Continuous alkanes

Methane is the only alkane of molecular formula CH4 ethane the only one that is C2H6 and propane the only one that is C3Hj Beginning with C4H10 however constitutional isomers (Section 1 8) are possible two alkanes have this particular molecular formula In one called n butane, four carbons are joined m a continuous chain The nmn butane stands for normal and means that the carbon chain is unbranched The second isomer has a branched carbon chain and is called isobutane... 

Bonding m n butane and isobutane continues the theme begun with methane ethane and propane All of the carbon atoms are sp hybridized all of the bonds are ct bonds and the bond angles at carbon are close to tetrahedral This generalization holds for all alkanes regardless of the number of carbons they have... 

Pick out the longest continuous carbon chain and find the lUPAC name m Table 2 2 that corresponds to the unbranched alkane having that number of carbons This is the parent alkane from which the lUPAC name is to be derived... 

As numbered on the structural formula the longest continuous chain contains eight car bons and so the compound is named as a derivative of octane Numbering begins at the end nearest the branch and so the ethyl substituent is located at C 4 and the name of the alkane is 4 ethyloctane... 

Find the longest continuous chain of carbon atoms and assign a basis name to the compound corresponding to the lUPAC name of the unbranched alkane having the same number of carbons... 

The longest continuous chain in the alkane shown is SIX carbons... 

Summary of lUPAC Nomenclature of Alkanes and Cycloalkanes (Continued)... 

The longest continuous chain that contains the —CH group provides the base name for aldehydes The e ending of the corresponding alkane name is replaced by al and sub stituents are specified m the usual way It is not necessary to specify the location of O... 

Section 17 1 The substitutive lUPAC names of aldehydes and ketones are developed by identifying the longest continuous chain that contains the carbonyl group and replacing the final e of the corresponding alkane by al for aldehydes and one for ketones The chain is numbered m the direction that gives the lowest locant to the carbon of the carbonyl group... 

Systematic names for carboxylic acids are derived by counting the number of car bons m the longest continuous chain that includes the carboxyl group and replacing the e ending of the corresponding alkane by oic acid The first three acids m Table 19 1 methanoic (1 carbon) ethanoic (2 carbons) and octadecanoic acid (18 carbons) illus trate this point When substituents are present their locations are identified by number... 

Alkane residues attached to miscellaneous atoms continued)... 

Work continues on improving the efficiency of this process, such as for freeing the alkan olamine from heat-stable salts that can form (125). Formulations have been developed which inhibit degradation of mono- and diethanolamine in processing (126). Models (127), computer programs (128), and kinetics and enthalpies (129—136) have been developed to help determine equiUbria of the acid gas—alkanolamine—water system. Additional references relate to the use of tertiary alkan olamines, such as triethanolamine, for gas conditioning (137—139). 

In contrast, the alkane chains on the polymeric phase cannot collapse in an environment of water as they are rigidly held in the polymer matrix. Thus, the retention of the solute now continuously falls as the methanol concentration increases as shown in Figure 4. It should be pointed out that if the nature of the solutestationary phase interactions on the surface of a bonded phase is to be examined in a systematic manner with solvents having very high water contents, then a polymeric phase should be used and brush type reversed phases avoided if possible. 

For a molecule as simple as Fl2, it is hard to see much difference between the valence bond and molecular orbital methods. The most important differences appear- in molecules with more than two atoms. In those cases, the valence bond method continues to view a molecule as a collection of bonds between connected atoms. The molecular- orbital method, however, leads to a picture in which the sane electron can be associated with many, or even all, of the atoms in a molecule. We ll have more to say about the similarities and differences in valence bond and molecular- orbital theory as we continue to develop their principles, beginning with the simplest alkanes methane, ethane, and propane. 

With ketones, the -e ending of an alkane is replaced by -one in the longest continuous chain containing the carbonyl group. The chain is numbered in the direction that provides the lower number for this group. The carbonyl carbon of a cyclic ketone is C-1 and the number does not appear- in the nfflne. 

Figure 4.12 continued) (c) An expansion of the inset region from (b), with the normal alkanes shown as (a-e). Other unidentified components (f-i) are presented to locate specific peaks for comparison purposes, (d) A light gas oil analysed under the same conditions as for the cycle oil, showing the same expanded region. In this case, the oil has not been ti eated in the same manner as the cycle oil, so it retains the components that were absent from the cycle oil. Peaks (a-i) are the same as those seen in (c). 

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