Unlocking PEG-400: A Sustainable Reaction Medium for Phthalocyanine Synthesis and Pd-Catalyzed C–C Bond Formation
Year: 2026
Type: preprint
Abstract: In this work, we demonstrate that poly(ethylene glycol)-400 (PEG-400) can efficiently replace conventional and hazardous solvents such as N,N-dimethylaminoethanol (DMAE) and N,N-dimethylformamide (DMF) in the synthesis of phthalocyanines, a class of functional molecular materials widely investigated for optoelectronic and energy-related applications. Used at a loading as low as 1.0 equivalent relative to the phthalonitrile precursor, PEG-400 enables cyclotetramerization reactions under operationally simple and comparatively safer conditions, providing isolated yields of 50-83% across a range of metalated and metal-free derivatives and substitution patterns. The robustness of the protocol was further demonstrated at the multigram scale, affording cobalt phthalocyanine in 79% yield, with 88% of the PEG-400 recovered from the reaction mixture. Remarkably, PEG-400 proved compatible with sequential cyclotetramerization followed by Sonogashira or Suzuki coupling without isolation of the macrocyclic intermediate, affording functionalized products in up to 75% yield and enabling pot-economical access to more complex derivatives. E-factor and Process Mass Intensity (PMI) analyses quantitatively support the improved material-efficiency profile of the method when compared to representative literature procedures. Overall, these results establish PEG-400 as a versatile and sustainable medium for the resource-efficient synthesis and functionalization of phthalocyanine derivatives.
Source: ChemRxiv
Institutions: Institute of Structure of Matter, Sapienza University of Rome
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Award: G3648505226
OpenAlex ID: W7213275716