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Chapter 23
Organic Chemistry
Hill, Petrucci, McCreary & Perry 4th Ed.
Alkane to Substituent Group
methane
CH4
methyl
CH3
ethane
CH3CH3
ethyl
CH3CH2
propane
CH3CH2CH3
propyl
CH3CH2CH2
isopropyl
butyl
(CH3)2CH
or
CH3CHCH3
CH3CH2CH2CH2
butane CH3CH2CH2CH3
sec-butyl
CH3CH2CHCH3
Alkane to Substituent Group
CH3
CH3
CH3CHCH2
isobutyl
isobutane CH3CHCH3
CH3
tert-butyl
or
CH3C
CH3
(CH3)3C
1
Free Rotation about Single Bonds
n-hexane
C
C
C
C
C
C C
C
C
C
C
C
C
C
C
C
C
C
Different Views of 2-Methylpentane
C
C
C
C
C
C
C C
C C
C
C
C C
C
C
C
C
C
C
C
C
C C
Distinguishing Isomers
A
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
D
C
C
C
C
C
C
C
C
C
C
C
C
B
C
C
E
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
2
Carbon Can Have Only Four Bonds
CH3CH2CH2CH2CH2CH3
CH3
CH3
CH3CH2CHCH2CH3
CH3CHCH2CH2CH3
CH3
CH3
CH3CCH2CH3
CH3CHCHCH3
CH3
CH3
What Is Wrong With Each of These?
CH3CH2CH2CH2CH2CH2
CH3
CH3
CH3CH2CHCH2CH3
CH3CH2CH2CH2CH3
CH3
CH2
CH3CHCH2CH3
CH3CCHCH3
CH3
CH3
Cycloalkanes
CH2
H2C
C
C C
C
C
C
H
C
C
H2C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CH2
C C
C
C
CH3
C
C C
C
C
C
C
C
CH2
C
C
C
C
C
3
IUPAC Systematic Naming of Alkanes
• Longest continuous carbon chain = Parent Alkane (PA)
• Locate any chain branching off PA, name as alkyl group.
• Assign smallest set of numbers to branch points counting from one
end of PA.
• For multiple branching – Locate identical alkyl groups, indicate
their number using bi, di (2); tri (3); tetra (4) … Locate different
alkyl groups.
• Construct the name by placing the alkyl groups in alphabetical
order (ignoring Greek prefixes, dimethyl = m) preceded by locator
number separated by hyphens from words and commas from
numbers. There should be a locator number for each alkyl group,
i. e. 2,2-dimethyl.
C C
C
C
C
C
C
C
C
3-ethyl-2,2-dimethylpentane
A nonane isomer!
IUPAC Systematic Naming of cycloAlkanes
• Largest carbon ring = Parent cycloalkane (PCA) – use
cyclo+(name of straight chain having same number of carbon atoms
as the ring)
• Locate any chain branching off PCA, name as alkyl group.
• For multiple branching assign consecutive numbers to ring
positions that give lowest set – Locate identical alkyl groups and
indicate their number using bi, di (2); tri (3); tetra (4) … Locate
different alkyl groups.
• Construct the name by placing the alkyl groups in alphabetical
order (ignoring Greek prefixes, dimethyl = m) preceded by locator
number separated by hyphens from words and commas from
numbers. There should be a locator number for each alkyl group.
CH3
H3C
CH3
Methylcyclopentane
1,3-dimethylcyclopentane
Reactions of Alkanes
Alkanes react with very few reagents, i.e. chlorine
CH4 + Cl2
CH3Cl + HCl
Cl2
HCl + CH2Cl2
Cl2
CHCl3 + HCl
HCl
+ CCl4
Cl2
4
Addition Reactions to the Double Bond
H
H
H
C
C
H
H
H + HCl
H
C C
H
H Cl
chloroethane
ethene
H H
H H
CH3 C C CH3 + HOH
CH3 C C CH3
H OH
2-butanol
cis-2-butene
Benzene Undergoes Addition Only Under
Forcing Conditions
3H2
It Mostly Undergoes Substitution
Cl
Cl2
+ HCl
FeCl3
Other Substitution Reactions
CH2CH3
AlCl3 CH3CH2Cl
Br
Br2
NO2
HNO3
FeBr3
H2SO4
SO3H
5
Naming of Benzene Derivatives
Mostly Common Names
NO2
Br
Cl
F
nitro-benzene
I
bromo-
chloro-
fluoroNH2
iodo-
phenol
OH
CH CH2
styrene
CH3
toluene
O
SO3H
C
aniline
H
O
C
OH
benzene sulfonic acid
benzoic acid
benzaldehyde
Simple Alcohols
CH3CH2CH2 OH
ethyl
alcohol
CH3CHCH3
OH
isopropyl
alcohol
ethanol
2-propanol
1-propanol
CH3 OH
CH3CH2 OH
methyl
alcohol
methanol
Common Names:
IUPAC Names:
n-propyl
alcohol
R-group then “alcohol”
Parent Alkane - e + ol
Diols, Triols & Higher
CH2CH2
OHOH
ethylene
glycol
propylene
glycol
1,2-ethandiol
OH
CH2CHCH2
CH3CH2CHCH2
CH3CHCH2
OH OH
OHOH
butylene
glycol
1,2-propandiol
O
OH
CH2CHCHCHCH
1,2-butandiol
OH
O
CH2CHCHCHCCH2
OH OH OH
OH
OH
OH OH OH OH
"aldopentose"
"ketohexose"
glycerol
1,2,3-propantriol
"sugars"
6
Properties of Alcohols
•Alcohols are polar, hydrogen bond with water, and each
other, have higher boiling points than alkanes of similar
molecular weight.
