ORGANIC CHEMISTRY:The study of compounds containing CARBON

There are more than a 10 million organic compounds!

AllotropesOne of two or more different molecular forms of the same element in the same physical state

Lonsdaleite

HYDROCARBONS

Prefix # of Carbons

Meth- 1

Eth- 2

Prop- 3

But- 4

Pent- 5

Hex- 6

Hept- 7

Oct- 8

Non- 9

Dec- 10

The simplest organic compounds that contain only carbon and hydrogen

Carbon has 4 valence electrons, and therefore always forms 4 covalent

bonds!

HYDROCARBON PREFIXES

ILLUSTRATING HYDROCARBONS

C4H10

Molecular FormulaComplete Structural Formula

Condensed Structural Formulas

CH3(CH2)3CH3

C-C-C-CCarbon Skeleton

Line-Angle Formula

Alkanes

• A hydrocarbon in which there are only single bonds

• In an alkane all the carbon-carbon bonds are single covalent bonds– All other bonds are carbon-hydrogen bonds

• The carbon atoms in an alkane can be arranged in a straight chain or in a chain that has branches.

• Alkanes are called saturated compounds because they contain only single covalent bonds

Straight Chain Alkanes• Contain any number of carbon atoms, one after the other, in

a chain– Homologous Series: A constant increment of change in

molecular structure from one compound in the series to the next

• In an alkane a CH2 group is the increment of change

Naming Straight-Chain AlkanesNaming Alkanes Drawing a Structural Formula

For all alkanes the name ends in -ane Write the symbol for carbon as many times as necessary to get the proper chain length

Count the carbon atoms and add the appropriate prefix

Complete each carbons bonds with hydrogen

Name: C6H14 Draw the structural formula for octane.

Branched Chain Alkanes

• An alkane with one or more alkyl groups– Substituent: An atom or group of atoms that can

take the place of a hydrogen atom on a parent hydrocarbon molecule

– Parent Alkane: The longest continuous carbon chain of a branched–chain hydrocarbon

– Alkyl Group: A hydrocarbon substituent

NAMING BRANCHED ALKANESEXAMPLE:

Find the largest chain of carbons in the molecule (the parent structure)

# the carbons in the main chain in sequence, starting so that the substituents will be on the carbons of the lowest possible numbers

Add numbers to the name of the substituent groups to identify their positions

Use prefixes to indicate the appearance of the same group more than once in the structural formula

List the names of the alkyl substituents in alphabetical order

Commas are used to separate #s. Hyphens to separate numbers and words. Entire name without spaces.

PROPERTIES OF ALKANES

• Molecules of hydrocarbons are nonpolar molecules– Attraction between

nonpolar molecules are weak van der Waals forces

– Alkanes of lower molar mass tend to be gases or liquids that boil at low temperatures

Will form a solution with nonpolar compounds because “Like dissolves Like”•Will not form solutions with polar compounds

UNSATURATED COMPOUNDS: Compounds that contain double or triple carbon-carbon bonds

Alkenes Alkynes

Hydrocarbons that contain one or more carbon-carbon double-covalent bonds

Hydrocarbons that contain one or more carbon-carbon triple covalent bonds

Examples: Examples:

To Name Alkenes/AlkynesTo Name Example

Find the longest chain in the molecule that contains the double/triple bond (parent chain). Name with the appropriate prefix and the ending –ene (for alkenes) or –yne (for an alkyne)

Number the chain so the carbon atoms with the double-triple bonds have the lowest numbers. Include the number in the name if there is more than one possible location for the double-triple bond.

Substituents are numbered and named as they are with alkanes

Draw the structural formulas for:

Propyne PropanePropene

ISOMERS

Compounds that have the same molecular formula but different molecular structures

Structural IsomersCompounds that have the same molecular

formulas but the atoms are joined in a different way

Structural isomers differ in physical properties such as melting/boiling points

•Have different chemical reactivities

PROPERTIES Methylpropane Butane

Structure

Melting Point (C)

-60 -217

Boiling Point (C)

30 31

Stability Reactively stable. Extremely flammable

Highly flammable

The more highly

branched the hydrocarbon, the lower the boiling point hydrocarbon

STEREOISOMERSMolecules in which the atoms are joined in the same order, but the positions of the atoms in space are different.1) Geometric Isomers: Atoms are joined in the

same order but differ in orientation around a double bond.

trans: Similar

groups are on

opposite sides

of the double

bond

cis: Similar groups are on the same side of the double bond

Which is cis and which is trans?

