NOMENCLATURE
Dr. Clower
CHEM 2411
Spring 2014
McMurry (8th ed.) sections 3.2, 3.3, 3.4, 4.1, 4.2, 7.3, 7.4, 9.1,
10.1, 15.1, 17.1,18.1, 18.8, 19.1, 20.1, 21.1, 24.1, Appendix A
Nomenclature
• The naming of organic molecules
• IUPAC system
• All names have Substituents-MainChain
• Substituents are groups attached to the main chain
• MainChain consists of Parent-Infix-Suffix
• Parent tells you number of carbons in main chain
• Infix tells you if the carbon-carbon bonds are single bonds
(saturated molecule) or double or triple bonds (unsaturated
molecules)
• Suffix tells you the functional group of your molecules
Parent
Number of carbons
Parent name
1
meth-
2
eth-
3
prop-
4
but-
5
pent-
6
hex-
7
hept-
8
oct-
9
non-
10
dec-
11
undec-
12
dodec-
Straight-chain alkanes
Infix
• “-an-” = only carbon-carbon single bonds (saturated)
• “-en-” = an alkene (double bond) is present (unsaturated)
• “-yn-” = an alkyne (triple bond) is present (unsaturated)
Suffix
Functional group
Suffix
alcohol
-ol
ether
ether
amine
-amine
nitrile
-nitrile
thiol
-thiol
sulfide
sulfide
aldehyde
-al
ketone
-one
carboxylic acid
-oic acid
ester
-oate
amide
-amide
acid chloride
-oyl chloride
acid anhydride
-oic anhydride
Nomenclature
• Consider the molecule 2-hexanol.
• How many carbons in the main chain?
• Saturated or unsaturated?
• What functional group?
• Consider the molecule octanoic acid.
• How many carbons in the main chain?
• Saturated or unsaturated?
• What functional group?
• Consider the molecule 4-methyl-2-pentanamine.
• How many carbons in the main chain?
• Saturated or unsaturated?
• What functional group?
• What is 4-methyl?
Substituents
• Groups off of main chain (branches)
• Parts of larger compounds (not stable by themselves)
• Alkyl groups = Alkane – H
• “-ane” changes to “-yl”
• Methyl
• methane – H
• CH4 – H
• CH3─
• Ethyl
• ethane – H
• CH3CH3 – H
• CH3CH2─
Substituents
• Propane – H gives two possible alkyl groups
• Propyl
• Isopropyl
• Similarly, there are multiple alkyl groups with 4 carbon
atoms, 5 carbon atoms, etc.
Alkyl groups you need to know
• Methyl
• Pentyl (amyl)
• Ethyl
• Isopentyl (isoamyl)
• Propyl
• Neopentyl
• Isopropyl
• tert-pentyl
• Butyl
• Hexyl, heptyl, etc.
• Isobutyl
• Halogens
• Fluoro
• Chloro
• Bromo
• Iodo
• sec-butyl
• tert-butyl (t-butyl)
Naming alkanes
1. Find the parent chain
• Longest continuous chain of C atoms
• Name of chain = parent name
• If 2 chains of equal length, parent is the chain with more substituents
2. Number each carbon in the parent chain
• Start from the end closest to the first substituent
• If there are substituents equal distance from both ends, number from
the end nearest the second substituent
Naming alkanes, cont.
3. Name and number substituents
• Name = alkyl group name
• Number = point of attachment to parent chain
• Two substituents on the same C get the same number
4. Write the name as a single word
• Substituents before parent name (include #)
• Separate # and word with hyphen
• Separate two numbers with a comma
• List substituents in alphabetical order
• Multiple identical substituents use prefixes di, tri, tetra, penta, hexa
• DO NOT use sec, tert, di, tri, etc. when alphabetizing
• DO use iso, neo when alphabetizing
Examples
Structure
Name
Examples
• Draw 3-ethylpentane.
• Draw all the constitutional isomers with the molecular
formula C6H14. Name each isomer.