•Alcohols are soluble in water if the substituent group part is
not too large and non-polar. C1-C7 = miscible to slightly
soluble, C8 and higher are insoluble.
H
R
O
•Alcohols are not
H
O
acidic or basic in
H
water, the pH is not
H
R
O
altered.
H
O
H
H
O
H
OH
H
H
OH
Reactions of Alcohols
Dehydration:
H OH
CH3CHCH2
CH3CH CH2
+ H2O
Note! Two carbon atoms involved!
HO H
CH3CHCH3
CH3CH CH2
minor
major
H OH H
+ H2O
major product
CH3CH CHCH3
CH3CHCHCH2
CH3CH2CH CH2
+ H2O
minor product
When two alkenes are possible: More highly branched is favored.
Oxidation of Primary Alcohols
[O] = oxidizing agent
O H
CH3C H
O
[O]
H
ethanol
O
CH3C
H2 O
+
H
ethanal (acetaldehyde)
Aldehydes are formed!
O H
CH3CH2C H
H
propanol
O
[O]
O
CH3CH2C
+
H2O
H
propanal (propionaldehyde)
7
Oxidation of Secondary Alcohols
[O] = oxidizing agent
O H
CH3C H
O
O
[O]
CH3C
H2O
+
CH3
CH3
2-propanol
propanone (acetone)
Ketones are formed!
O H
CH3CH2C H
O
O
[O]
CH3CH2C
+
H2O
CH3
butanone (methyl ethyl ketone)
CH3
2-butanol
Further Oxidation of Primary Alcohols
Aldehydes are formed first but oxidize easily to carboxylic acids:
O
CH3C
O
[O]
CH3C
O
O
H
ethanoic (acetic) acid
H
ethanal (acetaldehyde)
from ethanol
O
CH3CH2C
O
[O]
O
H
propanal (propionaldehyde)
CH3CH2C
O
H
propanoic (propionic) acid
Ketones and tertiary alcohols resist further oxidation.
Important Unsaturated Oxygen Functions
O
C
found
in
carbonyl
O
C
O
carboxyl
found
in
O
O
C
C
H
aldehydes
C
C
C
ketones
O
O
C
C
O H
carboxylic
acids
C
C
O C
esters
8
ETHERS
•
Ethers have two non-carbonyl hydrocarbon groups
bonded to oxygen.
•
Ethers are nearly as unreactive as the alkanes.
•
Ethers are as volatile as
alkanes of similar
molecular weight. They
cannot donate a hydrogen
bond to each other.
•
HO
R
H
H
O
H
R
R
R
O
H
Ethers are polar and can
accept a hydrogen bond
from water; they are about
as soluble in water as
isomeric alcohols.
OH
O
H
O
H
H
H
OH
OH
Synthesis of Ethers from Alcohols & Phenols
CH3CH2OH + HOCH2CH3
Ethyl alcohol = Ethanol
OH + HO
Phenol
OH
140 C
H2SO4
CH3CH2OCH2CH3
(di)Ethyl Ether
Phenol
+
HOCH2CH3
(di)Phenyl Ether
O CH2CH3
acid catalyst
Ethanol
Phenol
O
acid catalyst
Ethyl Phenyl Ether
Carboxylic Acids & Esters
O
O
C
OH
carboxylate
group is planar
-H
C
C
O
its anion
is also planar
9
Carboxylic Acids, R-COOH
•Carboxylic acids have a hydroxy group bonded to the
carbonyl group.
