Organic Chemistry

Number of Carbons: 1

Methane CH₄

Number of Carbons: 2

Ethane C₂H₆

Number of Carbons: 3

Propane C₃H₈

Number of Carbons: 4

Butane C₄H₁₀

Number of Carbons: 5

Pentane C₅H₁₂

Number of Carbons: 6

Hexane C₆H₁₄

Number of Carbons: 7

Heptane C₇H₁₆

Number of Carbons: 8

Octane C₈H₁₈

Number of Carbons: 9

Nonane C₉H₂₀

Number of Carbons: 10

Decane C₁₀H₂₂

IUPAC Naming Convention Steps

• Step 1: Find the parent chain, the longest carbon chain that contains the highest-priority functional group

• Step 2: Number the chain in such a way that the highest-priority functional group receives the lowest possible numbers

• Step 3: Name the substituents with a prefix. Multiple of the same type receive di-, tri-, tetra, etc.

• Step 4: Assign a number to each substituent depending on the carbon to which it is bonded

• Step 5: Alphabetize substituents and separate number from each other by command and form words by hyphens

Alkane

Saturated hydrocarbon with no double or triple bonds C_nH_2n+2

• Naming: Named according to the number of carbons present following by the suffix -ane

Isopropyl

Sec-butyl

Tert-butyl

Isobutyl

Alkene

Contains a double bond. Use suffix -ene

Alkyne

Contains a triple bond. Use suffix -yne

Alcohol

Contains a -OH group. Use suffix -ol or prefix hydroxy-

• Have higher priority than double or triple bonds

Diol

Contains 2 hydroxyl groups

• Geminal: If on same carbon

• Vicinal: If on adjacent carbons

Carbonyl Group

C=O

• Aldehydes and ketones both have a carbonyl group

Aldehyde

Carbonyl group on terminal C

Ketone

Carbonyl group on nonterminal C

Primary Alcohols

C attached to OH is only attached to 1 other C

Secondary Alcohols

C attached to OH is attached to 2 other Cs

Tertiary Alcohols

C attached to OH is attached to 3 other Cs

Primary Amines

N is only attached to 1 C

Secondary Amines

N is attached to 2 Cs

Tertiary Amines

N is attached to 3 Cs

Carboxylic Acid

The highest priority functional group because it contains 3 bonds to oxygen

• Suffix “-ioc acid”

Ester

Carboxylic Acid derivative where -OH is replaced with -OR

Amide

Replace the -OH group of a carboxylic acid with an amino group that may or may not be substituted

Structural Isomers

• Share only a molecular formula

• Have different physical and chemical properties

Stereoisomers

Compounds with atoms connected in the same order but differing in 3D orientation

Chiral Center

Four different groups attached to a central carbon

2ⁿ Rule

n = # of chiral centers

# of stereoisomers = 2ⁿ

Conformational Isomers

Differ by rotation around a single (σ) bond

Cyclohexane Substitutients:

Equitorial

In the plane of the molecule

Cyclohexane Substitutients:

Axial

Sticking up/down from the molecule’s plane

Enatiomers

Nonsuperimposable mirror images

• Opposite stereochemistry at every chiral carbon

• Same chemical and physical properties, except for rotation of plane polarized light

Optical Activity

The ability of a molecule to rotate plane-polarized light

• d- or (+) = RIGHT

• l- or (-) = LEFT 

Racemis Mixture

50:50 mixture of two enantiomers

• Not optically active because the rotations cancel out

Meso Compounds

Have an internal plane of symmetry, will also be optically inactive because the two sides of the molecule cancel each other out

Diastereomers

Stereoisomers that are NOT mirror image

Cis-Trans

• A subtype of diastereomers

  • Differ at some, but not all chiral centers

  • Different chemical and physical properties

Relative Configuration

Gives the stereochemistry of a compound in comparison to another compound

• Ex. D and L

Absolute Configuration

Gives the stereochemistry of a compound without having to compare to other compounds

• Ex. S and R

Cahn-Ingold-Prelog Priority Rules

Priority is given by looking at atoms connected to the chiral carbon or double-bonded carbons

• Whichever has the highest atomic # gets highest priority

(Z) for Alkenes

Highest priority on same side

(E) for Alkenes

Highest priority on opposite sides

(R) and (S) for Stereocenters

A stereocenter’s configuration is determined by putting the lowest priority group in the back and drawing a circle from group 1-2-3

• (R): Clockwise

• (S): Counterclockwise

Fischer Projection

Vertical lines go to back of page (dashes); horizontal lines come out of the page (wedges)

Alternating Fischer Projection

Switching 1 pair of substituents inverts the stereochemistry

• Switching 2 pairs retains stereochemistry

• Rotating entire diagram 90° inverts the stereochemistry

• Rotating 180° retains stereochemistry

Do the compounds have the same molecular formula?

YES

Then they are Isomers

Do the compounds have the same molecular formula?

NO

Then they are different

Do the isomers have the same connectivity of atoms?

YES

Then they are stereoisomers

Do the isomers have the same connectivity of atoms?

NO

Then they are constitutional isomers

Does the interconversion of stereoisomers require breaking bonds?

YES

Then they are configurational isomers

Does the interconversion of stereoisomers require breaking bonds?

NO

Then they are conformers

Are the configurational isomers non-superimposable mirror images?

YES

Then they are enatiomers

Are the configurational isomers non-superimposable mirror images?

NO

Then they are diastereoisomers

Bonding Orbitals

Created by head-to-head or tail-to-tail overlap of atomic orbitals of the same sign

• ↓ energy  ↑ stable

Antibonding Orbitals

Created by head-to-head or tail-to-tail overlap of atomic orbitals of opposite signs

• ↑ energy  ↓ stable

Single Bonds

1 σ bond, contains 2 electrons

Double Bonds

1 σ and 1 𝜋

• Pi bonds are created by sharing of electrons between two unhybridized p-orbitals that align side-by-side

Triple Bonds

1 σ + 2 𝜋 

• Multiple bonds are less flexible than single bonds because rotation is not permitted in the presence of a 𝜋 bond

• Multiple bonds are shorts and stronger than single bonds, although individual 𝜋 are weaker than σ bonds