporting Evidence ◽  
Simple Modification ◽  
Covalent Bond Formation

The combination of ion/ion chemistry with commercially available ion mobility/mass spectrometry systems has allowed rich structural information to be obtained for gaseous protein ions. Recently, the simple modification of such an instrument with an electrospray reagent source has allowed three-dimensional gas-phase interrogation of protein structures through covalent and non-covalent interactions coupled with collision cross section measurements. However, the energetics of these processes have not yet been studied quantitatively. In this work, previously developed Monte Carlo simulations of ion temperatures inside traveling wave ion guides are used to characterize the energetics of the transition state of activated ubiquitin cation/reagent anion long-lived complexes formed via ion/ion reactions. The ΔH<sup>‡</sup> and ΔS<sup>‡</sup> of major processes observed from collisional activation of long-lived gas phase ion/ion complexes, namely collision induced unfolding (CIU), covalent bond formation, or neutral loss of the anionic reagent via intramolecular proton transfer, were determined. Covalent bond formation via ion/ion complexes was found to be significantly lower energy compared to unfolding and bond cleavage. ΔG<sup>‡</sup> of activation of all three processes lie between 55 and 75 kJ/mol, easily accessible with moderate collisional activation. Bond formation is favored over reagent loss at lower activation energies, whereas reagent loss becomes competitive at higher collision energies. Though ΔG<sup>‡</sup> are between CIU of a precursor ion and covalent bond formation of its ion/ion product complex are comparable, our data suggest covalent bond formation does not require extensive isomerization, supporting evidence from previous structural studies that these ion/ion reactions measure compact gas phase structures.

Enzyme mediated silicon–oxygen bond formation; the use of Rhizopus oryzae lipase, lysozyme and phytase under mild conditions

2010 ◽  
Vol 39 (39) ◽  
pp. 9361 ◽  
Author(s):  
Vincenzo Abbate ◽  
Alan R. Bassindale ◽  
Kurt F. Brandstadt ◽  
Rachel Lawson ◽  
Peter G. Taylor
Keyword(s):  
Rhizopus Oryzae ◽  
Bond Formation ◽  
Rhizopus Oryzae Lipase ◽  
Mild Conditions ◽  
Oxygen Bond ◽  
Silicon Oxygen

Organocatalytic Electrochemical C–H Lactonization of Aromatic Carboxylic Acids

Synthesis ◽  
2018 ◽  
Vol 50 (15) ◽  
pp. 2924-2929 ◽  
Author(s):  
Sanzhong Luo ◽  
Longji Li ◽  
Qi Yang ◽  
Zongbin Jia
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Glassy Carbon ◽  
Bond Formation ◽  
Carbon Electrodes ◽  
Glassy Carbon Electrodes ◽  
Aromatic Carboxylic Acids ◽  
Radical Substitution ◽  
Carboxyl Radical ◽  
Oxygen Bond

An electrochemical strategy has been developed for radical arene carbon–oxygen bond formation. This reaction utilizes DDQ as a redox mediator, with inexpensive glassy carbon electrodes to facilitate an intramolecular lactonization of biphenyl-2-carboxylic acid derivatives via aromatic carboxyl radical substitution to give 6H-benzo[c]chromen-6-ones.

scholarly journals Experimental Determination of Activation Energies for Covalent Bond Formation via Ion/Ion Reactions and Competing Processes

2021 ◽  
Author(s):  
Melanie Cheung See Kit ◽  
Samantha O. Shepherd ◽  
James Prell ◽  
Ian Webb
Keyword(s):  
Gas Phase ◽  
Collisional Activation ◽  
Collision Cross Section ◽  
Bond Formation ◽  
Protein Structures ◽  
Covalent Bond ◽  
Activation Energies ◽  
Supporting Evidence ◽  
Simple Modification ◽  
Covalent Bond Formation

The combination of ion/ion chemistry with commercially available ion mobility/mass spectrometry systems has allowed rich structural information to be obtained for gaseous protein ions. Recently, the simple modification of such an instrument with an electrospray reagent source has allowed three-dimensional gas-phase interrogation of protein structures through covalent and non-covalent interactions coupled with collision cross section measurements. However, the energetics of these processes have not yet been studied quantitatively. In this work, previously developed Monte Carlo simulations of ion temperatures inside traveling wave ion guides are used to characterize the energetics of the transition state of activated ubiquitin cation/reagent anion long-lived complexes formed via ion/ion reactions. The ΔH<sup>‡</sup> and ΔS<sup>‡</sup> of major processes observed from collisional activation of long-lived gas phase ion/ion complexes, namely collision induced unfolding (CIU), covalent bond formation, or neutral loss of the anionic reagent via intramolecular proton transfer, were determined. Covalent bond formation via ion/ion complexes was found to be significantly lower energy compared to unfolding and bond cleavage. ΔG<sup>‡</sup> of activation of all three processes lie between 55 and 75 kJ/mol, easily accessible with moderate collisional activation. Bond formation is favored over reagent loss at lower activation energies, whereas reagent loss becomes competitive at higher collision energies. Though ΔG<sup>‡</sup> are between CIU of a precursor ion and covalent bond formation of its ion/ion product complex are comparable, our data suggest covalent bond formation does not require extensive isomerization, supporting evidence from previous structural studies that these ion/ion reactions measure compact gas phase structures.

Amine catalysed silicon–oxygen bond formation

2005 ◽  
Vol 8 (12) ◽  
pp. 1082-1084 ◽  
Author(s):  
Kaustavmoni Deka ◽  
Rupam Jyoti Sarma ◽  
Jubaraj B. Baruah
Keyword(s):  
Bond Formation ◽  
Oxygen Bond ◽  
Silicon Oxygen

A large scale enzyme screen in the search for new methods of silicon–oxygen bond formation

2011 ◽  
Vol 105 (2) ◽  
pp. 268-275 ◽  
Author(s):  
Vincenzo Abbate ◽  
Alan R. Bassindale ◽  
Kurt F. Brandstadt ◽  
Peter G. Taylor
Keyword(s):  
Large Scale ◽  
Bond Formation ◽  
New Methods ◽  
Oxygen Bond ◽  
Silicon Oxygen

Formation of Carbon-Oxygen Bond Mediated by Hypervalent Iodine Reagents Under Metal-free Conditions

2020 ◽  
Vol 17 ◽  
Author(s):  
Ayesha Jalil ◽  
Yaxin O Yang ◽  
Zhendong Chen ◽  
Rongxuan Jia ◽  
Tianhao Bi ◽  
...  
Keyword(s):  
Natural Products ◽  
Bond Formation ◽  
Building Blocks ◽  
Review Article ◽  
Hypervalent Iodine ◽  
Metal Free ◽  
Bioactive Natural Products ◽  
The Past ◽  
Oxygen Bond ◽  
Privileged Scaffolds

: Hypervalent iodine reagents are a class of non-metallic oxidants have been widely used in the construction of several sorts of bond formations. This surging interest in hypervalent iodine reagents is essentially due to their very useful oxidizing properties, combined with their benign environmental character and commercial availability from the past few decades ago. Furthermore, these hypervalent iodine reagents have been used in the construction of many significant building blocks and privileged scaffolds of bioactive natural products. The purpose of writing this review article is to explore all the transformations in which carbon-oxygen bond formation occurred by using hypervalent iodine reagents under metal-free conditions

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