Transcript IUBAC naming organic compounds

Organic Chemistry
For Dental Students
Dr. Nesma Mamdouh Bayoumy
Lecture (1)
Spring, 2015
1
An Introduction to Organic Compounds
Chapter 1
• Organic chemistry is that branch of chemistry that
deals with the structure, properties, and reactions
of compounds that contain carbon.
• Organic compounds are the compound which
contains mainly carbon and hydrogen.
2
Hydrocarbons
Saturated
Alkanes
Unsaturated
CnH2n+2
Alkenes
Alkynes
CnH2n
CnH2n-2
IUPAC Nomenclature
The Three Basic Parts
• The name for any organic molecule consists of three basic
parts:
Prefixes-Parent-Suffix
• Basic Part – Suffixes
• Suffixes on the end of the name of an organic molecule tell
you what major family the molecule belongs to
• The suffix for an alkane is “-ane”
• The suffix for an alkene is “-ene”
• The suffix for an alkyne is “-yne”
• Basic Part – the Parent
• The “parent” part of the name tells you how many carbons
are in the longest chain “main chain” of the molecule.
• Counting to Ten in Organic
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•
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•
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01 = meth
02 = eth
03 = prop
04 = but
05 = pent
06 = hex
07 = hept
08 = oct
09 = non
10 = dec
• Parent and suffix…
• The parent is named based on the number of carbons
• 1 carbon = “meth”
• So a one-carbon alkane is called methane
CH4
• 2 carbons = “eth”
• So a two carbon alkane is called ethane.
CH3CH3
Parent and suffix…
• 3 carbons = “prop”
• So a three carbon alkane is called propane.
CH3CH2CH3
• 4 carbons = “but”
• So a four carbon alkane is called butane.
CH3CH2CH2CH3
• So name the following alkane (shown as both condensed
formula and a skeletal structure)
Answer?
nine carbons + alkane family = NONANE
• Prefixes
• Prefixes are any substituent attached to the main chain
(parent) of the molecule.
• Prefixes – the Halides
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•
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Chlorine is called “chloro”
Fluorine is called “ Fluoro”
Bromine is called “bromo”
Iodine is called “iodo
Putting together a name…
• The rules for IUPAC nomenclature include:
• Step 1: Find the main chain (Longest chain)
• Step 2: Number the main chain
• Step 3: Identify all prefixes and their position numbers
• Step 4: Write the full name: Prefixes-Parent-Suffix.
• Step 5: Add punctuation.
o Put commas between numbers (2 5 5 becomes 2,5,5)
o Put a hyphen between a number and a letter (2 5 5
trimethylheptane becomes 2,5,5-trimethylheptane)
o Successive words are merged into one word (trimethyl
heptane becomes trimethylheptane)
• Follow the rules… Name the following…
Br
4-Bromoheptane
Br
Cl
3,4-Dibromoheptane
3-ethylhexane
3-Bromo-1-chloro-4-methylhexane
1,1-Dibromo-3-methyloctane
• Alkyl Groups
• Alkyl groups are named similarly to alkanes.
• If you remove a hydrogen atom from one of these you get an
alkyl group.
• A fragment of methane, CH4, would be CH3- called “methyl”
• A fragment of ethane, CH3CH3, would be CH3CH2-, called
“ethyl”.
Example:
6
H3C
3-ethylhexane
5
4
3
2
1
CH CH2 CH CH CH3
CH3 CH3
CH3
2,3,5-Trimethylhexane
IUPAC Systematic Nomenclature - Alkanes
•
If compound has two or more chains of the same length,
parent hydrocarbon is chain with greatest number of
substituents.
Quiz
Draw Some Simple Alkanes:
2-methylpentane
3-ethylhexane
Example 1: Write the structural formula for 2-methylpentane
• Start from counting the number of carbon atoms in the
longest chain - pent counts 5 carbons.
• Are there any carbon-carbon double bonds?
• No – an tells you there aren't any.
• Now draw this carbon
skeleton:
• Put a methyl group on the
number 2 carbon atom:
Write the structural formula:
2,3-dimethylbutane.
