Chapter 3: Functional Groups, Alkanes, and Newman Projections

Organic Chemistry

What is a functional group?

A recognizable arrangement of atoms and bonds associated with characteristic chemical behavior.

How do you recognize an alkene, alkyne, and arene?

Alkene: C=C

Alkyne: C≡C
Arene: aromatic ring, such as benzene

How do you recognize an alcohol, ether, and amine?

Alcohol: C-OH

Ether: C-O-C

Amine: nitrogen bonded to carbon or hydrogen but NOT directly to a carbonyl carbon

How do you distinguish an aldehyde from a ketone?

Aldehyde: C=O at the end of a carbon chain Ketone: C=O within the carbon chain

How do you recognize a carboxylic acid, ester, and amide?

Carboxylic acid: C=O and C-OH at the end of a carbon chain

Ester: C=O and C-O- within the carbon chain

Amide: nitrogen bonded to a carbonyl carbon

How do you recognize a nitrile, thiol, and alkyl halide?

Nitrile: C≡N group at the end of a carbon chain Thiol: C-SH group Alkyl halide: carbon bonded to a halogen (F, Cl, Br, I)

What is the formula for a saturated, open-chain alkane with n carbons?

C_nH_2n+2

What is a constitutional isomer?

A compound with the same molecular formula as another compound but different atom connectivity.

What distinguishes primary, secondary, tertiary, and quaternary carbons?

They are directly bonded to one, two, three, and four other carbons, respectively.

What is the first major decision when naming a branched alkane?

Identify the longest appropriate parent carbon chain.

How do you choose the numbering direction for an alkane parent?

Give substituents the lowest possible set of locants, comparing the numbers at the first point of difference.

How do you order different substituents in an IUPAC name?

Alphabetically; ignore multiplying prefixes such as di- and tri- when alphabetizing.

What does staggered mean in a Newman projection?

The bonds on the rear carbon lie between the bonds on the front carbon when viewed down their C-C bond. W

What does eclipsed mean in a Newman projection?

Front and rear bonds line up when viewed down their C-C bond.

For butane, which staggered arrangement is generally more stable?

Anti: the two methyl groups are 180º apart.

Why is staggered conformation generally more stable than an eclipsed one?

It has less torsional strain from eclipsing bonds.

When drawing a Newman projection, how do you keep from switching front and rear groups?

First label the three groups attached to each carbon. During a rotation, keep each group on its original carbon and rotate only one carbon relative to the other.

List the types of conformational isomers in order of increasing energy.

anti → gauche → CH₃/H eclipsed → CH₃CH₃ eclipsed

In conformational isomers, how do strain, energy, and stability relate?

more strain → higher energy → lower stability

less strain → lower energy → higher stability