Synthesis Approach

The optimization component of process integration drives the iterations between synthesis and analysis toward an optimal closure. In many cases, optimization is also used within the synthesis activities. For instance, in the targeting approach for synthesis, the various objectives are reconciled using optimization. In the structure-based synthesis approach, optimization is typically the main framework for formulating and solving the synthesis task.  [c.6]

As mentioned above, the solids process synthesis approach (Rossiter and Douglas, 1986) has been applied to the optimization of a continuous salt crystallization plant similar to that depicted in Figure 9.2 (Rossiter, 1986). In  [c.272]

This approach to synthesis is one of making a series of best local decisions. Equipment is added only if it can be justified economically on the basis of the information available, albeit an incomplete picture. This keeps the structure irreducible, and features which are technically or economically redundant are not included.  [c.8]

Grossmann, I. E., Mixed Integer Programming Approach for the Synthesis of Integrated Process Flowsheets, Camp. Chem. Eng., 9 463, 1985.  [c.14]

Given the choice of a batch rather than continuous process, does this need a different approach to the synthesis of the reaction and separation and recycle system In fact, a different approach is not needed. We start by assuming the process to be continuous and then, if choosing to use batch operation, replace continuous steps by batch steps. It is simpler to start with continuous process operation  [c.117]

Yee, T. F., and Grossmann, I. E., A Simultaneous Optimization Approach for the Synthesis of Heat Exchanger Networks, Paper 81d, Annual AIChE Meeting, Washington, 1988.  [c.398]

A major breakthrough in protein crystallization was the development over a decade ago of a technique for crystallizing proteins in two dimensions [28]. First developed to crystallize antibodies, this approach initially relied on the synthesis of lipids having ligands for binding the protein of interest. The lipid is mixed with lipids having no ligands, and they are spread on a water surface and compressed to the desired pressure. The proteins are introduced into the aqueous subphase and, on binding to the lipid monolayer, form a dense mono-layer that subsequently orders. The concentration and orientation afforded by  [c.542]

The first step in designing a precursor synthesis is to pick precursor molecules that, when combined in organic solvents, yield the bulk crystalline solid. For metals, a usual approach is to react metal salts with reducing agents to produce bulk metals. The main challenge is to find appropriate metal salts that are soluble in an organic phase.  [c.2901]

Few of us can any longer keep up with the flood of scientific literature, even in specialized subfields. Any attempt to do more and be broadly educated with respect to a large domain of science has the appearance of tilting at windmills. Yet the synthesis of ideas drawn from different subjects into new, powerful, general concepts is as valuable as ever, and the desire to remain educated persists in all scientists. This series. Advances in Chemical Physics, is devoted to helping the reader obtain general information about a wide variety of topics in chemical physics, a field that we interpret very broadly. Our intent is to have experts present comprehensive analyses of subjects of interest and to encourage the expression of individual points of view. We hope that this approach to the presentation of an overview of a subject will both stimulate new research and serve as a personalized learning text for beginners in a field.  [c.766]

To recognize the different levels of representation of biochemical reactions To understand metabolic reaction networks To know the principles of retrosynthetic analysis To understand the disconnection approach To become familiar with synthesis design systems  [c.542]

However, the synthe.sis of each compound was considered as a specific task on its own. A suitable strategy for the synthesis of a target compound was mostly found on the basis of the intuition and experience of the acting chemists, i.e., the planning of a synthesis of a complex organic molecule was considered as an art form. No systematic approach was attempted to handle the strategic design of an organic synthesis. However, the growth of knowledge resulting from the rapid development of analytical methods and other techniques was demanding a more systematic approach for synthesis design.  [c.569]

The so-called logic-oriented approach generates reactions as bond-breaking and bond-making steps. These steps are often combined with mechanistic or thermodynamic considerations. Logic-oriented systems are mostly based on a clear formal treatment of reactions. In principle, logic-oriented systems should not only be able to predict known reactions but should also generate novel reactions. This is both an advantage and a disadvantage. On one hand, such a system may suggest a reaction nobody has foreseen and thus the system provides a new approach to the synthesis problem being considered. On the other hand, it may generate a huge number of chemically invalid reactions, which an experienced chemist would intuitively avoid. Therefore, the output of a logic-oriented system has to be thoroughly verified by suitable evaluation techniques [29].  [c.573]

