Content check — Organic Chemistry, Chapter 3: Organic Compounds: Alkanes and Their Stereochemistry

Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 3: Organic Compounds: Alkanes and Their Stereochemistry

18 problems · 43 figures

3-1 §3.1 source ↗

Use Table 3.1 to identify the functional groups in each of the following molecules:

(a)

(b)

(c)

The general structure of arene. — Table 3.1 Structures of Some Common Functional Groups in the book ↗

Name	Structure*	Name ending	Example
Alkene (double bond)		-ene	H₂C═CH₂ Ethene
Alkyne (triple bond)	–C≡C–	-yne	HC≡CH Ethyne
Arene (aromatic ring)		None
Halide	(X=F, Cl, Br, I)	None	CH₃Cl Chloromethane
Alcohol		-ol	CH₃OH Methanol
Ether		ether	CH₃OCH₃ Dimethyl ether
Monophosphate		phosphate	CH₃OPO₃²⁻ Methyl phosphate
Diphosphate		diphosphate	CH₃OP₂O₆³⁻ Methyl diphosphate
Amine		-amine	CH₃NH₂ Methylamine
Imine (Schiff base)		None
Nitrile	–C≡N	-nitrile	CH₃C≡N Ethanenitrile
Thiol		-thiol	CH₃SH Methanethiol
Sulfide		sulfide	CH₃SCH₃ Dimethyl sulfide
Disulfide		disulfide	CH₃SSCH₃ Dimethyl disulfide
Sulfoxide		sulfoxide
Aldehyde		-al
Ketone		-one
Carboxylic acid		-oic acid
Ester		-oate
Thioester		-thioate
Amide		-amide
Acid chloride		-oyl chloride
Carboxylic acid anhydride		-oic anhydride

Answer (3 parts)

(a)

Sulfide, carboxylic acid, amine

(b)

Aromatic ring, carboxylic acid

(c)

Ether, alcohol, aromatic ring, amide, C = C bond

3-2 §3.1 source ↗

Propose structures for simple molecules that contain the following functional groups:

(a)

Alcohol

(b)

Aromatic ring

(c)

Carboxylic acid

(d)

Amine

(e)

Both ketone and amine

(f)

Two double bonds

Answer (6 parts)

(a)

(b)

(c)

(d)

(e)

(f)

3-3 §3.1 source ↗

Identify the functional groups in the following model of arecoline, a veterinary drug used to control worms in animals. Convert the drawing into a line-bond structure and a molecular formula (red = O, blue = N, black = C, gray = H).

Answer

3-4 §3.2 source ↗

Draw structures of the five isomers of C₆H₁₄.

Answer

3-5 §3.2 source ↗

Propose structures that meet the following descriptions:

(a)

Two isomeric esters with the formula C₅H₁₀O_2:

(b)

Two isomeric nitriles with the formula C₄H₇N

(c)

Two isomeric disulfides with the formula C₄H₁₀S₂

Answer (3 parts)

(a)

(b)

(c)

3-6 §3.2 source ↗

How many isomers are there with the following descriptions?

(a)

Alcohols with the formula C₃H₈O

(b)

Bromoalkanes with the formula C₄H₉Br

(c)

Thioesters with the formula C₄H₈OS

Answer (3 parts)

(a)

Two

(b)

Four

(c)

Four

3-7 §3.3 source ↗

Draw the eight 5-carbon alkyl groups (pentyl isomers).

Answer

3-8 §3.3 source ↗

Identify the carbon atoms in the following molecules as primary, secondary, tertiary, or quaternary:

(a)

(b)

(c)

Answer (3 parts)

(a)

(b)

(c)

3-9 §3.3 source ↗

Identify the hydrogen atoms on the compounds shown in Problem 3-8 as primary, secondary, or tertiary.

Answer

Primary carbons have primary hydrogens, secondary carbons have secondary hydrogens, and tertiary carbons have tertiary hydrogens.

3-10 §3.3 source ↗

Draw structures of alkanes that meet the following descriptions:

(a)

An alkane with two tertiary carbons

(b)

An alkane that contains an isopropyl group

(c)

An alkane that has one quaternary and one secondary carbon

Answer (3 parts)

(a)

(b)

(c)

3-11 §3.4 source ↗

Give IUPAC names for the following compounds:

(a)

(b)

(c)

(d)

Answer (4 parts)

(a)

Pentane, 2-methylbutane, 2,2-dimethylpropane

(b)

2,3-Dimethylpentane

(c)

2,4-Dimethylpentane

(d)

2,2,5-Trimethylhexane

3-12 §3.4 source ↗

Draw structures corresponding to the following IUPAC names:

(a)

3,4-Dimethylnonane

(b)

3-Ethyl-4,4-dimethylheptane

(c)

2,2-Dimethyl-4-propyloctane

(d)

2,2,4-Trimethylpentane

Answer (4 parts)

(a)

(b)

(c)

(d)

3-13 §3.4 source ↗

Name the eight 5-carbon alkyl groups you drew in Problem 3-7.

Answer

Pentyl, 1-methylbutyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl

3-14 §3.4 source ↗

Give the IUPAC name for the following hydrocarbon, and convert the drawing into a skeletal structure.

Answer

3-15 §3.7 source ↗

Make a graph of potential energy versus angle of bond rotation for propane, and assign values to the energy maxima.

Answer

3-16 §3.7 source ↗

Sight along the C2–C1 bond of 2-methylpropane (isobutane).

(a)

Draw a Newman projection of the most stable conformation.

(b)

Draw a Newman projection of the least stable conformation.

(c)

Make a graph of energy versus angle of rotation around the C2–C1 bond.

(d)

Assign relative values to the maxima and minima in your graph, given that an H ⟷ H eclipsing interaction costs 4.0 kJ/mol and an H ⟷ CH₃ eclipsing interaction costs 6.0 kJ/mol.

Answer (4 parts)

(a)

(b)

(c)

(d)

3-17 §3.7 source ↗

Sight along the C2–C3 bond of 2,3-dimethylbutane, and draw a Newman projection of the most stable conformation.

Answer

3-18 §3.7 source ↗

Draw a Newman projection along the C2–C3 bond of the following conformation of 2,3-dimethylbutane, and calculate a total strain energy:

Answer

Loading chapter 4…

Problems and answers are adapted from Organic Chemistry: A Tenth Edition by John McMurry, OpenStax, and are used under the CC BY-NC-SA 4.0 licence. Access for free at https://openstax.org/books/organic-chemistry/pages/1-why-this-chapter. Illustrations: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license. This adaptation is released under the same licence, is non-commercial, and is neither affiliated with nor endorsed by OpenStax or Rice University.