Outline schemes

Two approaches to the discovery and development of new pesticides will be considered. First, in order to illustrate how difficult it is to produce an acceptable pesticide, an exercise in listing the properties which the chemical requires will be carried out. A generalized scheme showing the main stages involved will then be considered. 

In this illustrative example let us assume that the pesticide is to be an insecticide which will control caterpillars, and that it will act by attacking the caterpillar s stomach. What are its desirable and/or essential properties The main properties only would be the following  

Several of these properties relate directly to the key point of selectivity of action. Thus (i) ensures that accidental ingestion by domestic animals or man himself does not have serious consequences (ii) means that the chemical will not be toxic to the growing crop, e.g. cabbages. Properties (vii) and (viii) are self-explanatory and clearly also influence selectivity. Property (iii) means that the chemical will not be degraded by the UV light in sunshine to a non-pesticidal product, nor will it be, say, washed away by heavy rainfall before it has a chance to do its job. The reasons for the other desirable properties are obvious. 

Bearing in mind that this is not a comprehensive list, but merely includes the main properties which the pesticide should have, it can easily be appreciated why it is so difficult to produce pesticides with perfect selectivity—the ultimate objective of the industry. 

I fate in plant biochemistry —fate in soil I residues 

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The outlined scheme is shown to yield stable solutions for non-zero Weissenberg number flows in a number of benchmark problems (Swarbric and Nassehi, 1992b). However, the extension of this scheme to more complex problems may involve modifications such as increasing of elemental subdivisions for stress calculations from 3 x 3 to 9 x 9 and/or the discretization of the stress field by biquadratic rather than bi-linear sub-elements. It should also be noted that satisfaction of the BB condition in viscoelastic flow simulations that use mixed formulations is not as clear as the case of purely viscous regimes. 

Fig. 1. An amplified outline scheme of the making of various wiaes, alternative products, by-products, and associated wastes (23). Ovals = raw materials, sources rectangles = wines hexagon = alternative products (decreasing wine yield) diamond = wastes. To avoid some complexities, eg, all the wine vinegar and all carbonic maceration are indicated as red. This is usual, but not necessarily tme. Similarly, malolactic fermentation is desired in some white wines. FW = finished wine and always involves clarification and stabilization, as in 8, 11, 12, 13, 14, 15, 33, 34, followed by 39, 41, 42. It may or may not include maturation (38) or botde age (40), as indicated for usual styles. Stillage and lees may be treated to recover potassium bitartrate as a by-product. Pomace may also yield red pigment, seed oil, seed tannin, and wine spidts as by-products. Sweet wines are the result of either arresting fermentation at an incomplete stage (by fortification, refrigeration, or other means of yeast inactivation) or addition of juice or concentrate.

Before we leave our discussion of preparing 6-aminopenicillanic acid for use as a starting material in the manufacture of semi-synthetic penicillins, we should point out that similar processes are used in the manufacture of semi-synthetic cephalosporins. Here tire key intermediate is 7-aminodeacetoxycephalosporanic add (7-ADCA). We have drawn outline schemes comparing the production of semi-synthetic penicillins and cephalosporins in Figure 6.15. You will see that the two schemes are very similar. 

The outlined scheme can also be used to calculate the amount of phosphoric acid triesters. In that case the difference must be formed of the total phosphorus content minus that of free phosphoric acid, phosphoric acid monoester, and phosphoric acid diester. The resulting value is then multiplied with the calculated molecular mass of the triester. 

Use retrosynthetic analysis to suggest syntheses of the following compounds. Develop at least three outline schemes. Discuss the relative merits of the schemes and develop a fully elaborated synthetic plan for the most promising retrosynthetic scheme. 

In this review, synthesis, structure, and redox properties of phosphaquinoid compounds are described, keeping the contribution of thienoquinoid structures in mind in the first part. In the second part, synthesis and structure of phosphorus substituted thiophene and related compounds, especially tetraphosphoryl derivatives, are outlined (Scheme 3). 

In the following sections we will describe recent developments and applications in the organocatalytic a-heteroatom functionalization of aldehydes and ketones catalyzed by chiral amines [1]. Notably, the C-H to C-Het transformations associated with amination, oxygenation, halogenation (fluorination, chlorination, bro-mination), and sulfenylation will be outlined (Scheme 2.24). 

To illustrate these preparative methods the synthesis of natural enkephalins and the potent synthetic analog FX 33-824 are outlined. Scheme 10.1 depicts the original synthesis of Met-enkephalin.<38)... 

