4. Alkanes and Cycloalkanes

Draw the structure and give the molecular formula for each of the following compounds.

a. 1-ethyl-3-methylcycloheptane

b. isobutylcyclohexane

Each of the following descriptions applies to more than one alkane. In each case, draw and name two structures that match the description.

c. a cis-diethylcyclohexane

d. a trans-dihalocyclopentane

Draw and name the six isomeric cyclopentanes of molecular formula C₇H₁₄. These will include four constitutional isomers, of which two show geometric (cis-trans) stereoisomerism.

Draw and name the five cycloalkane structures of formula C₅H₁₀. Can any of these structures give rise to geometric (cis-trans) isomerism? If so, show the cis and trans stereoisomers.

trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3-dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use drawings to explain these observations.

Name the following cycloalkanes using the IUPAC system of nomenclature. [Hint: Each molecule exemplifies one of the cycloalkane nomenclature rules in Table 3.10.]

(a) rule 1

Name the following cycloalkanes using the IUPAC system of nomenclature. [Hint: Each molecule exemplifies one of the cycloalkane nomenclature rules in Table 3.10.]

(c) rule 2

Name the following cycloalkanes using the IUPAC system of nomenclature. [Hint: Each molecule exemplifies one of the cycloalkane nomenclature rules in Table 3.10.]

(e) rule 3

Name the following cycloalkanes using the IUPAC system of nomenclature. [Hint: Each molecule exemplifies one of the cycloalkane nomenclature rules in Table 3.10.]

(g) rule 4

Give IUPAC names for the following compounds.

Classify each hydrogen atom in the following compounds as primary (1°), secondary (2°), or tertiary (3°).

c. 2-methylbutane

d. cyclohexane

Classify each hydrogen atom in the following compounds as primary (1°), secondary (2°), or tertiary (3°).

e. norbornane (bicyclo[2.2.1]heptane)

Label each hydrogen atom in the following compounds as primary (1°), secondary (2°), or tertiary (3°).

(c) (CH₃)₂CHCH(CH₃)CH₂CH₃

(d)

Label each hydrogen atom in the following compounds as primary (1°), secondary (2°), or tertiary (3°).

(e)

(f)

Correct the following incorrect names using standard IUPAC nomenclature. [Draw a compound that corresponds to the incorrect name, and then rename it.]

(e) 2,6-diethyl-1-methylcycloheptane