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Nomenclature. Dr. Clower CHEM 2411 Spring 2014 McMurry (8 th 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 - PowerPoint PPT Presentation
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NOMENCLATUREDr. ClowerCHEM 2411Spring 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
ParentNumber 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)
SuffixFunctional 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• Ethyl• Propyl• Isopropyl• Butyl• Isobutyl • sec-butyl• tert-butyl (t-butyl)
• Pentyl (amyl)• Isopentyl (isoamyl)• Neopentyl • tert-pentyl• Hexyl, heptyl, etc.• Halogens
• Fluoro• Chloro• Bromo• Iodo
Naming alkanes1. 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
ExamplesStructure Name
CH3 CH2 CH
CH3
CH3
CH3 CH CH2 CH
CH3 CH3
CH3
CH3 CH CH2 CH
CH2 CH3
CH3
CH3
Examples• Draw 3-ethylpentane.
• Draw all the constitutional isomers with the molecular formula C6H14. Name each isomer.
ExamplesStructure Name
CH3 CH CH
CH2CH2CH3
CH2CH3
CH2CH3
CH3 CH CH2 CH
CH3 CH2CH3
CH2CH3
CH3CH2 CH CH
CH
CH2CH2CH3
CH3
CH3
CHCH3CH3
ExamplesStructure Name
CH3 C CH2
CH3
CH3
CH
CH2CH3
CH2CH3
CH3 CH2 CH
CH3
CH
CH3
CH2 CH2 CH
CH3
CH2CH3
CH3 CH CH2 CH2
CH3
CH
Br
CH3
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
ExamplesStructure Name
CH2CH3
CH3
CH3
ExamplesStructure Name
CH2CH3
CH3
CH3
CH3
CH3
Br
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 stereoisomersCH3
CH3
CH3CH3
CH3 CH3
cis trans
CH3
CH3
ExamplesStructure Name
• Do these pairs represent constitutional isomers, cis-trans stereoisomers or the same compound?
(a)
(b)
CH3
CH2CH2CH3
Alkene Nomenclature• Similar to alkanes• Change infix from “-an-” to “-en-”
CH2 CH2 CH CH2CH3
ethene (ethylene) propene (propylene)
Naming Alkenes• For larger alkenes:1. Parent is longest C chain containing both carbons of C=C2. 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: CH3 CH CH CH2
CH2 CH2 CH2
CH3
ExamplesStructure Name
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
CH3
CH3CH2
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
CH3
HCH3
HH
CH3CH3
H
cis-2-butene trans-2-butene
Examples• Are the following alkenes cis, trans, or neither?
(a)
(b)
(c)
H
CH3
H
CH3
CH3H
H
Alkyne Nomenclature• Similar to alkenes• Change infix from “-en-” to “-yn-”
C CHCH3
ethyne (acetylene) propyne
CH CH
Naming Alkynes• For larger alkynes:1. Parent is longest C chain containing both carbons of C≡C2. 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:
CH3 C C CH2 CH CH3
CH3
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
CH2 CH CH2 CH2 C C H
CH CH CH C C HCH3
CH3
Naming Aromatic Compounds • Benzene
• Monosubstituted benzenes• Substituent name + “benzene”
Common Benzene Compounds
anisole
OCH3
Benzene Nomenclature• If substituent has greater than 6 carbons, it becomes the
parent, and benzene is called a phenyl group
• Benzene substituents:
2-phenylheptane
Disubstituted Benzenes• ortho (1,2)• meta (1,3)• para (1,4)
Br
Br
Br
Br
Br
Br
1,4-dibromobenzene
1,3-dibromobenzene1,2-dibromobenzene
p-dibromobenzene
m-dibromobenzeneo-dibromobenzene
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
ExamplesStructure Name
CO2H
Cl
CH2CH3
Cl
CO2H
NH2
ExamplesStructure Name
NH2
NH2
CH3
NH
CH3
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
ExamplesStructure Name
Br Br
OH
Br
Cl
CH2CH3
NO2
CH3
NO2
NO2
Another Aromatic Compound• Pyridine
• If substituted, nitrogen is atom 1 of the ring. Number in direction of other substituents.
