Renewable Terephthalates and Aromatic Diisocyanates from Galactose

Area of Science:

• Green Chemistry
• Polymer Science
• Organic Synthesis

Background:

• Aromatic diisocyanates are crucial for polymer production but are typically derived from petroleum.
• Current methods for renewable aromatic diisocyanates are limited by precursor availability.
• Phosgenation, the standard production route, poses safety and environmental concerns.

Purpose of the Study:

• To develop a robust and sustainable route for producing renewable aromatic diisocyanates.
• To utilize D-galactose, a renewable feedstock, for synthesizing terephthalates and diisocyanates.
• To demonstrate the feasibility of producing renewable monomers for thermoplastic polyurethanes.

Main Methods:

• Utilized Eastwood olefination and Diels-Alder cycloaddition for terephthalate synthesis from D-galactose.
• Employed electrochemical decarboxylative aromatization for a mild synthesis of aromatic compounds.
• Applied Curtius rearrangement in flow for efficient diisocyanate preparation.
• Formulated renewable monomers into thermoplastic polyurethanes.

Main Results:

• Successfully synthesized renewable terephthalates from D-galactose on a gram scale.
• Achieved gram-scale production of 1,4-phenylene diisocyanate and 2,5-toluene diisocyanate.
• Developed a process avoiding high-pressure gases and expensive transition metals.
• Demonstrated the creation of fully renewable thermoplastic polyurethanes.

Conclusions:

• Established a novel, scalable route to renewable aromatic diisocyanates from D-galactose.
• The developed method offers a sustainable alternative to petroleum-based chemical manufacturing.
• This work paves the way for more environmentally friendly polymer production.