thiolenemediated

Thiolene-mediated reactions refer to a class of chemical processes in which thiols (R–SH) add across carbon–carbon double bonds (enes) to form thioether linkages. These reactions are widely described as thiol-ene click chemistry because they proceed rapidly, with high yields, and are tolerant of many functional groups and reaction conditions. The approach is used to form polymers, networks, and surface attachments in a controlled, modular way.

Mechanism and scope

Most thiol-ene reactions are radical in nature. Under light or heat, a radical initiator generates a thiyl radical from the thiol. The thiyl radical adds to the alkene to yield a carbon-centered radical, which then abstracts a hydrogen atom from another thiol to regenerate the thiol and propagate the chain. The reaction typically proceeds with anti-Markovnikov regioselectivity and can occur in bulk, in solution, or at surfaces. Photoinitiation enables spatial and temporal control, and the method tolerates aqueous and bio-compatible environments, making it attractive for biomaterials.

Variants and conditions

There are two broad modes: step-growth thiol-ene polymerizations (often via multifunctional thiols and alkenes) and thiol-ene surface modifications or hydrogel formation, frequently using photoinitiators or photoredox catalysts. The thiol-ene paradigm is closely related to thiol-yne chemistry, which involves alkynes.

Applications

Thiolenemediated strategies are used for polymer synthesis, crosslinking of hydrogels, surface grafting, coatings, adhesives, and bioconjugation. The approach is valued for rapid curing, low metal catalyst requirements, and compatibility with biological systems.

Benefits and limitations

Advantages include high efficiency, chemoselectivity, and modularity. Limitations can involve the need for radical initiation, potential odor of thiols, and sensitivity to oxygen in certain conditions. Overall, thiolene-mediated chemistry provides a versatile toolkit across materials science and biology.