The disconnection approach has basically changed the view on planning a synthesis.  [c.592]

The retrosynthetic analysis of a target compound is a systematic approach in developing a synthesis plan starting with the target structure and working backward to available starting materials.  [c.592]

S. Warren, Organic Synthesis - The Disconnection Approach, Wiley, Chichester, 1982.  [c.595]

Reiterative Approach to the Synthesis of Carbohydrate  [c.28]

Clearly, there is a need for techniques which provide access to enantiomerically pure compounds. There are a number of methods by which this goal can be achieved . One can start from naturally occurring enantiomerically pure compounds (the chiral pool). Alternatively, racemic mixtures can be separated via kinetic resolutions or via conversion into diastereomers which can be separated by crystallisation. Finally, enantiomerically pure compounds can be obtained through asymmetric synthesis. One possibility is the use of chiral auxiliaries derived from the chiral pool. The most elegant metliod, however, is enantioselective catalysis. In this method only a catalytic quantity of enantiomerically pure material suffices to convert achiral starting materials into, ideally, enantiomerically pure products. This approach has found application in a large number of organic  [c.77]

Synthesis This is one possible approach - we don t actually know how it is done.  [c.26]

Using the common atom approach, design a synthesis of TM 332.  [c.108]

As an example, let s analyse the synthesis of y-lactones (e.g. TM 334) and see how we may choose one of a number of strategies depending on the structure of the target molecule. We ll consider in turn each of the three C-C bond disconnections. The one with the most appeal is probably b complete the analysis for this approach.  [c.109]

E.J.Corey was the originator of this analytical approach to synthesis and you might hke to read some of the articles in which he first explains it. Here is a selection J. Amer. Chem. Soc.. 1964, 478 1972, 94, 440 1974, 9 6516 1975, 97, 6116 1976, 98, 189 Pure  [c.125]

The third category avoids generating a large number of possible routes. These are systems most similar to the expert system approach to artificial intelligence. The program attempts to mimic the decision-making process of a synthetic chemist. It thus eliminates many possible synthesis strategies as unreasonable without having worked out the entire synthesis path. The quality of results depends on the reactions known to the program and the heuristics it has been given to choose between possible paths.  [c.278]

We shall now exemplify the solid-phase peptide synthesis approach by c )c/o-[-L-Val-[)-Pro-D-Val-L-Pro-]], which was prepared by Merrifield himself, the inventor of the method (B.F. Gisin, 1972).  [c.235]

El-Halwagi, M. M. (1993). A process synthesis approach to the dilemma of simultaneous heat recovery, waste reduction and cost effectiveness. In Proceedings of the Third Cairo International Conference on Renewable Energy Sources ( A. I. El-Sharkawy and R. H. Kummler, eds.), Vol. 2, pp. 579-594.  [c.82]

El-Halwagi, M. M. (1992). A process synthesis approach to the dilemma of simultaneous heat recovery, waste reduction and cost effectiveness, /n Proceedings of the Third Cairo International Conference on Renewable Energy Sources, (A. I. El-Sharkawy and R. H. Kummler, eds.) Vol. 2, pp. 579-594.  [c.246]

Papoulias, S. A., and Grossmann, I. E., A Structural Optimization Approach in Process Synthesis II. Heat Recovery Networks, Computers Chem. Eng., 7 707, 1983.  [c.211]

