Ammonium hydroxide

About: Ammonium hydroxide is a research topic. Over the lifetime, 3943 publications have been published within this topic receiving 40777 citations.

Oxidation of Aniline: Polyaniline Granules, Nanotubes, and Oligoaniline Microspheres

Abstract: Aniline was oxidized with ammonium peroxydisulfate in solutions of strong acid (0.1 M sulfuric acid), weak acid (0.4 M acetic acid), or alkali (0.2 M ammonium hydroxide). The properties of the oxidation products and their morphology are controlled by the initial acidity of the medium and the acidity profile during the oxidation; the acidity increases because sulfuric acid is a byproduct. Conducting polyaniline nanogranules, nanotubes, or nonconducting oligoaniline microspheres were obtained, respectively. FTIR spectra suggest that the oligomers produced by the oxidation of neutral aniline molecules at the beginning of oxidation are similar, regardless of the acidity of the medium. Neutral aniline molecules, prevailing under alkaline conditions, are easily oxidized to aniline oligomers composed of ortho- and para-coupled aniline constitutional units. Ortho-coupled units are further converted by oxidative intramolecular cyclization to phenazines. It is proposed that, in acidic media, N-phenylphenazine units...

Method for manufacturing cobalt catalysts

Abstract: A method for manufacturing cobalt complexes having the formula: [Co(NH3)5M]Ty, wherein M ligands are selected from substituted and unsubstituted C1-C30 carboxylic acids having the formulas: RC(O)O-; said method comprising reacting cobalt (II) complexes having the formula [Co(H2O)6] Ty (e.g., T is chloride) with concentrated ammonium hydroxide/ammonium chloride, followed by an oxidizing agent (e.g., peroxide), followed by carboxylic acid anhydride of the formula RC(O)O(O)CR.

Polyaniline nanotubes: conditions of formation

Abstract: The courses of aniline oxidation with ammonium peroxydisulfate in aqueous solutions of strong (sulfuric) and in weak (acetic) acids, followed by temperature and acidity changes, are different. In solutions of sulfuric acid, granular polyaniline (PANI) was produced; in solutions of acetic acid, PANI nanotubes were obtained. The external diameter of the nanotubes was 100–300 nm, the internal cavity 20–100 nm, and the length extended to several micrometres. The morphology of PANI, granular or tubular, depends on the acidity conditions during the reaction rather than on the chemical nature of the acid. PANI nanotubes were also produced when aniline was oxidized in the absence of any acid. The bulk conductivity of PANI prepared in solutions of acetic acid was 0.08–0.27 S cm−1, depending on the acid concentration. Protonated PANI prepared in sulfuric and acetic acids were deprotonated with ammonium hydroxide to obtain PANI bases and the ammonium salt of the protonating acid. FTIR spectroscopy showed the differences in the molecular structure of the PANI bases. Irrespective of whether the polymerization was performed in solutions of sulfuric or acetic acid, PANI had hydrogen sulfate counter-ions only. The PANI morphology is thus not controlled by the nature of counter-ions. The acidity of the reaction medium determines the protonation of monomer, oligomer and polymer species. The chemistry of aniline oxidation is likely to be affected especially by the protonation of an intermediate in the pernigraniline form. It is proposed that, in the course of aniline oxidation, pH-dependent self-assembly of aniline oligomers predetermines the final PANI morphology. Copyright © 2005 Society of Chemical Industry