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Organic Chemistry

Chapter 20

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Carbon

All living matterFour bondsDouble and triple bonds

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Diamond

Colorless crystalline solidExtremely high melting pointConducts heat very wellDoes not conduct electricityCovalent network bonding

Bonded to four nearest neighbors

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Graphite

Crumbles easilyFeels greasyAtoms arranged in thin layersWeak London dispersion forces

Layers slide past each other

Conducts electricity

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Fullerenes

Formed when carbon-containing materials are burned with limited oxygenNearly sphericalC60

Most stableCalled buckminsterfullerene or buckyball

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Organic compounds

Covalently bonded compounds containing carbonExcept:

Carbonates and oxides

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Catenation

Covalent bonding of an element to itself to form chains or rings

Carbon can also double or triple bond to itself

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hydrocarbons

Contain only carbon and hydrogenSimplest organic compounds

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Structural formula

Regular or condensed

Carbon makes four bonds, hydrogen makes oneHydrogen is understood to bond to the atom next to it

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Draw the condensed structural formulas

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Geometric isomers

Order of atom bonding is the same, but arrangement of atoms is space is differentNeed rigid structure in molecule

Double or triple bond

Need two carbons each with two different groups attachedCis and trans isomers

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Cis isomer

Like groups on same side of carbon atoms

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Trans iosmer

Like groups on opposite sides of carbon atoms

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Alkanes

AKA saturated hydrocarbonsHold maximum amount of hydrogenContain only single bondsGeneral formula CnH2n+2

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Cycloalkanes

Carbons arranged in ringFewer hydrogen atoms – no free endsGeneral formula CnH2n

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propane vs. cyclopropane

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Simplified cycloalkane structure

Carbon at each cornerEnough hydrogen so each carbon has four bonds

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IUPAC

International Union of Pure and Applied ChemistrySystematic naming system

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Unbranched chain alkanes

Count carbon atoms for prefixTable 20-3, page 636

And suffix -ane

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You try

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Branched-chain alkanes

Branches are alkyl groupsTable 20-4, page 637

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Alkane nomenclature

1. Name the parent hydrocarbonLongest continuous carbon chainMight be bentName as straight-chain alkane

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Alkane nomenclature

2. Add the names of the alkyl groupsIn frontalphabetizeAdd prefixes if necessary (di-, tri-, tetra-, penta-, etc.)

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Alkane nomenclature

3. Number the carbon atoms in parent alkaneGive lowest numbers to alkyl groupsIf two possibilities, make the first alkyl group in name have lowest number

4. Insert position numbersBefore alkyl group names

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Alkane nomenclature

5. PunctuateHyphens between numbers and namesCommas between numbers

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You try

Name the molecule aboveoctane

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You try

Name the molecule above3-ethyl-2,4,5-trimethyloctane

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You try

Name the molecule above5-butyl-2,2-dimethylnonane

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Example

Draw the condensed structural formula for 3,3,4-triethyl-4-methylhexane.

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You try

Draw the condensed structural formula for 3-ethyl-2,2-dimethylpentane.

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Alkenes

Unsaturated hydrocarbonsHave at least one double bond

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Alkene nomenclature

1. Name the parent hydrocarbonLongest continuous carbon chain containing double bondMight be bentAdd suffix –ene if only one double bond

If two, -adieneThree, - atrieneEtc.

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Alkene nomenclature

2. Add the names of the alkyl groups3. Number the carbon atoms in parent alkene

First carbon in double bond nearest end of chain has lowest numberIf two possibilities, number from end nearest first alkyl groups

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Alkene nomenclature

4. Insert position numbersDouble-bond position numbers before parent alkene nameBefore alkyl group names

5. Punctuate

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Example

Name the following alkene.

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You try

Name the following alkene

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You try

Draw 1,3-butadiene

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Alkynes

Contain at least one triple covalent bond.

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Alkyne nomenclature

1. Name the parent hydrocarbonLongest continuous carbon chain containing triple bondMight be bentAdd suffix –yne if only one triple bond

If two, -adiyneThree, - atriyneEtc.

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Alkyne nomenclature

2. Add the names of the alkyl groups3. Number the carbon atoms in parent alkyne.

First carbon in triple bond nearest end of chain has lowest numberIf two possibilities, number from end nearest first alkyl groups

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Alkyne nomenclature

4. Insert position numbersTriple-bond position numbers before parent alkyne nameBefore alkyl group names

5. Punctuate

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You try

Name the following compound

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You try

Draw 3,3-dimethyl-1-butyne

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Aromatic hydrocarbons

Contain six-membered benzene ringDelocalized electrons

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Aromatic hydrocarbon nomenclature

1. Name the parent hydrocarbonBenzene

2. Add the names of the alkyl groups3. Number the carbon atoms in ring

1 goes with alkyl group that comes first alphabeticallyNumber in the direction that gives the rest of the groups the lowest numbers

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Aromatic hydrocarbon nomenclature

4. Insert position numbers5. Punctuate

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You try

Name the following compound

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You try

Draw 1-ethyl-2-methylbenzene