Skeletal formulas

Five different structures may be written for the oxazolones. Their skeletal formulas, the Chemical Abstracts nomenclature (listed first), and the names with more common usage follow. 

FIGURE 2.5 Skeletal formulas of isotactic, syndiotactic, and atactic poly(vinyl chloride) (PVC). 

Complete fundamental cyclic formulas showing all carbons and hydrocarbons are given only in Charts 1, 2, 4, 8, and 9 in the other charts, the conventional ter-pene skeletal formulas have been used. For those not familiar with these common terpene formulas of the monocyclic and bicyclic structures, Chart 2 is included to show the different forms of identical structures which appear in current chemical literature. Only saturated structures are given. The three-dimensional type of skeletal formulas shown for the bicyclic structures is being used currently more and more because they often permit much more to be expressed concerning the properties of a compound and its relations to a fundamental type than do the classical structural formulas. 

See Chart 5 for the para structures and the recommended names. The familiar terpene skeletal formulas and a consistent orientation of these formulas were chosen for Chart 5 merely for convenience The recommendation of the American committees concerns only the names and fixed numbering of the menthane skeleton — it carries no stated preference for orientation or for the form in which formulas are drawn. 

Various numberings and orientations of the four typical saturated bicyclic types are summarized in Chart 8. The familiar terpene skeletal formulas are used in some of the columns merely for convenience. The fixed numberings recommended by the American committees for adoption are given in column 3. These numberings have... 

The recommended systematic names of the thujane, carane, and pinane bicyclic hydrocarbons are formed from the common terpene names of the saturated fundamental structures larger than the unsubstituted ring systems. Where these do not apply, the nor- forms of these terpene names are recommended for the carane and pinane types of structures, and the bicyclo names for the thujane type. For purposes of uniformity and convenience, skeletal formulas resembling the familiar terpene formulas are used they are oriented so that the isolated methyl group is at the top and the numbering runs clockwise. The general rules for forming the names are ... 

Skeletal formula The representation of an organic compound s carbon-to-carbon bonds by lines. A single line represents a single bond with double and triple lines for double and triple bonds, respectively. The carbon-to-hydrogen bonds are assumed but not shown apart from the outline, but other functional groups or elements use their conventional representation. 

Convert this structure of capsaicin to a skeletal formula. 

The skeletal formula should show only carbon-carbon bonds plus any functional groups present in the molecule. 

Draw both structural and skeletal formulas for each of the following compounds. 

What is the name of the compound whose skeletal formula is shown above ... 

This principle is also illustrated in the following example. If 1-aminobenzoic acid is treated with sodium nitrite, the diazo intermediate may be formed. This compound may then lose a proton from the carboxylic acid group to form an ion that contains both a positive and a negative charge. The skeletal formula of this compound is shown below. 

On the assumption that the simpler bases, with fewer substituents, might lend themselves more readily to degradative studies, attention has concentrated in recent years on the examination of some of the atisines, and particularly on the readily available atisine itself. These studies have permitted a tentative formulation (I) of atisine in terms of a pentacyclic structure for the present the related atisines are therefore assumed to have similar pentacyclic structures based on the skeletal formula CisHag-NH (cf. Table 1) the empirical formulas so far established (with the exception of... 

In the alphabetical systems list, each heterocyclic system is named as recommended in the above mentioned Chemical Abstracts Service publication either in its fully unsaturated or fully saturated form as appropriate. Each name is accompanied by a skeletal formula that includes neither double bonds nor indicated hydrogen(s). 

The most common type of structural formula used by organic chemists, and the fastest to draw, is the bond-line formula. (Some chemists call these skeletal formulas.) The formula in Fig. 1.3 is a bond-line formula for propyl alcohol. The sooner you master the use of bond-line formulas, the more quickly you will be able to draw molecules when you take notes and work problems. And, lacking all of the symbols that are explicitly shown in dash and condensed structural formulas, bond-line formulas allow you to more quickly interpret molecular connectivity and compare one molecular formula with another. 

Different representations of 2-methylbutane. (a) Structural formula, (b) Abbreviated formula. (c) Skeletal formula. 

It is possible to miss the hydrogen atoms from a structural formula. With the hydrogen atoms omitted we have what is known as a skeletal structure or skeletal formula (Figure 10.13). In certain cases of complex molecules this can be quite useful. 

The skeletal formula of the type in Figure 10.13a is very rarely used, and certainly should not be used in an examination answer. Skeletal formulas of the type in Figure 10.13b can be very useful for quickly writing out alternative structures and for depicting molecules of substantial complexity (Figure 10.14). We will use this type of skeletal structure later when working out the possible structural isomers for a given molecular formula. 

Figure 10.22 Using skeletal formulas to establish whether structures are Isomers or not-these are not ... 

Draw skeletal formulas for all the possible dichloro substitution products of propane and give their lUPAC names. 

However, benzene does not behave chemically like an alkene. The entire molecule lies in the same plane, as shown in Figure 2.12. Benzene contains resonance hybrid bonds, and the structure of the benzene ring allows electrons to be spread through delocalized p-orbitals over the whole ring. The structural and skeletal formulas below show benzene as a resonance hybrid, representing the delocalization of electrons. 

A simplified structure called the skeletal formula is a carbon skeleton in which carbon atoms are represented as the end of each line or as comers in a zigzag pattern. The hydrogen atoms are not shown, but each carbon is understood to have bonds to four atoms, including hydrogen. 

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