Transcript Document 7234533

Chapter 22
Organic and Biological
Molecules
1
Organic Chemistry and Biochemistry
The
study of carbon-containing
compounds and their properties.
The vast majority of organic
compounds contain chains or rings
of carbon atoms.
The study of the chemistry of living
matter
2
Hydrocarbons


compounds composed of carbon and
hydrogen.
Saturated compounds (alkanes) have
the maximum number of hydrogen
atoms attached to each carbon atom
H H
H C
C H
H H
3


Unsaturated compounds have fewer
hydrogen atoms attached to the carbon
chain than alkanes
Unsaturated: They contain carbon-carbon
multiple bonds (double or triple)
H H
H C
H
C
H
C
H
4
22.1 Alkanes: Saturated hydrocarbons

Saturated hydrocarbons, CnH2n+2
 “Saturated” because they can’t take
any more hydrogen atoms
 Normal straight chains (unbranched
hydrocarbons)
H3C–(CH2)n–2–CH3
 Waxes, oils, & fuel gases as n
decreases.
5
Alkanes: Saturated Hydrocarbons
The C-H Bonds in Methane
6
The Lewis structure of ethane.
7
Propane
8
Butane
9
The First 10 “Normal” Alkanes










Name
Formula
M.P.
B.P.
# Structural Isomers
Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane
Octane
Nonane
Decane
CH4
-183 -162
C2H6
-172 -89
C1 - C4 are
Gases
C3H8
-187 -42
Room Temperature
Cat
-138
0
4H10
C5H12
-130
36
C6H14
-95
68
C7H16
-91
98
C8H18
-57
126
C5 - C16 are
Liquids
C9H20
-54
151
Room Temperature
Cat
-30
174
10H22
1
1
1
2
3
5
9
18
35
75
10
IUPAC Rules for Naming Branched Alkanes
•
•
•
•
•
Find and name the parent chain in the hydrocarbon this forms the root of the hydrocarbon name
Number the carbon atoms in the parent chain
starting at the end closest to the branching
Name alkane branches by dropping the “ane” from
the names and adding “yl”. A one-carbon branch is
called “methyl”, a two-carbon branch is “ethyl”,
etc…
When there are more than one type of branch (ethyl
and methyl, for example), they are named
alphabetically
Finally, use prefixes to indicate multiple branches
11
Rules for Naming Alkanes
1. For alkanes beyond butane, add -ane to
the Greek root for the number of
carbons.
C-C-C-C-C-C : hexane
2. Alkyl substituents: drop the -ane and
add -yl
-C2H5 is ethyl
12
13
Rules for Naming Alkanes
3. Positions of substituent groups are
specified by numbering the longest
chain sequentially.
C

C-C-C-C-C-C
3-methylhexane
Start numbering at the end closest to
the branching
4. Location and name are followed by root
alkane name. Substituents are given in
alphabetical order and use di-, tri-, etc.

14
Normal vs Branched Alkanes

CH2
CH2
CH3
CH2
CH3

CH3
CH2
CH3
CH
CH3

Normal alkanes consist of
continuous chains of
carbon atoms
Alkanes that are NOT
continuous chains of
carbon atoms contain
branches
The longest continuous
chain of carbons is called
the parent chain
15
Structural Isomerism


Structural isomers are
molecules with the same
chemical formulas but
different molecular
structures - different
“connectivity”.
They arise because of the
many ways to create
branched hydrocarbons.
CH2
CH2
CH3
CH2
CH3
n-pentane, C5H12
CH3
CH2
CH3
CH
CH3
2-methlbutane, C516H12
Example : Show the structural formula
of 2,2-dimethylpentane

2
The parent chain is
4
indicated by the ROOT of
CH2 5
CH2 3
1
the name - “pentane”. This CH
CH3
CH2
3
means there are 5 carbons
in the parent chain.
• “dimethyl” tells us that there are
TWO methyl branches on the
parent chain. A methyl branch is
made of a single carbon atom.
CH3
4
CH2
C
1
CH3
CH2
3
CH3
CH3
5
• “2,2-” tell us that BOTH methyl
branches are on the second
carbon atom in the parent chain.17
Example: Structural formula of
3-ethyl-2,4-dimethylheptane?