2,2-dimethylbutane.
3-ethyl-2-methylhexane.
4-bromo-3-methylhexene.
H3C
H
C
CH 3
H2
C
H2
C
CH 3
Propyl Groups
• There are two possible three-carbon alkyl groups to form
from propane, CH3CH2CH3.
• The straight chain version: CH3CH2CH2- which is called
“propyl” or “n-propyl” (where n stands for “normal” or
straight-chained)
• The other possibility is to form the fragment on the central
carbon: CH3CHCH3, which is called “isopropyl”
 Name the following molecule:
• There are two options: Option 1 is highlighted in red:
•
The red one has two branches
• Option 2 is highlighted in blue:
• The blue one has three branches
•
•
•
•
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Eight carbons in main chain. Octane.
Three alkyl groups attached:
2-methyl
5-propyl
6-methyl
• Full name: 2,6-dimethyl-5-propyloctane.
Nomenclature of Substituents
• The name of the alkyl group followed by the name of the class
of compound constitutes the common name for alcohols
amines, and alkyl halides:
Function Class
General Formula
Suffix
Alcohols
OH
Ol
Aldehydes
CHO
al
Ketones
C=O
one
Ethers
-O-
ether
Esters
-COO-
oate
Carboxylic acids
-COOH
oic acid
Amines
NH2
amine
 For each of the compounds A through G shown below, enter the
appropriate IUPAC suffix in the designated answer box. In the second
answer box enter a number indicating the number of carbon atoms in the
longest chain.
Compound
OH
A
O
B
H
O
C
O
D
OH
O
OH
Cl
E
CH 2
O
G
O CH 3
F
IUPAC suffix
Chain length
Organic Chemistry
For Dental Students
Dr. Nesma Mamdouh Bayoumy
Lecture (2)
Spring, 2015
17
Examples:
Name the following:
3-methylpentanoic acid
but-3-enoic acid
4-bromo-5,6-dimethylheptan-2-amine
4-chloro-5,5-dimethylhex
-1-en-3-ol
3-ethyl-2,2,4,5-tetramethylhexane
Name the following:
Hexa-1,4-diene
Pent-3-en-1-yne
3,4-Dipropyl-1,3-hexadien-5-yne
Hexa-1,3-dien-5-yne
4-bromo-7-methyl-2-nonene
5-fluoro-7,7-dimethyl-2,4-octadiene
Nomenclature of Cycloalkanes
• Cycloalkanes generally are shown as skeletal structures:
Nomenclature of Cycloalkanes
• Ring is the parent hydrocarbon unless the alkyl substituent has
more carbons; in that case the substituent becomes the parent
hydrocarbon.
If only one substituent, no need to give it a number:
Examples:
cyclobutylhexane
2-chloro-1,3-dimethyl
cyclohexane
propylcyclopentane
3-isopropylcyclo
pent-1-ene
1,1,2-trimethylcyclobutane
3-ethylcyclohept-1-ene
The line formula for a cyclic compound is shown below.
Give the IUPAC name
Suffix
Number of ring
carbons
The IUPAC name :
3-ethyl-5,5-dimethylcyclohept-2-en-1-one
The Suffix:
ONE
The number of carbons:
7 carbons
• A line formula for a compound is shown below.
• How many carbon atoms are in the root chain?
• Give the IUPAC name for this compound?
Answer:
Number of carbons 5
The IUPAC name:
4-chloro-2-ethyl-3-methylpent-4-enoic acid
Give the IUPAC name for the following
• 4-isopropyl-1-ethyl-2-propylcyclohexane
• 3-ethyl-1,5,5-trimethylcyclohexene
• 1-cyclohexylheptan-3-ol
• 4-bromo-7-chloro-3-isopropylcyclo
hept-1-ene
Benzene Derivatives
Cl
Br
Chlorobenzene
Bromobenzene
NO 2
C 2 H5
nitrobenzene
ethylbenzene
Br
1-methyl-2-propylbenzene
1-bromo-4-ethyl-2-isopropylbenzene
1,3,5-trimethylbenzene