Insight into the Thiol-yne Kinetics via a Computational Approach

Abstract

Thiol-yne reactions have drawn attention because of the click nature as well as the regular step-growth network nature of their products, despite the radical-mediated reactant. However, the factors governing the reaction pathways have not been examined using quantum chemical tools in a comprehensive manner. Thereupon, we have systematically investigated the mechanism of thiol-yne reactions, focusing on the structural influences of thiol and alkyne functionalities. The reaction kinetics, structure–reactivity relations, and E/Z diastereoselectivity of the products have been enlightened for the first cycle of the thiol-yne polymerization reaction. For this reason, a diverse set of 11 thiol-yne reactions with four thiols and eight alkynes was modeled by means of density functional theory. We performed a benchmark study and determined the M06-2X/6-31+G­(d,p) level of theory as the best cost-effective methodology to model such reactions. Results reveal that spin density, the stabilities of sulfur radicals for propagation, and the stability of alkenyl intermediate radicals for the chain transfer are the determining factors of each reaction rate. Intramolecular π–π stacking interactions at transition-state structures are found to be responsible for Z diastereoselectivity.

Visible light-driven photocatalytic thiol–ene/yne reactions using anisotropic 1D Bi2S3 nanorods: a green synthetic approach

“…Also, favourable π–π interactions in the chain – transfer transition states might influence the E : Z ratio in free radical mediated thiol–yne reactions. 45 The highest TON of 95 was obtained for the photocatalytic thiol–yne reaction between phenylacetylene and benzyl thiol.…”

New Horizon in Phospha-Michael Reaction: Ultrafast Double Addition of P–H Bond-Bearing Nucleophiles to Electron-Deficient Triple Bonds and Its Use for Functional Monomer Synthesis and Polymer Modification

“…The most striking feature of the DPP TS structure is that the phenyl ring of DPP is perfectly parallel to the alkyne triple bond. The distance between them is 3.40 Å, which is a typical π–π interaction distance, which is known to be responsible for the stability of various systems. , As a result of this interaction, Figure b displays a remarkably greater NCI surface for DPP relative to DMP. The negative charge developing on the phosphorus atom is expected to enhance the electron donation from phenoxy oxygen to the aromatic ring and increase the electron density on the phenyl ring.…”

Computational Study on Radical-Mediated Thiol-Epoxy Reactions

“…In our study, epoxies with different chemical environments based on these structures (Table ) were selected, and their reaction kinetics were investigated. To our knowledge, there are many computational evaluations of the structure–reactivity of thiol–ene reactions − and other specific thioether-forming reactions. − However, there is no quantum chemical study explaining the reaction mechanism of thiol–epoxy systems. Within the scope of this study, we presented the computational approximation for the radical mechanism of epoxy ring-opening polymerization, which explains the reasons for side reactions to enable future experimental studies.…”