The parent chain is
indicated by the ROOT
of the name “heptane”. This means
there are 7 carbons in
the parent chain.
CH3
CH3
CH
CH
CH3
CH3
CH
CH2
CH2
CH2
2
1
CH3
CH2
4
3
CH2
CH2
5
CH2
H2C 6
7
CH3
• “2,4-dimethyl” tells us there are
TWO methyl branches on the
parent chain, at carbons #2 and
#4.
CH3
• “3-ethyl-” tell us there is an ethyl
branch (2-carbon branch) on
carbon #3 of the parent chain.18
Example: 2,3,3-trimethyl-4-propyloctane

The parent chain is indicated
by the ROOT of the name “octane”. This means there
are 8 carbons in the parent
chain.
2
1
3
2
5
4
6
7
1
8
CH3 tells us there are
• “2,3,3-trimethyl”
THREE
methyl
branches
CH
C
CH2 - one on
3
CH#2 andCH
CH2 #3.
carbon
two on carbon
5
4
3
6
7
8
CH3
CH3 tell CH
2
• “4-propyl-”
us there
isCH
a 2propyl
CH3
CH
2
branch (3-carbon branch)
on
carbon #4 of the CH
parent
chain.
3
19
Example : Name the molecules shown
CH3

parent chain has 5 carbons “pentane”
two methyl branches - start
counting from the right - #2
and #3

2,3-dimethylpentane


4

5
CH3
CH
CH3
CH3

3
CH
CH2

parent chain has 8 carbons - “octane”
two methyl branches - start counting
from the left - #3 and #4
one ethyl branch - #5
name branches alphabetically
5-ethyl-3,4-dimethyl octane
20
Reactions of alkanes

Combustion reactions
2C4H10 + 13 O2

8CO2 + 10 H2O(g)
Substitution Reactions
CH4 + Cl2
CH3Cl + HCl
CH3Cl + Cl2
CH2Cl2 + HCl
CH2Cl2 + Cl2
CH Cl3 + HCl
CHCl3 + Cl2
C Cl4
21
Dehydrogenation Reactions
CH3CH3
CH2
CH2
Ethylene
22
Cyclic alkanes
CnH2n

A cycloalkane is made of a hydrocarbon
chain that has been joined to make a
“ring”.
H2
C
109.5° bond angle
CH2
CH3
CH3
n-propane
C3H8
H2C
60° bond angle
unstable!!
CH2
cyclopropane
C3H6
•Note that two hydrogen atoms were lost in forming the ring
23
Ring Structures
24
Cyclohexane - Boat & Chair Conformations


Cyclohexane is NOT a planar molecule. To achieve
its 109.5° bond angles and reduce angle strain, it
adopts several different conformations.
The BOAT and CHAIR (99%) are two conformations
Boat
chair
25
22.2 Alkenes and Alkynes
Alkenes: hydrocarbons that contain a
carbon-carbon double bond. [CnH2n]
C=C
Ethene
C C=C
propene
Alkynes: hydrocarbons containing a
carbon-carbon triple bond. [CnH2n-2]
C ΞC
C C CΞC C
Ethyne
2-pentyne
26
Alkenes & Alkynes


Alkenes are
hydrocarbons that
contain at least one
carbon-carbon double
bond
Alkynes are
hydrocarbons that
contain at least one
carbon-carbon triple
bond


The suffix for the parent
alkane chains are
changed from “ane” to
“ene” and “yne”
 e.g. ethene, ethyne
Where it is ambiguous,
the BONDS are
numbered like branches
so that the location of the
multiple bond may be
indicated
27
Alkenes, CnH2n


Cycle formation isn’t the only possible
result of dehydrogenation.
Adjacent C’s can double bond, C=C,
making an (unsaturated) alkene.
Sp2
28
Nomenclature for Alkenes
1. Parent hydrocarbon name ends in -ene
C2H4; CH2=CH2
is ethene
2.With more than 3 carbons, double bond
is indicated by the lowest numbered
carbon atom in the bond.
C=C-C -C is 1-butene
29
Nomenclature alkenes and alkynes
30
Cis and Trans Isomers
Double bond is fixed (rotation around the
double bond is restricted)
 Cis/trans Isomers are possible

