Strain energy cycloalkanes, table

In marked contrast to the n-alkanes, the cycloalkanes exhibit thermodynamic properties where such regularities are no longer present. Heats of formation (AH ) for a substantial number of cycloalkanes are available from heats of combustion. With the exception of cyclohexane, AH°f is always more positive than the quantity — 4.926n. The difference between the two quantities leads to a quantitative assessment of the important notion of ring strain. The AH -values and strain energy data listed in Table 1 were taken from Skinner and Pilcher (1963). Other references give different but usually comparable... 

Comparison of the heats of combustion of cycloalkanes (Table 9.1) shows that cyclopropane, cyclobutane, and cyclononane yield more energy per methylene group than the other cycloalkanes. This can be attributed to strain resulting from bond-angle distortion (Baeyer strain), eclipsed conformations (Pitzer strain), and trans-annular, repulsive van der Waals interactions. Common (five- and six-membered) rings and large (more than twelve-membered) rings have little or no strain. This... 

Table 6.1 Heats of Combustion and Strain Energies of Some Cycloalkanes...

TABLE 6. Heats of formation and strain energies of cycloalkanes and cycloalkenes (kcal mol )... 

Table 2.9 Heats of Formation and Total Strain Energies of Cycloalkanes...

Table 1 The structural features and the strain energy of small cycloalkanes compared to n-alkane...

Table 12. Strain Energy of Cycloalkanes in Saturated Heterocyclic Rings (kcal mole V...

TABLE 5.2 Strain Energies for Some Cycloalkanes from Ai/° and A//7... 

As has been shown in [27], increase in the strain energy of epoxy cycloalkanes is accompanied by increase in the LUMO energy and the order of the C-O bond (Table 10.3). Obtained therein parameters of electron density distribution evidence that in the case of epoxides (3-5) and epoxybicycle[2.2.2]octane (9) values of... 

---