The Thiol-Michael Addition Click Reaction: A Powerful and Widely Used Tool in Materials Chemistry

Abstract

The key attribute of the thiol-Michael addition reaction that makes it a prized tool in materials science is its modular “click” nature, which allows for the implementation of this highly efficient, “green” reaction in applications that vary from small molecule synthesis to in situ polymer modifications in biological systems to the surface functionalization of material coatings. Over the past few decades, interest in the thiol-Michael addition reaction has increased dramatically, as is evidenced by the number of studies that have been dedicated to elucidating different aspects of the reaction that range from an in-depth analysis aimed at understanding the mechanistic pathways of the reaction to synthetic studies that have examined modifying molecular structures with the aim of yielding highly efficient thiol-Michael reaction monomers. This review examines the reaction mechanisms, the substrates and catalysts used in the reaction, and the subsequent implementation of the thiol-Michael reaction in materials science over the years, with particular emphasis on the recent developments in the arena over the past decade.

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

“…At the end of the second-stage photopolymerization reaction initiated via UV exposure, at the 320 min point, the acrylate conversion is seen to proceed to completion, implying 100% conversion of remaining acrylic double bonds within the network. 32 The two-stage TAMAP methodology provides facile control to explore structure-property relationships in LCEs. The influence of crosslinking density on stress-strain behavior is shown in Figure 3A.…”

Dithiothreitol activity by particulate oxidizers of SOA produced from photooxidation of hydrocarbons under varied NO<sub><i>x</i></sub> levels

“…We propose that electron-deficient alkenes, abundant in toluene SOA (Jang and Kamens, 2001), can substantially modify sulfhydryl groups in DTT via a Michael addition ( Fig. 1b; Nair et al, 2014). In the next section, the reactivity of electron-deficient alkenes with DTT will be demonstrated using selected model compounds.…”

“…Acrolein showed much higher DTT t than the other compounds. The susceptibility of an alkene to a Michael addition reaction depends on the nature of the electron-withdrawing group coupled to the C = C bond (Nair et al, 2014). The methyl group of methacrolein and mesityl oxide is an electron-donating Figure 6.…”

“…A trace amount of quinones can be found in aromatic SOA products (Forstner et al, 1997). Third, electron-deficient alkenes in SOA can react with the sulfhydryl groups of DTT via a Michael addition (Nair et al, 2014). Alkenes substituted with an electron-withdrawing group (e.g., conjugated carbonyls) are commonly found in ring-opening products from the photooxidation of aromatic HCs (e.g., toluene; Jang and Kamens, 2001;Saunders et al, 2003Saunders et al, , 1997Wyche et al, 2009).…”

“…Photooxidation products are not limited to the compounds shown. (b) Possible reaction mechanisms between sulfhydryl groups in DTT (represented by R-SH) and SOA products (Grek et al, 2013;Kumagai et al, 2002;Mudd, 1966;Mudd and McManus, 1969;Nair et al, 2014). EWG represents the electron-withdrawing group attached to an alkene.…”