The antibiotic norfloxacin recrystallizes from acetonitrile as a dihydrate with the norfloxacin molecule in a zwitterionic form, i.e. 1-ethyl-6-fluoro-1, 4-dihydro-4-oxo-7-(1-piperazin-4-io)-3-quinolinecarboxylate dihydrate, C(16)H(18)FN(3)O(3).2H(2)O.

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Researchers have developed numerous per- and polyfluoroalkyl substances (PFAS)-free aqueous film-forming foam (AFFF) formulations to replace PFAS-containing AFFF used for fire suppression. As part of the Department of Defense’s Strategic Environmental Research and Development Program (SERDP), we examined the direct lethal effects of seven PFAS-free AFFF and a PFAS-containing AFFF on 14 aquatic species using a series of lethal concentration (LC50) tests. We assessed the LC10, LC50, and LC90 values using log–logistic and logit analyses. Across all aquatic species tested, we discovered that exposure to at least one PFAS-free AFFF was more or as toxic as exposure to the PFAS-containing AFFF. For most cases, National Foam Avio F3 Green KHC 3% and Buckeye Platinum Plus C6MILSPEC 3% were the most and least toxic formulations, respectively. Moreover, we found consistency among results from multiple experiments using the same minnow species (Pimephales promelas) and among closely related taxa (e.g., daphnids, amphibians). Lastly, the LC50 values for AFFF formulations trended lower for tested marine species as compared to those of freshwater species. These results dramatically increase the current knowledge on the potentially toxic effects of AFFF but also highlight the need for additional research and the development of new PFAS-free AFFF that are more “ecologically friendly” than those containing persistent PFAS.

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Catalytic reduction of a representative set of imines, both aldimines and ketimines, to amines has been studied using transfer hydrogenation from 1,4dicyclohexadiene. Unusually, this has been achieved using s-block pre-catalysts, namely 1-metallo-2-tertbutyl-1,2-dihydropyridines, 2-tBuC 5 H 5 NM, M(tBuDHP), where M = Li-Cs. Reactions have been monitored in C 6 D 6 and tetrahydrofuran-d 8 (THF-d 8 ). A definite trend is observed in catalyst efficiency with the heavier alkali metal tBuDHPs outperforming the lighter congeners. In general, Cs(tBuDHP) is the optimal pre-catalyst with, in the best cases, reactions producing quantitative yields of amines in minutes at room temperature using 5 mol % catalyst. Supporting the experimental study, Density Functional Theory (DFT) calculations have also been carried out which reveal that Cs has a pathway with a significantly lower rate determining step than the Li congener. In the postulated initiation pathways DHP can act as either a base or as a surrogate hydride.