New Insights into the Diels–Alder Reaction of Graphene Oxide

Abstract

Graphene oxide is regarded as a major precursor for graphene-based materials. The development of graphene oxide based derivatives with new functionalities requires a thorough understanding of its chemical reactivity, especially for canonical synthetic methods such as the Diels-Alder cycloaddition. The Diels-Alder reaction has been successfully extended with graphene oxide as a source of diene by using maleic anhydride as a dienophile, thereby outlining the presence of the cis diene present in the graphene oxide framework. This reaction provides fundamental information for understanding the exact structure and chemical nature of graphene oxide. On the basis of high-resolution (13) C-SS NMR spectra, we show evidence for the formation of new sp(3) carbon centers covalently bonded to graphene oxide following hydrolysis of the reaction product. DFT calculations are also used to show that the presence of a cis dihydroxyl and C vacancy on the surface of graphene oxide are promoting the reaction with significant negative reaction enthalpies.

Are [6+4] Cycloadditions onto Graphene Possible?

“…Nevertheless, it represents a significant change with respect to pristine graphene since the reaction is possible thanks to the presence of these two oxygen atoms. These findings are in line with the results obtained by Brisebois et al., which indicated that the Diels‐Alder reactions are more likely to occur onto graphene oxide as compared with pristine graphene. In effect, the functional groups present in graphene oxide increase the diene character of graphene.…”

“…decided to investigate whether graphene can behave as diene or dienophile. This landmark investigation created a new subfield in the covalent functionalization of graphene, and several experimental and theoretical works have been performed to shed light into the thermodynamical and kinetics aspects of the [4+2] cycloadditions on 1D and 2D based carbon nanomaterials . Higher order [6+4] cycloaddition reactions are possible as Houk and Woodward showed as early as 1970, even though it is well known that they are much more difficult to attain than [4+2] Diels‐Alder reactions .…”

Heteroatom Promoted Cycloadditions for Graphene

“…Among them, we can highlight: the addition of aryl diazonium salts, alkylation, 1,3 dipolar cycloadditons, [2+2] cycloadditions, [2+1] cycloadditions . and the Diels‐Alder reactions, where graphene can be either diene or dienophile . As early as 2011, Sarkar et al .…”

“…High level theoretical calculations performed by us and Cao et al., showed that the central part of graphene, i. e. perfect graphene, is unreactive against TCNE, MA, 9MA and DMBD. Defects, edges, curvature, heating, force accelerated processes, or the presence of hydroxyl groups are required to achieve a successful Diels‐Alder reaction onto graphene. Bearing in mind that the diene/dienophile character of graphene depends on how the electron density is distributed over the CC bonds, we reasoned that it may be possible to facilitate Diels‐Alder reactions onto graphene by the introduction of the adequate heteroatoms onto graphene.…”

Functionalization of Graphene Oxide with Porphyrins: Synthetic Routes and Biological Applications

“…[105] Brisebois et al suggested that the reaction can occur through two different pathways: with a 1,3butadiene system (marked in red, Scheme 5a) or, through a cis-3,5-cyclohexadiene-1,2-diol system (marked in blue, Scheme 5b), in which both À OH groups are facing the opposite side of the MA addition to avoid steric hindrance. [106] GO may also act as a dienophile in addition to the previously discussed behavior as a diene. Tang et al have evaluated both the diene and dienophile character of GO in the presence of MA and of 2,3-dimethoxybutadiene (DMBD), respectively.…”