Download Modern Organic Chemistry

Power Point to Accompany
Principles and Applications of
Inorganic, Organic, and Biological
Chemistry
Denniston, Topping, and Caret
4th ed
Chapter 11
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
11-1
Organic Chemistry-History
Historically - compounds from living
systems (plants and animals)
A “vital force”, ie. life was thought to be
necessary to make organic chemicals.
In 1828 Wohler synthesized urea from
purely inorganic chemicals.
Urea, found in urine, was definitely an
organic compound!
O
KCNO + NH4Cl H2N C NH2+ KCl
urea
11-2
Modern Organic Chemistry
The Study of Carbon Compounds
(some exceptions: for example
carbonates, carbon dioxide, etc.)
Biochemistry is now the field that
studies chemicals of life.
11-3
Examples of Organic Chemicals
Foods
Carbohydrates
Fats
Proteins
Clothing
silk, linen, wool,
cotton, Dacron,
Nylon, Orlon,
etc.
Plastics
Pharmaceuticals
Detergents and
Soaps
Pesticides
Gasoline and oils
Water purification
11-4
11.1 Why is Carbon Unique?
1. Forms four covalent bonds
2. Bonds covalently to: H, O, N, P, S, and
all other nonmetals (except noble
gases)
3. Carbon atoms join to form:
H2
a. Chains and b. Rings
C
CH3CH2CH2CH3
H2C
CH2
H2C CH2
11-5
Why is carbon unique?: 2
4. Carbon can form H2C CH2
multiple bonds to
H2C O
itself, oxygen, and
nitrogen.
H2C NH
double bonds
HC CH
HC N
triple bonds
11-6
Why is Carbon Unique?: 3
4. Many carbon compounds exist in the
form of isomers.
Isomers are compounds with the same
molecular formula but different
structures.
An isomer example: A, B, and C all are
C4H10 but have different structures. See
the next slide!
11-7
Why is Carbon Unique?: 3b
Isomer Examples. All C4H8
CH3CH2CH CH2 A
CH3CH CH CH3 B
CH2 CH2
C
CH2 CH2
11-8
Organic vs Inorganic: Differences
Organic
Inorganic
Bonding
Covalent
Ionic
Physical State
(room temp)
Gas/liquid
common
Solids common
Melting points
Tend to be low
Tend to be very
high
Sol. In water
Tend to be
insoluble
Much higher
percent soluble
Conductivity
Nonconductors
Conduct in soln.
and molten
11-9
Families of Compounds: Hydrocarbons
Hydrocarbons contain only carbon and
hydrogen.
They are nonpolar molecules and
consequently are not soluble in water
but are soluble in typical nonpolar
organic solvents like toluene or
pentane.
Hydrocarbons are constructed of chains
or rings of carbon atoms with sufficient
hydrogens to fulfill carbons need for
four bonds.
11-10
Hydrocarbons
Aliphatics
Aromatics
Structures Based On:
Chains and
nonbenzenoid
rings
Benzene ring
11-11
Hydrocarbons
Aliphatics
Aromatics
Alkanes and cycloalkanes
Alkenes and cycloalkenes
Alkynes and cycloalkynes
11-12
Functional groups
CH3 CH3 ethane
Alkanes are
compounds that
CH3 CH2 CH3
contain only
propanecarbon-carbon and burned in a barbecue grill
carbon-hydrogen
CH2 CH2
single bonds.
CH2
For example:
CH2
CH2 CH2
cyclohexane-a ring alkane
11-13
Functional groups-2
alkenes have a
carbon-carbon
double bond
H2C
CH2
ethene: basis of
polyethylene plastics
H
H
C
CH2
alkynes have a
carbon-carbon triple
bond
CH3
CH2
H
CH2
CH2
CH2
CH2
H
C
C
CH2
C
CH2
CH2
CH2
CH2
female silkworm moth
OH sex attractant
HC CH
acetylene-welding gas
in oxyacetylene torch
11-14
Functional groups-3
alcohols have the general
formula:
ROH (R is a carbon
group)
ethers have the general
formulas:
R-O-R, Ar-O-R, Ar-O-Ar
Ar is also a carbon
group but is
“aromatic”
phenols have the general
formula:
Ar-OH (aromatic only!)