STEREOISOMERS2) Optical Isomers: Differ in the way that four

different groups are arranged around a central carbon atom.

• Asymmetric Carbon: A carbon with 4 different atoms or groups attached

FUNCTIONAL GROUPS

• Organic compounds can be classified according to their functional group.– Functional Group: A specific arrangment of atoms

in an organic compound that is capable of characteristic chemical reactions

• Organic compounds can be classified by their functional groups!

Compound Type Compound Structure Functional Group

Halocarbon R—X (X = F, Cl, Br, I) Halogen

Alcohol R—OH Hydroxyl

Ether R—O—R Ether

Aldehyde

Carbonyl

Ketone

Carbonyl

Carboxylic Acid

Carboxyl

Ester

Ester

Amine R—NH2 Amino

Amide

Amide

Halocarbons

A class of organic compounds containing covalently bonded fluorine, chlorine, bromine or iodine.

Naming: The halogen groups are named as substituents

Halocarbons

Properties:• Weak van der Waals interactions called

dispersion forces– Forces increase with halogen substitution

• More highly halogenated organic compounds have higher boiling points

• Very few are found in nature

Halocarbons

1987 Montreal Protocol on

Substances that Deplete the Ozone

Layer and its Amendments,

which have both high ozone

depleting potentials (ODPs)

Alcohols

An organic compound with an –OH group• Hydroxyl Group: The –OH functional group

“In many ways, prohibition was the catalyst for the first (and arguably biggest) large-scale Do-It-

Yourself science movement in the

nation's history”. Robert T. Gonzalez, BBC

Naming Alcohols1) Drop the –e ending of the parent alkane name and add the ending –ol2) Parent alkane is the longest continuous chain that includes the carbon

attached to the hydroxyl group3) If the hydroxyl group can occur at more than one position, its position

is designated with the lowest possible number.4) Alcohols containing 2, 3, or 4 –OH substituents are named diols, triols,

and tetrols

Properties of Alcohols

• Capable of intermolecular hydrogen bonding– Higher boiling points than alkanes & halocarbons

containing comparable numbers

• Alcohols up to 4 carbon atoms are soluble in water– Solubility with 4 carbons or more is much lower– Carbon chain is nonpolar (not attracted to water)…more

carbons = more nonpolar parts to the molecule• Hydroxyl part is polar…that’s why small alcohols are soluble in

water

Uses of Alcohols

Common Name: Isopropyl Alcohol

IUPAC Name:

•Rubbing alcohol

•Base for perfumes, creams & lotions

Common Name: Ethylene glycol

IUPAC Name:

•Main ingredient in antifreeze

•Soluble in water

•Freezes at -17.4C

Common Name: Ethanol

IUPAC Name:

•Alcoholic Beverages

•A depressant

•In industry: denatured alcohol

Aldehydes

An organic compound in which the carbon of the carbonyl group is always joined to at least one hydrogen• Carbonyl Group: a CO group

Ketones

An organic compound in which the carbon of the carbonyl group is joined to two other carbons

Naming Aldehydes & Ketones

1. Identify the longest hydrocarbon chain containing the functional group2. For aldehydes, replace the –e of the hydrocarbon with –al3. For ketones, replace the –e of the hydrocarbon with –one4. If the functional group can occur at more than one place, designate its

position with the lowest possible number.

Properties of Aldehydes & Ketones

• Form weak hydrogen bonds between the carbonyl oxygen and the hydrogen atoms of water– Low molar mass compounds are soluble in water– Above 5 or 6 carbon atoms, solubility is low

• Soluble in nonpolar solvents• Boiling points are lower than alcohols• Boiling points are higher than alkanes

– Because of polar ends they can have polar-polar interactions

• Typically liquids or solids at room temperature

Uses of Aldehydes & Ketones

• High molar mass aldehydes & ketones have fragrant or penetrating odors– Aromatic aldehydes often used as flavoring agents

• Almond odor (benzaldehyde) & Cinnamon odor (cinnamonaldehyde)

• Formaldehyde (methanal)• Acetone (propanone)

– Solvent for plastics, nail polish removers, etc.

Esters

Contain a carbonyl group and an ether link (C-O-C) to the carbonyl group

Properties of Esters

• Pleasant, fruity odors

Uses of Esters

• Give blueberries, pineapples, apples, pears, bananas and many other fruits their characteristic odors

• Give many perfumes their fragrances

Polymers