What causes molecular handedness? Look at generalized molecules of the type CH3X, CH2XY, and CHXYZ shown in Figure 5.2. On the left are three molecules, and on the right are their images reflected in a mirror. The CH3X and CH2XY molecules…
Figure 5.1 Like the mountain whose image is reflected in a lake, many organic molecules also have mirror-image counterparts. (credit: modification of work “Crystal Lake sunrise reflection” by Sandy Horvath-Dori/Wikimedia Commons, CC BY 2.0) Chapter Contents 5.1 Enantiomers and the Tetrahedral Carbon 5.2 The…
Cyclic molecules are so commonly encountered throughout organic and biological chemistry that it’s important to understand the consequences of their cyclic structures. Thus, we’ve taken a close look at cyclic structures in this chapter. Cycloalkanes are saturated cyclic hydrocarbons with the…
All the structural models in this book are computer-drawn. To make sure they accurately represent bond angles, bond lengths, torsional interactions, and steric interactions, the most stable geometry of each molecule has been calculated on a desktop computer using a…
The final point we’ll consider about cycloalkane stereochemistry is to see what happens when two or more cycloalkane rings are fused together along a common bond to construct a polycyclic molecule—for example, decalin. Decalin consists of two cyclohexane rings joined to…
Monosubstituted cyclohexanes are always more stable with their substituent in an equatorial position, but the situation with disubstituted cyclohexanes is more complex because the steric effects of both substituents must be taken into account. All steric interactions for both possible…
Even though cyclohexane rings flip rapidly between chair conformations at room temperature, the two conformations of a monosubstituted cyclohexane aren’t equally stable. In methylcyclohexane, for instance, the equatorial conformation is more stable than the axial conformation by 7.6 kJ/mol (1.8…
The chair conformation of cyclohexane has many consequences. We’ll see in Section 11.9, for instance, that the chemical behavior of many substituted cyclohexanes is influenced by their conformation. In addition, we’ll see in Section 25.5 that simple carbohydrates, such as glucose, adopt a…
Substituted cyclohexanes are the most common cycloalkanes and occur widely in nature. A large number of compounds, including steroids and many pharmaceutical agents, have cyclohexane rings. The flavoring agent menthol, for instance, has three substituents on a six-membered ring. Cyclohexane…
Cyclopropane Cyclopropane is the most strained of all rings, primarily due to the angle strain caused by its 60° C−C−C bond angles. In addition, cyclopropane has considerable torsional strain because the C−H bonds on neighboring carbon atoms are eclipsed (Figure…