Deoxygenation of water

Vladisavljevic G.T., Use of polysulfone hollow fibres for bubbleless membrane oxygenation/deoxygenation of water,... 

Processing intensities for the deoxygenation of water can be over two orders of magnimde higher than for packed or bubble columns, particularly for high values of gas/liquid volumetric flow rates. The unit is designed for offshore applications. 

It was found that 1,2,4-triazine 4-oxides 55 are active enough to react with cyanamide under basic conditions according to the deoxygenative mechanism to form 5-cyanamino-l,2,4-triazines 73 (00TZV1128). This reaction seems to be facilitated by the easy aromatization of cr -adducts by the Elcb elimination of water. 

Deoxygenative autoaromatization was reported to occur in the reaction of 3-amino-1,2,4-triazine 2-oxides 42 with alcohols in the presence of HCl or acetyl chloride. In this case the intermediate cr -adducts undergo elimination of water or acetic acid, resulting in 6-alkoxy-3-amino-l,2,4-triazines 75 (77JOC3498). 1,2,4-Triazine 1-oxides do not react with alcohols under these conditions (77JOC3498). 

Kinghorn, Patrick H. Haas, William E. (Ecolochem, Inc.). Low Level Deoxygenation of Boiler Makeup Water Using Gas Transfer Membranes. Pittsburgh International Water Conference, USA, 1999. 

In a related approach from the same laboratory, the perfluorooctylsulfonyl tag was employed in a traceless strategy for the deoxygenation of phenols (Scheme 7.82) [94], These reactions were carried out in a toluene/acetone/water (4 4 1) solvent mixture, utilizing 5 equivalents of formic acid and potassium carbonate/[l,T-bis(diphe-nylphosphino)ferrocene]dichloropalladium(II) [Pd(dppf)Cl2] as the catalytic system. After 20 min of irradiation, the reaction mixture was subjected to fluorous solid-phase extraction (F-S PE) to afford the desired products in high yields. This new traceless fluorous tag has also been employed in the synthesis of pyrimidines and hydantoins. 

Wood [127] reported an innovative development of the Barton-McCombie deoxygenation of alcohols allowed to work under tin-free conditions. A trimethylborane-water complex proves to be an efficient reagent for the reduction of xanthates. Complexation of water by trimethylborane induces a strong decrease of O - H bond dissociation energy from 116 kcal/mol (water) to 86 kcal/mol (Me3B-water complex). 

Microbial deoxygenation of benzo[f]cinnolin-5-ium oxide with Bakers yeast-NaOH in EtOH/water at reflux yielded 90% of benzo[f]cinnoline <1997TL845>. The same deoxygenation has been achieved in a similar yield via heating in EtOH with NaOEt at 160°C in a sealed tube <2004JOC7720>. 

The freshly prepared chromous(II) acetate is suspended in 50 mL of distilled water previously deoxygenated and saturated with argon. To the resulting mixture is added, under inert atmosphere, an aqueous solution of potassium cyanide (82 g, 1.26 mol in 200 mL of water). A deep green precipitate of K4[Cr - (CN)6] is formed. 

Filter Extraction. Each spiked or field filter sample was placed in the titration beaker containing 25 mL deoxygenated distilled water at room temperature. After five minutes, the filter was lifted with tweezers above the water level and was rinsed slowly on both sides with 25 mL of deoxygenated distilled water. Then the filter was rolled with the tweezers and squeezed against the inside wall of the beaker to remove excess water. Then the filter was discarded. The procedure described in the "Titration" section was followed to analyze the extract. 

Oxygen is soluble in water to the extent of 9.4 ppm from air at 100 kPa and 20 °C, and 02 is the oxidant responsible for most metallic corrosion. Consequently, deaeration of water by purging with nitrogen or vacuum degassing may be desirable in some circumstances this should not be undertaken without circumspection, since deoxygenation may cause activation of otherwise passive metals or cause cathodic areas to become anodic (Chapter 16). At high temperatures, aqueous oxygen is consumed quite rapidly by hydrazine or sodium sulfite (Section 16.7). 

If an alkylammonium salt is desired, it can be obtained by a metathesis reaction. In a typical reaction, 3g of K[B9B14] is dissolved in 30 mL of deoxygenated distilled water, and a solution of 8.8 g of [(C2H5)4N]Br in 20 mL of deoxygenated distilled water is added. A precipitate forms immediately. The solution is filtered and the solid is dried by evacuation using a liquid nitrogen trapped two-stage vacuum pump. The product is obtained in 90% yield. 

Pollution 1) W.T. Gormley R.E. Ford, Deoxygenation of Environmental Waters. 1. Hydrazine-Type Fuels , ProcAnnualConfEn-vironToxicol, 4th, 1973 (1973) (AD-781031)... 

The static method of estimating KLa for a fermenter is not always satisfactory. The use of pure water instead of the fermentation medium can lead to inaccuracies, and the deoxygenation of a complex broth with sodium sulphite can result in undefined changes to the broth and be expensive to carry out on a large scale. An... 

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