China
Africa
Explore chapters and articles related to this topic
Biofabrication of Graphene Oxide Nanosheets
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
In organic chemistry by addition reactions, two or more molecules combine to form larger molecule via electrophilic attack or biradical pathway. Interestingly, a nitrene (R-N:) is the nitrogen analogue of a carbene. Having six valence electrons (two for C-N covalent bond, two for two p-orbitals and remaining two as a lone pair of electrons), nitrogen atom is coined as an electrophile. This nitrene is a reactive intermediate and participates in many chemical reactions via (1,3) cycloaddition or biradical pathway to form functionalized GO surfaces (He and Gao, 2010). In addition, a nitrene intermediate can undergo C-H insertion via an oxime or acetic anhydride formation which results in cyclo compounds (Savarin et al., 2007). This nitrene-based method is used for the functionalization of epitaxial rapheme (Choi et al., 2009). Similarly, rGO surfaces are modified after grafting GO surfaces with maleic anhydride (Hsiao et al, 2010) or polyacetylene (Vadukumpully et al., 2011).
Structural Design for Molecular Catalysts
Published in Qingmin Ji, Harald Fuchs, Soft Matters for Catalysts, 2019
Qingmin Ji, Qin Tang, Jonathan P. Hill, Katsuhiko Ariga
Various ligands have been employed for the Cu center, to enhance its reactivity, selectivity, and stability. Several privileged ligand structures have proven to be extremely versatile and useful ligands, especially iminopyridines, which show particular effectiveness in stereoselective transformations such as nitroaldol reactions, allylic oxidations, and conjugate additions. Chelucci et al. evaluated the catalytic efficiency of Cu complexes with chiral iminopyridine ligands in carbene (cyclopropanation) and nitrene transfer reactions (aziridination, C–H amidation) [47]. They found that a better catalytic performance can be achieved for nitrene transfers, particularly in the amidation of C–H bonds.
Functionalization of Graphite and Graphene
Published in Titash Mondal, Anil K. Bhowmick, Graphene-Rubber Nanocomposites, 2023
Akash Ghosh, Simran Sharma, Anil K. Bhowmick, Titash Mondal
Nitrene-based chemical modification of carbon nanomaterial is well known for synthesizing functional and smart materials. Organic azides are a significant source for nitrene generation, which initiates the C–N bond formation. This azide group liberates a molecule of nitrogen gas and a highly active nitrene in the presence of heat or light. However, there are plenty of azides in the market; but aromatic azide has attracted the scientific community for its various isomeric forms. A singlet phenyl azide gets isomerized to benzazirine and further to cyclic ketone imine. Both the singlet and the triplet do not react with alkene or alkane.
The gas-phase pyrolysis of methyl azidoformate in the absence and presence of water: a theoretical study
Published in Molecular Physics, 2019
The mechanisms of decomposition of a number of other organic azides including 2-azidoacetic acid (N3CH2COOH) [18,19], 2-azidoacetone (N3CH2COCH3) [20], 2-azidoethanol (N3CH2CH2OH) and 2-azidoethyl acetate (N3CH2COOCH2CH3) [21], 2-azidoacetamide (N3CH2CONH2) [22], methyl azidoformate (MA) (N3COOCH3) and ethyl azidoformate (N3COOCH2CH3) [23], sulfonyl azide (CF3SO2N3) [24] and phenyl azidoformate (PhOC(O)N3) [25] have been also investigated experimentally or theoretically. Particularly, Dyke et al. [23] studied the thermal decomposition pathways of MA using matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy and developed a pyrolysis mechanism for MA based on the observed products HNCO, H2CO, CH2NH and CO2 and the results of molecular orbital calculations. Theoretically, Dyke et al. [23] constructed the energy profile for the studied reaction at the MP2/6-31G** level. The mechanism is a stepwise process analogous to the one traditionally proposed for alkyl azides. First, a nitrene is formed by the release of molecular N2. Then, the nascent nitrene can undergo intramolecular hydrogen migration to produce a four-membered-ring intermediate, followed by dissociation to produce the final products. However, they did not find the Curtius-type rearrangement route and the reaction pathway that the four-membered-ring intermediate produces directly from the reactant.