Structural isomerism, alkane

In Problem 2 5 you were asked to write structural formulas for the five isomeric alkanes of molecular formula C6H14 In the next section you will see how the lUPAC rules generate a unique name for each isomer... 

In this section you have seen how heats of com bustion can be used to determine relative stabilities of isomeric alkanes In later sections we shall expand our scope to include the experimentally determined heats of certain other reactions such as bond dissociation energies (Section 4 16) and heats of hydrogenation (Section 6 2) to see how AH° values from various sources can aid our understanding of structure and reactivity... 

Alkane Hydrocarbon containing only single carbon-carbon bonds. The simplest example is methane, CK, 580 cis-trans isomer in, 598 isomers in, 580-582 nomenclature, 582t physical properties, 591t sources, 583-585 structural isomerism, 597 tests for, 602 uses, 583-585... 

Draw two-dimensional structural formulas for all the isomeric alkanes of formula C5H12. 

Self-Test 18.4A Write the condensed structural formulas for the five isomeric alkanes of molecular formula C6H14. 

The alkanes make up a homologous series of hydrocarbons with the general formula C H2 +2 in is the number of carbon atoms). Alkanes exhibit a type of structural isomerism called chain isomerism, where the arrangement of the carbon atoms in the molecules is different. 

Wiener H (1948a) Relation of the physical properties of the isomeric alkanes to molecular structure. Surface tension, specific dispersion, and critical solution temperature in aniline. J. Phys. Chem. 52 1082-1089. 

The direct summation of vertex degree products in M2 has been changed in (G) to a summation of inverse-square-root terms. This specific function selection has been made to provide better correlations of with the properties of isomeric alkanes. This shows the high sensitivity of the new molecular descriptor to variations in molecular structure. More recently, some restrictions in the applicability of the inverse-square-root function to compounds with large numbers of atoms (Gutman and Lepovic, 2001) and new values for the exponent were investigated (Gutman and Lepovic, 2001 Estrada, 2002). 

Butane and all succeeding members of the alkanes exhibit structural isomerism. Recall from Section 20.4 that structural isomerism occurs when two molecules have the same atoms but different bonds. For example, butane can exist as a straight-chain molecule (normal butane, or -butane) or with a branched-chain structure (called isobutane), as shown in Fig. 22.4. Because of their different structures, these molecules exhibit different properties. For example, the boiling point of -butane is -0.5°C, whereas that of isobutane is — 12°C. 

As we shall see, there are several different types of structural isomer. Isomers have to be named so that you can tell the difference between them. Consider the first member of the alkane series that shows structural isomerism, butane. 

No element forms such a variety of hydrides as carbon. In addition to the numerous known alkanes, structural isomerism predicts many... 

Wiener, H. (1948a). Relationship of Physical Properties of Isomeric Alkanes to Molecular Structure Surface Tension, Specific Dispersion and Critical Solution Temperature in Aniline. J.Phys.Colloid Chem., 52,1082-1089. 

Wiener, H. (1948a) Relationship of physical properties of isomeric alkanes to molecular structure surface tension, specific dispersion and critical solution temperature in aniline. /. Phys. Colloid Chem., 52, 1082-1089. 

Two or more compounds with the same molecular formula but different properties are called isomers. Isomers with different arrangements of bonded atoms are constitutional (or structural) isomers alkanes with the same number of C atoms but different skeletons are examples. The smallest alkane to exhibit constitutional isomerism has four C atoms two different compounds have the formula C4H10, as shown in Table 15.3 on the next page. The unbranched one is butane (common name, /t-butane n- stands for normal, or having a straight chain), and the other is 2-methylpropane (common name, i obutane). Similarly, three compounds... 

Draw the structural formulas for at least five isomeric alkanes having the formula CgHjg. 

Draw structural formulas for all isomeric alkanes having the general formula C5HJ2. 

Butane and all succeeding members of the alkanes exhibit stractural isomerism. Recall from Section 21.4 that structural isomerism occurs when two molecules have the same... 

In structural Isomerism, first met in the discussion of alkanes and which exists between but-l-ene, but-2-ene and 2-methylpropene, the compounds have their atoms bonded to different groups of atoms. For example, consider the underlined carbon atoms in the structural isomers of butene (C4H8) ... 

Structural isomerism in alkanes involves the formation of branched structures. Specific rules for systematically naming alkanes indicate the point of attachment of any substituent group, the length of the root chain, and so on. 

The Structure of Alkanes Constitutional Isomerism in Alkanes Nomenclature of Alkanes and the lUPAC System Cycloalkanes... 

In Problem 2.24, you drew structural formulas for all isomeric alkanes with molecular formula C Hjg. Predict which isomer has the lowest boiling point and which has the highest boiling point. 

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