Transcript functional groups 2. PPT

Functional Groups:
- Aldehydes
- Ketones
- Organic Acids
- Esters
- Amines
- Amides
Aldehydes
Group is always on a terminal C – no need to specify
location by number
Condensed it is symbolized by a -CHO group at the
end of the formula
C = O is known as a carbonyl group
– Drives the physical and chemical properties of these
compounds
Aldehydes have characteristic scents and tastes
– Cinnamon is an example
Aldehydes
Drop the –e from the end of the
alkane and add –al; C=O is C #1
Name these two compounds:
Methanal
(formaldehyde)
Butanal
Ketones
Like the aldehydes the Functional group is the
carbonyl group C=O
Contains an alkyl group on either side of the C=O
– In aldehydes one side is an alkyl group the other is H
Often used as a solvent
– Acetone is one example
Naming Ketones
Number the C chain so C=O has the lowest #
Drop the final e from the alkane name and add -one
Name these compounds:
4-methyl-2-pentanone
C
3-hexanone
C-C-C-C-C
o
Properties
Both aldehydes & ketones have
A carbonyl functional group.
C=O is polar & their compounds
Are polar. This leads to:
-Higher B.P’s than non-polar molecules
-Lower than alcohols that can
H-bond w/ each other
-Can not H-bond between each other
but can H-bond to solvents like water
- Lower MW compounds
are appreciably soluble in water
Propanone
Propanal
Properties
Butane
Diethyl
ether
Propanal
Propanone 1-propanol
M.W.
58
58
58
58
60
B.P (deg.C)
0
35
49
56
97
Solubility
g/100g H2O
Insol.
8
16
Fully
miscible
Fully
miscible
Organic Acids
Condensed form is written –COOH
– A carbonyl group and a hydroxyl group bonded to C
– Known as a carboxyl group
A terminal functional group
The carboxyl group is an organic acid.
– It is the H on the end of COOH that is donated as a
proton (H+)
– What is left is the anion R-COO-
Carboxylic acids ionize in water to form a proton and
A carboxylate anion
Naming Organic Acids
The carboxyl group is a terminal group
– no need to give it a number. It’s always on C #1
Drop the –e from the alkane name and add –oic
acid
Name this compound:
Butanoic acid
Naming Organic Acids
Name this compound:
Butanoic acid
Name this compound:
C-C-C-C-C-COOH
C C
2,4-dimethylhexanoic acid
Some Common Carboxylic acids
HC=O
OH
CH3C=O
OH
Methanoic acid
“formic acid”
Ethanoic Acid
“Acetic Acid”
The sting of ants
Vinegar
C-C-C-COOH
Butanoic acid
Rancid butter smell
Physical properties
- Sharp or noxious smells
- polar and can form 2 hydrogen bonds with
themselves and with water
C-C=O
OH
HO
O=C- C
C-C=O
OH
O
H
H
This leads to high B.P. and high solubility in water
- 1st four acids are totally miscible in water
Comparison of properties
Butane Diethyl
ether
Propanal
Propanone
1-propanol ethanoic
M.W.
58
58
58
58
60
60
B.P
(deg.C)
0
35
49
56
97
118
Insol.
8
16
Fully
miscible
Fully
miscible
Fully
miscible
Solubility
g/100g
H 2O
Esters
Esters are derivatives of Carboxylic acids
– Combination of an Alcohol and an Acid
– The alcohol provides the alkyl portion of the ester name
– Esters are polar but can not form hydrogen bonds with
one another
– BP’s of esters are lower than alcohols or acids with
similar mass
Physical properties
Butanal
Butanone
Methyl
1-butanol
ethanoate
Propanoic
Acid
M.W.
72
72
74
74
74
B.P (deg.C)
76
80
57.5
118
141
Properties
Esters have distinctive odors (flowers, flavors etc.)
