Download Functional Groups

Organic Structure
• Among neutral (uncharged) organic compounds
–
–
–
–
–
carbon: four covalent bonds and no unshared pairs of electrons
hydrogen: one covalent bond and no unshared pairs of electrons
nitrogen: three covalent bonds and one unshared pair of electrons
oxygen: two covalent bonds and two unshared pairs of electrons
a halogen: one covalent bond and three unshared pairs of electrons
Models
• Draw a lewis structure, make the model, draw ther 3-D
structure, and decribe the bond angles for the following:
• C2H6
• C2H4
• C2H2
• C2H5Cl
• C2H4O
• CH2O
• CH5N
Alcohols
• Alcohol: contains an OH (hydroxyl) group
bonded to a tetrahedral carbon atom
:
R
R-C-O-H
R
Function al group
(R = H or carbon
goup
:
HH
H-C-C-O-H
HH
S tructural
formula
CH3 CH2 OH
Cond ensed
stru ctural
formu la
– may be primary (1°), secondary (2°), or tertiary
(3°)
H
CH3 -C-OH
H
A 1° alcohol
H
CH3 -C-OH
CH3
CH3 -C-OH
CH3
A 2° alcohol
CH3
A 3° alcoh ol
Alcohols
• Problem: Draw Lewis structures, make the
model, and describe the geometry and
polarity for the two alcohols of molecular
formula C3H8O
Alcohols
• Problem: draw Lewis structures and condensed structural
formulas for the two alcohols of molecular formula C3H8O
• Solution:
: :
Lew is stuctu res
HH H
H-C-C-C-O-H
HH H
Cond ensed stru ctural
formulas
CH3 CH2 CH2 OH
A p rimary alcohol
H
H:O: H
OH
H C-C-C-H
HH H
CH3 CHCH3
A secon dary alcohol
Amines
• Amine: a compound containing an amino
group
– the amino group may be primary (1°), secondary
(2°), or tertiary (3°)
CH3 NH2
CH3 NH or (CH3 ) 2 NH
Methylamin e
(a 1° amine)
CH3
D imethylamin e
(a 2° amine)
CH3 NCH3 or (CH3 ) 3 N
CH3
Trimethylamin e
(a 3° amine)
Amines
– Problem: Draw Lewis structures, make the model,
and describe the geometry and polarity for the
two primary amines of molecular formula C3H9N
Amines
– Problem: draw condensed structural formulas for
the two primary amines of molecular formula
C3H9N
– Solution:
NH2
C-C-C-NH2
C-C-C
Th e three carbon s may
be bond ed to n itrogen
in tw o w ays
CH3 CH2 CH2 NH2
NH2
CH3 CHCH3
Add s even hydrogens to give each
carbon four b on ds an d give the
correct molecu lar formula
Aldehydes and Ketones
• Both contain a C=O (carbonyl) group
– aldehyde: contains a carbonyl group bonded to a hydrogen; in
formaldehyde, the simplest aldehyde, the carbonyl group is bonded to
two hydrogens
– ketone: contains a carbonyl group bonded to two carbon atoms
RO
R C-C-H
O
CH3 CH
R
Fun ctional A cetaldeh yde
grou p
(an aldehyde)
RO R
O
R C-C-C R CH3 CCH3
R R
Functional
group
Acetone
(a ketone)
Aldehydes and Ketones
– Problem: Draw Lewis structures, make the model,
and describe the geometry and polarity for the
two aldehydes of molecular formula C4H8O
Aldehydes and Ketones
– Problem: draw condensed structural formulas
for the two aldehydes of molecular formula
C4H8O
• Solution:
O
CH3 CH2 CH2 CH
or
CH3 CH2 CH2 CHO
O
CH3 CHCH
CH3
or
CH3 CHCHO
CH3
Carboxylic Acids
• Carboxylic acid: a compound containing a
-COOH (carboxyl: carbonyl + hydroxyl)
group
• in a condensed structural formula, a carboxyl
group may also be written -CO2H.
O
O
CH3 COH
RCOH
Fu nctional
Acetic acid
group
(a carb oxylic acid )
Carboxylic Acids
– Problem: Draw Lewis structures, make the model,
and describe the geometry and polarity for the
single carboxylic acid of molecular formula
C3H6O2
Carboxylic Acids
– Problem: draw a condensed structural formula
for the single carboxylic acid of molecular
formula C3H6O2
• Solution: the only way the carbon atoms can
be written is three in a chain; the -COOH
group must be on an end carbon of the chain
O
CH3 CH2 COH or CH3 CH2 COOH