CH3CH2 OH
ethanol,
drinking alcohol
CH3 CH2 O CH2 CH3
diethyl ether, a general
anesthetic
OH
aromatic ring
phenol-an early topical
anesthetic
11-15
Functional groups-4
aldehydes have the O
general formula R1 C H
R1 may be H or
any carbon
group
ketones have the O
general formula R1 C R2
aldehyde carbonyl
O
2H C CH CH2OPO3
OH
glyceraldehyde-3-phosphate
from glucose metabolism
ketone carbonyl
O
O
neither R1 nor R2
CH3C CH2 C O
can be H
acetoacetate ion, product
of fat metabolism
11-16
Functional groups-5
acid groups
carboxylic acids have the
O
general formula O
CH2 C OH
R1 C OH HO C CO2H condensed
formula
CH
C
OH
2
R1 may be carbon or H
O
esters have the general
citric acid, found in fruits
O
formula
O
R1 C OR2
R1 may be carbon or H
but R2 cannot be H or
it would be an acid!
ester carbonyl
C O CH
3
OH
methyl salicylate
oil of wintergreen
11-17
Functional groups-6
acid chlorides have the
general formula O
R1 C Cl
R1 is usually carbon
anhydrides have the
general formula
O
O
R1 C O C R2
R1 usually is the
same as R2 and
neither is H
O
O
ClC CH2CH2CH2CH2C Cl
pivaloyl chlorideused to make nylon
O O
CH3C O C CH3
acetic anhydrideused to transfer
an acetyl group
11-18
Functional groups-7
amines have one of these
general formulas
R2
R2
R1 NH2 R1 NH R1 N R3
R groups may be alkyl
or aromatic
amides have the general
O
formula
R2
R1 C N
R3
All Rs may be carbon or
H
Tryptophan- an
essential amino O
acid
CH2 CH C OH
N
O
NH2
amine nitrogens
N C CH3
amide bond
acetaminophen-the
HO analgesic found in
Tylenol (Reg)
11-19
Functional Groups-8
thiols (mercaptans) have
the general formula
R1 SH
R1 is any carbon
group
disulfides have the
general formula
R S S R
R is any carbon
group
Rs may be different
COOH
H C CH2 SH
NH2 cysteine, an
amino acid
cystine-anfound
aminoinacid
important in
3-D structure of proteins.
COOH
COOH
H C CH2 S S CH2 C H
NH2
NH2
11-20
Test: Identify the groups 1-9
1 an amine
2 a carboxylic acid
3 an ester
4 an alkene
5 an aldehyde
6 an alcohol
7 a ketone
8 a thiol
9 an anhydride
O
2.
CH3 CH C
1.
O
OH CH3 C
3.
NH2
4.
CH2 CH CH CH2
CH3
7. C
CH2
8.
CH2 SH
O
CH3 C
CH3
O
H C
CH
HO CH
CH
HO CH
CH2
OH
O
CH2
5.
O
9.
O
O
C CH3
OH
6.
OH
11-21
11.2 Alkanes, CnH2n+2
The title shows the general formula for a
chain alkane.
The first ten alkanes are:
methane CH4
hexane C6H12
ethane
heptane C7H16
C2H6
propane C3H8
octane
butane
nonane C9H20
decane C10 H22
C4H10
pentane C5H12
C8H18
11-22
Lewis vs Condensed Formulas
The Lewis dot
and condensed
H
H C H CH4
formulas for
H
methane.
The Lewis dot
HH
and condensed H C C H CH3 CH3
HH
formulas for
ethane .
