Reaction minimum concentration

The reaction of neomycin with fluorescamine to form a fluorescent complex has been reported by Kusnir Barna The fluorescence intensity varies with both the pH of the solution (optimum pH range 7.5-9.5) and the amount of fluorescamine added. This procedure may be used to determine neomycin at very low levels, the minimum concentration determinable being 45 ng/ml. 

Water has also been shown to be essential for the liquid phase polymerization of isobutylene with stannic chloride as catalyst (Norrish and Russell, 87). The rates of reaction were measured by a dilatometric method using ethyl chloride as common solvent at —78.5°. With a mixture consisting of 1.15% stannic chloride, 20 % isobutylene, and 78.8% ethyl chloride, the rate of polymerization was directly proportional to the amount of added water (up to 0.43% of which was added). A rapid increase in the rate of polymerization occurred as the stannic chloride concentration was increased from 0.1 to 1.25% with higher concentrations the rate increased only gradually. It was concluded that a soluble hydrate is formed and functions as the active catalyst. The minimum concentration of stannic chloride below which no polymerization occurred was somewhat less than half the percentage of added water. When the concentration of the metal chloride was less than about one-fifth that of the added water, a light solid precipitated formation of this insoluble hydrate which had no catalytic activity probably explains the minimum catalyst concentration. The addition of 0.3% each of ethyl alcohol, butyl alcohol, diethyl ether, or acetone in the presence of 0.18% water reduced the rate to less than one-fifth of its normal value. On the other hand, no polymerization occurred on the addition of 0.3 % of these substances in the absence of added water. The water-promoted reaction was halved when 1- and 2-butene were present in concentrations of 2 and 6%, respectively. 

Both methods require that the polymerization of the first monomer not be carried to completion, usually 90% conversion is the maximum conversion, because the extent of normal bimolecular termination increases as the monomer concentration decreases. This would result in loss of polymer chains with halogen end groups and a corresponding loss of the ability to propagate when the second monomer is added. The final product would he a block copolymer contaminated with homopolymer A. Similarly, the isolated macroinitiator method requires isolation of RA X prior to complete conversion so that there is a minimum loss of functional groups for initiation. Loss of functionality is also minimized by adjusting the choice and amount of the components of the reaction system (activator, deactivator, ligand, solvent) and other reaction conditions (concentration, temperature) to minimize normal termination. 

The main processes occurring in this system are the following [219] bromate oxidizes trivalent cerium to tetravalent cerium Ce4+ oxidizes bromomalonic acid, and is reduced to Ce3+. The bromide ion, which inhibits the reaction, is isolated from the oxidation products of bromomalonic acid. During the reaction, the concentration of the Ce4+ ions (and Ce3+) oscillates several times, passing through a maximum and a minimum. The shape of the peaks of concentrations and the frequency depend on the reaction conditions. The autooscillation character of the kinetics of the cerium ions disappears if Ce4+ or Br are continuously introduced with a low rate into the reaction mixture. The autooscillation regime of the reaction takes place only in a certain interval of concentrations of the reactants [malonic... 

In Table III, the specifications we require on our final product are summarized. This process is performed on a "no carrier added" level. The only strontium present in the final sample is that produced in the nuclear reaction and introduced as an impurity in the target and reagents. Usually the concentration of Sr-82 in the final product is on the order of a factor of ten higher than that listed in the table. When the minimum concentration is approached, the volume to be shipped becomes unreasonably large. We do not check the actual acid concentration of the final product. As described earlier, the 6 M HC1 is taken to dryness and then brought up in HjO. There is enough residual HC1 in the... 

