Catalyst-Free Thia-Michael Addition to α-Trifluoromethylacrylates for 3D Network Synthesis

Area of Science:

• Organic Chemistry
• Polymer Chemistry
• Reaction Mechanisms

Background:

• Thia-Michael additions typically require Brønsted or Lewis base catalysts.
• The reactivity of α-trifluoromethyl acrylates in such additions is not well-understood.
• Thermoset preparation often relies on efficient and catalyzed polymerization reactions.

Purpose of the Study:

• To describe a spontaneous (uncatalyzed) Thia-Michael addition of thiols to α-trifluoromethyl acrylates.
• To investigate the mechanism of this uncatalyzed reaction.
• To demonstrate the application of this reaction in efficient thermoset preparation.

Main Methods:

• Experimental kinetic studies were performed.
• Density Functional Theory (DFT) calculations were employed for mechanistic investigation.
• Reactions involved various arene- and alkanethiols with tert-butyl trifluoromethyl acrylate in polar aprotic solvents.

Main Results:

• A spontaneous Thia-Michael addition of thiols to α-trifluoromethyl acrylates was achieved without external catalysts.
• A probable solvent-assisted proton transfer was identified as the rate-determining step.
• The electron-withdrawing CF3 group was found to significantly lower the reaction's energy barrier.
• The reaction was successfully applied to the efficient synthesis of a thermoset material.

Conclusions:

• The study demonstrates a novel, uncatalyzed Thia-Michael addition pathway for trifluoromethyl acrylates.
• The findings provide a deeper mechanistic understanding, highlighting the role of solvent and the CF3 group.
• This reaction offers a more efficient and potentially greener route for synthesizing thermoset polymers.