mari do now: – take out hw – any questions on the handout from yesterday? agenda: – alkenes...
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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.
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; n, sec, tert don’t count; iso does).
5. If the numbering is the same in both directions, choose the numbering to follow the alphabetical order.
IUPAC rules
6-ethyl-5-isopropyl-2,2-dimethyloctane
5-ethyl-6-methyldecane
cyclic 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 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. EthersIn 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.
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
7
Diethyl ether
4. KetonesIn a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.
Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings
10
Acetone
Chapter 18 11
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 12
Examples
CH3 C
O
CH
CH3
CH3
O
Br
CH3 C
O
CH
CH3
CH2OH
3-methyl-2-butanone
3-bromocyclohexanone
4-hydroxy-3-methyl-2-butanone =>
Chapter 18 13
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 14
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.
=>
14 | 16
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.Section 14.4
NamingNamed after alcohol & carboxylic acid from which
they are derived.
Names of esters end in –oate.
CH3C
CH2 O
O
CH3
ethyl ethanoate
this part from the acid and is named after it
this part comes from the alcohol & is named after it
let’s name some esters!
Structural formulaeAlthough the previous structural formula are the
clearest way of showing esters, they can draw out in a shortened form.
ethyl ethanoate
CH3CCH2 O
O
CH3
Either…Or…
CH3C CH2O
O
CH3
In this version the acid part has been
written first
Identify the group attached to the C=O – this is from the acid
The group attached to the –O- is from the alcohol.
Wait! What’s that smell?
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.
ester fragranceethyl methanoate raspberries3-methylbutyl ethanoate pearsethyl 2-methylbutanoate applesphenylmethyl ethanoate jasmine
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