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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
The Diels–Alder reaction is renowned and widely used in organic chemistry to form carbon-carbon bonds between dienophile alkene and a conjugated diene. This reaction proceeds through the [4+2] cycloaddition pathway to yield a six-membered cyclic compound and successfully applied on various carbon nanomaterials (Chang and Liu. 2009; Wang et al. 2005; Delgado et al. 2004; Munirasu et al. 2010). Graphene being a polyaromatic system can resemble both dienophile and diene depending on the counter reactant. Sarkar et al. investigated the dual character of graphene in Diels–Alder cycloaddition reaction. Graphene acts as diene when reacting with tetracyanoethylene (TCNE) and maleic anhydride, whereas reaction with 2,3-dimethoxy-1,3-butadiene (DMBD) or 9-methyl anthracene resembles dienophile like behavior (Sarkar et al. 2011). This reaction has unique features like thermal reversibility and rapid reaction kinetics involving catalyst-free reaction. Pristine graphene can be regenerated using thermal treatment and can regain its electronic properties. The reaction scheme is shown in Figure 4.6.
Conjugation and Reactions of Conjugated Compounds
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Dienophile means “diene loving” and refers to a molecule that reacts with the diene in a Diels–Alder reaction. This is, of course, the alkene (ene). Which of the following dienophiles is the most reactive with buta-1,3-diene in a Diels–Alder reaction?(a) CH2=CHCH3(b) CH2=CHCO2Et(c) CH2=CHOMe
Organic Synthesis
Published in Suresh C. Ameta, Rakshit Ameta, Garima Ameta, Sonochemistry, 2018
Chetna Ameta, Arpit Kumar Pathak, P. B. Punjabi
The Diels-Alder reaction is a reaction (specifically, a [4 + 2] cycloaddition) between a conjugated diene and a substituted alkene, to form a substituted cyclohexene system. It was first described by Diels and Alder (1928; 1929). Ultrasonic irradiation provides efficient promotion of the reaction between substituted buta-1,3-dienes with substituted 2,3-dime- thoxycyclohexadiene-1,4-diones in a Diels-Alder cycloaddition, which affords a variety of bicyclo[4.4.0] fused-ring systems just in one step with high yields. Sonochemistry provides an increase in yield over a much shorter period than the conventional methodology for reactions performed in benzene, toluene, and methylene chloride. It provides a convenient route to naphthaquinols and lonapalene, a 5-lipooxygenase inhibitor in the treatment of psoriasis (Javed et al., 1995).
Reactive atomistic simulations of Diels-Alder-type reactions: conformational and dynamic effects in the polar cycloaddition of 2,3-dibromobutadiene radical ions with maleic anhydride
Published in Molecular Physics, 2021
Uxía Rivero, Haydar Taylan Turan, Markus Meuwly, Stefan Willitsch
Figure 2 shows stationary points on the PES of the Diels-Alder reaction between DBB and MA at the M06-2X/6-31G* level of theory [26]. For the s-cis conformer of DBB, both reactant molecules (DBB and MA) are symmetric. Thus, there are two possible pathways for a concerted Diels-Alder reaction referred to as ‘endo’ and ‘exo’ depending on the relative orientation of the reactants (Figures 2(a ,b)). For the exo configuration, an additional stepwise pathway via an intermediate INT-exo was identified (Figure 2(b)). For the s-trans conformer of DBB, a stepwise pathway was found (”trans”, Figure 2(c)). The endo product (P-endo) was defined as the zero of the energy scale in Figure 2.
Biocompatible conjugation for biodegradable hydrogels as drug and cell scaffolds
Published in Cogent Engineering, 2020
The Diels-Alder reaction in aqueous environments, which involves a highly selective [4 + 2] cycloaddition reaction between a diene and a dienophile, is diverse in scope and efficient in reactivity, results in very high yields, produces no byproducts, and occurs under mild reaction conditions (Dantas De Araújo et al., 2006; Jia et al., 2015; Sun et al., 2006; H. Tan et al., 2011; Tiwari & Kumar, 2006). The compatibility of aqueous Diels-Alder chemistry with biomolecules has been exploited elegantly in the bioconjugation of protein, peptides and oligonucleotides, which were site-specific without the interference of the many functional groups present in the polysaccharide backbone (Hill et al., 2001; Kim et al., 2005; Shi et al., 2009, 2007; Tona & Häner, 2005). Given the high specificity and efficiency, the success of aqueous Diels-Alder chemistry in biomolecule conjugation and immobilization may be extended to the synthesis of biodegradable hydrogels. The aqueous Diels-Alder cycloaddition reaction was used as a new methodology to conjugate a polysaccharide hydrogel, which provides a competitive alternative to conventional methodologies to prepare biodegradable hydrogels. For example, a polysaccharide derivative hydrogel with novel structures has been developed via aqueous Diels-Alder cycloaddition reaction of bio-conjugation that specifically allows for biopharmaceutical delivery (H. Tan et al., 2011). Hydrogel precursors were designed with furan groups (diene) on the outer PEG, corona that are accessible for reaction with maleimide (dienophile) functionalized HA derivatives in an aqueous environment at 37°C (Figure 6a).
Recent developments in edge-selective functionalization of surface of graphite and derivatives – a review
Published in Soft Materials, 2019
Solmaz Aliyeva, Rasim Alosmanov, Irada Buniyatzadeh, Abdulseid Azizov, Abel Maharramov
Diels-Alder reaction, i.e., [4 + 2] cycloaddition occurs between 1,3-dienes and the unsaturated compounds that are dienophiles. Commonly, a diene contains an electron-donor substituent, and a dienophile is an electron-acceptor group (94). There are numerous works on functionalization of carbon allotropes, i.e. CNTs (95–97), fullerenes (98–100) and diamond (101) via Diels-Alder reaction. But there are few works about edge-selective functionalization of graphite through Diels-Alder reaction.