Efficient synthesis of amine-functionalized graphene oxide by ultrasound-assisted reactions and density functional theory mechanistic insight

Abstract

Herein described is a facile preparation protocol by which amino-alcohol derivatives of graphene oxide (GO) can be conveniently synthesized in high yield and a short time by an ultrasound treatment of ethanol-graphite-oxide suspensions and amines. Linear primary amines of different chain length rapidly react with graphite oxides prepared from powder and flakes, leading to the formation of GO amino-alcohol derivatives. Characterization of the amine-modified materials by XRD, TGA, FTIR, and Raman demonstrates the proposed derivatization; the findings are corroborated by SEM and TEM observations. Additionally, quantum-chemical investigations shed additional light on the reaction, suggesting an alcohol-accelerated SN2 mechanism where the initial step, the simultaneous formation of a C-N bond (GO-amine) and rupture of an epoxide bond in GO, is rate-determining. Energy barriers lower than 8 kcal/mol are estimated, which can be overcome with the energy supplied by the sonotrode tip (ca. 2 kcal) and the use of ethanol to facilitate it.

Amine-Functionalized Graphitic Carbon Nitride as a Sustainable Metal-free Catalyst for Knoevenagel Condensation

“…To synthesize amine-functionalized GCN, a reported method with some modifications was followed . The NH 2 –GCN was prepared using butylamine as a precursor.…”

Amine Functionalized Graphitic Carbon Nitride as Sustainable, Metal-Free Catalyst for Knoevenagel Condensation

“…Thermal stability of the catalyst was examined using TGA, as shown in Figure 1 (d) and it was observed that the thermal stability of GCN was less than that of NH2-GCN, due to its surface functionalization. 23 A weight loss of 4.6 % was observed for GCN up to 450 o C and for NH2-GCN it was about 2.4 % up to 450 o C. This weight loss, up to 160 o C, is due to the absorbed water molecules in the nanosheets. This loss is less in the case of NH2-GCN due to less absorption of water molecules because of increased hydrophobicity.…”

“…This loss is less in the case of NH2-GCN due to less absorption of water molecules because of increased hydrophobicity. 23,39 The second weight loss observed between 200 -400 o C for NH2-GCN is very less whereas, in the case of GCN, the second weight loss is more due to disintegration of -NH2 group. Furthermore, in the range of 450 -650 o C, complete decomposition of the C-N network of the heptazine ring occurs in both, GCN and NH2-GCN.…”

“…To synthesize amine-functionalized GCN, a reported method with some modifications was followed. 23 The NH2-GCN was prepared by using butylamine as a precursor. In detail, 500 mg of GCN was taken in a beaker having 50 mL of ethanol and sonicated for 2 h to disperse the solid particles and GCN suspension was formed.…”

Influence of the ultrasound cavitation intensity on reduced graphene oxide functionalization

“…An interesting study was performed by Shen B. et al where the functionalization was achieved solely by ultrasonication on the aqueous mixture of pristine graphene and PVA with the estimated content of PVA on graphene to be approximately 35 % [39] . In addition, ultrasound-assisted direct functionalization of GO with nitrogen [40] , 5-aminoindazole [41] , and amino-alcohol [42] were recently presented. However, most of the studies lack of systematic approach on how to control the degree of functionalization by controlling ultrasound parameters.…”