Deoxygenated aqueous acidic

The first illustration is fashioned after Problem 29 [13] of iron corrosion in deoxygenated aqueous acid. It is assumed that four identically shaped iron-containing specimens labeled A, B, C, D are chosen randomly, and inserted in the acid carrying a corrosion inhibitor. The percentage reduction in the specific rate loss is 93.3(A), 97.3(B), 96.7(C) and 90.0(D). As shown in Table 1, the hypothesis H of no treatment effect (i.e. the hypothesis of all rankings being equally possible) can be stated as... 

The role of oxygen in this chemical transformation can be addressed if the reaction shown in Figure 8 is conducted as a deoxygenated aqueous acidic suspension. Under these conditions, monodecarboxylation can still be detected, eqn 10,... 

Leitner, N.K.V. and Dore, M., Hydroxyl radical induced decomposition of aliphatic acids in oxygenated and deoxygenated aqueous solutions, /. Photochem. Photo-biol, A, 99(2-3) 137-143, 1996. 

One gram (1.7 mmol) of (>/6-benzene)tris(dimethylphenylphosphine)-molybdenum synthesized as described in Sec. C is dissolved in 10 mL (135.0 mmol) of freshly distilled, deoxygenated trifluoroacetic acid to give a yellow solution. Four milliliters (33.0 mmol) of 65% aqueous hexafluoro-phosphoric acid is added, and the solution is concentrated slowly in vacuo to a volume of about 5 mL. Very small, yellow crystals are produced. The mixture is centrifuged and the mother liquor is decanted off. The solid is washed three times with 5-mL portions of cold (0°) water and is dried in vacuo. The yield is ca. 1.1 g [75% yield based on (>/6-benzene)tris(di-methylphenylphosphine)molybdenum]. Anal. Calcd. for C30H39P 5F 12Mo C, 40.9 H, 4.7. Found C, 40.5 H, 4.9. 

The cobalt-bound methyl group of (4) is not readily removed by acid. Treatment of (4) with acid in aqueous solution leads to proteolytic decoordination of the nucleotide base (pXa = 2.9). The cobalt-bound methyl group of methyl-Co "-corrins can be abstracted (1) by nucleophiles, such as thiol(ate)s, " > " (2) by radicaloid species, such as other Co"-corrins, or (3) by electrophilic species, such as Hg"-ions. A reversible and rapid methyl-group transfer occurs in deoxygenated aqueous solution between methyl-Co "-corrins and Co -corrins. From the pair, methyl-Co "-cobinamide and Co -cobalamin (6), methylcobalamin (4) and Co -cobinamide are generated and prevail at equilibrium. 

The interesting photoisomerizations observed for 2- and 4-cyanophenols (18 and 23) led Richard and Bonnichon to study the meta-isomer 27. Unlike 18 and 23, Kekule resonance forms of azirine products stemming from 27 cannot be drawn, suggesting that formation of isonitriles may be an unfavorable pathway for 27. Photolysis of 27 in deoxygenated aqueous media (pH > 4.0) led to formation of 28 with low yields (O < 0.001) for photolyses performed in more acidic media (pH < 4.0), a second photoproduct (29) was also formed with quantum yields up to 0.002 ... 

Iron hahdes react with haHde salts to afford anionic haHde complexes. Because kon(III) is a hard acid, the complexes that it forms are most stable with F and decrease ki both coordination number and stabiHty with heavier haHdes. No stable F complexes are known. [FeF (H20)] is the predominant kon fluoride species ki aqueous solution. The [FeF ] ion can be prepared ki fused salts. Whereas six-coordinate [FeCy is known, four-coordinate complexes are favored for chloride. Salts of tetrahedral [FeCfy] can be isolated if large cations such as tetraphenfyarsonium or tetra alkylammonium are used. [FeBrJ is known but is thermally unstable and disproportionates to kon(II) and bromine. Complex anions of kon(II) hahdes are less common. [FeCfy] has been obtained from FeCfy by reaction with alkaH metal chlorides ki the melt or with tetraethyl ammonium chloride ki deoxygenated ethanol. 

Ghromium(II) Compounds. The Cr(II) salts of nonoxidizing mineral acids are prepared by the dissolution of pure electrolytic chromium metal ia a deoxygenated solution of the acid. It is also possible to prepare the simple hydrated salts by reduction of oxygen-free, aqueous Cr(III) solutions using Zn or Zn amalgam, or electrolyticaHy (2,7,12). These methods yield a solution of the blue Cr(H2 0)g cation. The isolated salts are hydrates that are isomorphous with and compounds. Examples are chromous sulfate heptahydrate [7789-05-17, CrSO 7H20, chromous chloride hexahydrate... 

The standard reduction potential of Cr " (Table 2) shows that this ion is a strong reducing agent, and Cr(II) compounds have been used as reagents in analytical chemistry procedures (26). The reduction potential also explains why Cr(II) compounds are unstable in aqueous solutions. In the presence of air, the oxidation to Cr(III) occurs by reaction with oxygen. However, Cr(II) also reacts with water in deoxygenated solutions, depending on acidity and the anion present, to produce H2 and Cr(III) (27,28). 

Nitropyridazines are reduced catalytically either over platinum, Raney nickel or palladium-charcoal catalyst. When an N-oxide function is present, palladium-charcoal in neutral solution is used in order to obtain the corresponding amino N-oxide. On the other hand, when hydrogenation is carried out in aqueous or alcoholic hydrochloric acid and palladium-charcoal or Raney nickel are used for the reduction of the nitro group, deoxygenation of the N- oxide takes place simultaneously. Halonitropyridazines and their N- oxides are reduced, dehalogenated and deoxygenated to aminopyridazines or to aminopyridazine N- oxides under analogous conditions. 

Deoxygenation of alcohols and ethers. Treatment of alcohols and methyl or trlmethylsilyl ethers in acetonitrile with this iodoirimethylsilane equivalent and then zinc (previously activated with aqueous hydrochloric acid) and a little acetic acid results in deoxygenation to alkanes, usually in 60-90% yield. Presumably an alkyl iodide is an intermediate. 

A solution of 15 ml. of glacial acetic acid and 30 ml. of water is deoxygenated as described above and then slowly injected with a syringe into the reaction. Refluxing is continued for 6 hours, the flask is cooled, and its contents are poured into a 1-1. separatory funnel along with 200 ml. of water. The solution is extracted four times with 100-ml. portions of ether, and the combined ether extracts are washed successively with 100 ml. of 6N aqueous hydrochloric acid, 100 ml. of water, and 100 ml. of brine. The organic extracts are dried over anhydrous magnesium sulfate, filtered, concentrated with a rotary evaporator, and distilled to yield 13.2-13.8 g. (65-67%) of l-methyl-4,... 

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