Reaction principles

The most important discovery in dyeing cellulose with reactive dyes was the appHcation of Schotten-Baumaun principles. Reaction of alcohols proceeds more readily and completely in the presence of dilute alkali, and the cellulose anion (cell- O ) is considerably more nucleophilic than is the hydroxide ion. Thus the fixation reaction (eq. 1) competes favorably with hydrolysis of the dye (eq. 2). [Pg.415]

There have been many extensive and intensive studies of metal oxalate decompositions. Boldyrev et al. [1015] have suggested that these may be classified according to the three principle reactions... [Pg.218]

In principle, reaction schemes similar to that given in the preceding paragraph may be developed for other comparable rate processes, for example spinel formation. However, Stone [27] has pointed out that, where the barrier phase is not an efficient ionic conductor, the overall reaction may be controlled by the movement of a single cation and anion. In addition, there is the probability that lattice imperfections (internal surfaces, cracks, leakage paths [1172], etc.) may provide the most efficient route to product formation.]... [Pg.271]

Taylor CD, Wasileski SA, Filhol JS, Neurock M. 2006b. First principles reaction modeling of the electrochemical interface Consideration and calculation of a tunable surface potential fi om atomic and electronic structure. Phys Rev B, 73. [Pg.127]

L. Masteron and C. L. Hunley, Chemistry Principles Reactions, Saunders College Publishing,... [Pg.118]

In principle, reactions can be carried out in UHV similarly to the proton formation reaction. By performing experiments in UHV rather than in situ one can manipulate the interface with a high level of precision, and the interface can be probed using the surface techniques mentioned in 4.3, which cannot be used in situ. In practice, the low temperature requirement of UHV and the lack of bulk solution are obstacles not easily overcome.50... [Pg.318]

In principle, reactions which are subject to electrophilic catalysis by protons can be catalysed by metal ions also (e.g. Tee and Iyengar, 1988 Suh, 1992). However, metal ions may function in other ways, such as to deliver a hydroxide ion nucleophile to the reaction centre (e.g. Dugas, 1989 Chin, 1991), and it is often difficult to decide between kinetically equivalent mechanisms without resorting to extensive (and intensive) model studies. Use of the Kurz approach may help to resolve such ambiguities, as shown below. [Pg.52]

Several reviews on various aspects of the chemistry of these allenes have been published [1-10] and therefore this chapter concentrates on the presentation of principle reaction patterns, on important applications of known processes and on new developments in this area. [Pg.426]

One of the first studies of how these secondary phases form was performed by van Roosmalen and Cordfunke. These authors used SEM/EDS and XRD to study postannealed diffusion couples of LSM and YSZ as well as pressed and fired powder mixtures of LSM and YSZ. These experiments showed that reaction products in sufficient quantity to detect by XRD (1—3%) form at temperatures as low as 1170 °C. The two principle reaction products observed were La2Zr207 (LZ) and SrZrOs (SZ), with the relative amount of LZ and SZ depending on the La/Sr ratio in the LSM. Calcia- and baria-doped LaMnOs were found to be similarly reactive with YSZ, and reactivity of LSM with YSZ having 3% or 8% yttria was found to be similar. In the case of the diffusion couples, the layer of reaction products formed at the interface was found (using SEM) to be on the order of 1 /xm after 600 h at 1280 °C and 10—15 fim after 600 h at 1480 °C. By employing Pt diffusion markers... [Pg.587]

Synthetic methods for the preparation of six-membered heterocyclic systems which proceed via the formation of three or four bonds are virtually restricted in application to the monocyclic heterocycles and have been most widely applied to pyridine and pyrimidine derivatives. In principle, reactions which proceed with the formation of three ring bonds can be sub-classified into three groups, namely, those involving [4 + 1 + 1] atom fragments, [3 + 2 + 1] atom fragments and [2 + 2 + 2] atom fragments. [Pg.86]

The complex is a brick red to brown, highly insoluble solid believed to have a polymeric, halogen-bridged structure.10 The principle reaction pathways of this complex involve chloride-bridge cleavage leading to a range of ruthenium(II) products.11... [Pg.251]

Unfortunately, there are no simple mles to predict reaction quantum yields from chemical structure, and, therefore, Ojr(A) values have to be determined experimentally. We will address such experimental approaches in Section 15.4, and confine ourselves here to a few general remarks. First, we should note that, in principle, reaction quantum yields may exceed unity in cases in which the absorption of a photon by a given compound causes a chain reaction to occur that consumes additional compound... [Pg.626]

When analyzing the energetics of a reaction one must remember that chemical equilibria depend on the total pressure of the system and that, therefore, the heat of reaction of an expln or of a propint changes as the products expand and the total pressure decreases. This problem is particularly acute in detonations for which the compn of the shocked state is unknown and for which the calorimetrically measured heat is in fact for the frozen or the expanded compn. Moreover, often the tabulated heats of detonation are corrected for the heat of vaporization of the water which is one of the principle reaction products. Whereas tabulated data constitute the base from which the theoretical properties of expls can be calcd, there is no connection between the heat of expln, the heat of formation and the sensitivity of an expl. For instance, aliphatic... [Pg.684]

In principle, reaction of enolate ions with electrophiles should be influenced by stereoelectronic effects. For instance, protonation of enolate ions in acidic medium could provide information about the stereochemistry of the forming of a C —H bond. [Pg.148]

