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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
Carbene is one of the most reactive organic intermediates capable of forming C–C bonds with graphene. This intermediate mainly undergoes an insertion reaction with C–H, X–H bond (where X=O, S, N), and cyclopropanation reaction (cycloaddition type [1+2]) with C=C to give a three-membered cycloalkane. As graphene has the basis of sp2 carbon and some sp3 carbon present in the edge or defect, it gives an opening as an interactive site for carbene to form a functionalized graphene. Highly reactive carbene is mainly produced from the haloform and cyclic diazoalkane precursor. The chloroform in the concentrated alkaline medium forms in situ dichlorocarbene. This electron-deficient carbene can be transferred to graphene nanoplates and form a three-membered ring by the [1+2] addition reaction. Sainsbury et al. (2016) exhibited covalent functionalization of graphene with dibromocarbene in additive fashion and tuned the electronic properties. The intermediate generated from the bromoform in situ and can be modified with nucleophilic substitution or reductive coupling as shown in Figure 4.7.
Reactions of thiocarbonyl compounds with electrophilic and nucleophilic carbenes as well as with their metal complexes
Published in Journal of Sulfur Chemistry, 2020
Grzegorz Mlostoń, Heinz Heimgartner
Another method to generate reactive thiocarbonyl ylides comprises the electrophilic attack of a two-valent carbene 8 or carbenoid onto the electron-rich sulfur atom of the C = S group. Diazomethane derivatives are known as the most important source of carbenes/carbenoids, which are formed upon heating, photolysis or by metal-assisted decomposition. It is well established that diazomethanes, functionalized at the α-position with electron withdrawing groups, display reduced reactivity as 1,3-dipoles, and in most cases their reactions with thiocarbonyl groups require the involvement of a catalyst to change the reaction type from the [3 + 2]-cycloaddition to the electrophilic approach of the carbene. The formation of thiocarbonyl ylides can also be achieved when reactive carbenes are generated from other precursors, e.g. dichlorocarbene from chloroform in a two-phase system or by thermal decomposition of Seyfert's reagent (PhHgCCl3).