Two examples

Having discussed the choice of reactor type and operating conditions at length, let us try two examples. 

For physical processes, two examples are the elimination of normal paraffins from a mixture by their adsorption on 5 A molecular sieves or by their selective formation of solids with urea (clathrates)... 

We will give two examples of analysis of these components, bearing in mind that the distinction between condensable and noncondensable hydrocarbons rarely holds in actual refining streams, most of them producing both classes of hydrocarbons simultaneously. 

First, the typical characteristics of inspection problems which result in heterogeneous data are presented. Next, typical AI techniques which can be used for the automated data interpretation are presented. The applicabihty of the techniques to various inspection problems is discussed. Two example apphcations for automatic NDT data interpretation are briefly described, and finally, the conclusions are given. 

Leaking fi om process flows may pose operational risks and cause environmental problems as well as economic losses. Two examples of tracer methods for testing, localising and quantifying leaks are given below. 

Discuss (a) the acidity and (b) the substitution reactions of metal hexa-aquo cations. [MfH O) ]" (where n = 2 or 3), giving two examples of each type of reaction. Discuss the effect upon the stabilities of the -t- 2 and -f- 3 oxidation states of... 

Two examples of condensed phosphoricfV) acids are heptaoxo-diphosphoric(V) (pyrophosphoric) and polytrioxophosphoric (meta-phosphoric) acids. 

We shall illustrate the SISM described with two examples. The model system of a box of water molecules and the system of a box of linear molecules which are depicted in Figure 2. 

Figure 7-10. Two examples of torsional potentials plotted using Eq, (24) with the parameters rt = 2, V = 5.0, y = Fi (solid line), and n = 3. = 3.0, y = 0 (broken line). All other V, ...

We will use the term energy surface to refer not only to systems in which the bonding remains unchanged, as in these two examples, but also where bonds are broken and/or formed. Our discussion will be appropriate to both quantum mechanics and molecular mechanics, except where otherwise stated. 

The Michael reaction is of central importance here. This reaction is a vinylogous aldol addition, and most facts, which have been discussed in section 1.10, also apply here the reaction is catalyzed by acids and by bases, and it may be made regioselective by the choice of appropriate enol derivatives. Stereoselectivity is also observed in reactions with cyclic educts. An important difference to the aldol addition is, that the Michael addition is usually less prone to sterical hindrance. This is evidenced by the two examples given below, in which cyclic 1,3-diketones add to o, -unsaturated carbonyl compounds (K. Hiroi, 1975 H, Smith, 1964). 

Now we turn to syntheses of simple, noncommercial or very expensive difunctional open-chain compounds. We have chosen one or two examples each of 1,2- up to 1,6-difunctional target molecules. 

Natural products that contain carbon-carbon triple bonds are numerous Two examples are tariric acid from the seed fat of a Guatemalan plant and cicutoxin a poi sonous substance isolated from water hemlock... 

In the two examples cited so far the chlorination of propene and the bromination of cyclohexene both criteria are met... 

Laboratory syntheses of conjugated dienes can be achieved by elimination reactions of unsaturated alcohols and alkyl halides In the two examples that follow the conjugated diene is produced m high yield even though an isolated diene is also possible... 

Table 13 1 collects chemical shift information for protons of various types The beginning and major portion of the table concerns protons bonded to carbon Within each type methyl (CH3) protons are more shielded than methylene (CH2) protons and meth ylene protons are more shielded than methme (CH) protons These differences are small as the following two examples illustrate... 

Many naturally occurring substances are epoxides You have seen two examples of such compounds already m disparlure the sex attractant of the gypsy moth (Section 6 18) and m the carcinogenic epoxydiol formed from benzo[a]pyrene (Section 118) In most cases epoxides are biosynthesized by the enzyme catalyzed transfer of one of the oxy gen atoms of an O2 molecule to an alkene Because only one of the atoms of O2 is trans ferred to the substrate the enzymes that catalyze such transfers are classified as monooxy genases A biological reducing agent usually the coenzyme NADH (Section 15 11) is required as well... 

Conjugate addition is most often observed when the nucleophile (Y ) is weakly basic The nucleophiles m the two examples that follow are C=N and C6H5CH2S respectively Both are much weaker bases than acetylide ion which was the nucleophile used m the example illustrating direct addition... 

Several naturally occurring amines mediate the transmission of nerve impulses and are referred to as neurotransmitters Two examples are epinephrine... 

A commonplace variation on the general pattern seen m carbohydrate structure is the replacement of one or more of the hydroxyl substituents by some other atom or group In deoxy sugars the hydroxyl group is replaced by hydrogen Two examples of deoxy sugars are 2 deoxy d nbose and l rhamnose... 

Some ammo acids have side chains that bear acidic or basic groups As Table 27 3 indicates these ammo acids are characterized by three values The third pK reflects the nature of the side chain Acidic ammo acids (aspartic and glutamic acid) have acidic side chains basic ammo acids (lysine arginine and histidine) have basic side chains The isoelectric points of the ammo acids m Table 27 3 are midway between the pK values of the zwitterion and its conjugate acid Take two examples aspartic acid and lysine Aspartic acid has an acidic side chain and a pi of 2 77 Lysine has a basic side chain and a pi of 9 74... 

Systematic names formed by applying the principles of substitutive nomenclature are single words except for compounds named as acids. First one selects the parent compound, and thus the suffix, from the characteristic group listed earliest in Table 1.7. All remaining functional groups are handled as prefixes that precede, in alphabetical order, the parent name. Two examples may be helpful ... 

The distribution of the results of an analysis around a central value is often described by a probability distribution, two examples... 

Two examples from the analysis of water samples illustrate how a separation and preconcentration can be accomplished simultaneously. In the gas chromatographic analysis for organophosphorous pesticides in environmental waters, the analytes in a 1000-mL sample may be separated from their aqueous matrix by a solid-phase extraction using 15 mb of ethyl acetate. After the extraction, the analytes are present in the ethyl acetate at a concentration that is 67 times greater than that in... 

As shown in the following two examples, this approach is easily extended to situations that require an indirect analysis or a back titration. 

Chemical kinetic methods also find use in determining rate constants and elucidating reaction mechanisms. These applications are illustrated by two examples from the chemical kinetic analysis of enzymes. 

Two examples of dual-channel manifolds for use In flow Injection analysis where R1 and R2 are reagent reservoirs P Is the pump S Is the sample I Is the Injector B Is a bypass loop W Is waste C Is the mixing and reaction coll and D Is the detector. 

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