The groundwater transport of radionuclides through waterbearing interbed layers in the Columbia River basalt formation will be controlled by reactions of the radionuclides with groundwater and interbed solids. These interactions must be understood to predict possible migration of radionuclides from a proposed radioactive waste repository in basalt. Precipitation and sorption on interbed solids are the principle reactions that retard radionuclide movement in the interbeds. The objective of the work described herein was to determine the sorption and desorption behavior of radionuclides important to safety assessment of a high-level radioactive waste repository in Columbia River basalt. The effects of groundwater composition, redox potential, radionuclide concentration, and temperature on these reactions were determined. [Pg.9]

This book concentrates on the basic principles, reaction mechanisms and engineering concepts of technologies that use UV radiation (or light) as a selective reagent for the cleavage of chemical bonds and hence for the destruction of unwanted chemicals or microorganisms. Accordingly, these methods include UV... [Pg.5]

Advanced Oxidation Processes (AOPs) Principles. Reaction Mechanisms, Reactor Concepts... [Pg.369]

Subsequently, experimental procedures of dilution principle reactions were further improved and standardized, so that today it is possible to synthesize many desired compounds by suitable choice of components and dilution conditions. [Pg.11]

Yield increases in a similar order of magnitude as in the synthesis of the lower homologues were achieved also in the preparation of hexathia[18]crown-6 ( 18S6 , 72) by the cesium effect . Cooper et al. [70] obtained 72 from the dithiol 70 and the dichloro compound 71 in a one-component dilution principle reaction [1] in a yield of 76% using a suspension of cesium carbonate in DMF. When the reaction was carried out under analogous conditions with potassium carbonate, 72 was isolated in a much lower yield of only 38% [70]. [Pg.54]

The first-principles reaction coordinate calculations at the B3LYP/6-31-i-G(d) level led to the optimized geometries of the rate-determining transition states (i.e., the transition states for the first reaction step of the ester hydrolysis), as depicted in Fig. 5. For benzoyl ester hydrolysis of protonated cocaine in its chair conformation, the nucleophilic hydroxide ion can also approach from two faces, denoted by Si and Re, of the carbonyl to form two stereoisomer... [Pg.120]

To examine the above mechanistic hypotheses, detailed first-principles reaction coordinate calculations [100] were performed on the fundamental reaction pathways for BChE-catalyzed hydrolysis of (-)-cocaine with a BChE active site model. The BChE active site model used in the reaction coordi-... [Pg.132]

Relatedly, despite the synthesis and structural characterization of numerous arsine and stibine oxides, bomb calorimetry measurements have only been reported on triphenylarsine oxide . While corresponding measurements have been made on triphenylarsine, it is clearly premature to make general observations as to E—O bond enthalpies in the absence of additional data. In principle, reaction calorimetry should prove useful. Indeed, we note a solution phase (benzene) enthalpy of reaction study of triphenylarsine and -butyl hydroperoxide according to the reaction... [Pg.163]

This review of CVD principles, reactions, and applications begins with an introduction to the fundamental processes involved in CVD processing. These include thermodynamics, kinetics, and transport issues. Then the discussion briefly touches on the desirable qualities of the deposit that is formed. Next the chemistry and precursors are introduced, to familiarize the reader with common reactions that are widely used, followed by a brief discussion of nonconventinal or enhanced CVD technologies. Finally, the CVD of several technologically significant materials is reviewed to illustrate the direction of current work in the field. [Pg.150]

Line narrowing could be due to dissolution of the sample or, in principle, reaction of the solid particles with the support medium these possibilities were discounted also by the inability to observe either 23Na or 3IP signals from the filtered support liquor after the SINNMR experiment. [Pg.93]

Oppenlander, T. Photochemical Purification of Water and Air Advanced Oxidation Processes (AOPs) Principles, Reaction Mechanisms, Reactor Concepts, Vch Verlagsgesellschaft Mbh, 2003. [Pg.48]

It is easier to measure concentration than rate a plot of concentration against time is shown in Figure 2.1(a). This type of process is known as exponential decay. In principle, reactions of this type are never complete. However, 99.9% completion corresponds to about 10 half-lives, and 99.9999% to 20 half-lives, at which point for all practical purposes the reaction is complete. [Pg.21]

CP/MAS NMR. In the first of these papers the structures within the resins were examined as a function of cure temperature [17]. The chemistry of the resins is very complex but one of the principle reactions is the formation of stable isocyanurate structures from three isocyanate units. Other species are also present e.g., amine, urea and biuret. These are formed by the reactions shown in Fig. 15.2.13. CP/MAS NMR spectra of the resins indicated that the optimum cure temperature was 120°C at which most of the isocyanate groups were converted to isoeyanurate (Fig. 15.2.14). [Pg.523]

The principle reaction cycles during main-sequence burning are the proton-proton (p-p) chains and the CNO cycles. [Pg.46]

In principle reactions that are induced by a light signal could be in the conventional time range, or rapid, requiring rapid data acquisition. The latter class of reactions became a reality in the history of this research area upon the development of fast... [Pg.12]

Doepp and his co-workers have reported the synthesis and photochemical activity of some novel 3,5-diacetyl-1,4-dihydropyridines. The principle reaction is aromatization. Crystals of ethyl l-acetyl-4-phenyl-l,4-dihydro-3-pyri-dinecarboxylate contain centrosymmetric pairs of molecules. The irradiation of these brings about dimerization to yield the anti-dimer (101). Irradiation in solution alfords mixtures of the dimer (101) and the cage compound (102). ... [Pg.29]

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