Single-stage reduction

Single-stage reduction of tantalum seems to be typical mostly for fluoride complexes due to the ionic nature of the bonds. 

Single-stage reduction and trimethylsilylation of a number of hydroxylated naphthoquinones and anthraquinones have been carried out using N-m ethy l-N-tri methyI s i ly 11r i fl u o roacetamide in the presence of NH4I (Bakola-Christianopoulou et al. 1993). 

By now it should be obvious that a direct, single-stage reduction of the particle size from the agglomerated feed to the granulated product will normally result in an excessive amount of fines. Therefore, in a first step, agglomerates from any process source must be cracked, taking into consideration the surface layer with higher... 

Single-stage reduction means that the material is reduced to the desired product fineness by the action of just one machine, which may operate either on the open-circuit (single-pass) or the closed-circuit principle (Fig.1). Multistage reduction is effected in two or more machines in series, each of which constitutes one stage of the reduction process and which operates either in open or in closed circuit. 

The iron carbide process is alow temperature, gas-based, fluidized-bed process. Sized iron oxide fines (0.1—1.0 mm) are preheated in cyclones or a rotary kiln to 500°C and reduced to iron carbide in a single-stage, fluidized-bed reactor system at about 590°C in a process gas consisting primarily of methane, hydrogen, and some carbon monoxide. Reduction time is up to 18 hours owing to the low reduction temperature and slow rate of carburization. The product has the consistency of sand, is very britde, and contains approximately 6% carbon, mostly in the form of Ee C. 

The majority of researchers, however, are inclined to believe that the tantalum reduction process takes place in a single step. Experimental results and discussions confirm that tantalum is reduced from fluoride, fluoride-chloride and oxyfluoride melts containing K2TaF7, via a single stage in which five electrons are transfered [546 - 548] ... 

Table 14 can be regarded as providing a reasonable overall picture, even if the results cannot applied to any particular case. However, if the underlying principle is accepted, it becomes clear that improvements in a single stage, for example the reduction of instrument variation, has a negligible beneficial effect (if this variation was not outside the normal range ). Even if the contribution of repeatability is re-duced to zero, the cumulative uncertainty is reduced by 10% only, i.e. from 2.2 to y(0.0)2 (0.8)2 (1.0)2 + (1.5)2 = 2.0. This statistical view of errors should help to avoid some unnecessary efforts to improve, e.g., calibration. Additionally, this broad view on all sources of error may help to detect the most important ones. Consequently, without participation in proficiency tests, any method validation will remain incomplete. 

S,6S)-Hydroxy-sulfone 7 Trusopt Treatment for glaucoma Reduction Neurospora crassa Single-stage fermentation [6]... 

Reduction of the dimer appears to take place in two stages. In the first cathodic wave, a single-electron reduction generates a radical which decomposes in a chemical step in an ECE sequence ... 

From all the above observations, it was concluded that, for diphosphine chelate complexes, the hydrogenation stage occurs after alkene association thus, the unsaturated pathway depicted in Scheme 1.21 was proposed [31 a, c, 74]. The monohydrido-alkyl complex is formed by addition of dihydrogen to the en-amide complex, followed by transfer of a single hydride. Reductive elimination of the product regenerates the active catalysts and restarts the cycle. The monohydrido-alkyl intermediate was also observed and characterized spectroscopically [31c, 75], but the catalyst-substrate-dihydrido complex was not detected. 

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