Types of synthesizers

The absence of reverse arrows indicates diat the design process does not need to iterate because of faulty transformations from one description to another. In practice, getting the design wrong, having too big or too slow a design, will result in further modifications of the descriptions. 

So far synthesizers have been outlined only as a tool for transformation from one level of description to a net-list of some form. In practice, it is clear that a number of different types of synthesis tools exist. 

They usually synthesize into a system with limited use of bus structures. They often have limitations in their ability to synthesize largely memory-based structures and data-path structures, although the precise limitations vary from tool to tool. 

These tools are typically used for syndiesizing systems into bus-based structures in whiA ALU and register-file-like structures are attaAed to a common bus. These tools are often considerably more restrictive than the more general-purpose arAitectural synthesizers, but for many applications that map weU to a bus structure they can be mu A more efficient. Often a suite of CAD tools will provide both an architectural synthesizer and data-path s)mthesis tools. 

The use of test synthesis software lies outside the scope of this book, but we eagerly anticipate the arrival on die market of books devoted to this topic. 

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A. y-Oxygen-Substituleel Stannanes. Oxygenated allylic stannanes have been synthesized and used advantageously in several types of syntheses. Both a- and y-alkoxy and silyloxy stannane can be prepared by several complementary methods.177 C-y-Alkoxy and silyloxy allylic stannanes react with aldehydes to give primarily syn... 

In this chapter, we first review the nature of the several forms of elemental phosphorus and then proceed to consider their uses for specific types of syntheses of compounds containing the carbon-phosphorus bond. Prior reviews have also been concerned with these topics.1 2 Our purpose here is to update these presentations and provide fundamentals for the practicing chemist venturing into the use of elemental phosphorus. We limit this discussion to the more-or-less direct syntheses of organophosphorus compounds from elemental phosphorus. We will consider reactions that generate monophosphorus species without C-P bonds as critical intermediates, pro-... 

The various possibilities for the first two types of syntheses are listed schematically in Table 4, and the possibilities for synthesis from other heterocycles are listed in Table 5. In each case the method is discussed in more detail in the following sections Tables 4 and 5 indicate the section(s) in which a particular reaction is described. In the case of sulfur-containing heterocycles, 5-oxides and 5,5-dioxides are treated alongside the basic parent structures, since for 1,3,2-dioxathiolane, 1,2,3-oxadithiolane, and 1,2,5-oxadithiolane the unoxidized rings are unknown. 

Described below is one of the three types of syntheses of metallacyclic a-hydroxyalkyl complexes that we have developed.3 It is simple to execute and employs two starting materials that have been reported in previous volumes of Inorganic Syntheses. 5... 

Solid-phase methods are applicable to syntheses of sequence-specific oligomers and dendritic structures. The triazene chemistry developed for this specific purpose may also be useful in other types of syntheses. Further development of solid-phase syntheses of this type into combinatorial synthesis of oligomers is the next logical step. Solid-phase methods will never completely replace solution-phase approaches to oligomers, but either technique should be considered with respect to the special characteristics and requirements for the system under investigation. 

The reactions (3.98) of Group VI metal pentacarbonyls with diorganoditellurides also belong to the discussed type of syntheses [268] ... 

The various possibilities for these three types of syntheses are listed schematically in Table 10. Several of these reactions are of special preparative importance and they will be discussed in more detail in the subsection indicated in the last column in Table 10. In all other cases literature references are given. 

Synthesis With TBA. As with the DPA-VPI-5 crystallization, the TBA synthesis involves the use of a precursor aluminophosphate mixture. (This is summarized also in Table I.) However, there is an important distinction between the two types of syntheses during step 4. When TBA is used, the precursor mixture is not agitated. The quiescent mixture exhibits a pH profile in time nearly that with agitation (see Figures 2 and 4). If the precursor mixture is agitated during aging, either TBA-VPI-5 is formed and accompanied by H3 or only H3 is crystallized. 

In most cases convergent types of syntheses are the most cost effective and preferred for various reasons. However, that was not the case with ERH-1 as it will show in the following examples. In the convergent approach (see Scheme 3) it was assumed that barbituric acid would be a cheap source ( 4 per kg) for the pyrimidine portion since it was prepared from inexpensive materials such as ethyl malonate and urea with sodium ethoxide as a condensing agent. Numerous reports [4] have shown that barbituric acid is easily converted to 2,4,6-trichloropyrimidine by heating with phosphorus oxychloride and a trialkylamine. Our intent was to couple 2,4,6-trichloropyrimidine 10 to 2,2-dimethyl-1-indanone followed by various reactions that would lead to ERH-1 [5] as shown in Scheme 3. 

