A Semicrystalline Furanic Polyamide Made from Renewable Feedstocks.
Journal of the American Chemical Society
Semi-aromatic polyamides (SAPs) synthesized from petrochemical diacids and diamines are high-performance polymers that often derive their desirable properties from a high degree of crystallinity. Attempts to develop partially renewable SAPs by replacing petrochemical diacids with biobased furan-2,5-dicarboxylic acid (FDCA) have resulted in amorphous materials or polymers with low melting temperatures. Herein, we report the development of poly(5-aminomethyl-2-furoic acid) (PAMF), a semicrystalline SAP synthesized by the polycondensation of CO2 and lignocellulose-derived monomer 5-aminomethyl-2-furoic acid (AMF). PAMF has glass-transition and melting temperatures comparable to that of commercial materials and higher than that of any previous furanic SAP. Additionally, PAMF can be copolymerized with conventional nylon 6 and is chemically recyclable. Molecular dynamics (MD) simulations suggest that differences in intramolecular hydrogen bonding explain why PAMF is semicrystalline but many FDCA-based SAPs are not.
View details for DOI 10.1021/jacs.2c11806
View details for PubMedID 36573894
A framework for automated structure elucidation from routine NMR spectra.
2021; 12 (46): 15329-15338
Methods to automate structure elucidation that can be applied broadly across chemical structure space have the potential to greatly accelerate chemical discovery. NMR spectroscopy is the most widely used and arguably the most powerful method for elucidating structures of organic molecules. Here we introduce a machine learning (ML) framework that provides a quantitative probabilistic ranking of the most likely structural connectivity of an unknown compound when given routine, experimental one dimensional 1H and/or 13C NMR spectra. In particular, our ML-based algorithm takes input NMR spectra and (i) predicts the presence of specific substructures out of hundreds of substructures it has learned to identify; (ii) annotates the spectrum to label peaks with predicted substructures; and (iii) uses the substructures to construct candidate constitutional isomers and assign to them a probabilistic ranking. Using experimental spectra and molecular formulae for molecules containing up to 10 non-hydrogen atoms, the correct constitutional isomer was the highest-ranking prediction made by our model in 67.4% of the cases and one of the top-ten predictions in 95.8% of the cases. This advance will aid in solving the structure of unknown compounds, and thus further the development of automated structure elucidation tools that could enable the creation of fully autonomous reaction discovery platforms.
View details for DOI 10.1039/d1sc04105c
View details for PubMedID 34976353
View details for PubMedCentralID PMC8635205
- A High-T-g Polyamide Derived from Lignocellulose and CO2 MACROMOLECULES 2021; 54 (21): 9978-9983
- A framework for automated structure elucidation from routine NMR spectra CHEMICAL SCIENCE 2021
SuFEx Activation with Ca(NTf2)(2) : A Unified Strategy to Access Sulfamides, Sulfamates, and Sulfonamides from S(VI) Fluorides
2020; 22 (11): 4389–94
A method to activate sulfamoyl fluorides, fluorosulfates, and sulfonyl fluorides with calcium triflimide and DABCO for SuFEx with amines is described. The reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions. Additionally, we highlight this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds.
View details for DOI 10.1021/acs.orglett.0c01397
View details for Web of Science ID 000538848600065
View details for PubMedID 32459499
View details for PubMedCentralID PMC7294807
Sulfonamide Synthesis via Calcium Triflimide Activation of Sulfonyl Fluorides
2018; 20 (13): 3943–47
A method using calcium triflimide [Ca(NTf2)2] as a Lewis acid to activate sulfonyl fluorides toward nucleophilic addition with amines is described. The reaction converts a wide array of sterically and electronically diverse sulfonyl fluorides and amines into the corresponding sulfonamides in good yield.
View details for DOI 10.1021/acs.orglett.8b01520
View details for Web of Science ID 000438469500052
View details for PubMedID 29888600