Oxidation transfer

Many accidents occur because process materials flow in the wrong direction. Eor example, ethylene oxide and ammonia were reacted to make ethanolamine. Some ammonia flowed from the reactor in the opposite direction, along the ethylene oxide transfer line into the ethylene oxide tank, past several non-return valves and a positive displacement pump. It got past the pump through the relief valve, which discharged into the pump suction line. The ammonia reacted with 30m of ethylene oxide in the tank, which ruptured violently. The released ethylene oxide vapor exploded causing damage and destruction over a wide area [5]. A hazard and operability study might have disclosed the fact that reverse flow could occur. 

Procedure. Wdgh out accurately about 2.5g of finely powdered arsenic(III) oxide, transfer to a 500 mL beaker, and dissolve it in a concentrated solution of sodium hydroxide, prepared from 2g of iron-free sodium hydroxide and 20 mL of water. Dilute to about 200 mL, and neutralise the solution with 1M hydrochloric add, using a pH meter. When the solution is faintly add transfer the contents of the beaker quantitatively to a 500 mL graduated flask, add 2 g of pure sodium hydrogencarbonate, and, when all the salt has dissolved, dilute to the mark and shake well. 

Triphenylarsine oxide transfers its oxygen to triphenylphosphine in dichloromethane at 105 °C. 

Fig. 1 Oxidative transfer of a radical cation through DNA and reductive transfer of an excess electron through DNA...

Methylhydroxyurea (28, Fig. 7.5) oxidizes oxyHb to metHb and reduces metHb to deoxyHb but neither of these reactions produces HbNO, further supporting the mechanism depicted in Scheme 7.16 for the formation of NO and HbNO from the reactions of hydroxyurea and hemoglobin [115]. The O-methyl group of 27 prevents the association and further reaction of 27 with the heme iron [115]. Scheme 7.16 predicts the redox chemistry observed during the reaction of 28 with hemoglobin and the failure to detect HbNO shows the inability of 28 or any derivative radicals to transfer NO during these reactions [115]. These results indicate that nitric oxide transfer in these reactions of hydroxyurea requires an unsubstituted acylhydroxylamine (-NHOH) group. 

Factors That Control the Reactivity of Cobalt(III)-Nitrosyl Complexes in Nitric Oxide Transfer and Dioxygenation Reactions... 

Actually, the more interesting situation is (b) where the conjugate acid is an oxidizing agent (12). A striking demonstration of the interdependence of electron transfer and oxide transfer is inherent in the following observations. It is possible to prepare a solution of potassium iodide in a very pure nitrate melt and maintain... 

The interesting reaction to this sequence is the last step it must necessarily proceed via a mechanism which is consistent with the transient appearance of the color of NO2 in the bulk of the solution. Figure E contains two alternatives which can account for this observation. The reaction sequence on the left is basically an oxide transfer mechanism and is consistent with some of Prof. Duke s ideas hydrogen is assumed to reduce nitrate to NO2 NO2 acts as a mixed acceptor for oxide yielding nitrate plus nitrite and hydroxyl ions are reconverted to oxide and water via a known reaction. 

Pyrite oxidation transfers atmospheric 02 to the solid phase (as hydroxysulphate minerals Table 3) and or the dissolved phase (as SO4 reaction (1)), thereby reducing the atmospheric concentration of the gas. 

The mechanism of catalysis by HRP [Eqs. (5)—(7)] is generally well understood (8). The enzyme in its iron(III) resting state reacts initially with hydrogen peroxide to afford the so-called Compound I of HRP, which is two oxidation equivalents above the resting state. Compound I is involved in two one-electron oxidations. Transfer of the first electron at Compound I generates Compound II, which is one... 

A novel illustration of the electrophilic behavior of coordinated NO+ is provided in a recent report by Feltham (226) in which the specifically labeled nitro nitrosyl complex m-Fe(15N0)(14N02)(S2CNMe2)2 was found to undergo an intramolecular oxide transfer according to (102). 

