organic chemistry organic chemistry is the chemistry of the carbon atom. it is the chemistry of all...
TRANSCRIPT
Organic Chemistry Organic chemistry is the chemistry of the carbon
atom. It is the chemistry of all life on earth. Carbon atoms bond to other atoms of
carbon hydrogen and sometimes oxygen, nitrogen, sulfur and
phosphorus A few compounds contain carbon but are not
considered to be organic: CO2, CO, H2CO3, CaCO3
Hydrocarbons Hydrocarbons are the simplest organic molecules. They are made of only carbon C and hydrogen H
atoms Each carbon atom makes 4 bonds Each hydrogen atom makes 1 bond -H If each carbon makes only one bond to each of its
neighbours, it is called an ‘alkane’
Systematic NomenclatureSystematic NomenclatureInternational Union of Pure and Applied
Chemistry (IUPAC)Committee on Organic Nomenclature
# C #C
1 meth- 6 hex-
2 eth- 7 hept-
3 prop- 8 oct-
4 but- 9 non-
5 pent- 10 dec-
Methane (CH4) CH4
Ethane (C2H6) CH3CH3
Propane (C3H8) CH3CH2CH3
bp -160°Cbp -160°C bp -89°Cbp -89°C bp -42°Cbp -42°C
The Simplest Alkaneshave only C and H, only single bonds, and all names end in ‘ane’
CHCH33CHCH22CHCH22CHCH22CHCH22CHCH33
PentanePentane
HexaneHexane
CHCH33CHCH22CHCH22CHCH22CHCH33
CHCH33CHCH22CHCH22CHCH22CHCH22CHCH22CHCH33
HeptaneHeptane
ButaneButane
CHCH33CHCH22CHCH22CHCH33
The alkanes The alkanes
Methane (CH4)
Ethane (C2H6)
Propane (C3H8)
Butane (C4H10)
Pentane (C5H12)
Hexane (C6H14)
Heptane (C7H16)
Octane (C8H18)
Nonane (C9H20)
Decane (C10H22)
CH4
CH3 CH3
CH3 CH2 CH3
CH3 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3
Nomenclature of the AlkanesNomenclature of the Alkanes
Alkanes always have the ending -ane.Side chains (substituents) are named as
alkyl groups.
Common alkyl groupsCommon alkyl groups (C (C11 through C through C44))
CH3
CH3 CH2
CH3 CH2 CH2
CH3 CH2 CH2 CH2
Methyl
Ethyl
Propyl
Butyl
Isopropyl
Isobutyl
(1-Methylethyl)
(2-Methylpropyl)
sec-Butyl
(1-Methylpropyl)
tert-Butyl
(1,1-Dimethylethyl)
CH3 CH
CH3
CH3 CH CH2
CH3
CH3 CH2 CH
CH3
CH3 C
CH3
CH3
IUPAC nomenclature of alkanesIUPAC nomenclature of alkanes
1. identify the longest chain -- parent
2. number from the end closest to first branch
3. Name the groups attached to the chain, using the carbon number as the locator.
4. Alphabetize substituents.
5. Use di-, tri-, etc., for multiples of same substituent
6. combine number and name of substituent with parent name, separating with hyphen
Longest Chain The number of carbons in the longest chain
determines the base name: ethane, hexane. If there are two possible chains with the
same number of carbons, use the chain with the most branches (substituents).
C
CH3
CH2
CH3
CH CH2 CH2 CH3
CH CH2 CH3H3C
H3C
=>
Number the Carbons
Start at the end closest to the first attached group.
If two substituents are equidistant, look for the next closest group.