To remedy this situation and reduce the often excessive gel s polarity, the silanol groups are exploited in order to provide sites of covalent bonding for organic molecules. Bonded silica gel, modified in this way, behave as a liquid in that the separation mechanism now depends on the partition coefficient instead of adsorption coefficient. These covalently bonded phases, whose polarity can be easily adjusted, constitute the bases of the reversed phase polarity partition chromatography or RP-HPLC, used in the majority of HPLC separations. Two types of syntheses lead to monomeric or polymeric bonded surfaces ... 

The community of chemists who check these syntheses perform an invaluable service. I am truly grateful for their help and extend to them my personal thanks. I encourage you to let editors of future volumes know if you are willing to check various types of syntheses. Your help will be appreciated and the service you render will be most beneficial to future generations of chemists. 

To systematize and clarify the many types of syntheses reported for 1, methods for preparing this ring system are divided into three categories ... 

Reviews of the synthesis of isoquinoline alkaloids (341-343) and of biogenetic types of syntheses (4, 344, 345) have been published. 

We will not repeat the tables and summaries published in the monographs mentioned above in the following sections on syntheses of diazo compounds. Some miscellaneous methods, which do not belong to the types of syntheses in Table 2-1, are known, but have no significance. They have been discussed by Regitz and Maas (1986). 

Similar types of syntheses are commonly used for the preparation of compounds of interest for their possible physiological action. For example, Morgan and coworkers (24) recently described the use of aryllithium compounds in the preparation of some stilbestrol analogs. The general procedure is shown by the reaction of ethyl a-(p-anisyl) propyl ketone with an aryllithium compound to yield a lithium salt of a tertiary alcohol, where Ar = — CeHs,... 

Only a few examples of o-bonded metal-carbon porphyrins are now known, but it is theoretically possible to prepare and characterize representative complexes with almost all elements in the periodic table. These types of syntheses could lead to the related synthesis of numerous novel bimetallic or dimeric derivatives. 

A reaction retriever program is applicable to all four types of syntheses A synthesizer program applies primarily to the P class of problem, althougn a forward working synthesizer would apply to SM problems The applicability of these programs by synthesis type is summarized in Figure 2 ... 

The syntheses we have just considered exemplify the types of syntheses that are now within the capabilities of organic chemists. Indeed, substantially more complex molecules have been synthesized. The complete synthesis of Vitamin B12, for example, was announced in 1972 after an effort that spanned more than 10 years." In terms of complexity of the target molecule and the logistical demands of the synthetic effort, this achievement ranks as the most imposing synthesis that has been accomplished to date. 

This contribution describes the chemistry and uses of the poly(aryleneethynylene)s (PAEs). The different types of syntheses for PAEs are described first and the most important classes of PAEs are highlighted. Their properties and uses are outlined. Polymer analogous reactions of poly(paraphenyleneethynylene)s (PPEs), i.e., hydrogenation, complexation with suitable organotransition metal fragments, and side chain manipulation are discussed with regard to the synthetic processes and the properties of the formed novel polymeric materials. 

The alkoxyl group of the ester and the alkoxide must be the same so as to avoid transesterification (which occurs with alkoxides by the same mechanism as base-promoted ester hydrolysis Section 17.7B). Ethyl esters and methyl esters, as it turns out, are the most common ester reactants in these types of syntheses. Therefore, we use sodium ethoxide when... 

For example, the production of chlorine and sodium hydroxide alone accounts for approximately 2% of the total consumption of electricity in the United States and, together with that for Al, much more. This apparent lack of acceptance of organic electrode processes as viable means for (certain types) of syntheses (see later) is perhaps all the more surprising when it is noted that electrolytic reactions are simply very direct oxidation and reduction processes which do not produce in the solution other conjugate reduced or oxidized species, respectively, such as would occur with homogeneous redox reagents. 

The first group of methods involves end-group analyses. Many types of syntheses leave a special group on one or both ends of the molecule, such as hydroxyl and carboxyl. These can be titrated or analyzed instrumentally by such methods as infrared. For molecular weights above about 25,000 g/mol, however, the method becomes insensitive because the end groups are present in too low a concentration. 

This study states that the uses of renewable somces which are vegetable oils, polymers synthesis is stepping forward. In this study we were reviewed about the different types of syntheses and the importance of polymer composites such as crossed-linked polymers and step-growth polymers from the vegetable oils. The polymer composites have achieved importance in industrial and biomedical applications. To our knowledge from various somces we have reviewed the preparation and applications of polymers from vegetable oil. 

The results are relevant to a number of practical situations. The most important applications will be found in the development of chemical reactors for liquid phase reactions which are not very fast, such as we often encounter in the synthesis of organic products. For this type of syntheses, we can easily design, e.g., large scale continuous stirred tank reactors on the basis of data obtained with small scale batch-reactors. Examples of these are discussed in Chapter 10. 

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