Examples
Structure
Name
Examples
Structure
Name
Naming Cycloalkanes
• Unsubstituted cycloalkanes:
• Add “cyclo” to the parent name
• Bicycloalkanes
• Two rings
• Most common is norbornane
• Bicyclo[2.2.1]heptane
Naming Cycloalkanes
• Substituted cycloalkanes:
• Parent = ring or substituent (whichever has more carbons)
• Number the substituents
• Do not need to show number if only one substituent on a ring
• If two substituents, start with the first alphabetically, number in the
direction of the second substituent
• If more than two substituents, number so that the substituents have the
lowest set of numbers
Examples
Structure
Name
Examples
Structure
Name
Cycloalkane Stereoisomers
• Cycloalkanes are roughly planar
• Substituents are either above or below this plane
• Shown with dash and wedges
• Dash = back; wedge = forward
• In a disubstituted cycloalkane, two substituents on the same
side (both back or both forward) are cis. Two substituents on
opposite sides (one back, one forward) are trans.
• Cis and trans versions of the same molecule are stereoisomers
Examples
Structure
Name
• Do these pairs represent constitutional isomers, cis-
trans stereoisomers or the same compound?
(a)
(b)
Alkene Nomenclature
• Similar to alkanes
• Change infix from “-an-” to “-en-”
Naming Alkenes
• For larger alkenes:
1. Parent is longest C chain containing both carbons of C=C
2. Number chain so C=C has lowest possible number
• If the double bond is equidistant from both ends, start numbering at
end nearest the first substituent
• Show location of C=C by first number
• Alkenes with >1 C=C use “-adiene”, “-atriene”, etc. in place of “-ene”
and show location of all double bonds
3. Name and number substituents and write the full name
• Example:
Examples
Structure
Name
Cycloalkenes
• The carbon atoms of the C=C are numbered 1 and 2
• Number ring in direction to give first substituent lowest
possible number
Structure
Name
Alkene substituents
Substituent
Name
CH2═
methylene
CH2═CH─
vinyl
CH2═CH─CH2─
allyl
Alkene Stereoisomers
• Cis-trans stereoisomers
• Seen with disubstituted alkenes
• Cis means groups are on the same side of the double
bond; trans means groups are on opposite sides
• Cannot convert through bond rotation
• Example: 2-butene
Examples
• Are the following alkenes cis, trans, or neither?
(a)
(b)
(c)
Alkyne Nomenclature
• Similar to alkenes
• Change infix from “-en-” to “-yn-”
Naming Alkynes
• For larger alkynes:
1. Parent is longest C chain containing both carbons of C≡C
2. Number chain so C≡C has lowest possible number
• If the triple bond is equidistant from both ends, start numbering at
end nearest the first substituent
• Show location of C≡C by first number
• Alkynes with >1 C≡C use “-adiyne”, “-atriyne”, etc. in place of “-yne”
and show location of all double bonds
3. Name and number substituents and write the full name
• Example:
Enyne
• Contains both alkene and alkyne
• Number from end closest to first multiple bond (either
C=C or C≡C) and show both numbers
• If the C=C and C≡C are equidistant from the ends, C=C
gets the lower number
• Examples:
Structure
Name
Naming Aromatic Compounds
• Benzene
• Monosubstituted benzenes
• Substituent name + “benzene”
Common Benzene Compounds
Benzene Nomenclature
• If substituent has greater than 6 carbons, it becomes the
parent, and benzene is called a phenyl group
• Benzene substituents:
Disubstituted Benzenes
• ortho (1,2)
• meta (1,3)
• para (1,4)
Naming Disubstituted Benzenes
• If one substituent is part of a common name, that name is
the parent and that substituent is at carbon 1
• If neither substituent is part of a common name, list the
substituents in alphabetical order (first alphabetically is at
carbon 1)
• If both substituents are part of common name, use this
order of priority to determine the parent name:
-CO2H > -CHO > -OH > -NH2 > -CH3
Examples
Structure
Name
Examples
Structure
Name
Naming Polysubstituted Benzenes
• With 3 or more substituents do not use ortho, meta, para
• Number ring to give smallest set of numbers
• If a common name, use as parent (substituent at carbon 1)
• List substituents in alphabetical order
Examples
Structure
Name
Another Aromatic Compound
• Pyridine
• If substituted, nitrogen is atom 1 of the ring. Number in
direction of other substituents.
