Dakin reaction

Synthesis This cyclisation version of the Claisen ester condensation is sometimes called the Dieckmann Reaction.  [c.33]


Dieckmann reaction (Section 21 2) An intramolecular version of the Claisen condensation  [c.1281]

Deacon equilibrium Deacon process Deacon reaction Deactivating groups Deactivation  [c.280]

Chlorine may be formed by the Deacon reaction at temperatures below about 900°C,  [c.53]

CAD /CAM techniques have provided the framework for using the computer as a tool in the drawing and analysis of chemical stmctures and, more recently, in the use of chemical stmctures to design reaction pathways and new products. The essential elements in these appHcations of CAD/CAM are that the possible stmctures are relatively deterministic and that allowable changes in stmcture through reaction are governed by thermodynamic, stoichiometric, and steric constraints.  [c.63]

CycHzation with loss of one carboxyl takes place in the presence of metal oxides, notably barium and thorium. Thus adipic acid yields cyclopentanone, carbon dioxide, and water (Dieckmaim reaction).  [c.62]

The intramolecular Claisen condensation of diesters, or Dieckman reaction, occurs readily to give five- or six-membered rings, and it has been extensively used for cyclopentanone and cyclohexanone derivatives.  [c.389]

Dieckmann reaction (Section 21.2) An intramolecular version of the Claisen condensation.  [c.1281]

The Dakin reaction proceeds by a mechanism analogous to that of the Baeyer-Villiger reaction. An aromatic aldehyde or ketone that is activated by a hydroxy group in the ortho or para position, e.g. salicylic aldehyde 12 (2-hydroxybenzaldehyde), reacts with hydroperoxides or alkaline hydrogen peroxide. Upon hydrolysis of the rearrangement product 13 a dihydroxybenzene, e.g. catechol 14, is obtained  [c.21]

The synthesis of the correct structure and the optimization of parameters in the design of the reaction and separation systems are often the single most important tasks of process design. Usually there are many options, and it is impossible to fully evaluate them unless a complete design is furnished for the outer layers of the onion. For example, it is not possible to assess which is better.  [c.7]

Creating and optimizing a reducible structure. In this approach, a structure known as a superstructure or hyperstructure is first created that has embedded within it all feasible process operations and all feasible interconnections that are candidates for an optimal design. Initially, redundant features are built into the structure. As an example, consider Fig. 1.7. This shows one possible structure of a process for the manufacture of benzene from the reaction between toluene and hydrogen. In Fig. 1.7, the hydrogen enters the process with a small amount of methane as an impurity. Thus in Fig. 1.7 the option is embedded of either purifying the hydrogen feed with a membrane or passing directly to the process. The hydrogen and toluene are mixed and preheated to reaction temperature. Only a furnace has been considered feasible in this case because of the high temperature required. Then two alternative reactor options, isothermal and adiabatic reactors, are embedded, and so on. Redundant features have been included in an effort to ensure that all features that could be part of an optimal solution haVe been included.  [c.9]

The lack of suitable catalysts is the most common reason preventing the exploitation of novel reaction paths. At the first stage of design, it is impossible to look ahead and see all the consequences of choosing one reaction path or another, but some things are clear even at this stage. Consider the following example.  [c.16]

Having made a choice of the reaction path, we need to choose a reactor type and make some assessment of the conditions in the reactor. This allows assessment of reactor performance for the chosen reaction path in order for the design to proceed.  [c.18]

Multiple reactions. The arguments presented for minimizing reactor volume for single reactions can be used for the primary reaction when dealing with multiple reactions. However, the goal at this stage of the design, when dealing with multiple reactions, is to maximize selectivity rather than to minimize volume for a given conversion.  [c.41]

Catalytic degradation. The performance of most catalysts deteriorates with time. The rate at which the deterioration takes place is another important factor in the choice of catalyst and the choice of reactor conditions. Deterioration in performance lowers the rate of reaction, which, for a given reactor design, manifests itself as a lowering of the conversion. This often can be compensated by increasing the temperature of the reactor. However, significant increases in temperature can degrade selectivity considerably and often accelerate the mechanisms that cause catalyst degradation. Loss of catalyst performance can occur in a number of ways a. Physical loss. Physical loss is particularly important with homogeneous catalysts, which need to be separated from reaction products and recycled. Unless this can be done with high efficiency, it leads to physical loss (and subsequent environmental problems). However, physical loss as a problem is not restricted to homogeneous catalysts. It also can be a problem with heterogeneous catalysts. This is particularly the case when catalytic fluidized-bed reactors are employed. Attrition of the particles causes the catalyst particles to be broken down in size. Particles which are carried over from the fluidized bed are normally separated from  [c.48]

The first reaction is exothermic, and the second is endothermic. Overall, the reaction evolves considerable heat. Figure 2.7 shows two alternative reactor designs. Figure 2.1a shows a shell and tube type of device which generates steam on the shell side. The temperature profile through the reactor in Fig. 2.7a is seen to be relatively smooth. Figure 2.76 shows an alternative reactor design that uses cold-shot cooling. By contrast with the tubular reactor, the cold-shot reactor shown in Fig. 2.76 experiences significant temperature fluctuations. Such fluctuations can cause accidental catalyst overheating and shorten catalyst life.  [c.56]

