Role of pre-corrosion of Fe0 on its efficiency in remediation systems: An electrochemical study.

The duration of in-situ generation of iron corrosion products (FeCPs) prior the remediation process (so called "aging" of metallic iron (Fe0)), was found as the key parameter affecting the efficiency of Fe0 for water remediation. Batch experiments were performed in buffered solutions (pH 4.0, 4.7 and 5.5) and under oxic conditions (presence of dissolved oxygen) using Zn2+ as probe contaminant. The time-dependent (0-16 d) concentration changes of aqueous Fe2+ and Zn2+ were monitored using differential pulse polarography (DPP). During the time of pre-corrosion varying from 0 to 6 d, an "induction period" of the corrosion occurs in the first one - 2 h when no Fe2+ ion is released in the solution. After this period, Fe2+ was identified in solution and its concentration progressively increases up to 6 h, then starts to decrease and after 6 d nearly disappears. Experiments with Zn2+ reveal that the most efficient Fe0 remediation occurs after 6 h of pre-corrosion. This coherence thus proves that the presence, the amount and the age of FeCPs ("degree" of corrosion) significantly impact the removal efficiency of Zn2+ in Fe0/H2O systems. The present study severely refute the wording 'reactivity loss' and states that progress in designing sustainable Fe0/H2O systems will not be achieved before the role of "active" FeCPs is clarified.

Crystal structure of 2-tert-butyl-2,3-di-hydro-1H-benzo[c]pyrrol-1-one.

The asymmetric unit of the title compound, C12H15NO, comprises two sym-metry-independent mol-ecules which differ mainly in the conformations of the tert-butyl groups. The mol-ecules contain an essentially planar five-membered 3-pyrroline ring incorporating a carbonyl substituent (pyrrolinone) which forms part of an isoindolinone skeleton. The planarity of the pyrrole ring is compared to other structures with isoindolinone. There are only weak intra- and inter-molecular C-H⋯O and C-H⋯π-electron-ring inter-actions in the crystal structure.

A study of the planarity of the pyrrolone fragment in 2-isopropyl-2,3-dihydro-1H-isoindol-1-one.

Orthophthalaldehyde (o-phthalaldehyde, OPA) is an aromatic dialdehyde bearing two electron-withdrawing carbonyl groups. The reactions of OPA with primary amines are broadly applied for the synthesis of important heterocyclic compounds with biological relevance. A number of such reactions have been investigated recently and several structures of condensation products have been reported, however, the complex reaction mechanism is still not fully understood and comprises concurrent as well as consecutive reactions. The reaction products depend on the primary amine which reacts with OPA, the reaction environment (solvent) and the proportion of the reactants. The title molecule, C11H13NO, the product of the reaction of OPA with isopropylamine, contains a five-membered pyrrole C4N ring with a carbonyl substituent, which forms part of the isoindolinone unit. Though this pyrrole ring contains one C atom in the sp(3)-hybridized state, it is fairly planar. The title molecule has been compared with similar structures retrieved from the Cambridge Structural Database in order to study this phenomenon. The planarity of this fragment has been explained by the presence of partially delocalized C-C, C-N and C-O bonds, and by an inner angle in the planar pentagonal ring (∼108°), which is close to the ideal tetrahedral value for the sp(3)-hybridized state of the constituent C atom. Due to this propitious angle, this C atom can be present in states intermediate between sp(3)- and sp(2)-hybridized in different structures, while still maintaining the planarity of the ring. There are only weak intermolecular C-H...O hydrogen bonds and C-H...π-electron ring interactions in the structure. In particular, it is the pyrrole ring which is involved in these interactions.