Control chemical reaction

Shapiro M and Brumer P 1989 Coherent chemistry—Controlling chemical reactions with lasers Acc. Chem. Res. 22 407... 

Seideman T, Shapiro M and Brumer P 1989 Coherence chemistry—controlling chemical reactions with lasers Chem. Phys. 90 7132... 

Resins can be divided into natural and synthetic types. Natural resins have a vegetable or animal origin. Typical examples are rosins. Synthetic resins result from controlled chemical reactions, and can be divided into two subgroups. 

The frontier orbital theory [7-9] assumes that the stabihzation by the electron delocalization could control chemical reactions. The stabilization comes from the interactions between the occupied molecular orbitals of one molecule and the unoccupied molecular orbitals of another (Sect. 1.4). The strong interaction occurs when the energy gap is small (Sect. 1.3). The HOMO and the LUMO are the closest in energy to each other. The HOMO-LUMO interaction, especially the interaction between the HOMO of electron donors and the LUMO of electron acceptors, controls the chemical reactions (Scheme 20). The HOMO and the LUMO are termed the frontier orbitals. ... 

The reactivity of steam can be reduced via pH control. The injection or addition of a buffer such as ammonium chloride inhibits the dissolution of certain mineral groups, controls the migration of fines, inhibits the swelling of clays, controls chemical reactions in which new clay minerals are formed, and... 

Iwamori H (1992) Melt-solid flow with diffusion-controlled chemical reaction. Geophys Res Lett 19 309-... 

Theoretically, it is possible to control chemical reactions by the different solubilities of the reactants or of special intermediates (e.g., according to their nucleophilicity) in different solvents or various catalyst fluids. The principle has been proven but is not yet used for special applications in industry [32]. 

The main business of most chemical companies is to manufacture products by means of controlled chemical reactions. The reactivity that makes chemicals useful can also make them hazardous. Chemical reactions are usually carried out without mishap, but sometimes they get out of control because of problems such as the wrong or contaminated raw material being used, changed operating conditions, unanticipated time delays, failed equipment, incompatible materials of construction, or loss of temperature control. Such mishaps can be worse if the chemistiy under both normal and abnormal conditions is not fully understood. Therefore, it is essential that chemical process designers and operators understand the nature of the reactive materials andchemistry involved and what it takes to control intended reactions and avoid unintended reactions throughout the entire life cycle of a process facility. 

Ministry of Education Key Laboratory of Science and Technology of Controllable Chemical Reactions P.O. Box 98... 

Both batteries and fuei cells utilize controlled chemical reactions in which the desired process occurs electrochemically and all other reactions including corrosion are hopefully absent or severely kinetically suppressed. This desired selectivity demands careful selection of the chemical components including their morphology and structure. Nanosize is not necessarily good, and in present commercial lithium batteries, particle sizes are intentionally large. All batteries and fuel cells contain an electropositive electrode (the anode or fuel) and an electronegative electrode (the cathode or oxidant) between which resides the electrolyte. To ensure that the anode and cathode do not contact each other and short out the cell, a separator is placed between the two electrodes. Most of these critical components are discussed in this thematic issue. 

The remainder of this section considers several experimental studies of reactions to which the Smoluchowski theory of diffusion-controlled chemical reaction rates may be applied. These are fluorescence quenching of aromatic molecules by the heavy atom effect or electron transfer, reactions of the solvated electron with oxidants (where no longe-range transfer is implicated), the recombination of photolytically generated radicals and the reaction of carbon monoxide with microperoxidase. 

In 1860, an international conference of chemists convened to discuss how the masses of atoms of different elements could be measured and compared with one another. (As we explore in Section 9.2, knowing the relative masses of atoms helps chemists understand and control chemical reactions.) At the time, there was little agreement because different chemists using different experimental procedures and assuming different theories came up with different results. Progress in chemistry was stymied by this problem. 

Scientists have learned how to control chemical reactions to produce many useful materials—nitrates and other nitrogen-based fertilizers from atmospheric nitrogen, metals from rocks, plastics and pharmaceuticals from petroleum. These materials and the thousands of others produced by chemical reactions, as well as the abundant energy released when fossil fuels take part in the chemical reaction called combustion, have dramatically improved our living conditions. 

Note. It may happen that the boundary extends its influence over several sites, so that several additional lines have to be written. An example is the model for diffusion-controlled chemical reactions in section 7. Also impurities may occur, i.e., internal sites at which the rn and g deviate from the analytic expression used in (5.1). Then the equations for the pn of two or more internal sites have to be written separately. For the time being we exclude such complications. 

Only a few problems with artificial boundaries can be treated by the reflection principle. In this section the method of normal modes is expounded, which in principle is able to deal with artificial boundaries of all types. Rather than develop this method in full generality we demonstrate it on the example (ii) of section 7 the model for diffusion-controlled chemical reactions. 

J. Manz Prof. V. Engel s question points to the virtues of using (i) ultrashort laser pulses for controlling chemical reactions, in comparison with (ii) continuous-wave lasers. Compare, for example, the strategies of... 

Now, I would like to pose a question to Prof. Field and Quack and to the entire conference. How do we use spectroscopic information to devise effective schemes to control chemical reactions Should we try to force the molecule to follow our will Or should we try to make use of what we learn from spectroscopy about what the molecule wants to do and use this knowledge to get the molecule to do what we actually want ... 

Gaddis E S, Vogelpohl A (1992) The Impinging-stream reactor A high performance loop reactor for mass transfer controlled chemical reactions, Chemical Engineering Science 47 2877-2882. 

In heterogeneous solid state reactions, the phase boundaries move under the action of chemical (electrochemical) potential gradients. If the Gibbs energy of reaction is dissipated mainly at the interface, the reaction is named an interface controlled chemical reaction. Sometimes a thermodynamic pressure (AG/AK) is invoked to formalize the movement of the phase boundaries during heterogeneous reactions. This force, however, is a virtual thermodynamic force and must not be confused with mechanical (electrical) forces. 

Described in Section 2.1.1 the formal kinetic approach neglects the spatial fluctuations in reactant densities. However, in recent years, it was shown that even formal kinetic equations derived for the spatially extended systems could still be employed for the qualitative treatment of reactant density fluctuation effects under study in homogeneous media. The corresponding equations for fluctuational diffusion-controlled chemical reactions could be derived in the following way. As any macroscopic theory, the formal kinetics theory operates with physical quantities which are averaged over some physically infinitesimal volumes vq = Aq, neglecting their dispersion due to the atomistic structure of solids. Let us define the local particle concentrations... 

Organic Source Material and a Subsurface Temperature Controlled Chemical Reaction Mechanism, in Advances in Organic Geochemistry, pp. 25-46, Pergamon, Oxford, 1969. 

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