The theoretical quantity of nitric acid is added to a large excess of cone, sulphuric acid, and the mixed acid added to the compound to be nitrated. Or the compound may be dissolved in excess of cone, sulphuric acid, and the theoretical quantity of strong nitric acid then added. The excess of sulphuric acid is added to absorb the water formed in the reaction, and which would reduce the concentration of nitric acid ultimately to a point where no nitration would take place. The quantity of sulphuric acid added must be such that its final concentration after nitration, i.e., when it contains the water formed in the reaction plus the water originally present in the nitric acid, must be above a certain minimum, depending on the compound to be nitrated. When this minimum concentration of sulphuric acid is reached nitration again stops. 

It is clear from Fig. 6 that the concentration of a reacting species decreases at the electrode surface as the current is increased. The minimum concentration is zero at the surface, which corresponds to the maximum rate at which the electrodeposition reaction can proceed. The current density corresponding to this maximum rate is called the limiting current density i, which can be approximated by... 

In the PhoSAI process of Scottish Agricultural Industries (Figure 12.1), ammonia reacts with phosphoric acid (minimum concentration 42 % P2O5) in a stirred-tank reactor to produce a slurry with an N/P ratio of 1.4 (the point of maximum solubility) under atmospheric pressure. The slurry flows to a pin mixer in which the N/P ratio is brought back to 1.0 by the addition of more concentrated phosphoric acid. During this step the solubility decreases and more water vaporizes due to the heats of reaction and crystallization. A solid product is formed that typically contains 6% to 8 % moisture. The product is screened, the oversize particles are ground and the product is sent to storage296. 

Sulfur Modified with Dicyclopentadiene. The beneficial use of dicyclopentadiene to modify sulfur has been reported by a number of workers including Currell et al. (3), Sullivan et al. (4), and also Diehl (5). Currell et al. showed that the interaction of dicyclopentadiene and elemental sulfur at 140 °C gives a mixture of polysulfides and free elemental sulfur which, even after standing for 18 mo, is held as a mixture of presumably monoclinic and noncrystalline sulfur. Sullivan et al. reported that the minimum concentration of dicyclopentadiene required to stop permanently the embrittlement of elemental sulfur is 13% if the reaction temperature is less than 140°C and only 6% if the reaction temperature is greater than 140 °C. Presumably the polysulfide reaction products form a solid solution with the unreacted sulfur from which orthorhombic sulfur cannot crystallize. 

Toxicity. The estimated minimum lethal dose is 15 g. Plasma concentrations of salicylic acid greater than 300 pg/ml are likely to produce toxic reactions and concentrations greater than 500 pg/ml are associated with moderate to severe intoxication. The maximum permissible atmospheric concentration is 5 mg/m. ... 

Polymer or residue formation is minimized by maintaining proper reaction conditions, i.e., good mass transfer, high isobutane-to-olefin ratio, proper catalyst activity, and minimum concentration of alkylate in the reaction zone. 

Ppeiii] with respect to [H ] and equating the result to zero will produce the minimum concentration of ippeiii and, thus, the optimum pH determined. Using the equilibrium reactions, Eqs. (12.33) through (12.37), along with the ion product of water, we now proceed as follows ... 

Analysis for traces of substances that act as catalysts for reactions can be both highly specific and sensitive. Calculations of the type carried out by Yatsimirskii indicate that, if the rate of a catalytic reaction can be measured spectrophoto-metrically with a change in concentration equivalent to 10 moles/1, and if the catalytic coefficient amounts to 10 cycles/min, the minimum concentration of catalyst that can be measured by following the reaction for 1 min is about 10 moles/1. Such sensitivities can be attained by few other analytical techniques. Tolg considers only mass spectroscopy, electron-probe microanalysis, and neutron-activation analysis methods applied to favorable cases to have better limits of detection than catalytic methods. 

In addition to the right Co/Mn ratio a minimum concentration of catalyst must be applied otherwise, side reactions become predominant and decrease the selectivity of the oxidation reactions. This is shown, for example, in the oxidation of 4-methoxytoluene at different catalyst concentrations. Figure 4 shows the conversion of 4-methoxytoluene and the formation of intermediates (both in mol%) versus the corresponding catalyst concentration. 

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