Partial structure

naphthalene has only 10 Jt electrons, one from each carbon, whereas the incorrect two-circle version suggests it has 12 jr electrons. 

Do appreciate that there is no strict convention for how you orientate the structure on paper. In fact, we will turn structures around, as appropriate, to suit our needs. For example, the amino acid tyrosine has three functional groups, i.e. a carboxylic acid, a primary amine, and a phenol. How we draw tyrosine will 

You will need to be able to reorientate stmctures without making mistakes, and also to be able to recognize different versions of the same thing. A simple example is with esters, where students have learnt that ethyl acetate (ethyl ethanoate) can be abbreviated to CH3CO2C2H5. When written backwards, i.e. C2H5OCOCH3, the ester functionality often seems less recognizable. 

In the representations overleaf, you can see the line drawing and the version with methyls that stresses the bond ends. Both are satisfactory. When we wish to consider the reactivity of the double bond, and perhaps want to show that reaction occurs irrespective of the alkyl groups attached to the double bond, we put in the abbreviation R (see below), or usually just omit them. When we omit the attached groups, it helps to show what we mean by using wavy lines across the bonds, but in our urge to proceed we tend to omit even these indicators. This may 

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Several methods for the synthesis of thiazole compounds are available, which can be classified into the partial structures illustrated in Scheme 1. The first of these structures (la) is by far the most useful and versatile of all the thiazole syntheses. By a judicious choice of reactants it allows... 

The partial structure in step 3 contains 6 bonds equivalent to 12 electrons Because CH3NO2 contains 24 electrons 12 more electrons need to be added... 

Given the following partial structure add a substituent X to C 1 so that It satisfies the indicated stereochemical requirement You may find it help ful to build a molecular model for reference... 

A certain species of grasshopper secretes an allenic substance of molecular formula C13H20O3 that acts as an ant repellent The carbon skeleton and location of various substituents in this substance are indicated in the partial structure shown Complete the structure adding double bonds where appropriate... 

Fig. 9. Partial structural formulas and shorthand notations for principal hemiceUuloses found in wood, where the sugar units ate noted as P-D-xylopyranose (Xylp), 4-Omethyl-a-D-glucopyranosyluronic acid (GlupU), a-L-arabinofuranose (Araf), P-D-glucopyranose (Glup), P-D-mannopyranose (Manp), and P-D-galactopyranose (Galp) for (a) arabino-4-O-methylglucuronoxylan from softwood, (b) 0-acetyl-galactoglucomannan from softwood, and...

Characterisation of the antibiotic monordene (also referred to as radicicol) with the elemental composition Cig/Zz/OgCl isolated from Monosporium bonorden gave the macrolide structure 1. The relative configuration of the H atoms on the two conjugated double bonds (6,7-cis, %,9-trans-) could be deduced from the 60 MHz H NMR spectrum The relative configuration of the C atoms 2-5, which encompass the oxirane ring as a partial structure, has yet to be established. 

Rational arrangement of these partial structures leads to /ran5-stilbene-4-aldehyde E. 

Carbon-proton bonds are then assigned by means of the one-bond CH connectivities observed in the CH COSY diagram (Table 44.2). This completes partial structures A and B to the CH skeletons C and D. 

Two- and three-bond CH eonneetivities of the methyl protons deteeted in the CH COLOC diagram identify the partial structures E and F. Only one bond from 5c = 72.6 to 5c = 44.5 could not be directly identified because of the absenee of the eorresponding eross signal (<5// =1.17 with 5c = 44.5). Nevertheless, partial strueture E is reasonable, assuming the six-membered ring to be retained during metabolism. 

Table 45.1. Partial structures from the CH COSY and CH COLOC plots (the protons are given in Italic numerals, C atoms separated by a single bond are given in bold numerals and C atoms separated by two or three bonds...

Table 47.2. Assembly of the partial structures A-E to form the decalin framework F of the sesquiterpene...

Partial structure Protons Sh CH a one bond Sc C Sc atoms separated by two or three bonds Sc Sc Sc Sc Sc... 

Table 50.2. Partial structures from the CH COLOC plot. Each partial structure B-I is deduced from the two- or three-bond couplings Jew for the H atoms of B-I (with italic values)...

Those C atoms which are bonded to the protons that have already been located can be read from the CH COSY plot (Table 51.1) and thus partial structure C is the result. 

TOCSY Total correlation spectroscopy, in the homonuclear COSY format, e.g. HH TOCSY traces out all proton-proton coimectivities of a partial structure in addition to the coimectivities (V, V, V, J) as detected by HH COSY... 

Polymerization and curing rates of novolacs depend strongly on the acidity of the reaction mixture. Fig. 16 depicts the general pH dependence. Fig. 17 shows a partial structure for a hexa-cured novolac. Incorporation of amine is widely, though not universally, reported in hexa-cured novolac structures. In addition to the structure shown in Fig. 17, A, A -dibenzyl and A, A, A -tribenzylamine linkages have been reported [185-192]. The main by-products of hexa-curing conditions are water and ammonia, though formaldehyde is also produced. The structure and abundance of the amino portions of the cured polymer vary considerably with conditions. 

Kurath described the conversion of 3a,17y5-diacetoxy-5)9-androstan-12-one (partial structure 78) to diketone (79) by bromination of (78) and hydrolysis of the C-11 epimeric bromo ketones... 

An interesting one-step combined oxidation and benzilic acid rearrangement has been described by Holden and Kerwin in connection with the synthesis of C-norpregnanes from 3a,20yS-dihydroxy-5j9-pregnan-12-one (partial structure 85). 

In this chapter, we will discuss the present status of CHIRBASE and describe the various ways in which two (2D) or three-dimensional (3D) chemical structure queries can be built and submitted to the searching system. In particular, the ability of this information system to locate and display neighboring compounds in which specified molecular fragments or partial structures are attached is one of the most important features because this is precisely the type of query that chemists are inclined to express and interpret the answers. Another aspect of the project has been concerned with the interdisciplinary use of CHIRBASE. We have attempted to produce a series of interactive tools that are designed to help the specialists or novices from different fields who have no particular expertise in chiral chromatography or in searching a chemical database. 

The data taken is normally presented as the total structure factor, F(Q). This is related to the neutron scattering lengths hi, the concentrations C , and the partial structure factor Sy(Q) for each pair of atoms i and j in the sample, by Equation 4.1-1 ... 

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