Organic Compounds Cycloalkanes and Their Stereochemistry

Cycloalkanes have the general formula CnH2, if they have one ring. 

Unlike open-chain alkanes, cycloalkanes have much less rotational freedom. 

Substituents in the two types of disubstituted cycloalkanes are connected in the same order but differ in spatial orientation. 

In this conformation, one carbon is bent out of plane hydrogens are nearly staggered. 

In methylcyclohexane, 95% of molecules have the methyl group in the equatorial position. 

Online homework for this chapter may be assigned in Organic OWL. 

We ve discussed only open-chain compounds up to this point, but most organic compounds contain of carbon atoms. Chi ysanthcmir acid, for instance, whose esters occur naturally as the active insecticidal constituents of chrysanthemum flowers, contains a three-membered (cyclopropane) ring. 

Steroiils, such as cortisone, contain four rings joined together—A six-membered (cyclohexane) and 1 five-nicmbcrcd. We ll discuss steroids and their properties in more detail in Sections 27.6 and 27.7. 

VVeTJ sec numerous instances in future chapters where the chemistry of a given functional group is strongly affected by being in a ring rather than an open chain, because cyclic molecules are sr commonly encountered in all classes of biomolecules, including proteins, lipids, carbohydrates, and nucleic adds, it s important that the effects of their cyclic structures be understood. 

Prostaglandins, potent hormones that control an extraordinary variety of physiological functions in humans, contain a five-membered (cyclopentane) ring. 

Saturated cyclic hydrocarbons are called cycloalkanes, or alicyclic compounds (aliphatic cyclic). Because cycloalkanes consist of rings of -CH2-units, they have the general formula (CH2)n, or C H2n, and can be represented by polygons in skeletal drawings. 

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CHAPTER 4 Organic Compounds Cycloalkanes and Their Stereochemistry... 

Chapter 4, Organic Compounds Cycloalkanes and Their Stereochemistry—The chapter has been revised to focus exclusively on cycloalkanes. 

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