Identical conditions, chemical reactions under

Solvent coordination (i.e., solvation) in such cases is a typical coordination chemical reaction. Under identical concentration conditions, the decisive factor in the determination of its course is the relative donor strength of the solvent molecule. 

The technique involving simultaneous absorption with chemical reaction and physical desorption was employed to determine mass transfer coefficients with and without chemical reaction under identical hydrodynamic conditions. The gas phase consisted of CO2 and N2, and the liquid phase consisted of 0.2M NaOH solution containing dissolved oxygen. 3mm and 4mm glass beads were used as the solid phase. 

Prior to conducting the DOE (design of experiments) described in Table 3, it was established that no reaction took place in the absence of a catalyst and that the reactions were conducted in the region where chemical kinetics controlled the reaction rate. The results indicated that operating the reactor at 1000 rpm was sufficient to minimize the external mass-transfer limitations. Pore diffusion limitations were expected to be minimal as the median catalyst particle size is <25 pm. Further, experiments conducted under identical conditions to ensure repeatability and reproducibility in the two reactors yielded results that were within 5%. 

Antibacterial sulfonamides contain two N-atoms, the sulfonamido (N1) and the para primary amino (N4). The sulfonamido group, in contrast to a carboxamido group, is chemically and metabolically stable. In other words, hydrolytic cleavage of sulfonamides to produce a sulfonic acid and an amine has never been observed. We, therefore, focus our discussion on the primary amino group, acetylation of which is one of the major metabolic pathways for some sulfonamides. Hydrolysis of the N4-acety luted metabolites back to the parent sulfonamide can occur in the liver, kidney, and intestinal tract. The reaction is strongly influenced by the structure of the parent amine e.g., N4-acetylsulfisoxazole (4.121) was deacetylated by intestinal bacteria whereas /V4-acctyIsulI anilamide (4.122) under identical conditions was not [78][79],... 

C-Aminoindoles autoxidize extremely rapidly. Consequently, comparatively few chemical reactions have been examined. The 2-amino derivative exists in the 3H-indole tautomeric form (473) and is protonated and alkylated on the annular nitrogen atom (72HC(25-2)179). The 1-methyl derivative (474) exits predominantly as such and not as the alternative 2-imino-3//-indole tautomer and is protonated at the 3-position to give a cation having the same electronic structure as that of the protonated (473). Acylation of (473) yields l-acetyl-2-acetylaminoindole, via the initial acylation of the annular nitrogen atom. Confirmation of this route has been established by the observation that 2-acetylaminoindole, obtained by hydrolysis of the diacetylated compound, is acetylated under identical conditions... 

Sakamoto et al. also demonstrated an absolute oxetane synthesis in the solid-state photolysis of Y-( ,(3-unsaturatcd carbonyl)benzoylformamides 43. [28] The X-ray analysis of Y-isopropyl substituted imide 43a revealed that the crystal system was monoclinic and the space group P2. Crystals of 43a were powdered and photolyzed at 0°C. The imide undergoes the [2+2] cycloaddition to afford the bicyclic oxetane 44a, which is a mixture of diastereomers, namely, syn- and anh-isomers at the C-7 position. In this reaction optically active. syn-oxctanc 44a with 37% ee (84% chemical yield) and racemic anti-44a were obtained. The solid-state photoreaction proceeded even at -78°C, and optically active syn-44n which showed ee value as high as >95% ee, (conv 100%, chemical yield 89%) was formed in a higher diastereomeric ratio (syn/anti = 6.5). Under identical conditions A-bcnzyl substituted 43b was irradiated in the solid state. 

Kabasakalian and coworkers 87) have achieved the cathodic reduction of steroidal ketones in ethanol-20% H20 with 0.2 M (C4H9)4NC1 as the supporting electrolyte. The reactions proceeded with very high chemical yield and were rather stereoselective. Electrolysis of androstane-17 3-ol-3-one (64) at —2.6 V(SCE) gave the 3p-equatorial alcohol 65 quantitatively. Under identical conditions the exocyclie carbonyl of 66 was also reduced and the corresponding alcohol was obtained in 92% yield. But, the reaction was less stereoselective and the ratio of the 2O0-/2Oa epimers was 74/26. 

It is convenient for comparison to define the mass transfer rate in the absence of chemical reaction under otherwise identical conditions by... 

We have not made any distinction between in situ and in operando experiments. In operando requires the system studied to be under identical conditions as in, for example, an industrial process, while in situ could describe simulated conditions such as time-resolved studies of synthesis and chemical reactions. 

