NAMING ALKANES
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Naming Alkanes
•
Compounds are given systematic names by a process that uses
•
Follows specific rules
• Find parent hydrocarbon chain
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IUPAC Names
The name of an alkane with a branched chain of carbon
atom consists of:
• a parent name: the longest chain of carbon atoms.
• substituent names: the groups bonded to the parent
chain.
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IUPAC Names
The IUPAC name of an alkane with an unbranched chain of
carbon atoms consists of two parts:
(1) A prefix shows the number of carbon atoms in the
chain.
(2) The suffix -ane: shows that the compound is a saturated
hydrocarbon.
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IUPAC Names
1. The name for an alkane with an unbranched chain of
carbon atoms consists of a prefix showing the number of
carbon atoms and the ending -ane.
2. For branched-chain alkanes, the longest chain of carbon
atoms is the parent chain and its name is the root name.
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Naming Alkanes (Continued)
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Carbons in that main chain are numbered in sequence
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IUPAC Names
3. Give each substituent on the parent chain a name and a
number. Use a hyphen to connect the number to the
name.
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IUPAC Names
4. If there is one substituent, number the parent chain from
the end that gives the substituent the lower number.
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IUPAC Names
5. If the same substituent occurs more than once:
• Number the parent chain from the end that gives the lower
number to the substituent encountered first.
• Indicate the number of times the substituent occurs by a
prefix di-, tri-, tetra-, penta-, hexa-, and so on.
• Use a comma to separate position numbers.
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IUPAC Names
6. If there are two or more different substituents:
• List them in alphabetical order.
• Number the chain from the end that gives the lower
number to the substituent encountered first.
• If there are different substituents at equivalent positions
on opposite ends of the parent chain, give the substituent
of lower alphabetical order the lower number.
alphabetize nyo sila
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kaya una si ethyl before
methyl.
assign lower # to ethyl
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Naming Alkanes (Continued)
▪
Substituents are identified and numbered
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IUPAC Names
7. Do not include the prefixes di-, tri-, tetra-, and so on or the
hyphenated prefixes sec- and tert- in alphabetizing;
• Alphabetize the names of substituents first, and then
insert these prefixes. In the following example, the
alphabetizing parts are ethyl and methyl, not ethyl and
dimethyl.
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