Solution The reversible nature of the reaction means that neither of the feed materials can be forced to complete conversion. The reactor design in Fig.  [c.118]

Once the process route has been chosen, it may be possible to synthesize flowsheets that do not require large inventories of materials in the process. The design of the reaction and separation system is particularly important in this respect, but heat transfer, storage, and pressure relief systems are also important.  [c.262]

As shown in Fig. 10.6, the vapor from the reactor flows into the bottom of a distillation column, and high-purity dichloroethane is withdrawn as a sidestream several trays from the column top. The design shown in Fig. 10.6 is elegant in that the heat of reaction is conserved to run the separation and no washing of the reactor  [c.286]

The structure of the reaction-separation system has now been fixed, and some optimization of the major design variables (reactor conversion, recycle inert concentration, etc.) has been carried out. This optimization has been carried out using only targets for the heat exchanger network and utilities. Minimization of process waste has been considered. Utility waste and cost have been minimized by improving heat integration. Again, the process changes to improve heat integration have been carried out using targets for the heat exchanger network and utilities.  [c.363]

The synthesis of reaction-separation systems. The recycling of material is an essential feature of most chemical processes. The use of excess reactants, diluents, or heat carriers in the reactor design has a significant effect on the flowsheet recycle structure. Sometimes  [c.400]

Heat exchanger network and utilities targets. Having established a design for the two inner layers of the onion (reaction and separation and recycle), the material and energy balance is known. This allows the hot and cold streams for the heat recovery problem to be defined. Energy targets can then be calculated directly from the material and energy balance. It is not necessary to design a heat exchanger network in order to establish the energy =costs. Alternative utility scenarios and combined heat and power schemes can be screened quickly and conveniently using the grand composite curve.  [c.401]

The fundamental physical properties of a compound such as its polarity or lipophi-licity determine its behavior in chemical, biochemical, or environmental processes and are therefore required for understanding and modeling the action of the compound in fields of high interest such as drug design, reaction prediction, or biodegradation. Although the amount of experimental data is growing rapidly, the number of newly synthesized or designed compounds is increasing even more quickly, especially through high-throughput methods such as parallel synthesis and combinatorial chemistry CombiChem. With techniques such as virtual screening, compounds are not synthesized at all but their activity against potential drug receptors should nevertheless be modeled. Thus, the need for reliable methods for the prediction of physicochemical properties is evident.  [c.487]

Esters of dicarboxyUc acids having hydrogen on tbe 8 or e carbon atoms undergo intramolecular cyclisation when heated with sodium or with sodium ethoxide. This cyclisation is known as the Dieckmann reaction. It is essentially an application of the Claiseu (or acetoacetic eater) condensation to the formation of a ring system the condensation occurs internally to produce s  [c.856]

Benzilic acid rearrangement Benzoin reaction (condensation) Blanc chloromethylation reaction Bouveault-Blanc reduction Bucherer hydantoin synthesis Bucherer reaction Cannizzaro reaction Claisen aldoi condensation Claisen condensation Claisen-Schmidt reaction. Clemmensen reduction Darzens glycidic ester condensation Diazoamino-aminoazo rearrangement Dieckmann reaction Diels-Alder reaction Doebner reaction Erlenmeyer azlactone synthesis Fischer indole synthesis Fischer-Speior esterification Friedel-Crafts reaction  [c.1210]

The Weldon-Pechiney process for manufacturing CI2 from HCl involves the use of Mn02 as the oxidizing agent instead of the O2 employed in the Deacon reaction.  [c.444]

Dieckmann reaction, 4, 471 Indolizidine alkaloids mass spectra, 4, 444 Indolizidine immonium salts reactions, 4, 462 Indolizi dines basicity, 4, 461 circular dichroism, 4, 450 dipole moments, 4, 450 IR spectra, 4, 449 reactivity, 4, 461 reviews, 4, 444 stereochemistry, 4, 444 synthesis, 4, 471-476 Indolizine, 1-acetoxy-synthesis, 4, 466 Indolizine, 8-acetoxy-hydrolysis, 4, 452 synthesis, 4, 466 Indolizine, I-acetyl-2-methyI-iodination, 4, 457 Indolizine, 3-acyloxy-cyclazine synthesis from, 4, 460 Indolizine, alkyl-UV spectra, 4, 449 Indolizine, amino-instability, 4, 455 synthesis, 4, 121 tautomerism, 4, 200, 452 Indolizine, 1-amino-tautomerism, 4, 38 Indolizine, 3-amino-synthesis, 4, 461, 470  [c.672]

The problem with the fiowsheet shown in Fig. 10.5 is that the ferric chloride catalyst is carried from the reactor with the product. This is separated by washing. If a reactor design can be found that prevents the ferric chloride leaving the reactor, the effluent problems created by the washing and neutralization are avoided. Because the ferric chloride is nonvolatile, one way to do this would be to allow the heat of reaction to raise the reaction mixture to the boiling point and remove the product as a vapor, leaving the ferric chloride in the reactor. Unfortunately, if the reaction mixture is allowed to boil, there are two problems  [c.285]

See pages that mention the term Dakin reaction : [c.909]    [c.279]    [c.308]    [c.318]    [c.890]    [c.909]    [c.160]    [c.28]   
Named organic reactions 2nd edition (2005) -- [ c.19 ]