This class of methods differ from inverse micelle methods in that the reactions are completed in organic solvents. Such solvents penult the reactions to proceed at much higher temperatures, leading to nearly perfect crystalline solids [55]. In addition, the use of organic solvents penults nanocrystals to be prepared from a wide variety of molecular precursors under oxygen-free and water-free conditions. Metal [12, 56, 52, 58, 59, 60, 61, 62, 63, 64, 65 and 66], semiconductor [62, 68, 69, 20, 21, 22, 23, 24, 25, 26, 22 aiid 28] aiid ceramic nanocrystals [29, 80] have been generated using this basic strategy. These stringent controls over reaction conditions are important in the synthesis of covalent semiconductors, which require reactive organometallic starting materials. This can also be an advantage in the preparation of metal nanocrystals free from oxide or hydroxide contamination. Precursor methods have also shown remarkable success in producing highly monodisperse (a < 5%) nanocrystals, especially for II-VI semiconductor nanocrystals [10, 81]- For these reasons, this particular approach to nanocrystal synthesis is becoming a popular strategy despite the fact that it requires more involved synthetic methodology.  [c.2901]

A challenging task in material science as well as in pharmaceutical research is to custom tailor a compound s properties. George S. Hammond stated that the most fundamental and lasting objective of synthesis is not production of new compounds, but production of properties (Norris Award Lecture, 1968). The molecular structure of an organic or inorganic compound determines its properties. Nevertheless, methods for the direct prediction of a compound s properties based on its molecular structure are usually not available (Figure 8-1). Therefore, the establishment of Quantitative Structure-Property Relationships (QSPRs) and Quantitative Structure-Activity Relationships (QSARs) uses an indirect approach in order to tackle this problem. In the first step, numerical descriptors encoding information about the molecular structure are calculated for a set of compounds. Secondly, statistical and artificial neural network models are used to predict the property or activity of interest based on these descriptors or a suitable subset.  [c.401]

After the Second World War, our knowledge about chemical reactions and their mechanisms increased tremendously. This provided a major step forward to a more systematic and sophisticated approach to planning organic syntheses, which was made possible by the development of chromatographic methods for product separation and the introduction of spectroscopic methods for structure elucidation. The conformational analysis of organic structures and transition states based on stereochemical principles was introduced. Furthermore, the application of new selective chemical reagents was discovered and improved. Thus, in the 1950s the synthesis of quite complex molecules and natural products was achieved. Some examples are vitamin A (O. Isler, 1949), cortisone (R.B. Woodward, R. Robinson, 1951), morphine M. Gates, 1956), penicillin J. Sheehan, 1957), and chlorophyll (R.B. Woodward, 1960).  [c.568]

Then, in 1960, Corey introduced a general methodology for planning organic syntheses. Corey s synthon concept [2.1-25] was a downright change of the perception of an organic synthesis. The synthesis plan for a target molecule is developed by starting with the target structure (the product of the synthesis ) and working backwards to available starting materials, The rctrosynthctic analysis or disconnection of the target molecule in tbc reverse direction is performed by the systematic use of analytical rules which have been formulated by Corey. For the example of tropinonc, this is shown in Figure 10.3-29. Corey s approach is nowadays widely accepted as the disconnection approach and is taught in a number of textbooks (e.g Ref. [26 ).  [c.569]

The Japanese program system AlPHOS is developed by Funatsu s group at Toyo-hashi Institute of Technology [40]. AlPHOS is an interactive system which performs the retrosynthetic analysis in a stepwise manner, determining at each step the synthesis precursors from the molecules of the preceding step. AlPHOS tries to combine the merits of a knowledge-based approach with those of a logic-centered approach.  [c.576]

A drawback of this approach is that it typically generates enormous and imwieldy synthesis trees which contain a large number of dead-end branches which are not worth further consideration. Furthermore, the chemist is forced to follow a rigid scheme during the planning process, alternating between the application of transforms, the derivation of new precursors, and again the application of further transforms to these precursors.  [c.577]

In the 1970 s, chemists increasingly encountered varying aspects of the triumvirate chemistry-information-computer (CIC) while conducting their research. Common to all was the use of computers and information technologies for the generation of data, the mixing of data sources, the transformation of data into information and then information into knowledge for the ultimate purpose of solving chemical problems, e.g. organic synthesis planning, drug design, and structure elucidation. These activities led to a new field of chemical expertise which had distinctly different features compared with the traditional archiving approach of chemical information, which has been established about 200 years ago and comprises primary journals, secondary literature, and retrieval systems like Chemical Abstracts.  [c.656]

