Carbon monoxide reaction with ferrous iron

The sihcates formed in reactions 2 and 3 fuse with the added fluxes to form a Hquid slag at which point carbon monoxide loses its effectiveness as a reducing agent. Unreacted carbon from the fuel then becomes the predominant reductant in reducing both staimous siUcate to tin and ferrous siUcate to iron. The metallic iron, in turn, reduces tin from stannous siUcate ... 

Table 1(b) on the formation or removal in vacua of carbon monoxide by reaction of surface oxides with carbon in the metal shows the results of these calculations. The reactions are feasible thermodynamically in vacua of the order of 10-10 atm. at temperatures of 600°C. or higher for the metals tungsten, chromium, and iron. Thus, carbon monoxide will be formed by the diffusion of carbon to the surface and subsequent reaction with the surface oxides. This reaction has been discussed for the case of steels by Holm (11). The effect of carbon content on the reaction is not shown in the table. However, the effect can be seen from the expression for the equilibrium constant K for the reaction of ferrous oxide with carbon in the iron ... 

When iron is heated m contact with carbon and its oxides, many interesting reactions occur. At 900° C. in a current of carbon dioxide iron yields ferrous oxide, whilst at 1200° C. magnetite is produced, which is both magnetic and crystalline. Ignition in carbon monoxide at 1000° C. yields ferrous oxide.6... 

The inhibitors of tryptophan pyrrolase may be classified into those that prevent activation of the enzyme and those that inhibit the active form. Catalase, as mentioned earlier, was required in certain amounts to balance peroxide-generating systems, but inhibited in higher concentrations. These effects have now been shown to concern only the activation process, and catalase has been found to have no influence on the activated tryptophan pyrrolase (Tanaka and Knox, 1959). Similarly, peroxides are required for the activation, but cause irreversible inactivation if added in the absence of tryptophan. Cyanide is a potent inhibitor if added before activation, but has very little effect if added during the reaction. Ferricyanide causes almost complete cessation of activity when added during the reaction, as was expected if only the ferrous form of the enzyme were active. This interpretation is supported by the reactivation of ferricyanide-treated enzyme by ascorbic acid, which presumably reduces the iron back to the ferrous state. However, if cyanide is added before the ascorbic acid, there is very little reactivation. Carbon monoxide causes an inhibition that is reversed by light. All of these observations are consistent with a model in which an inactive ferric enzyme is reduced to an active form by peroxide and tryptophan. The ferric form combines readily with cyanide (and also with azide and hydroxylamine), while the ferrous form combines with carbon monoxide. 

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