- Function of which alcohol is combined with which acid
Alcohol
Acid
Ester
Fragrance
Ethanol
Butanoic acid
Ethyl butanoate
Pineapple
Pentanol
Ethanoic acid
Pentyl ethanoate
Banana
Octanol
Ethanoic acid
Octyl ethanoate
Orange
Methanol
Salicylic acid
Methyl salicylate
wintergreen
Methanol
Butanoic acid
Methyl butanoate
apple
Naming Esters
Esters are not a terminal group but they are
unique because of the carboxyl group therefore
the carbonyl carbon is considered to be C #1
Name the group attached to the hydroxyl oxygen
first (the alkyl group)
Next name the carboxylate carbon chain,
dropping the –e and adding –oate
Written condensed format is RCOOR’
Name this compound:
Ethyl butanoate
Name this compound:
O
CH3-C-O-CH2-CH2-CH-CH3
CH3
3-methylbutyl ethanoate
(Not IUPAC)
2-methylbutyl ethanoate
What alcohols and acids produce the above esters?
(Not IUPAC)
Amide
Like esters the amide functional group is a
derivative of carboxylic acids
– OH replaced by the amine group
The amide group is a terminal group
Important biological molecules
– Links amino acids together to form proteins
Amide Physical Properties
-Amides have very high BP’s due to strong
intermolecular hydrogen bonding
- higher than similar esters and acids
- H-bonding can occur between N, H and O
CH3 – C=O
NH2
B.P. (deg. C)
CH3COOCH3
CH3COOH
CH3COONH2
57.5
118
221
Amide
Take the name of the alkane with the same number of
carbon atoms
Drop the –e from the alkane name and add –amide
Amide carbon is carbon #1 when naming side chaines
Ethanamide
Name this compound:
C-C-C=O
C NH2
2-methylpropanamide
Amines
Nitrogen is the functional part of an amine
Nitrogen can form three bonds (just like NH3)
– One must be to the carbon chain
– The other two bonds can be to Carbon and/or H2
C-C-NH2 or C-C-N-H or
C
Secondary
Primary
Amine
Amine
C-C-N-C
C
Tertiary
Amine
Physical properties of Amines
Like ammonia, amines are polar compounds
H can also be Carbon
Based groups
And like ammonia, amines are Bronsted-Lowery
Bases
- both are Proton acceptors
H
H+
:N-H
H
Physical properties of Amines
- Since amines can act as proton acceptors reaction
With a proton donor like HCl will lead to a salt,
i.e. an ionic compound
H
HCl + :N-H
H
H
Cl- H :N-H+
H
Physical Properties of Amines
Amines can hydrogen bond like alcohols or
Carboxylic acids
- Contains N and H
- H-bonding raises the B.P. but it is not as
high as the alcohols or acids
H
C-C-N
H
H
N-C-C
H
Ethanoic
acid
B.P. (deg
C)
118
Ethanol
78
Ethyl
amine
17
Tertiary amines have higher BP’s than secondary and secondary
is higher than primary
Physical properties of Amines
-Amines can H-bond with water
-Leads to high water solubility up to about 6C
Sol
(g/100g H20)
Methyl
Amine
Ethyl
Amine
Propyl
Amine
Butyl
Amine
v. Sol
Totally
miscible
Totally
Miscible
v. sol
-Amines have very strong odors
- Methyl and ethyl amine smells like ammonia
-Higher MW amines often have a fishy smell
-Aromatic amines are generally toxic
-Readily absorbed through skin often with fatal results
Amines
Need #’s to designate the location of the amine
Name your carbon chain as an alkane, drop the –
e and add –amine
If there are 2 amines indicate their location and
add –diamine to the alkane name
2-butanamine
Name this compound:
C-C-C-C-C-C
N
N
1,3-hexadiamine
Amino Acids
Related to amines are the Amino Acids
If you have a “N” and a COOH it is an amino acid
GLYCINE
Since the amino group is a proton acceptor and the
Carboxylic acid is a proton donor amino acids are
Actually NH3+ and COO-.