N
N
CH3
3-methylpyridine
Naming Alcohols• Acyclic alcohols
1. Parent chain is longest chain containing C bonded to –OH2. Change suffix from “-e” to “-ol”3. Number from end closest to –OH. Show location of –OH.4. Name/number substituents
• Cyclic alcohols1. Ring is the parent2. 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≡C2. Suffix is “-ol”, infix is “-en-” or “-yn-”3. Number chain so –OH has the lowest number4. Show numbers for –OH and the unsaturation5. Name/number substituents
ExamplesStructure Name
CH3 CH2 CH2 CH2 OH
CH3 CH
OH
CH2 CH3
CH3 CH
CH3
CH2 OH
OH
ExamplesStructure Name
CH3
OH
HO CH2 CH2 OH
HC C CH2 CH2 OH
OH
Naming Thiols• Thiols are sulfur analogs of alcohols• Name like alcohols, but keep the “-e” and use “-thiol” in
place of “-ol”
CH3 SH
methanethiol
SH
CH3
HS
2-butanethiol
SH
Naming Amines1. Parent chain is longest containing C bonded to –N2. Change suffix “-e” to “-amine”3. Number from end closest to –N. Show location of –N.4. Name/number substituents
NH2
2-butanamine
ExamplesStructure Name
NH2
CH3 CH2 CH2 CH2 CH CH3
NCH3 CH3
Naming Aldehydes• Parent chain contains carbon of CHO• Suffix is “-al”• CHO carbon is carbon 1 (do not need to show in name)
O
CH H
O
CCH3 H H
O
methanal (formaldehyde)
ethanal(acetaldehyde)
3-methylbutanal
Naming Aldehydes• Cyclic molecules with –CHO substituents
• -CHO is bonded to carbon 1 of ring• Add “carbaldehyde” to end of ring parent name
CH3 CHO
trans-4-methylcyclohexanecarbaldehyde
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:
O
2-propanone(acetone)
O
2-pentanone
O
CH3
O
acetophenone benzophenone
ExamplesStructure Name
H
O
CHO
CH3 CH CH CH2 C CH3
O
OCH3
Order of Precedence of Functions • Used when more than one functional group in a 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-
Incr
easi
ng p
rece
denc
e
ExamplesStructure Name
H
OO
OH O
HO NH2
CO2HNH2
Naming Carboxylic Acids• Parent chain contains carbon of –CO2H• Suffix is “-oic acid”• –CO2H is carbon 1
CH3 CH
CH3
CH2 CO2H H C OH
O
CH3 C OH
O
3-methylbutanoic acid methanoic acid(formic acid)
ethanoic acid(acetic acid)
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
CO2HHO
(cis)-3-hydroxycyclopentanecarboxylic acid
ExamplesStructure Name
O O
OH
CO2H
Naming Acid Chlorides• Name corresponding carboxylic acid• Change “-ic acid” to “-yl chloride”• Examples:
Structure Name
CH3 C Cl
O
C Cl
O
R C
O
Cl
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
R C
O
O C R'
O
O O
O
CH3
O
Ph
O
O
Naming Esters• Name alkyl group bonded to oxygen (R’)• Name carboxylic acid RCO2H• Change “-ic acid” to “-ate”• Examples:
Structure Name
R C
O
O R'
O
O
CH3 CH2 O C
O
CH3
Naming Amides• Name corresponding carboxylic acid• Change “-oic acid” to “-amide”• Examples:
Structure Name
R C
O
NH2
CH3 CH2 C
O
NH2
O
NHO
N
Example• DMF (N,N-dimethylformamide) is a common solvent in
organic chemistry. Draw the structure of DMF.
Naming Nitriles• Two methods1. 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”
CN
4-methylpentanenitrile
CCH3 N
acetonitrile
C N
benzonitrile
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 Name
CH3Cl
(CH3)2CHBr
CH3CH2OH
CH3CH2NHCH3
(CH3CH2)2NH
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
CH3 C CH3
O
O
Ph O CH2 CH3
CH3 S CH3