CH3
CH3
CH = CH
cis
CH3
CH = CH
trans
CH3
31
Reactions of alkenes and alkynes
1. Addition Reactions

in which (weaker)  bonds are broken
and new (stronger)  bonds are formed
to atoms being added.
32
Hydrogenation reaction

Adds a hydrogen atom to each carbon atom
of a double bond
H H
H–C=C–H + H2
catalyst
H H
H–C–C–H
CH3-CH3
H H
Ethene
Ethane
33
Halogenation reaction

Adds a halogen atom to each carbon atom
of a double bond
H H
H–C=C–H + Cl2
catalyst
H H
H–C–C–H
Cl Cl
Ethene
Dichloro ethane
34
Halogenation Reactions
CH2
CHCH2CH2CH2 + Br2
CH2Br
CHBrCH2CH2CH2
1,2-dibromopentane
35
Alkynes, CnH2n–2
•sp triple bonding makes a rigid 180°
segment in a hydrocarbon.
 Carbon-carbon
triple bonds
 Names end in -yne
HCCH
ethyne(acetylene)
HCC-CH3
propyne
36
The Bonding in Acetylene
37
Naming Alkenes and Alkynes
When the carbon chain has 4 or more C atoms,
number the chain to give the lowest number to the
double or triple bond.
1
2 3 4
CH2=CHCH2CH3
1-butene
CH3CH=CHCH3
2-butene

2-butyne
CH3CH CHCH3
38
Question
Write the IUPAC name for each of the following
unsaturated compounds:
A.CH3CH2CCCH3
CH3
B.
CH3
2-pentyne
CH3C=CHCH3
2-methyl-2-butene
C.
3-methylcyclopentene
39
Question

Name the following compound
CH3CH2C CCHCH2CH3
CH2
CH3
1
2
3
4 5
6
7
CH3CH2C CCHCH2CH3
CH2
CH3
5-ethyl-3-heptyne
40
Additions reactions:Hydrogenation and
Halogenation
Hydrogens and halogens also add to
the triple bond of an alkyne.
Br Br
CH3C CCH2CH3
+ Br2
CH3C CCH2CH3
Br Br
41
22.3 Aromatic hydrocarbons
Unsaturated Cyclic hydrocarbons

Alternating single/double bond
cycles occur in many organic molecules
 This class is called “aromatic” (by
virtue of their aroma).
• Delocalized  bonds
possess a great stability
thus benzene does not
react like unsaturated
hydrocarbons
42
Benzene C6H6
 structure is
often preserved in
benzene chemical
reactions
 Aromatic rings
do not add, they
substitute instead
The
sp2
sp2
sp2
43
Shorthand notation for benzene rings
The bonding in the
benzene ring is a
combination of different
Lewis structures
44
Aromatic Hydrocarbons
Substitution reaction
Nitroobenzene
Chlorobenzene
Cl
+ Cl2
benzene
FeCl3


HNO3
H
NCH3Cl
O
3
-NO2
-CH3
Toluene
+ HCl
+H2O
+HCl
45
46
Nomenclature of benzene derivatives
47
More Complex Aromatic Systems
48
22.4 Hydrocarbon Derivatives
(Functional Groups)
 Molecules that are fundamentally hydrocarbons



but have additional atoms or group of atoms
called functional groups
Part of an organic molecule where chemical
reactions take place
Replace an H in the corresponding alkane
Provide a way to classify organic compounds
49
The Common Functional Groups
Class
Halohydrocarbons
Alcohols
Ethers
Aldehydes
General Formula
RX
ROH
ROR
R
O
C H
50
Class
Ketones
Carboxylic Acids
Esters
Amines
General Formula
R
O
C R'
R
O
C OH
R
O
C OR'
R
NH2
51
Some Types of Functional Groups
Haloalkane -F, -Cl, -Br CH3Cl
Alcohol
-OH
CH3OH
Ether
Aldehyde
Ketone
-O-
CH3-O-CH3
O
O
C H
CH3CH
O
O
C
CH3CCH3
52
More Functional Groups
Carboxylic acid
-COOH
CH3COOH
Ester
-COO-
CH3COOCH3
Amine
-NH2
CH3NH2
Amide
-CONH2
CH3CONH2
53
54
Haloahydrocarbons
An alkane in which one or more H atoms is
replaced with a halogen (F, Cl, Br, or I)
CH3Br
bromomethane
(methyl bromide)
Br
CH3CH2CHCH3
2-bromobutane
Cl
chlorocyclobutane
55
Name the following:
Br
bromocyclopentane
Cl
1,3-dichlorocyclohexane
1 2
3
Cl
56
Substituents
List other attached atoms or groups in
alphabetical order
Br = bromo, Cl = chloro
Cl
Br
1
2
3
4
5
CH3CHCH2CHCH2CH2CH3
4-bromo-2-chloroheptane
57
Nomenclature
The name of this compound is:
Cl
CH3
CH3CH2CHCH2CHCH3
4-chloro-2-methylhexane
58