Some of the reactions of diaminomaleonitrile have already been outlined (Schemes 11 and 17). Reactions of this versatile compound which lead to the formation of the 1,2- and 2,3-bonds of imidazole have also been described. When heated in alcoholic solution with an alkyl orthoformate, 4,5-dicyanoimidazole is formed with formic acid in refluxing xylene,... 

Purine has also been obtained by heating formamide alone (72CPB623) and detected in reactions involving hot formamide (77CPB1923). Interpretation of mechanisms of reactions carried out in formamide solution must clearly be made with care. However the distribution of and labels in purine derived from [ C, NJHCN and formamide has suggested the mechanism outlined (Scheme 55) (78TL4039). 

On the 24 December the Treasury agreed in principle to the outline scheme and asked BSA to produce detailed, fiilly costed plans, a request with which the company eventually complied towards the end of April. It transpired, however, that BSA had already contracted for work valued in excess of 30,000 without Treasury approval and that much more expenditure would be required to complete the job. A Supply Board investigation undertaken in August revealed that, because of further unauthorized contractual obligations made by BSA, the Treasury was committed to approve a revised estimate of 50,000. The company was sharply rebuked for what was regarded as a serious irregularity. 

OUTLINE SCHEME FOR THE ANALYSIS OF NfTRO-EXPLOSrVES substance with Anhydrous Ether in Soxhlet s Fat Extraction Apparatus. 

Other substituents, such as the pseudohalo groups (CN, NCO, OCN, NCS, SCN) and carboxyl groups, can be attached to the --C(X)=N— system, and compounds of this type are discussed within the outlined scheme. Likewise, O-substituted derivatives of hydroxamoyl halides are included in Chapter 6. Since the imidoyl halides can be part of a heterocyclic system, the cyclic homologs are treated separately in the last chapter. The fully aromatic compounds, such as halopyridines, halopyrimidines, and halo-1,3,5-triazines, are discussed only briefly in Chapter 8, as their chemistry is somewhat different. 

Because no mechanistic information about this reaction is available, the routes to form the three different products are tentatively outlined (Schemes 1-3.)... 

In 1957 the late Dr W. H. J. Vernon presented an outline scheme of Methods of Preventing Corrosion in which four categories were defined, i.e. (a) modification of procedure, (b) modification of environment, (c) modification of metal, and (d) protective coatings the scheme also indicated the suitability of the method for protecting a metal in different natural environments. 

The above outlined scheme leads to the conclusion that completely ionized thiols would give exclusively sulphinic and sulphonic acids nevertheless, the experimental results indicate formation of ca. 5% of disulphide in the oxidation of potassium benzenethiolate even with base in large excess. Since formation of disulphide would require the presence of undissociated thiol, other mechanisms must be operative. Again it is possible that the intervention of trace metal catalysis in the oxidation reaction has to be taken into account. Cullis, Hopton and Trimm reported that copper ions in concentrations as low as 10 M are still active as catalysts and indeed it is very hard to detect metal ions at such low concentrations and to exclude adventitious impurities of this order of magnitude. 

Outline scheme for removal of standpipe region to give access for removal of reactor core and Internals. 

Fig 41 OUTLINE SCHEME FOR REMOVAL OF STANDPIPE REGION TO GIVE ACCESS FOR REMOVAL OF REACTOR CORE AND INTERNALS... 

A flood protection scheme is to be provided in a river valley where the flood level reaches up to 4.5 m above ground level (agl). Prepare an outline scheme that ensures protection of facilities based to the right of the line X shown in Figure A1 if the river reaches 4-4.5 m for a period of up to 7 days. The length of the flood defence system is 500 m. 

In the presence of 70% perchloric acid at 100 °C, the acetophmiones Ar COMe (Ar = C Hs or CeFj) react with the benzaldehydes Ar CHO (Ar = C Hs or C(Fg) during 10 min to give the chalcones (72), but reaction during 2 h yields the pyiylium perchlorates (74 Ar = Ar ), which may also be obtained from the chalcones and perdiloric add or, in better yield, from the chalcones and the appropriate acetophenone Ar COMe (Ar = CfHg or C Fs) in the presence of perchloric acid. A mechanism for these condensations has been outlined (Scheme 19), and the pyrylium salts yield triaryl-pyridines (73) on treatment with ammonium carbonate in acetic acid. ... 

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