1
2
3 4 5
6 7CHH3C
CH3
CH
CH2CH3
CH2 CH2 CH
CH3
CH3
CH3 CH2 CH CH3
CH2 CH3
Find the longest continuousFind the longest continuouscarbon chaincarbon chain
1 2 3
4 5
3-methylpentane
CH3 CH2 CH CH2 CH2 CH3
CH2 CH2 CH3
You must choose the longestYou must choose the longestcontinuous carbon chaincontinuous carbon chain
4 3 2 1
5 6 7
4-ethylheptane
CH3 CH2 CH2 CH CH CH2 CH3
CH3
CH2 CH3
Number from the end nearestNumber from the end nearestthe first substituentthe first substituent
7 6 5 4 3 2 1
4-ethyl-3-methylheptane
CH3 CH2 CH2 CH CH2 CH CH2 CH3
CH2 CH3
CH3
Number from the end nearestNumber from the end nearestthe first substituentthe first substituent
8 7 6 5 4 3 2 1
3-ethyl-5-methyloctane
CH3 CH CH CH3
CH3
CH3
Use “di-” with two substituentsUse “di-” with two substituents
1 2 3 4
2,3-dimethylbutane
CH3 CH2 C CH2 CH2 CH3
CH3
CH3
Every substituent must get a numberEvery substituent must get a number
1 2 3 4 5 6
3,3-dimethylhexane
CH3 CH2 CH CH CH2 CH2 CH2 CH2 CH CH3
CH3CH3
CH3
Number from the end nearestNumber from the end nearestfirst substituentfirst substituent
10 9 8 7 6 5 4 3 2 1
2,7,8-trimethyldecane
CH3 CH2 CH CH CH2 CH2 CH2 CH CH2 CH3
CH3
CH3
CH3
Number from the end which hasNumber from the end which hasthe “first difference”the “first difference”
1 2 3 4 5 6 7 8 9 10
3,4,8-trimethyldecane
CH3 CH CH2 C CH3
CH3 CH3
CH3
A More-Highly-SubstitutedA More-Highly-SubstitutedCarbon Takes PrecedenceCarbon Takes Precedence
5 4 3 2 1
2,2,4-Trimethylpentane
CH3 CH2 CH CH2 CH2 CH CH2 CH3
CH3 CH2 CH3
Which end do we number from?Which end do we number from?
8 7 6 5 4 3 2 1
3-ethyl-6-methyloctane
IUPAC rules
1. Find the longest straight chain = parent chain
2. Number the parent chain in the direction that gives the lowest number to the substituents at the first point of difference.
3. Two or more identical groups are indicated by di, tri, tetra, etc.
CH3 CH2 CH2 CH2 CH
CH2 CH3
CH3Longest chain is 7 (not 6).This is 3-methylheptane.
.
2,3,6-trimethylheptane (not 2,5,6-trimethyl heptane)
2,2,6,6,7-pentamethyloctane (not 2,3,3,7,7-pentamethyloctane)
4. Different groups are listed in alphabetical order (di, tri, tetra, etc. don’t count).
5. If the numbering is the same in both directions, choose the numbering to follow the alphabetical order.
IUPAC rules
6-ethyl-2,2-dimethyloctane
5-ethyl-6-methyldecane
6. When two or more chains compete for the longest, the choice goes to the one with the greater number of side groups.
IUPAC rules
2,4,6-trimethyl-5-propyloctane
IUPAC rules
6-ethyl-2,2,5,7-tetramethylnonane (not 6,7-diethyl-2,2,5-trimethyloctane.
Name the following compounds.
CH2CH2
CH2CH
CH2CH3 C
CH2CH2
CH2CH2
CH2CH3
CH3
CCH3 CH2
CH3 CH2 CH3
CH3
Good Luck!Good Luck!
7-(1,1-Dimethylbutyl)-3-ethyl-7-methyldodecane
Common Nomenclature Common Nomenclature PitfallsPitfalls
Did not find the longest carbon chainNumbered chain from the wrong endForgot to repeat number for each identical
substituent; forgot to use di- tri- tetra-, etc.Writing the name as more than one wordIncorrect punctuation
cyclic moleculescyclic molecules
CC
C
H H
H
H
H
H
CH2
CH2
CH2
Cyclopropane
C
C C
C
H
H
H
H
H
H
H
H
CH2
CH2 CH2
CH2
Cyclobutane
C
C
C
C
C
H HH H
HH
HH
HH
CH2
CH2
CH2
CH2
CH2
Cyclopentane
C
CC
C
CC
H HH
H
H
H
HH
H
H
H
HCH2
CH2
CH2
CH2
CH2
CH2
Cyclohexane
Nomenclature for Cyclic Alkanes For compounds with a single ring, add the
prefix “cyclo-” to the root name for the alkane comprising the ring.
Nomenclature of the Substituted Nomenclature of the Substituted CycloalkanesCycloalkanes
If there is only one substituent, do not use the “1”. If there is more than one substituent, you must use all
numbers, including “1”! Number around the ring in a direction to get from the
first substituent to the second substituent by the shorter path.
For equivalent degrees of substitution, number in a direction that follows the alphabetical sequence.
A carbon with greater substitution has precedence in numbering.
Numbering Starts at the Most Numbering Starts at the Most Highly-Substituted CarbonHighly-Substituted Carbon
Cl CH3
CH3
CH3
2 13 74 6 5
2-Chloro-1,1,6-trimethylcycloheptane