•The group is polar like aldehydes and ketones but like
alcohols it can donate a hydrogen bond to itself. The
carboxylic acids are much higher boiling ( less volatile )
than even the alcohols of similar molecular weight.
•Lower carboxylic acids have
very pungent and irritating
odors.
O
•They are unsaturated
undergo addition reactions
with polar molecules forming
acid derivatives not true
addition compounds.
C
H
O H
O
C
O
carboxylate
group dimerizes easily
Carboxylic Acids – Common/IUPAC Names
formic acid
O
HCOH
methanoic acid
acetic acid
O
CH3COH
ethanoic acid
propionic acid
O
CH3CH2COH
propanoic acid
butyric acid
O
CH3CH2CH2COH
butanoic acid
O
benzoic acid
COH
phenylmethanoic acid
Esters - RC(O)OR’
•Esters have an alkyl group bonded to the carboxylate group.
The group is polar but unlike carboxylic acids it cannot
donate a hydrogen bond to itself.
•Esters are more volatile (lower boiling) than carboxylic acids
and are somewhat less soluble in water than carboxylic acids
of similar molecular weight.
•Esters have pleasant, fruity
odors and most are nontoxic.
• They are also unsaturated
and undergo many reactions
with polar molecules.
O
C
C
O
R
ester
group is planar
10
Naming Esters –Common & IUPAC
Common Name
IUPAC Name
O
CH3COCH3
methyl acetate
methyl ethanoate
O
CH3OCCH2CH3
methyl propanoate
ethyl propionate
O
CH3CH2COCH2CH3
ethyl propanoate
methyl butyrate
O
CH3CH2CH2COCH3
methyl butanoate
methyl propionate
O
phenyl acetate
OCCH3
phenyl ethanoate .
Synthesis of Esters & Acyl Transfer Agents
direct esterification:
O
CH3C OH
O
H
+ H OCH2CH3
acyl group alcohol group
alcohol group
acyl group
CH3C OCH2CH3
acyl group transfer reactions:
O
CH3C
O
acid chloride
Cl
+ H OCH2CH3
100%
acyl group alcohol group
alcohol group
acyl group
CH3C OCH2CH3
acid anhydride
O
O
O
CH3C OCCH3
+ H OCH2CH3
100%
acyl group alcohol group
alcohol group
acyl group
CH3C OCH2CH3
Saponification (Breakdown) of Esters
saponification:
O
O
CH3C O + H OCH2CH3
CH3C OCH2CH3 + OH
acyl group alcohol group
reverse of direct esterification:
O
CH3C OCH2CH3 + HOH
acyl group alcohol group
acyl group
alcohol group .
O
H
CH3C OH + H OCH2CH3
acyl group
alcohol group
11
Properties of Amides
•Amides are polar, hydrogen bond with water, and each other
when the nitrogen bears a hydrogen atom.
•Amides have much higher melting and boiling points than
alcohols or amines of similar molecular weight, are also
soluble in water if the substituent group part is not too large
and non-polar.
O
•Amides do NOT affect
the pH of a water solution.
CH3CH2C
• The amide linkage can
be hydrolysed in strong
acid solution back to the
carboxylic acid and the
salt of the amine from
which it was synthesized
acyl part
amine part
N
H
CH
CH3
amide linkage
CH3
Synthesis of Amides with Acyl Transfer Agents
acyl group transfer reactions:
O
acid chloride
CH3C Cl
CH3
O CH3
100%
+ H NCH2CH3
acyl group amine group
amine group
acyl group
CH3C NCH2CH3
+ HCl
acid anhydride
O
CH3
O
CH3C OCCH3
+ H NCH2CH3
100%
acyl group amine group
amine group
acyl group
O CH3
CH3C NCH2CH3
O
+ HOCCH3
Carboxylic Acids & Amines Give Salts
A carboxylic acid & amine react as acid & base:
O
acyl group
O
CH3
CH3C OH + H NCH2CH3
amine group
100%
CH3
CH3C O + H NCH2CH3
H amine group
acyl group
The acyl group transfer reaction does not occur.
12
Acids & Bases Hydrolyze Amides
Acid Promoted Hydrolysis (Breakdown) of Amides
O
CH3CH2C
H O
water
H
O
H Cl strong acid
H
H
CH
CH
C O +
3
2
N
Cl
CH3
H
carboxylic acid
CH
CH3
H N
CH
CH3
ammonium salt
H
CH3
Base Promoted Hydrolysis (Breakdown) of Amides
O
O
Na
H
CH
CH
C O +
3
2
CH3CH2C N
CH3
H
carboxylate anion
CH
CH3
H N
Na O
CH
H
CH3
amine
sodium hydroxide
CH3
13