MCAT Organic Chemistry Review

Nomenclature

Answers to Concept Checks

·        1.1

1.    1. Find the longest carbon chain in the compound with the highest-order functional group; 2. Number the chain; 3. Name the substituents; 4. Assign a number to each substituent; 5. Complete the name

2.   

Note: There are two possible answers; however, the longest chain must include the hydroxyl group.

3.    Numbers are separated from each other by commas with no spaces. Numbers are separated from words within the compound name by hyphens.

·        1.2

1.     

Molecular Formula

IUPAC Name (Straight-Chain Alkane)

Alternative Structure

CH4

Methane

No alternative structures

C2H6

Ethane

No alternative structures

C3H8

Propane

No alternative structures

C4H10

Butane

See below

C5H12

Pentane

See below

C6H14

Hexane

See below

C7H16

Heptane

See below

C8H18

Octane

See below

C9H20

Nonane

See below

C10H22

Decane

See below

2.    Butane and all hydrocarbons that are larger than butane may have a branched appearance, which shortens the parent chain. An example is isobutane, properly named methylpropane, shown on the next page. Any branched hydrocarbon with the correct number of carbons and no multiple bonds or rings is correct.

3.   

2.    The alcohol would take precedence because the carbon to which it is attached has a higher oxidation state.

3.    Diols are alcohols with two hydroxyl groups. For geminal diols, these are on the same carbon. For vicinal diols, they are in the vicinity of one another—on adjacent carbons.

4.    Isopropyl alcohol and ethyl alcohol, respectively.

·        1.3

1.    An aldehyde has a carbonyl group at the end of the chain. A ketone has a carbonyl group somewhere in the middle of the carbon chain. Another way to think of this is that the carbonyl carbon of an aldehyde has at least one bond to a hydrogen atom, whereas the carbonyl carbon of a ketone is always bound to two other carbons.

2.    Aldehydes are referred to with the suffix –al, while ketones are given the suffix –one. Carbonyl groups of both aldehydes and ketones are labeled as oxo– substituents (ketones may also be called keto– substituents).

3.     

IUPAC Name

Common Name

Methanal

Formaldehyde

Ethanal

Acetaldehyde

Propanal

Propionaldehyde

Propanone

Acetone

4.    Ketones and aldehydes both take precedence over both alcohols and hydrocarbon chains, and the functional group that is the highest priority determines the suffix. Therefore, the aldehyde would determine the suffix when naming this compound.

·        1.4

1.    The ester derivative would be methyl pentanoate. The amide would be pentanamide. The anhydride would be pentanoic anhydride.

2.    3-methyl-2-oxopentanoic acid