The in situ racemization can be achieved by different means either spontaneously or catalytically. Due to their chemical properties certain substrates may racemize spontaneously under the reaction conditions. Useful catalysts could be ordinary chemicals such as bases, transition metal complexes and in theory another type of biocatalyst. Having identified a suitable enzyme promoting the enantiomer-differentiating process by hydrolysis or alcoholysis of a carboxylic ester or by acylation of an alcohol one has to find the appropriate racemizing catalyst. Lipase and catalyst must tolerate each other they must work under identical conditions. The product must be chemically and configurationally stable in the presence of the catalyst. 

In marked contrast to the direct photoreduction of PQ2+ by aqueous isopropyl alcohol, where a limiting yield of PQ + is formed, the same process sensitized by benzophenone proceeds efficiently with complete conversion of PQ2+ to PQ +. Chemical analysis shows that very little benzophenone is consumed during this part of the reaction, the quantum yield for formation of PQ + is 0-6, and the oxidation product is acetone. Under identical conditions the quantum yield for photoreduction of benzophenone in the absence of PQ2+was 1-4. 

Purity is very important in chemistry. Pure elements and compounds, for example a pure sample of the element copper or pure salt (the compound sodium chloride), have reproducible properties. In other words, different samples of salt behave in exactly the same way under identical conditions they have the same melting points, undergo the same chemical reactions and so on. Mixtures, because they can have varying... 

The quantities k , k,p, kpp, and kp, are the rate constants of the four basic propagation reactions of copolymerization. The Stockmayer distribution function takes into account only a chemical polydispersity resulting fi om the statistical nature of copolymerization reactions. This means that all units of all chains are formed under identical conditions. If a monomer is removed from the reacting mixture at a rate which changes the monomer concentration ratio, the monomer concentration will drift, forming a copolymer which varies in the average composition and is broader in the chemical distribution. No such chemical polydispersity can be described by the Stockmayer distribution. Therefore, Eq. (84) has to be restricted in its application to random copolymers synthesized at very low conversions or under azeotropic conditions. For azeotropic copolymers, the feed monomer concentrations [a ] and are chosen in such a way that the second factor on the right-hand side of the basic relation of copolymerization kinetics... 

In the previous section, we have referred to the way in which the overall rate of the reaction depends on the chemical potential of the transition state when rates for identical processes are compared under identical conditions on different substrates. It was also implied that an equilibrium could be assumed between processes taking place before the rate-determining step in simple cases. This concept will be examined in more detail in this section for the case of more complex processes in which parallel reaction pathways can and do occur. One of the most characteristic (and one of the simplest and most studied) of such processes is that of hydrogen evolution, where three possible steps involving adsorbed species are generally considered to occur. " These are known respectively as the discharge or Volmer process, the electrochemical desorption or Heyrovsky process, and the hydrogen atom combination (Tafel) reaction, as follows (written in the cathodic direction) ... 

A collection of results of combinatorial chemistry tests. The library is built by performing a number of parallel chemical reactions under nominally identical conditions, each of them differing in only one or a small number of variable parameters. The library may consist of the reaction products themselves, which makes them available for additional testing, or the library is virtual, consisting of only sets of numerical data. The data is needed in either case, because the are used as inputs into sometimes very sophisticated optimum seeking mathematical algorithms yielding as its result the optimum value of the variable parameter. 

Since we are concerned here with the development of a chemical process for use on a commercial scale, it is evident that the kinetics equation should describe the process not only under laboratory conditions, but also on a large-scale industrial production scale. In many cases the processes are carried out under identical conditions, both in the laboratory and industrially. Thus, for example, the hydrochlorination process mentioned above can be carried out in an isothermal reactor consisting of a set of tubes filled with catalyst. The size of the tubes and the catalyst particles, and the conditions under which the process is carried out, arc the same as in the laboratory equipment. As an example of a process that is already carried out commercially, we can mention the reaction of the hydrogenation of iso-octene in the U.O.P. (Universal Oil Product) process. However, in many other cases the dimensions of the individual items and of the apparatus as a whole, and the conditions under which the process is carried out, change radically on transition from the laboratory to the industrial process as a result, the kinetics equations derived from laboratory tests are not applicable in industry. 

Method Cyanide is destroyed by reaction with sodium hypochlorite under alkaline conditions. System component Reaction tanks, a reagent storage and feed system, mixers, sensors, and controls two identical reaction tanks sized as the above-ground cylindrical tank with a retention time of 4 h. Chemical storage consists of covered concrete tanks to store 60 d supply of sodium hypochlorite and 90 d supply of sodium hydroxide. 

Moving on to some wider stereochemical considerations, just as enantiomers are indistinguishable as far as their physical and chemical properties are concerned (except, of course, as regards their reactions with other optically active reagents) so their spectra, acquired under normal conditions, are identical. The NMR spectrometer does not differentiate between optically pure samples and racemic ones. Note there is a way of differentiating between enantiomers by NMR but it involves using certain chiral reagents which we ll discuss in detail later. 

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