Negligible reactions

There is negligible reaction with water and steam at moderate temperatures and pressures, as indicated by the free-energy change for the solution reaction ... 

As shown in Figure 3, solubilization roughly conforms to first-order kinetics, where rate = k[unconverted coal]. Rate constants of 3 x 10 and 1 x 10 min l are found for 250° and 275°C respectively, with nearly total conversion in less than 30 minutes at the higher temperature. Although negligible reaction takes place with heatup to 250°C (so-called "zero time), considerable reaction occurs in the few minutes of heatup between 250° and 275°C. During this period, solubility rises 20%, incorporation approaches its maximum extent, and the H/C ratio drops to 0.75. 

The times necessary to fill and drain the reactor may be assumed to be equal to 10 and 12 min, respectively. It may be assumed that negligible reaction occurs during the 14 min it takes to heat the feed from the temperature at which it enters the reactor to 163 °C. After 97% of the A has been isomerized, the hot product mixture is discharged to a cooling tank. 

If the reaction occurs at high temperature, but the rate at room temperature is negligible (i.e., negligible reaction even for 4 billion years), the integration can be carried out to f= co, leading to... 

Therefore, under the conditions of continuous cooling and negligible reaction rate at room temperatures, the degree of the reaction is equivalent to that at the high temperature To (where the rate coefficient is ko) for a finite duration of x = Xc(RTq/E). An example of calculations is shown below. 

The nonsteady state methods described in this section are all based on no or negligible reactions taking place in the system. If reactions are present, the treatment of the mass balances becomes more complicated since... 

Sometimes termination by primary radicals is negligible [reaction (19)]. Polymerizations where termination occurs by primary radicals and/or by degradative transfer are called non-ideal . A number of other causes may lead to deviation from ideality . 

The corresponding W complexes, (L—L)W(CO)4, are less reactive, and negligible reaction occurs in boiling THF. However, further exchange of a carbonyl group for a pyridine (i) introduces a ligand easy to displace and (ii) enhances electron density on the metal. Thus from complexes (L—L)M(CO)3py (M = Mo, W L—L = bipy, phen) (/ -allyl)M(CO)2(L—L)X is obtained where M is Mo as well as W. The coordinated-halide counter ion in these -allyl complexes can be replaced by ligands such as pyridine... 

Sample calculations of the optimum pressure and optimum temperature and the maximum centerline deposition rate are shown in Eigure 5 as a function of the normalized preform thickness, These results are all for the special case of negligible reaction yield, y = 0. As noted... 

Negligible reaction and no phase changes during heating. 

Without giving any details in their published article Wagner and Moylan also pointed out that the exposure of Ni(lOO) to a purified argon atmosphere, water vapor and pure liquid water caused negligible reaction with or contamination of the surface. But in similar experiments in our laboratory, exposure of UHV-... 

Lead azide reacts with copper to fonn a very sensitive cuprous azide. Polished copper strips in contact with lead azide for 9-20 days at 90% relative humidity and 50 C react. In contrast, magnesium-aluminum alloys and magnesium strips show a negligible reaction under the same conditions even after 18 months exposure [24]. 

The influences of W/F, methane and oxygen partial pressures in methane rich (up to 80 kPa CH4 in the feed) and methane lean (up to 4 kPa CH4 in feed) conditions were examined at 550 and 600 °C. Negligible reaction was observed at lower temperatures. 

Incidentally, if we tried to measure the rates of reactions (2.13) or (2.15) by measuring the rate of appearance of the products, we would find that the rates would almost exactly match those of the disappearance of the starting materials. Even though intermediates are involved, they are so unstable as not to build up any measurable concentration during the reaction. However, in the acid-catalysed hydrolysis of the diester 6 (reaction 2.16), the initial rate of disappearance of 6 will be greater than the rate of formation of 8 because the intermediate 7 will have a similar reactivity to the initial diester 6, so it will build up in concentration initially, and until an appreciable amount of the intermediate is formed, the rate of production of the diacid product will be negligible. Reactions where the rate offormation of the products is initially slower than the rate of disappearance of starting materials cannot be elementary. 

In a true biphasic system (i.e. with no PTC agent) with toluene as the organic phase, nitrobenzene and nitrotoluene were reduced with high efficiency with CO + H20 catalyzed by RhCl3.3H20, [Rh CO ] or [ RhCl(l,5-hexadiene) 2] (12 mol aniline/mol Rh.h, at room temperature and 1 bar CO) [364], Other nitroarenes reacted similarly, however, no or only negligible reaction took place with nitroaliphatics. Nitrobenzene is the standard substrate in such reactions, its reduction to aniline was also catalyzed by c/s-[Rh(CO)2(2-picoline)2]PF6 [365] and analogous cis-[Rh(CO)2(amine)2]PF6 complexes immobilized on poly(4-vinylpyridine) [366],... 

Ans. (a) There is No (or negligible) Reaction because alcohols are only very weakly acidic. 

A different picture emerges when this template effect is extended to flexible substrates such as all-tran.v-farnesol and all-/rani-geranylgeraniol. Thus the ester 4 under the conditions of Sharpless epoxidation is epoxidized to the 6,7-epoxide and the 10,11-epoxide in the ratio 40 60, with only negligible reaction at the allylic position. Similarly the ester 5 is converted into the 6,7-epoxide, the... 

As was indicated in sections 2.2.1 and 2.3.1, the occurrence of an induction period is a prominent feature of shock-wave experiments sensitive to the macroscopic hydrogen-oxygen reaction. The acceleration at the beginning of the reaction is so marked that in any linear measure of the reaction profile there is a perceptible period of negligible reaction which is followed by an abrupt S-shaped portion. We now... 

Thus there is negligible reaction in the film. In other words, regimes 3 and 4 may be ruled out. Hence we may conclude that the reaction falls in regime 2, slow reaction. 

CO2 hydration (2.120) is relatively slow and in comparison with total dissolved CO2 the concentration of H2CO3 is very low (negligible). Reaction (2.120) occurs for pH < 8 for pH > 10 reaction (2.123) is dominant, in the pH region 8-10 both reactions are parallel and it is complicated to study the kinetic. Hence, reliable kinetic data are valid only for pH < 8 and pH > 10, respectively. ... 

Here V, B, and I denote virus, host bacteria, and infected bacteria, respectively. Y is the production or yield of new viruses per host. We focus on the relevant factors by excluding negligible reactions, such as virus desorption and their adsorption to infected hosts. Consider a homogeneous medium composed initially of host bacteria and a few free viruses. The adsorption process can be described by the classical kinetic equations... 

If one or several negligible reactions in the mechanism are eliminated, only very small differences between the concentrations Cj calculated with the simplified mechanism and the concentrations Cj calculated with the complete mechanism, must be observed. 

By definition, these are non-negligible reactions, which have been eliminated during the previous step. A reaction i is considered to be non-determining if the global sensitivity of the reaction i ... 

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