Membranes based on 3M's perfluoro imide acid (PFIA) ionomer have been studied using the open circuit voltage (OCV) hold accelerated stress test. For these samples, a decay in the OCV potential within the first 200 hours was observed along with an increase in cell resistance that rapidly grows near the end of life. A multi-membrane electrode assembly (MEA) technique was employed to study the origins of these phenomena. Effluent water collected at the beginning of life and later, during a recovery protocol, was analyzed using liquid chromatography -mass spectroscopy (LC-MS). A variety of small molecule fragments were detected that could be traced to the ionomer side chain. The center layer of a three-membrane MEA was separated at the end of life and analyzed by 19 F nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Peaks associated with the bis(sulfonyl)imide group of the PFIA ionomer were observed to have reduced in intensity and new peaks, assigned to a perfluorosulfonamide side chain, appeared. The combination of the fragments detected in the effluent water, along with the spectral changes in the membranes after aging, point to one or more degradation processes involving the PFIA ionomer side chain. This decomposition is likely analogous to reactions described for perfluorosulfonic acid (PFSA) ionomers but with new consequences owing to the greater number of potential fragments.

Cyclohexadienones are versatile platforms for performing asymmetric synthesis as evidenced by the numerous natural product syntheses that exploit their diverse reactivity profile. However, there are few general methods available for the direct asymmetric synthesis of chiral cyclohexadienones. To circumvent this problem, several researchers have developed catalytic asymmetric methods that employ readily available achiral 2,5-cyclohexadienones as substrates. Many of these reactions are desymmetrizations in which one of the enantiotopic alkenes of an achiral dienone is transformed. Others involve selective reaction at one alkene of an unsymmetrically substituted, achiral dienone. This review will cover advances in this area over the last 20 years and the application of these strategies in complex molecule synthesis.

The cyclization of 2,5-cyclohexadienones tethered to activated methylene groups was studied. The substitution around the cyclohexadienone ring serves to regioselectively direct these cyclizations based primarily on electronic effects. In the case of brominated substrates, these reactions proceed to give highly unusual electron-deficient tricyclic cyclopropanes. By using a Cinchona alkaloid-based phase-transfer catalyst, prochiral cyclohexadienones can be desymmetrized with moderate stereoselectivity.

The effects of ligand and substrate choice on the Pd-catalyzed cyclization of alkyne-tethered cyclohexadienones were examined. In the presence of a chiral ligand, the enantioselectivity of the desymmetrization is remarkably sensitive to structural changes in both the ligand and the substrate. Additionally, the regioselectivity of the reaction (5- vs. 6-membered ring formation) is dependent on the proximity of heteroatoms to the alkyne.

New ionomers based on perfluoro bis(sulfonyl)imides have been made by 3M and show promise for use in fuel cell membranes and electrodes. These ionomers have exceptionally high proton conductivity that can result in improved performance especially at low relative humidities. Fundamental to the success of these ionomers is oxidative stability in the fuel cell operating environment. Accelerated open circuit voltage (OCV) hold tests have been used to evaluate the durability and chemical stability of perfluoro bis(sulfonyl)imide ionomers in both membrane and electrode applications. A multi-layer membrane technique was employed to recover degraded samples for FTIR analysis and effluent water was collected and analyzed using LC-MS. These experiments show evidence that the carbon-sulfur bonds in the imide group are subject to the same cleavage mechanism proposed for the traditional perfluoro sulfonic acid (PFSA) ionomers.