Naming Alcohols
• Acyclic alcohols
1. Parent chain is longest chain containing C bonded to –OH
2. Change suffix from “-e” to “-ol”
3. Number from end closest to –OH. Show location of –OH.
4. Name/number substituents
• Cyclic alcohols
1. Ring is the parent
2. Number ring so –OH is at carbon 1 and other substituents have
lowest possible numbers. You do not need to show the location
of the –OH.
3. Name/number substituents.
Naming Alcohols
• Multiple hydroxyl groups
• Two –OH groups is a diol; 3 is a triol
• Two adjacent –OH groups is a glycol
• Name as acyclic alcohols, except keep the “-e” suffix and add “-diol”
• Indicate numbers for all –OH groups
• Unsaturated alcohols (enol or ynol)
1. Parent chain contains carbon bonded to –OH and both carbons of
C=C or C≡C
2. Suffix is “-ol”, infix is “-en-” or “-yn-”
3. Number chain so –OH has the lowest number
4. Show numbers for –OH and the unsaturation
5. Name/number substituents
Examples
Structure
Name
Examples
Structure
Name
Naming Thiols
• Thiols are sulfur analogs of alcohols
• Name like alcohols, but keep the “-e” and use “-thiol” in
place of “-ol”
Naming Amines
1. Parent chain is longest containing C bonded to –N
2. Change suffix “-e” to “-amine”
3. Number from end closest to –N. Show location of –N.
4. Name/number substituents
Examples
Structure
Name
Naming Aldehydes
• Parent chain contains carbon of CHO
• Suffix is “-al”
• CHO carbon is carbon 1 (do not need to show in name)
Naming Aldehydes
• Cyclic molecules with –CHO substituents
• -CHO is bonded to carbon 1 of ring
• Add “carbaldehyde” to end of ring parent name
Naming Ketones
• Parent chain contains carbon of carbonyl; suffix is “-one”
• Number so carbonyl has lowest number
• Cyclic ketones carbonyl is carbon 1 of the ring
• Some more common names:
Examples
Structure
Name
Order of Precedence of Functions
• Used when more than one functional group in a
Increasing precedence
molecule
Functional Group
Suffix
(High Precedence)
Prefix
(Low Precedence)
-CO2H
-oic acid
-
-CHO
-al
formyl-
-C(O)-
-one
oxo-
-OH
-ol
hydroxy-
-NH2
-amine
amino-
Examples
Structure
Name
Naming Carboxylic Acids
• Parent chain contains carbon of –CO2H
• Suffix is “-oic acid”
• –CO2H is carbon 1
Naming Carboxylic Acids
• Cyclic molecules with –CO2H substituents
• –CO2H is bonded to carbon 1 of ring
• Add “carboxylic acid” to end of ring parent name
Examples
Structure
Name
Naming Acid Chlorides
• Name corresponding carboxylic acid
• Change “-ic acid” to “-yl chloride”
• Examples:
Structure
Name
Naming Acid Anhydrides
• If R = R’, name carboxylic acid RCO2H. Replace “acid”
with “anhydride”
• If R ≠ R’, list the two acids alphabetically and add the
word “anhydride”
• Examples:
Structure
Name
Naming Esters
• Name alkyl group bonded to oxygen (R’)
• Name carboxylic acid RCO2H
• Change “-ic acid” to “-ate”
• Examples:
Structure
Name
Naming Amides
• Name corresponding carboxylic acid
• Change “-oic acid” to “-amide”
• Examples:
Structure
Name
Example
• DMF (N,N-dimethylformamide) is a common solvent in
organic chemistry. Draw the structure of DMF.
Naming Nitriles
• Two methods
1. Nitrile carbon is carbon 1 of parent chain. Add “-nitrile” to end of
alkane name.
2.
Name as carboxylic acid derivative. Replace “-ic acid” with “-onitrile”
Common Name System
• Can be used for some simple molecules
• Alkyl halides, alcohols, amines
• Name alkyl group
• Add “chloride” or “bromide” or “alcohol” or “amine”
• Examples:
Structure
CH3Cl
(CH3)2CHBr
CH3CH2OH
CH3CH2NHCH3
(CH3CH2)2NH
Name
Common Name System
• Ketones, ether
• Name both alkyl groups bonded to carbonyl (ketone), oxygen (ether),
or sulfur (sulfide)
• Add “ketone” or “ether” or “sulfide”
• Examples:
Structure
Name