Transcript IUPAC Names - OldForensics 2012-2013

Mari Mari
• Do Now:
– Take out HW
– Any questions on the handout from yesterday?
• Agenda:
– Alkenes and Alkynes
– Ethers, Ketones, Esters
• HW:
– #4-9,30,31,38-41
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.
CH2
CH3
CH2
CH2
CH2
CH3
CH CH3
Longest chain is 7 .(not 6).
This is 3-methylheptane.
3. Two or more identical groups are indicated by di, tri, tetra, etc.
2,3,6-trimethylheptane
(not 2,5,6-trimethyl heptane)
2,2,6,6,7-pentamethyloctane
(not 2,3,3,7,7-pentamethyloctane)
IUPAC rules
4. Different groups are listed in alphabetical order (di, tri, tetra, etc.
don’t count; n, sec, tert don’t count; iso does).
6-ethyl-5-isopropyl-2,2-dimethyloctane
5. If the numbering is the same in both directions, choose the
numbering to follow the alphabetical order.
5-ethyl-6-methyldecane
cyclic molecules
H
H
H
H
C
H
H
CH2 CH2
H
H
C
C
H
CH2 CH2
H
C
C
H
CH2 CH2
H
Cyclobutane
H
H
C
C
H
H
HH
C
H
H
H
H
C
C
C
C
C
H
CH2
Cyclopentane
C
H
CH2
CH2 CH2
H
H
H
H
CH2
C
C
Cyclopropane
H
H
H
CH2
C
C
H
H
H
CH2
H
H
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
Cycloalkanes

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.
2. Ethers
In an ether, an oxygen
atom is bonded to two
carbon atoms.
–C–O–C– .
has a common name
that gives the alkyl
names of the attached
groups followed by
ether.
Diethyl ether
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Publishing as Benjamin Cummings
7
Ethers are named in two ways: the common
naming system, and the IUPAC naming
system

Common Names: The alkyl groups attached to the
ether linkage are named in alphabetical order and are
followed by the word ether.

IUPAC Names: The carbon(s) attached to the
oxygen atom are named as branches by adding the –
oxy suffix to the stem name.
Ether Example
CH3-CH2-CH2-CH2-O-CH2-CH3

Common Name: butyl ethyl ether

IUPAC Name: ethoxybutane
Ether Practice

R-O_R
Draw the condensed structural formula of
methoxy propane:
Ether Practice
More Practice
4. Ketones
In a ketone, the carbon of
the carbonyl group is
attached to two other
carbon atoms.
Acetone
Copyright © 2005 by Pearson Education, Inc.
Publishing as Benjamin Cummings
13
IUPAC Names for Ketones

Replace -e with -one. Indicate the position
of the carbonyl with a number.

Number the chain so that carbonyl carbon
has the lowest number.

For cyclic ketones the carbonyl carbon is
assigned the number 1.
Chapter 18
14
Examples
O
O
CH3
C CH CH3
CH3
Br
3-methyl-2-butanone
3-bromocyclohexanone
O
CH3
C CH CH2OH
CH3
4-hydroxy-3-methyl-2-butanone
=>
Chapter 18
15
Boiling Points


More polar, so higher boiling point than
comparable alkane or ether.
Cannot H-bond to each other, so lower
boiling point than comparable alcohol.
=>
Chapter 18
16
Solubility



Good solvent for alcohols.
Lone pair of electrons on oxygen of
carbonyl can accept a hydrogen bond from
O-H or N-H.
Acetone and acetaldehyde are miscible in
water.
=>
Chapter 18
17
Ketones Practice

R-C-R
Draw the condensed structural formula for
3-pentanone
Esters

Ester – a compound that has
the following general formula
RCOOR’

In the general formula for an ester the R and R’
can be any alkyl group.
•

Although R and R’ can be identical, they are usually
different.
Most esters have pleasant odors.
•
Many flowers and ripe fruits have fragrances and
tastes due to one or more esters.
14 | 19
Section 14.4
Names of esters
end in –oate.
Naming
Named after alcohol & carboxylic acid from which they are
derived.
O
C
CH3
CH2
CH3
let’s name
some esters!
O
ethyl
this part comes from the
alcohol & is named after it
ethanoate
this part from the acid
and is named after it
Structural formulae
Although the previous structural formula are the clearest
way of showing esters, they can draw out in a
shortened form.
In this version
ethyl ethanoate
O
Either…
CH3 CH2
O
C
CH3
Or…
O
CH3 C
the acid part
has been
written first
O
CH2
CH3
 Identify the group attached to the C=O – this is from
the acid
 The group attached to the –O- is from the alcohol.
Esters Practice R-O-C-R
 Draw the condensed structure for
butyl hexanoate
Wait! What’s that
smell?
fragrance
ester
ethyl methanoate
3-methylbutyl ethanoate
ethyl 2-methylbutanoate
phenylmethyl ethanoate
raspberries
pears
apples
jasmine
 Esters have strong, sweet smells.
 Their bouquet is often floral or fruity.
 This means they are used in food flavourings & perfumes.
 Also, very good at dissolving organic compounds so often
used as solvents.