The committed step in a metabolic pathway is usually under metabolic control. Inhibition of the committed step in a metabolic sequence or pathway prevents the accumulation of unneeded intermediates and effectively precludes activity of the enzymes using those intermediates as substrates. The decarboxylation of pyruvate and the oxidative transfer of the hydroxyethyl group by pyruvate dehydrogenase constitutes the committed step in the pyruvate dehydrogenase catalytic sequence and is a logical control point. 

This oxidation transfers four electrons to the Manganese Center, a complex metalloprotein, which then donates the electrons through an intermediate to oxidized P680. The protons derived from water are transported into the thylakoid lumen. The protons pumped into the thylakoid lumen by PSII are used to make ATP through the action of coupling factor, in a mechanism similar to that of mitochondrial ATP synthesis. 

Assay for Magnesium Oxide Transfer about 1.5 g of sample, accurately weighed, into a 250-mL conical flask. Add... 

An important aspect of empirical potential parameterization is the question of transferability. Are, for example, models derived in the study of binary oxides, transferable to ternary oxides Considerable attention has been paid to this problem by Cormack et al., who have examined the use of potentials in spinel oxides, for example, MgAl204, NiCr204, and so on in addition Parker and Price have made a very careful study of silicates especially Mg2Si04. These studies conclude that transferability works well in many cases. However, systematic modifications are needed when potentials are transferred to compounds with different coordination numbers. For example, the correct modeling of MgAl204 requires that the potential developed for MgO, in which the magnesium has octahedral coordination, be modified in view of the tetrahedral coordination of Mg in the ternary oxide. The correction factor is based on the difference Ar between the effective ionic radii for the different coordination numbers. If an exponential, Bom-Mayer, repulsive term is used, the preexponential factor is modified as follows ... 

The pH dependence may be due to the reactive periodate species being lOJ, but the mechanism of hydroxylation is uncertain. The exceptions noted above show that enolisation cannot be the sole factor determining whether or not hydroxylation occurs, furthermore some weakly enolised compounds (e.g. malonic acid) are readily oxidised. Bose et suggested a cyclic mechanism, but such a mechanism cannot be extended readily to malonic acid, or, for steric reasons, to 1,3-cyclohexanedione (Sklarz ). Bunton has suggested that hydroxylation may occur by IO4 acting as an electrophilic oxidant transferring oxygen to the substrate, viz. 

Interconversion of Ru-CO and Ru-ti1-C02 through reversible oxide transfer reaction... 

CQ2/CO conversion is achieved by oxide transfer reactions from metal-C02 to various oxide... 

Highly reduced T l-C02 complexes, [W(CO)5(T 1-C02)]2 , [CpFe(CO)2(Tl 1-C02)] and [Ru(bpy)2(qu)( nl-C02)] react with CO2 to produce W(CO)6, [CpFe(CO)3]- - and [Ru(bpy)2(qu)(CO)]2+, respectively (eq 2). 2 To promote smooth CO2/CO conversion in aprotic media, characters of M-CO2 bond should be revealed. The knowledge on the bond character, however, is quite limited due to the lack of well characterized metal complexes with T) I-CO2 ligands. This paper describes the interconversion of Ru-CO and Ru-COj complexes through a reversible oxide transfer. 

Oxide transfer from C032" to [Ru(bpy)2(CO)2] . We conducted the reaction between [Crown K]2C03 (Crown = 18-crown-6 ) and [Ru(bpy)2(CO)2] in dry CHjCN. A colorless CH3CN solution of [Ru(bpy)2(CO)2](PF6)2 rapidly turned to yellow by an addition of equimolar amount of [Crown K]2C03, and the yellow solution subsequently... 

Interconversion of Ru-CO and Ru-ri -COj complexes. We have reported the oxide transfer reaction from carbonate to [Ru(bpy)2(CO>2]"" in DMSO solution as the first... 

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