An Environmentally Friendly Class of Fluoropolyether: α,ω-Dialkoxyfluoropolyethers

Abstract

Abstract:The α,ω-dialkoxyfluoropolyethers (DA-FPEs) characterized by the structure R H O(CF 2 CF 2 O) n (CF 2 O) m R H have been developed as a new class of environmentally friendly hydrofluoroethers (HFEs) suitable as solvents, long-term refrigerants, cleaning fluids, and heat transfer fluids. Synthetic methodologies for DA-FPEs described here consist of radical-initiated oxypolymerization of olefin, peroxy-elimination reaction in peroxidic perfluoropolyethers (P-PFPEs) and further chemical modification of α,ω-diacylfluoride PFPE. The physical properties of selected α,ω-dimethoxyfluoropolyethers (DM-FPEs) have been evaluated and compared with analogous hydrofluoropolyethers (HFPEs) having -OCF 2 H as end-groups. Atmospheric implications and global warming potentials (GWPs) of selected DA-FPEs are also considered.

Assessment of model chemistries for hydrofluoropolyethers: A DFT/M08‐HX benchmark study

“…From these considerations, it seems that the claim stating that the extra reactive sites for OH radical attack provided by the groups in DM‐FPEs are advantageous in limiting their atmospheric lifetimes is only addressing issue (2). The extension and magnitude to which the number of reactive sites benefits one or the other class might not be so obvious after taking the previous paragraph into account.…”

“…The more recent and promising ‐dialkoxyfluoropolyethers (DA‐FPEs) may be written as with . One of the most representative classes of DA‐FPEs is obtained considering , being called ‐dimethoxyfluoropolyethers (DM‐FPEs), which have been designed and developed as potential CFC replacement compounds in a number of applications, like foaming and fire extinguishing agents, cleaning agents for sophisticated electronic devices and heat transfer fluids . Here, they will also be referred as ‐ qp…”

“…Studies concerning the environmental impact and toxicology of HFPEs (and respective fluorinated esters, FEs, sole oxidation decomposition product of DM‐FPEs) are recent and incomplete. In fact, they recognize the need to address key aspects of the unestablished atmospheric chemistry of HFPEs: environmental impact, reactivity and atmospheric degradation mechanisms of HFEs and HFPEs, the sparsity of the database of OH initiated reactions of HFPEs and FESs, uncertainty of how FESs are removed from the atmosphere and their atmospheric implication .…”

“…In fact, they recognize the need to address key aspects of the unestablished atmospheric chemistry of HFPEs: environmental impact, reactivity and atmospheric degradation mechanisms of HFEs and HFPEs, the sparsity of the database of OH initiated reactions of HFPEs and FESs, uncertainty of how FESs are removed from the atmosphere and their atmospheric implication . Moreover, since it is claimed that the extra reactive sites for OH radical attack provided by the groups in DM‐FPEs are advantageous in limiting their atmospheric lifetimes (and hence GWP), a pertinent question immediately arises: putting aside possible indirect cumulative GWP effects from FESs, are the promising DM‐FPEs environmental friendlier than the already commercialized DH‐FPEs? More specifically, what is the ratio between rate constants of the HG‐ and ‐ reactions?…”

Special Feature Organo-Fluorine Chemical Science

“…The α,ω-dialkoxyfluoropolyethers (DA-FPEs) prepared and characterized by Menghua Wu and coworkers [3] the dipole moments really tell the story of the degree of polar interactions due to the presence of fluorine atoms. Interestingly, it is known that the presence of oxygen in PFPE impacts on chain flexibility but not on molecular polarity when compared with perfluoroalkyl analogues.…”