Organic ChemistryOrganic Chemistry

Nomenclature: Nomenclature: AlkanesAlkanes

What is Organic Chemistry?

Study of hydrocarbons and derivatives

7 million Organic Compounds1.5 million Inorganic Compounds

Animal and plant matter, Foods, Pharmaceuticals, Cosmetics,

Fertilizers, Plastics, Petrochemicals, Clothing

Organic Compounds

Contain carbon

Have covalent bonds

Have low melting points

Have low boiling points

Burn in air (oxygen)

Are soluble in nonpolar solvents

Form large molecules

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Consumption (%)

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Separated by the physical property

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Boiling Point

Boiling Point Trends

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AlkanesAlkanes

• Hydrocarbon chains where all the bonds Hydrocarbon chains where all the bonds between carbons are SINGLE bondsbetween carbons are SINGLE bonds

• spsp3 3 Hybridized Orbitals– tetrahedral,109.5Hybridized Orbitals– tetrahedral,109.5oo

• Name uses the ending –Name uses the ending –aneane

• Examples: MethExamples: Methaneane, Prop, Propaneane, But, Butaneane, , OctOctaneane, 2-methylpent, 2-methylpentaneane

IUPAC Names

Name # carbons Structural Formula

Methane 1 CH4

Ethane 2 CH3CH3

Propane 3 CH3CH2CH3

Butane 4 CH3CH2CH2CH3

Pentane 5 CH3CH2CH2CH2CH3

IUPAC NAMES

Name # carbons Structural Formula

Hexane 6 CH3CH2CH2CH2CH2CH3

Heptane 7 CH3CH2CH2CH2CH2CH2CH3

Octane 8 CH3CH2CH2CH2CH2CH2CH2CH3

Nonane 9 CH3 CH2 CH2CH2CH2CH2CH2CH2CH3

Decane 10 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3

Prefixes for # of CarbonsPrefixes for # of Carbons

11 MethMeth 66 HexHex

22 EthEth 77 HeptHept

33 PropProp 88 OctOct

44 ButBut 99 NonNon

55 PentPent 1010 DecDec

More Alkanes

H H Condensed Structural Formulas

H C C H CH3 CH3

H H Ethane

H H H

H C C C H CH3 CH2 CH3

H H H Propane

Learning Check Alk1

A. What is the condensed formula for H H H H

H C C C C H

H H H H

B. What is its molecular formula?C. What is its name?

What is the

General formula for Alkanes?

Summary: IUPAC Rules for Alkane Summary: IUPAC Rules for Alkane NomenclatureNomenclature

 1. Find Find and name the longest continuous carbon and name the longest continuous carbon chain.chain.

AKA: AKA: parent chainparent chain. .

  2. 2. NumberNumber the chain consecutively the chain consecutively, starting at the end , starting at the end nearest an attached group (nearest an attached group (substituentsubstituent). ).

3. 3. IdentifyIdentify and and name groups attached name groups attached to this chain.to this chain. (Examples: methyl-, bromo-, etc.)(Examples: methyl-, bromo-, etc.)

4. 4. Designate the location Designate the location of each substituent group of each substituent group withwith the number the number of the carbon parent chain on which of the carbon parent chain on which the group is attached. Place a dash between the group is attached. Place a dash between numbers and letters.numbers and letters. (Example: 3-chloropentane) (Example: 3-chloropentane)

  5. 5. Assemble the Assemble the namename, listing groups in , listing groups in alphabetical alphabetical order.order.     The prefixes di, tri, tetra etc., used to designate     The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered several groups of the same kind, are not considered when alphabetizing. Place a comma between multiple when alphabetizing. Place a comma between multiple numbers. (Example: 2,3-dichloropropane)numbers. (Example: 2,3-dichloropropane)

Step 1. Find the parent chain.Step 1. Find the parent chain.

• Where is the longest continuous chain of Where is the longest continuous chain of carbons?carbons?

EndingsEndings• Alkanes (all C-C single bonded parent Alkanes (all C-C single bonded parent

chain) end in chain) end in –ane–ane– MethMethaneane CHCH44

– EthEthaneane CC22HH66

– PropPropaneane CC33HH88

• Attached carbon groups (substituents) end Attached carbon groups (substituents) end in in –yl–yl– MethMethylyl CH CH33 - -– EthEthylyl CHCH33CHCH22--– PropPropylyl CH CH33CHCH22CHCH2 2 –  –     

3-ethylpentane

Step 2. Number the parent chain.Step 2. Number the parent chain.

• Number the parent chain so that the attached groups are on the lowest numbers

1 2 3 4 5

Methyl is on carbon #2 of the parent chain

5 4 3 2 1

Methyl is on carbon #4 of the parent chain

GREEN is the right way for this one!

