Magal Saphier

Copper(I) as a Homogeneous Catalyst for the Ullmann Reaction in Aqueous Solutions − The Transformation of 2-Bromobenzoate into Salicylate

The CuI-catalyzed transformation of 2-bromobenzoic acid (2-Br-BA) into salicylic acid (main product), benzoic acid, and diphenoic acid was studied. The reaction was monitored by UV/Vis spectroscopy, HPLC, and ESR. Up to 25 turnovers were achieved for low CuI concentrations. An intermediate was observed that was assigned to a complex between copper and a follow-up product of the aromatic acid, probably a complex with a copper−carbon σ-bond. The process is probably initiated by the formation of a d-π* complex of CuI with the aromatic ring of 2-Br-BA followed by the reaction with a second CuI ion. The effect of the addition of CH3CN or NH3 on the catalytic process is reported. Both were found to accelerate the process when present at relatively low concentrations and slow it down at higher concentrations. A side product, 2-aminobenzoate was observed in the presence of NH3.

Elements in maternal blood and amniotic fluid determined by ICP-MS

Abstract Objective: Knowledge about levels of toxic and non-toxic elements in amniotic fluid is limited. The aims of this study were: (1) to measure levels of trace elements Cu, Fe, Zn, B, Sr and Co in amniotic fluid and maternal serum during second trimester of pregnancy; and (2) to determine what correlations exists between elements levels in amniotic fluid and maternal serum. Methods: The levels of, iron, copper, zinc, cobalt, strontium and boron were measured in blood and amniotic fluid during genetic amniocentesis using inductively coupled plasma mass spectrometry (ICP-MS). Results: Concentrations of the elements: Fe, Cu, Zn, Co, Sr and B in amniotic fluid were significantly lower than in maternal blood. For iron, zinc, cobalt, strontium and boron there was a linear correlation between levels in amniotic fluid and maternal serum. Conclusions: The concentration of trace elements in amniotic fluid was found to be lower than maternal serum and linearly correlated to its level.

The redox chemistry of copper tetraphenylporphyrin revisited

Mixing Cu(II)Cl2 with free base tetraphenylporphyrin ((H2(TPP)) in dry deaerated 1,2-dichloroethane surprisingly yields a mixture of Cu(II)(TPP) and Cu(III)(TPP). The later is long-lived in the absence of water and slowly decomposes within days to yield Cu(II)(TPP). Furthermore, in the presence of air, a slightly different CuIII porphyrin species forms, presumably, Cu(III)(TPP)•+, in which the Q-band is subject to a 10 nm red shift. The new Cu(III)(TPP) and Cu(III)(TPP)•+ differ in terms of absorption, fluorescence, electron paramagnetic resonance (EPR), and X-ray photoemission spectroscopy (XPS) when compared to the well-characterized Cu(II)(TPP), Cu(II)(TPP)•+, and Cu(II)(TPP)2+ species.

Complexes of copper(I) with aromatic compounds facilitate selective electrophilic aromatic substitution

ABSTRACT We report on the selective formation of ortho-nitrophenol, ortho-nitrotoluene (1-Methyl-2-nitrobenzene) and ortho-phenolsulfonic acid (2-Hydroxybenzenesulfonic acid) through reaction of the Cu(I)-aromatic ring complex of phenol or toluene. In the case of nitration of phenol, the reaction could be formulated as: The copper(I)-aromatic ring complex is formed in situ from Cu(II) and metallic copper in deaerated aqueous solutions containing the aromatic compounds. Phenol or toluene shift the comproportionation reaction of copper(0) and copper(II) towards the formation of Cu(I): The stability constant of Cu(I)-phenol in aqueous solutions was reported previously as 900 ± 100 M−1. The surprisingly stable d⟶π* Cu(I)-phenol complex causes distortion of the ring structure which facilitates selective substitutions. Similar results are reported for sulfonation of phenol (in aqueous solutions) and for nitration and sulfonation of toluene in a two phase process. Graphical Abstract

Prevalence of Monovalent Copper Over Divalent in Killing Escherichia coli and Staphylococcus aureus

This study opens the investigation series focused on antimicrobial effects of copper (Cu) compared to silver (Ag), which is currently used to treat wound infection in burn victims as well as in chronic wounds. Noticeably, in its ionized state, Cu is more commonly present as Cu2+ rather than as Cu+, while electronic configuration similarity of Cu+ and Ag+ indicates that actually it may be the active state. To test this hypothesis, effect of Cu+ and Cu2+, using Ag+ ions and metallic copper as controls on Escherichia coli and Staphylococcus aureus bacteria, was examined under anaerobic conditions. Cu+ was produced by two different methods, and its effect on microorganism growth was tested using a syringe and Petri dish methods. It was found that the presence of Cu+ causes a dramatic depletion in the viability of both microorganisms. Metallic copper did not have any effect on the viability, whereas Cu2+ and Ag+ ions had much lower activity than Cu+ ions. Minimal inhibitory concentration of Cu+ for E. coli was twice lower than that of Cu2+. The obtained results show that Cu+ proves to be a potent antimicrobial agent.