ORGANIC CHEMISTRYORGANIC CHEMISTRY

The chemistry of The chemistry of compounds thatcompounds that

contain both contain both carboncarbon and and hydrogenhydrogen

Before we start, let’s Before we start, let’s get one thing straight…get one thing straight…

THE SYMBOL FOR THE SYMBOL FOR CARBON IS “C” CARBON IS “C” NOT “Ca” !!!NOT “Ca” !!!

Carbon (C)Carbon (C) There are more than a million organic There are more than a million organic compoundscompounds

More than 95% of the compounds from More than 95% of the compounds from natural sources or synthesized in the natural sources or synthesized in the laboratory are organiclaboratory are organic

The simplest organic compounds contain The simplest organic compounds contain only carbon and hydrogen and are called only carbon and hydrogen and are called hydrocarbons (HC)hydrocarbons (HC)

In other organic molecules, Carbon can In other organic molecules, Carbon can bond with many other atoms, such as bond with many other atoms, such as Oxygen, Nitrogen, Fluorine, Bromine, Oxygen, Nitrogen, Fluorine, Bromine, Sulfur, Phosphorus and ChlorineSulfur, Phosphorus and Chlorine

One Carbon can form 4 covalent bondsOne Carbon can form 4 covalent bonds

HydrocarbonsHydrocarbons

Made up of only Hydrogen and CarbonMade up of only Hydrogen and Carbono In these molecules, Carbon will bond In these molecules, Carbon will bond with either Hydrogen or another Carbonwith either Hydrogen or another Carbon

o Hydrogen can only form ONE bondHydrogen can only form ONE bondo Carbon will form FOUR bondsCarbon will form FOUR bondso The two simplest Hydrocarbons (HC) are The two simplest Hydrocarbons (HC) are methane and ethanemethane and ethane

o Nonpolar molecules (charge and Nonpolar molecules (charge and electrons are evenly distributed)electrons are evenly distributed)o Because of this, hydrocarbons tend to be Because of this, hydrocarbons tend to be gases or liquidsgases or liquids

(a) Methane: CH(a) Methane: CH44

+ →

o Major form of natural gaso Formed by bacterial decay of dead organic mattero Livestock and termites emit large amountso Carbon has four valence electrons and so it ALWAYS forms four covalent bondso Not a typical HC as there is no carbon-carbon bond

(b) Ethane: C(b) Ethane: C22HH66

o Carbon-carbon single bond (shared Carbon-carbon single bond (shared pair of electrons)pair of electrons)

o Six single bonds with six hydrogen Six single bonds with six hydrogen atomsatoms

o A gas at STPA gas at STP

(c) HC Formulas and (c) HC Formulas and ModelsModelso Molecular formulas: e.g. Molecular formulas: e.g.

o Structural formulas e.g. Structural formulas e.g.

o Ball-and-stick models e.g.Ball-and-stick models e.g.

o Space-filling models e.g. Space-filling models e.g.

CHCH44

2. Alkanes2. Alkanes

o Methane and Ethance are Methane and Ethance are examples of alkanesexamples of alkanes

o A HC with all single covalent A HC with all single covalent bondsbonds

o The carbon atoms can be The carbon atoms can be arranged in a straight chain arranged in a straight chain (bends don’t matter) or (bends don’t matter) or branched chainbranched chain

(a)(a) Straight Chain AlkanesStraight Chain Alkanes

o Ethane is the simplest alkaneEthane is the simplest alkaneo Straight chain of any number of Straight chain of any number of carbon atomscarbon atoms

o These compounds form a homologous These compounds form a homologous series, having the same formula: series, having the same formula: CCnnHH2n+22n+2

o The boiling point of alkanes increase The boiling point of alkanes increase as the number of carbon atoms as the number of carbon atoms increases increases

(reflects increase in molar mass)(reflects increase in molar mass)Propane used in

air balloons

(b) Naming (b) Naming Straight-Straight-

Chained Chained AlkanesAlkanes

o End with the End with the suffix suffix – ane– ane

o The Latin prefix The Latin prefix indicates the indicates the number of carbonsnumber of carbons

o Molecular Molecular Formula: Formula: CCnnHH2n+22n+2

#C

Name MolecularFormula

1 Methane

 CH4 

2  Ethane  C2H6 

3 Propane

 C3H8 

4  Butane  C4H10 

5 Pentane

 C5H12 

6  Hexane  C6H14 

7 Heptane

 C7H16 

8  Octane  C8H18 

9  Nonane  C9H20 

10  Decane  C10H22 

(c) Formulas for (c) Formulas for AlkanesAlkanes

= Some bonds or atoms are left out

(d) Branched-Chain Alkanes(d) Branched-Chain Alkanes

o An atom or group of atoms that take the An atom or group of atoms that take the place of an H atom is called a place of an H atom is called a substituentsubstituent

o The longest continuous carbon chain is The longest continuous carbon chain is the the parentparent alkane alkane

o Substituents can include halogens, Substituents can include halogens, oxygen, nitrogen, sulfur, and oxygen, nitrogen, sulfur, and phosphorusphosphorus

o If the substituent is another If the substituent is another hydrocarbon (only H and C atoms), it is hydrocarbon (only H and C atoms), it is called an called an alkylalkyl group group

(e) Naming Branched-Chain (e) Naming Branched-Chain AlkaneAlkane

o Name the longest chain of carbons (bends Name the longest chain of carbons (bends don’t matter)don’t matter)

o Circle all branchesCircle all brancheso Number the carbons, so that branches have Number the carbons, so that branches have lowest numbers possiblelowest numbers possible

o Name each substituent using its number, the Name each substituent using its number, the prefixes, and the adding the ending “-yl” prefixes, and the adding the ending “-yl”

o List the substituents in alphabetical orderList the substituents in alphabetical ordero If you have more than 1 of the same branch, If you have more than 1 of the same branch, add “di”, “tri”, “tetra”, or “penta” to the add “di”, “tri”, “tetra”, or “penta” to the name of the branchname of the branch

o Write the full name starting with branches, Write the full name starting with branches, and ending with the parent chainand ending with the parent chain

Structural IsomersStructural Isomers

Some hydrocarbons differ only in Some hydrocarbons differ only in the positions of their alkyl groupsthe positions of their alkyl groups

They have the same molecular They have the same molecular formula, but different structures formula, but different structures (atoms are joined in a different (atoms are joined in a different order)order)

They are called They are called structural isomersstructural isomers Structural isomers have different Structural isomers have different physical and chemical propertiesphysical and chemical properties

Structural Isomers of Structural Isomers of CC44HH1010

Butane

2-methylpropane

Notice how both have 4 carbons and 10 hydrogens, but one is branched, and one is a straight-chain alkane