11-23
Drawing Methane and Ethane
H
C
H
in plane
H
behind plane
H
H in front of plane
H
H
H
C
H
109.5 o
H
Staggered form of ethane
11-24
Lewis vs Condensed Formulas-2
Lewis dot vs condensed formulas: propane.
Terminal carbons condense to CH3 with the
hydrogens usually to the right of the carbon.
Interior carbons condense to CH2 .
H H H
H C C C H CH3CH2CH3
H H H
11-25
Lewis vs Condensed Formulas-3
A branch or substituent on a chain may
be condensed into the chain usually
after the carbon from which it branches.
H
HCH
H
H H H
H C C C C C H
H H Cl H H
CH3CH(CH3)CHClCH2CH3
11-26
IUPAC Names
The IUPAC (International Union of Pure
and Applied Chemistry) is
responsible for chemistry names.
Before learning the IUPAC rules for
naming alkanes, the names and
structures of eight alkyl groups must
be learned.
These alkyl groups are historical names
accepted by the IUPAC and integrated
into modern nomenclature.
11-27
Alkyl Groups
H
H C H
H
H
H C or CH3
H
An alkyl group is an alkane with one
hydrogen atom removed. It is named by
replacing the ane of the alkane name
with -yl.
Methane becomes a methyl group.
11-28
Alkyl Groups-2
All six hydrogens on ethane are
equivalent. Removing one H
generates the ethyl group.
HH
HCCH
HH
CH3 CH2
CH2 CH3
C2H5
11-29
Alkyl Groups-3
Propane: removal of a hydrogen generates
two different propyl groups depending on
whether an end or center H is removed.
CH3 CH2 CH3
CH3CH2CH2
n-propyl
CH3CH CH3
isopropyl
11-30
Alkyl Groups-4a
n-butane gives two butyl groups
depending on whether an end (1o)
or interior (2o) H is removed.
CH3 CH2 CH2 CH3
CH3 CH2 CH2 CH2 CH3 CH CH2 CH3
n-butyl
sec-butyl
11-31
Alkyl Groups-4b
Isobutane gives two butyl groups
0
0
depending on whether a 1 or 3 H
is removed.
CH
3
CH3 CH CH3
CH3 1 C
CH3 CH CH2
o
isobutyl
CH3
CH3 C CH3
3o C
t-butyl
11-32
IUPAC Names for Alkanes-1
1. The base or parent name for an
alkane is determined by the longest
chain of carbon atoms in the formula.
Note: the longest chain may bend and
twist. It is seldom horizontal!
Any carbon groups not part of the
base chain are called branches or
substituents.
These carbon groups are also called
alkyl groups.
11-33
IUPAC Names for Alkanes-1a
Rules 1 applied. Find the longest chain
in each molecule. (Click for answer.)
A=7
B=8
CH
3
A
CH2CH2CH CH2CH3
B CH3
CH2
CH3CH2CH2
CH2
CH3
CH3CH2CH CH2CH CH3
11-34
IUPAC Names for Alkanes-2
2. Number the carbon atoms in the chain
starting from the end with the first
branch. If both branches are equally
from the ends, continue until a point of
difference occurs.
11-35
IUPAC Names for Alkanes-2a
Number the carbon atoms correctly.
Left: first branch is on carbon 3.
Right: first branch is on carbon 3 (From
top) not carbon 4 (If from right).
1
4
CH3
2
CH3
CH2
6
7 CH3
8
CH2CH2CH3
5 CH2CH2CH CH2CH3 CH3CH CH2CH
3
2
1
3
4
5
6 CH
2
7
CH2CH3
this branch would be on C-4
if you started at correct C-8.
11-36
IUPAC Names for Alkanes-3
3. Prefix the branches/substituents
in alphabetical order before the
base/stem name (longest chain).
Halogens usually come first.
Indicate the position of the branch
on the main chain by prefixing its
name with the carbon number to
which it is attached. Separate
numbers and letters with a
hyphen.
