Performance Equations for an Excess of

Vanadium pentoxide and mercuric oxide were used as catalysts for the hydrogen peroxide oxidation of bis(phenylthio)methane to its monooxide 17a31 (equation 5). From the synthetic point of view, it is interesting to note that vanadium pentoxide, in addition to its catalytic action, functions also as an indicator in this reaction. In the presence of hydrogen peroxide, the reaction mixture is orange while in the absence of hydrogen peroxide a pale yellow colour is observed. Thus, it is possible to perform the oxidation process as a titration ensuring that an excess of oxidant is never present. 

On the basis of self-ionic dissociation, these compounds can be prepared by acid-base reactions. Heteropolyhalogen cations are usually prepared by reacting the parent compound with a Lewis acid (equation 51) in which XY = interhalogen and MYm = Lewis acid, for example, hahdes of B, Al, P, As, and Sb, and so on (equations 52 and 53). Such reactions can be performed by direct interaction of the reactants with an excess of the more volatile reactant, which can then be pumped off, after completion of the reaction, leaving behind the pure product. Sometimes it is preferable to perform such reactions in solution, such as in anhydrous hydrogen fluoride (AHF), and pump off the solvent at the end of the reaction. 

In the reactions with amines or amino derivatives (Equations 3-5), either an excess of the amino compound is employed or the reaction is carried out in the presence of a tertiary base, e.g. pyridine or triethylamine. It is preferable for the reaction to be performed in non-aqueous media, e.g. acetone or acetonitrile to avoid competing base-catalysed hydrolysis. 

This equation has two unknowns Xq and Xe), and an empirical relation between them is needed. Many have been tried, and one of the best is to assume that the excess of To over Te expressed as a ratio to Tp (zero for a perfectly stirred chamber) is a constant A [ (Tg — Tg)/ Tp]. Although A should vaiy with burner type, the effects of firing rate and percent excess air are small. In the absence of performance data on the land of furnace under study, assume A = 300/Tp, °R or 170/Tp, K. The left side of Eq. (5-178) then becomes D 1 —Xc + A), and with coefficients of Xc and Xc collected, the equation becomes... 

Due to the poor nucleophilicity of aliphatic alkoxides, the intermolecular O-allylation of aliphatic alcohols has been performed, for the most part, using a large excess of structurally simple primary alcohols (Equation (37))165 and/or unsubstituted allylic substrates.166,167 When allylic systems activated with an electron-withdrawing substituent were employed, only a slight excess of the alcohol was necessary to achieve complete stereospecificity, as exemplified by Equation (38).168,169... 

A method based on equation 21 may be performed, where the organic residue of an organometallic compound becomes derivatized with excess dimethylphenylchlorosUane (67) and determined by GC, using cumene (i -PrPh) as internal standard. Although lithium alkoxide impurities also react with 67, the product appears at a different retention time. The method is also suitable for Grignard reagents. ... 

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