Scale-up synthesis of a deuterium-labeled cis-cyclobutane-1,3-Dicarboxylic acid derivative using continuous photo flow chemistry

Technological Innovations in Photochemistry for Organic Synthesis: Flow Chemistry, High-Throughput Experimentation, Scale-up, and Photoelectrochemistry

Photoinduced chemical transformations have received in recent years a tremendous amount of attention, providing a plethora of opportunities to synthetic organic chemists. However, performing a photochemical transformation can be quite a challenge because of various issues related to the delivery of photons. These challenges have barred the widespread adoption of photochemical steps in the chemical industry. However, in the past decade, several technological innovations have led to more reproducible, selective, and scalable photoinduced reactions. Herein, we provide a comprehensive overview of these exciting technological advances, including flow chemistry, high-throughput experimentation, reactor design and scale-up, and the combination of photo- and electro-chemistry.

4-Carboalkoxylated Polyvalerolactones from Malic Acid: Tough and Degradable Polyesters

Eight 4-carboalkoxyvalerolactones (CRVLs), varying in the composition of their alkyl (R) side chains, were synthesized from malic acid and subjected to ring-opening transesterification polymerization (ROTEP) using diphenyl phosphate [DPP, (PhO)2PO2H] as a catalyst. Each CRVL produced a semicrystalline poly(4-carboalkoxyvalerolactone) (PCRVL), and the nature of the R group impacted the thermal transitions of these polyesters. Bulk polymerizations at 70 °C allowed for preparation of high molar mass samples that contained small amounts of branching, as evidenced by 1H NMR spectroscopy, MALDI spectrometry, size-exclusion chromatography, and eliminative degradation. Tensile testing of these lightly branched, high molar mass samples revealed that these polyesters are tough (tensile toughness values up to 88 ± 33 MJ•m-3) and have Young's moduli (E) up to 186 ± 13 MPa. The acid- and base-catalyzed hydrolytic degradation of the PCRVLs was quantitatively monitored using total organic carbon analysis, and effect of the alkyl chain length on PCRVL hydrolysis rate was determined. Finally, the methyl ester variant of these malic acid-derived thermoplastics is known to be chemically recyclable.