Combinatorial chemistry has significantly increased the nurnjjers of molecules that can be synthesised in a modern chemical laboratory. The classic approach to combinatorial synthesis involves the use of a solid support (e.g. polystyrene beads) together with a scheme called split-mix. Solid-phase chemistry is particularly appealing because it permits excess reagent to be used, so ensuring that the reaction proceeds to completion. The excess  [c.727]

We hit it off well. I liked his approach and his outspoken honesty about his goals. He also must have seen something in me that he liked, and we started seriously discussing my coming to USC. There were, however, difficulties. The chemistry department of USC, was (and still is) heavily centered around chemical physics (at the time, concentrating on spectroscopy). Organic chemistry for whatever reasons was much of a stepchild, although Jerry Berson spent a decade at USC before he left for Wisconsin and then Yale. Ivar Ugi was also a faculty member for three years (1969-1971) before returning to Germany. He laid the foundation of multicomponent synthesis (i.e., combinatorial chemistry) while at USC, although it did not attract much attention at the time.  [c.110]

Aiylethylamines (e.g. TM 244) are important intermediates in the synthesis of alkaloids as you will see later. Suggest an approach to TM 244.  [c.77]

In the synthesis of molecules without functional groups the application of the usual polar synthetic reactions may be cumbersome, since the final elimination of hetero atoms can be difficult. Two solutions for this problem have been given in the previous sections, namely alkylation with nucleophilic carbanions and alkenylation with ylides. Another direct approach is to combine radical synthons in a non-polar reaction. Carbon radicals are. however, inherently short-lived and tend to undergo complex secondary reactions. Escheirmoser s principle (p. 34f) again provides a way out. If one connects both carbon atoms via a metal atom which (i) forms and stabilizes the carbon radicals and (ii) can be easily eliminated, the intermolecular reaction is made intramolecular, and good yields may be obtained.  [c.36]

Within the cubane synthesis the initially produced cyclobutadiene moiety (see p. 329) is only stable as an iron(O) complex (M. Avram, 1964 G.F. Emerson, 1965 M.P. Cava, 1967). When this complex is destroyed by oxidation with cerium(lV) in the presence of a dienophilic quinone derivative, the cycloaddition takes place immediately. Irradiation leads to a further cyclobutane ring closure. The cubane synthesis also exemplifies another general approach to cyclobutane derivatives. This starts with cyclopentanone or cyclohexane-dione derivatives which are brominated and treated with strong base. A Favorskii rearrangement then leads to ring contraction (J.C. Barborak, 1966).  [c.78]

The problems involved are exemplified here by Knorr s pyrrole synthesis (A. Gossauer, 1974). It has been known for almost a century that or-aminoketones (CjN components) react with 1,3-dioxo compounds (Cj components) to form pyrroles (C N-heterocycles). A side-reaction is the cydodimerization of the a-aminoketones to yield dihydropyrazines (C4N2), but this can be minimized by keeping the concentration of the a-aminoketone low relative to the 1.3-dioxo compound. The first step in Knorr s pyrrole synthesis is the formation of an imine. This depends critically on the pH of the solution. The nucleophilidty of the amine is lost on protonation, whereas the carbonyl groups are activated by protons. An optimum is found around pH S, where yields of about 60% can be reached. At pH 4 or 6 the yield of the pyrrole may approach zero. The ester groups of -keto esters do not react with the amine under these conditions. If a more reactive 1,3-diketone is used, it has to be symmetrical, otherwise mixtures of two different imines are obtained. The imine formed rearranges to an enamine, which cyclizes and dehydrates to yield a 3-acylpytrole as the "normal Knorr product (A. Gossauer, 1974 G.W. Kenner, 1973 B).  [c.150]

See pages that mention the term Synthesis Approach : [c.1248]    [c.153]    [c.199]    [c.201]    [c.226]    [c.706]    [c.707]    [c.726]    [c.732]    [c.36]    [c.210]   
See chapters in:

Pollution prevention through process integration  -> Synthesis Approach