Stereoselective synthesis of quaternary α-amino acids. Part 1: Acyclic compounds

4.1 – Aluminium and Aluminium Alloys

In the two decades since the first issue of Indoor Air, there have been over 250 peer-reviewed publications addressing chemical reactions among indoor pollutants. The present review has assembled and categorized these publications. It begins with a brief account of the state of our knowledge in 1991 regarding ‘indoor chemistry’, much of which came from corrosion and art conservation studies. It then outlines what we have learned in the period between 1991 and 2010 in the context of the major reference categories: gas-phase chemistry, surface chemistry, health effects and reviews/workshops. The indoor reactions that have received the greatest attention are those involving ozone—with terpenoids in the gas-phase as well as with the surfaces of common materials, furnishings, and the occupants themselves. It has become clear that surface reactions often have a larger impact on indoor settings than do gas-phase processes. This review concludes with a subjective list of major research needs going forward, including more information on the decomposition of common indoor pollutants, better understanding of how sorbed water influences surface reactions, and further identification of short-lived products of indoor chemistry. Arguably, the greatest need is for increased knowledge regarding the impact that indoor chemistry has on the health and comfort of building occupants.

Practical Implications
Indoor chemistry changes the type and concentration of chemicals present in indoor environments. In the past, products of indoor chemistry were often overlooked, reflecting a focus on stable, relatively non-polar organic compounds coupled with the use of sampling and analytical methods that were unable to ‘see’ many of the products of such chemistry. Today, researchers who study indoor environments are more aware of the potential for chemistry to occur. Awareness is valuable, because it leads to the use of sampling methods and analytical tools that can detect changes in indoor environments resulting from chemical processes. This, in turn, leads to a more complete understanding of occupants’ chemical exposures, potential links between these exposures and adverse health effects and, finally, steps that might be taken to mitigate these adverse effects.

Chemistry in indoor environments: 20 years of research.

Outdoor and indoor atmospheric corrosion of non-ferrous metals

Publisher Summary The anodizing and allied anodic processes on aluminum have been studied widely because of the great commercial exploitation of the metal, the requirement of protection against corrosion, and to gain further understanding of the mechanisms of the anodic behavior in the appropriate electrolytes. On one hand, fundamental investigators have been fascinated by many aspects of its behaviour, such as the apparently unique, relatively regular, and controlled morphology of its porous anodic films and, on the other hand, the mechanisms of pit initiation where aluminum is lost to solution as solvated ions. A review dealing with anodic film formation on aluminum should also take into account the behavior of the metal when immersed in solutions containing anions that are aggressive to aluminum surface. The anodic film formation implies thickening of the natural air-formed film on the macroscopic metal surface. However, in reality, flaws or weak spots are also present in the air-formed/passive film and in anodic films. Flaws, which can be of micro- or macro-dimensions, usually represent thinner regions of film or impure film or holes above some surface heterogeneity or cracks produced by a mechanical rupture of the film.

Anodic Films on Aluminium

http://jes.ecsdl.org/content/138/5/1238.full.pdf

Indoor Corrosion of Copper and Silver Exposed in Japan and ASEAN1 Countries

The incorporation of sulfate into anodic film formed on aluminium in an H2SO4–MgSO4 solution was investigated by infrared spectroanalysis using the compensation method. The sulfate content of the film was very small at the initial stage of anodizing, but increased with time to a nearly constant value. This result is explained in terms of the variation of strength of electric field and the mobility of each anion in the barrier layer. The distribution of sulfate across the cell wall also was examined. The sulfate content was relatively small near the wall/solution interface, but increased with the distance across the wall from the surface, reached a maximum value on the intermediate layer between the wall/solution interface and the cell boundary, and decreased gradually. Such distribution is considered to be similar to that across the barrier layer. The SO4 distribution and the transfer of anions from the barrier layer to the porous layer are explained.

Behavior of Sulfate Ions daring Formation of Anodic Oxide Film on Aluminium

Anodic oxidation of aluminium in sulphuric acid containing aluminium sulphate or magnesium sulphate

1) The optical resolution of DL-2-methylglutamic acid has been performed using brucine as a resolving reagent; the two optically active isomers have been obtained. 2) DL-2-Benzylglutamic acid has been synthesized using benzyl cyanide and diethyl succinate as the starting materials. Moreover, the optical resolution of this amino acid has been performed using strychinine as a resolving reagent. The two optically active isomers were obtained.

The Preparation of Optically Active α-C-Substituted Glutamic Acid

Low resistivity p-type porous silicon (PS) samples are subjected to oxidation treatment in an ammonia hydrogen peroxide mixture (APM) and to etching in 0.00035% and 0.0014% ammonia solutions at room temperature for 10 to 2700 s. Photoluminescence (PL) properties of the treated PS are correlated with chemical states and microstructures analyzed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The intensity of the red PL from PS is increased by 0.00035% ammonia solution, decreased by 0.0014% ammonia solution, and almost completely quenched by an APM. FTIR analysis shows that the ammonia solutions do not affect the chemical states of the PS surface, which is terminated primarily by hydrogen. Immersion in an APM replaces the hydrogen-terminated surface with an oxygen-terminated surface. SEM observations indicate that the thickness of the PS layer is reduced with aqueous ammonia treatment for 2700 s, but not with APM treatment. These results suggest that the PL quenching by an APM may relate to the dehydrogenated surface.

Yoshio Fukuda

Papers

Indoor Corrosion of Copper and Silver Exposed in Japan and ASEAN1 Countries

Behavior of Sulfate Ions daring Formation of Anodic Oxide Film on Aluminium

Anodic oxidation of aluminium in sulphuric acid containing aluminium sulphate or magnesium sulphate

The Preparation of Optically Active α-C-Substituted Glutamic Acid

Quenching of Porous Silicon Photoluminescence by Ammonia Hydrogen Peroxide Mixture