Compounds and functional groups

In the next sections, we will discuss the chemical and kinetic details of the main reactions and the product-quality relevant side reactions. This information is the basis for a proper understanding of reactor and process design in PET production. The compounds and functional groups which have to be considered are given in Table 2.2. 

Table 2.2 Compounds and functional groups involved in PET synthesis ...

All of these classes of compounds are summarized in the table of Common Organic Compounds and Functional Groups, given on the front inside cover for convenient reference. 

One of die most popular reactions in organic chemistry is dissolving metal reductions [1-3], Two systems are frequently used - sodium dissolved in ammonia with alcohol and lithium dissolved in alkylamines [4]. Although calcium is seldom used, it has been successfully applied to the reduction of a variety of compounds and functional groups [5], including aromatic hydrocarbons, carbon-carbon double and triple bonds, benzyl ethers, allyl ethers, epoxides, esters, aliphatic nitriles, dithianes, als well as thiophenyl and sulfonyl groups. 

Infrared and Raman spectroscopy are complementary methods used, for instance, to study molecular structure, identify compounds and functional groups, determine interatomic forces and bond-stretching distances, perform quantitative and qualitative analyses, and determine thermodynamic properties. The three states of matter may be studied by these methods over wide ranges of temperature and pressure. Selection rules for different molecular structures determine which spectral lines are allowed, and these rules differ for the infrared and Raman methods. This difference is used to advantage in studies of molecular structure, because two types of information are brought to bear on the same problem. 

Fig.2. Potential ranges for the reduction/oxidation of number of compounds and functional groups, found in the explosives area. 

Step 10 Extract Scaffolds from chemicals (ring compounds) and functional groups. Linkers... 

In many cases, the type of compound and functional group should be discovered after completing Part One. Spectroscopy (Part Two) will be used principally to confirm the structural assignment and to provide further information toward identifying the unknown. Your instructor may not allow you to obtain spectroscopic information (infrared or NMR) until you have completed Part One. Show your test results to your instructor for approval. Once this part has been completed, you should have narrowed the list of possible compounds to a few likely candidates, all containing the same functional group. In other words, you should have determined the principal functional group. You must obtain approval from the instructor to perform specfroscopy. 

The chemistry of carboxylic acids is the central theme of this chapter The impor tance of carboxylic acids is magnified when we realize that they are the parent com pounds of a large group of derivatives that includes acyl chlorides acid anhydrides esters and amides Those classes of compounds will be discussed m Chapter 20 Together this chapter and the next tell the story of some of the most fundamental struc tural types and functional group transformations m organic and biological chemistry... 

This tendency is especially significant in compounds containing functional groups capable of addition with the formation of both five- and six-membered rings. It has been shown that for amides and hydrazides of azolecarboxylic acids, selectively, and for the acids with any arrangement of a function and triple bond, heterocyclization always leads to the closure of the six-membered ring. Similar reactions in the benzoic series mainly lead to the formation of five-membered rings. 

With some alkenes, the initial p-halo nitroso compound is oxidized by the NOCl to a P-halo nitro compound. Many functional groups can be present without interference (e.g., COOH, COOR, CN, OR). The mechanism in most cases is probably simple electrophilic addition, and the addition is usually anti, though syn addition has been reported in some cases. Markovnikov s rule is followed, the positive NO going to the carbon that has more hydrogens. 

The versatility, predictability and functional-group tolerance of free radical methodology has led to the gradual emergence of homolytic reactions in the armory of synthetic chemistry. Tin hydrides have been successfully employed in radical chemistry for the last 40 years however, there are drawbacks associated with tin-based chemistry. Organotin residues are notoriously difficult to remove from desired end products, and this, coupled with the fact that many organotin compounds are neurotoxins, makes techniques using tin inappro-... 

Hydrozirconation of various alkenylboranes [118-121] and alkenylzinc halides [34] with 1 provides the corresponding 1,1-bimetalloalkanes, which can be selectively converted to functionalized organic compounds [122-125]. Interestingly, alkenylzinc halides (RCH=CHZnX) show remarkable chemoselectivity, and functional groups such as chloride, cyanide, or ester functionality are tolerated [126]. 

Reduction by diimide can be advantageous when compounds contain functional groups that would be reduced by other methods or when they are unstable to hydrogenation catalysts. There are several methods for generation of diimide and they are illustrated in Scheme 5.4. The method in Entry 1 is probably the one used most frequently in synthetic work and involves the generation and spontaneous decarboxylation of azodicarboxylic acid. Entry 2, which illustrates another convenient method, thermal decomposition of p-toluenesulfonylhydrazide, is interesting in that it... 

Table 7. Clathrate inclusion compounds of functional group-free binaphthyl and bianthryl hosts...

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