1 2

3 7 8

4 5 6

8 7

6 2 1

5 4 3

Groups on 2, 3, and 5

Groups on 4, 6, and 7

1 2 3 4 5 6

7

Groups on 2 and 5

7 6 5 4 3 2 1

Groups on 3 and 6

Step 3. Name the attached groups.Step 3. Name the attached groups.

• Carbon (alkCarbon (alkylyl) groups) groups– MethMethylyl CH CH33 - -– EthEthylyl CHCH33CHCH22--– PropPropylyl CH CH33CHCH22CHCH2 2 ––

• HalogensHalogens– Fluoro (F-)Fluoro (F-)– Chloro (Cl-)Chloro (Cl-)– Bromo (Br-)Bromo (Br-)– Iodo (I-)Iodo (I-)

Step 4. Designate where the group Step 4. Designate where the group is attached to the parent chain.is attached to the parent chain.

• Use the numbers of the parent chain from step 2 to designate the location of the attached groups to the parent chain.

1 2 3 4 5

2-methyl

Step 5. Alphabetize the groups, Step 5. Alphabetize the groups, combine like groups, and assemble.combine like groups, and assemble.

• The prefixes di, tri, tetra The prefixes di, tri, tetra etc., used to designate etc., used to designate several groups of the several groups of the same kindsame kind

• Prefixes are not Prefixes are not considered when considered when alphabetizing (Example: alphabetizing (Example: dimethyl = m for dimethyl = m for alphabetizing)alphabetizing)

• Parent chain goes LASTParent chain goes LAST

1,1,1-trichloro-1-fluoromethane

1,1-dichloro-1,1-difluoromethane

Draw Some Simple AlkanesDraw Some Simple Alkanes

• 2-methylpentane2-methylpentane

• 3-ethylhexane3-ethylhexane

• 2,2-dimethylbutane2,2-dimethylbutane

• 2,3-dimethylbutane2,3-dimethylbutane

Structural FormulasStructural Formulas

• “Lazy” way to write the Hydrogens

• Instead of drawing the bonds, just state how many hydrogens are attached

• NOTE: The bonds are between CARBONS in a parent chain, and not hydrogens!

Structural FormulaLewis Structure

Order of PriorityOrder of Priority

• IN A TIE, halogens get the lower number IN A TIE, halogens get the lower number before alkyl groupsbefore alkyl groups

4-chloro-2-methylpentane or4-chloro-2-methylpentane or2-chloro-4-methylpentane?2-chloro-4-methylpentane?

Order of PriorityOrder of Priority

• IN A TIE between SIMILAR GROUPS, the IN A TIE between SIMILAR GROUPS, the group lower ALPHABETICALLY gets the group lower ALPHABETICALLY gets the lower numberlower number

4-bromo-2-chloropentane or 2-bromo-4-chloropentane ?

IsomersIsomers

• Straight chain alkanes: Straight chain alkanes: – Alkane with straight carbon back boneAlkane with straight carbon back bone

• Branched chain alkanes:Branched chain alkanes: –Alkane with a branching connection of Alkane with a branching connection of carbons.carbons.

• Isomers: Isomers: –Same molecular formula but different Same molecular formula but different structures.structures.

Only one possible atom arrangement Only one possible atom arrangement methane (CHmethane (CH44) ) ethane (Cethane (C22HH66)) propane (Cpropane (C33HH88))

Butane (CButane (C44HH1010): 2 isomers): 2 isomers linear alkane or branched alkanelinear alkane or branched alkane

Isomers are completely different compounds. Isomers are completely different compounds. VariedVaried

StructuresStructures

Physical properties (MP, BP)Physical properties (MP, BP)

Types of Carbon AtomsTypes of Carbon Atoms

• Primary carbon (1Primary carbon (1oo))

– a carbon bonded to a carbon bonded to

one other carbonone other carbon

• Secondary carbon (2Secondary carbon (2oo))

– a carbon bonded to a carbon bonded to

two other carbonstwo other carbons

• Tertiary carbon (3Tertiary carbon (3oo))

– a carbon bonded to a carbon bonded to

three other carbonsthree other carbons

C

C

C

C

H

H

H

C C

H

HC

C

C

H

C

C

C

C

H

H

H

C C

H

HC

C

C

H

C

C

C

C

H

H

H

C C

H

HC

C

C

H

C

C

C

C

H

H

H

C C

H

HC

C

C

H

AlkanesAlkanes

Example:Example: Name the following compounds: Name the following compounds:

CH3

CH3CH(CH

3)2CH

2CH

2Br

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

C CH2 CH

2Br

CHCH3

CH2CH

3

CH3

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

AlkanesAlkanes

Example: Write the condensed structure Example: Write the condensed structure for the following compounds:for the following compounds:

3,3-dimethylpentane3,3-dimethylpentane

2-methyl-4-sec-butyloctane2-methyl-4-sec-butyloctane

1,2-dichloro-3-methylheptane1,2-dichloro-3-methylheptane

Test Your Knowledge

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