An Exclusive Synthesis of Macrocyclic Trimer over Polymers

Area of Science:

• Organic Chemistry
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Macrocycle synthesis often faces competition from linear polymerization.
• Controlling cyclization versus polymerization is crucial for efficient macrocycle production.

Purpose of the Study:

• To achieve exclusive synthesis of a macrocyclic trimer.
• To investigate the mechanism of dynamic Friedel-Crafts alkylation in macrocycle formation.
• To understand the competition between cyclization and polymerization.

Main Methods:

• Exclusive synthesis of a macrocyclic trimer from 1,2,3,4-tetramethoxybenzene and paraformaldehyde.
• Utilizing dynamic Friedel-Crafts alkylation.
• Employing Nuclear Magnetic Resonance (NMR) spectroscopy for reaction monitoring.
• Conducting Density Functional Theory (DFT) studies.

Main Results:

• The reaction exclusively yielded a macrocyclic trimer, avoiding polymer formation.
• Dynamic Friedel-Crafts alkylation proceeded via linear oligomeric intermediates that converted to the cyclic trimer.
• NMR monitoring confirmed the stepwise conversion process.
• DFT calculations identified the cyclic trimer as the thermodynamically most stable species.

Conclusions:

• The developed system successfully circumvents the cyclization-polymerization equilibrium.
• This work provides valuable insights into the mechanistic competition during macrocycle synthesis.
• The exclusive formation of the macrocyclic trimer highlights a novel synthetic strategy.