organic chemistry nomenclature: alkanes. what is organic chemistry? study of hydrocarbons and...
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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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Distillation towers
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Boiling Point
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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
• http://chemed.chem.pitt.edu/Jeopardy/organic/index.htm