Alcohols: R–OH
The –OH makes alcohol polar enough to
hydrogen bonding
Thus, they are water soluble
Ethanol is produced by the fermentation of
glucose
C6H12O6
Glucose
•
yeast
2CH3CH2OH
Ethanol
+ 2 CO2
Methanol is produced industrially by hydrogenation
of carbon monoxide
CO + 2H2O
CH3OH
Methanol
59
Uses of alcohols
Methanol is used to synthesize adhesives, fibers,
plastics and recently as motor fuel
 It is toxic to human and can lead to blindness and
death
 Ethanol can be added to gasoline to form gasohol
and used in industry as solvent
 Commercial production of ethanol:
CH2=CH2 + H2O
CH3CH2OH

60
Classes of alcohols
Alcohols can be classified according to the
number of hydrocarbon fragments bonded to
the carbon where the –OH group is attached
R
CH2OH Primary alchol
R
CHOH Secondary alcohol
R'
R
R' C OH Tertiary alcohol
R"
61
Naming Alcohols

In IUPAC name, the -e in alkane name is
replaced with -ol.
CH4 methane
CH3OH methanol
(methyl alcohol)
CH3CH3 ethane
CH3CH2OH ethanol
(ethyl alcohol)
62
OH
Phenol
(Aromatic alcohol)
63
Some Typical Alcohols
OH
“Rubbing alcohol”
CH3CHCH3
2-propanol (isopropyl alcohol)
Antifreeze HO-CH2-CH2-OH
1,2-ethanediol (ethylene glycol)
64
Naming Alcohols

IUPAC names for longer chains number the chain
from the end nearest the -OH group.
CH3CH2CH2OH
1-propanol
OH
CH3CHCH3
CH3
5
2-propanol
OH
2
CH3CHCH2CH2CHCH3
5-methyl-2-hexanol
65
Example
Name the following alcohols:
OH
CH3CHCHCH2CH3
CH3
3-methyl-2-pentanol
66
Aldehydes and Ketones


In an aldehyde, an H atom is attached to a carbonyl
group
O
carbonyl group

CH3-C-H
In a ketone, two carbon groups are attached to a
carbonyl group
O

CH3-C-CH3
carbonyl group
67
Naming Aldehydes


IUPAC name: Replace the -e in the alkane name by
-al
Common Add aldehyde to the prefixes form (1C),
acet (2C), propion(3), and butry(4C)
O
methane 
H-C-H
methanal
O

ethane
CH3-C-H
ethanal
O
propane

CH3CH2C-H
propanal
(formaldehyde) (acetaldehyde) (propionaldehyde)
68
Aldehydes as Flavorings
O
O
CH
CH
O
CH=CH CH
HO
OCH3
Benzaldehyde
(almonds)
Vanillin
(vanilla beans)
Cinnamaldehyde
(cinnamon)
69
Naming Ketones


IUPAC name: the -e in the alkane name is replaced with –one
and a number to indicate the position of carbonyl group when
needed.
In the common name, add the word ketone
after naming the alkyl groups attached to the
carbonyl group
butane
O

CH3 -C-CH3
2-Propanone
propane O

CH3-C-CH2-CH3
O
cyclohexane
2-Butanone
(Dimethyl ketone) (Ethyl methyl ketone)
Cyclohexanone
Acetone
70
Name the following compounds
O

A. CH3CH2CCH3
B.
O
2-butanone (ethyl methyl ketone)
CH3
O

C. CH3-C-CH2CH
CH3
3,3-dimethylbutanal
cyclohexanone
71
Draw the structural formulas for each of the following
compounds
CH3
O