11-37
IUPAC Names for Alkanes-3a
CH
3
Name
CH2
CH3
CH3 CH2 CH CH2 CH CH3
4-ethyl-2-methylhexane
11-38
IUPAC Names for Alkanes-3b
Hyphenated and number prefixes are not
considered when alphabetizing groups.
Name the compound below.
5-sec-butyl-4-isopropylnonane
CH3
CH3
CH CH2 CH3
CH CH CH CH2 CH2 CH2 CH3
CH2 CH2 CH3
CH3
11-39
IUPAC Names for Alkanes-4
When a branch/substituent occurs more
than once, prefix the name with di, tri,
tetra,etc. Then prefix the number to
the name with a separate number for
each occurance. Separate numbers
with commas.
eg. 3,4-dimethyl or 4,4,6-triethyl
11-40
IUPAC Names for Alkanes-4a
Name
CH3
CH2CH3
CH3CH CH CH2CH CH2CH3
CH3
5-ethyl-2,3-dimethylheptane
ethyl>dimethyl
11-41
Test: IUPAC Names
Name
CH3 CH3CH CH3
CH2
CH2
CH3C CH2CH2C CH2CH3
CH3
CH2CH2CH2CH3
6-ethyl-6-isobutyl-3,3-dimethyldecane
11-42
Constitutional/Structural Isomers
Constitutional/Structural Isomers differ
in how atoms are connected. The two
isomers of butane are shown below.
The carbon atoms are connected in
different patterns.
CH
3
CH3 CH2 CH2 CH3 CH3 CH CH3
butane
Bp –0.4 oC
Mp –139 oC
Isobutane
Bp –12 oC
Mp –145 oC
11-43
11.3 Cycloalkanes
Cycloalkanes have two less hydrogens than
the corresponding chain alkane.
Hexane=C6H14; cyclohexane=C6H12
To name cycloalkanes, prefix cyclo to the
name of the corresponding alkane.
Place substituents in alphabetical order
before the base name as for alkanes.
For multiple substituents, use the lowest
possible set of numbers. A single
substituent requires no number.
11-44
Cycloalkanes-cont.
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
C
H
H
or
Cyclopropane
H
C
H
H
C
H H
C
H
or
Cl
C
H
H
C
H
H
C
H
Cl
H
C
CH3
H
C
H H
C
H
CH3
1-chloro-3cyclohexane methylcyclohexane11-45
Cis-trans Isomers in Cycloalkanes
Two groups may be on the same side (cis) of
the imagined plane of the cycloring or they
may be on the opposite side (trans). The
two isomers are referred to geometric or cistrans isomers. E. g.
Cl
CH3
Cl
cis-1-chloro-3-ethylcyclohexane
trans-1-chloro-3-ethylcyclohexane
CH3
Cl
Cl Cl
cis-1,4-dichlorolcyclohexane
trans-1,4-dichlorocyclohexane
Cl
11-46
11.4 Conformations of Alkanes
Conformations differ only in rotation about
carbon-carbon single bonds. Two
conformations of butane are shown below.
The first (staggered form) is more stable
because it allows hydrogens to be farther
apart and thus the atoms are less crowded.
Insert Fig 11.6
11-47
Two conformations of Cyclohexane
Chair form
Boat form
(more stable) E=equitorial
A A=axial
H
H
A
H
H
H
H
E A E
E
A
E
H H
E
E
H H
A
A
H
H
11-48
11.5 Reactions of Alkanes
All alkanes undergo:
Combustion to carbon dioxide and water
Halogenation to haloalkanes
2 C2H6 + 7 O2
CH3CH3 + Cl2
H
H + Br2
4 CO2 + 6 H2O
heat or
light
heat or
light
CH3CH2Cl +HCl
Br
H
+HBr
11-49
The End
Organic Introduction
Saturated Hydrocarbons
11-50