A. 3-Methylpentanal
CH3CH2CHCH2CH
Br O

B. 2,3-Dibromopropanal
Br-CH2CHCH
O

C. 3-Methyl-2-butanone
CH3CHCCH3
CH3
72
Preparation of aldehydes and Ketones
They are produced by oxidation of alcohols:
CH3CH2OH
Oxidation
CH3C
Primary alcohol
Oxidation
CH3CHCH3
OH
O
acetaldehyde
H
ethanal
CH3CCH3 acetone
propanone
O
Secondary alcohol
73
Carboxylic Acids and Esters
Carboxylic acids contain the carboxyl group as
carbon 1.
O
R

CH3 — C—OH
CH3—COOH
carboxyl group
General formula
R—COOH
74
Nomenclature of Carboxylic Acids
Formula
IUPAC
alkan -oic acid
Common
prefix – ic acid
HCOOH
methanoic acid
formic acid
CH3COOH
ethanoic acid
acetic acid
CH3CH2COOH
propanoic acid
propionic acid
CH3CH2CH2COOH butanoic acid
butyric acid
75
IUPAC nomenclature for Carboxylic acids


Identify longest chain
Number carboxyl carbon as 1
CH3
|
4
1
2
3
CH3 — CH—CH2 —COOH
3-methylbutanoic acid
76
CH3
|
CH3CHCOOH
2-methylpropanoic acid;
77
Reaction of carboxylic acid with alcohol
Esterification
O
CH3C OH
Carboxylic acid
+
H OCH2CH3
Alcohol
O
CH3C OCH2CH3
+
H2O
Ester
78
Esters
In ester, the H in the carboxyl group is replaced with
an alkyl group
O

CH3 — C—O —CH3
CH3—COO —CH3
ester group
•Esters give fruity odors
79
Naming Esters
• The parent alcohol is named first with a –yl
ending
• Change the –oic ending of the parent acid to
–ate
acid
alcohol
O

methyl
CH3 — C—O —CH3
Ethanoate
methyl ethanoate (IUPAC)
(acetate)
methyl acetate (common)
80
Amines
Organic compounds of nitrogen N; derivatives of
ammonia
 Classified as primary, secondary, tertiary
CH3
CH3


CH3—NH2 CH3—NH CH3—N — CH3

Primary
one N-C
bond
Secondary
two N-C
bonds
Tertiary
three N-C
bonds
81
Naming Amines
IUPAC aminoalkane Common alkylamine
CH3CH2NH2
aminoethane
(ethylamine)
NH 2
NH2
|
CH3CHCH3
2-aminopropane
(isopropylamine)
Aniline
82
22.5 Polymers
Poly= many; mers=parts

Polymers are large, usually chainlike
molecules that are built from small
molecules called monomers joined by
covalent bonds
Monomer
Polymer
Ethylene
Polyethylene
Vinyl chloride
Polyvinyl
chloride
Tetrafluoroethylene Teflon
83
Some common synthetic polymers, their
monomers and applications
84
Types of Polymerization
Addition Polymerization: monomers “add
together” to form the polymer, with no other
products. ( Polyethylene and Teflon)
Condensation Polymerization: A small
molecule, such as water, is formed for each
extension of the polymer chain. (Nylon)
85
Addition Polymerization
H
H
C C
H
H
H H
H C C
OH H
A species with
an unpaired
electron such as
hydroxyl free radical
OH
The polymerization process
Is initiated by a free radical
H
H
C C
H
H
H H
H C C
H H H H
H C C C C
OH H H H
Free radical attacks and break
The  bond of ethylene molecule
To form a new free radical
OH H
• Repetition of the process thousands of times creates a long chain
polymer
• The process is terminated when two radicals react to form a bond;
thus there will be no free radical is available for further repetitions.
86
Condensation Polymerization
Formation of Nylon
H
H
O
O
N (CH2)6 N
C (CH2)4 C
H
H
H O
O H
Adipic acid
Hexamethylendiamine
Diamine
H
H
N
Dicarboxylic acid
H O
O
(CH2)6 N C (CH2)4 C
O H
Dimer
+ H2O
• Small molecule such as H2O is formed
from each extension of the polymer chain
• both ends are free to react
87
Nylon
H
(
N
H O
O
(CH2)6 N C (CH2)4 C )n
88