Download Organic Compounds

Carbon and Organic
Compounds
Organic vs. Inorganic
• Organic compounds contain carbon that
is covalently bonded to non-metals
The position of carbon in the periodic table.
Carbon’s Key Properties
• Has a mid-range electronegativity value
so it forms covalent bonds and shares
electrons
• Can form a maximum of four bonds
• Can form chains, sheets, and rings
• Usually combined with H and often
bonds with O, S, N and P
Hybridization
HYDROCARBONS
Carbon Skeletons and Hydrogen Skins
Each C can form a maximum of four single bonds, OR two
single and one double bond, OR one single and triple bond.
The arrangement of C atoms determines the skeleton, so a
straight chain and a bent chain represent the same
skeleton.
Groups joined by single bonds can rotate, so a branch
pointing down is the same as one pointing up.
Isomers
• When two compounds have the same
chemical formula but different
structural formulas they are called
isomers.
• There are many kinds of isomers
depending on where the carbons are
placed and how bonds are arranged.
Structural (Constitutional) Isomers
• Same formula, different arrangement of the bonds
• CAREFUL– rotation of the bond does not make an
isomer!
Stereoisomers
• Differ in SPATIAL orientation
– Geometric
– Enantiomers
– Diasteromers
Geometric
Isomers
Enantiomers
• Not superimposable
• S(+)-carvone =
caraway
• S(-)-carvone = mint
An analogy for optical isomers.
Diastereomers
Hydrocarbons (CnH2n+2)
Physical Properties
Polarity of
functional
group
 The
C-H bond is non-polar so most hydrocarbons are
non-polar
 The addition of halides results in polar regions.
 The predominant intermolecular force in dispersion forces
Hydrogen
bonding
 None
Solubility in
Water
 Very
Melting &
Boiling
Points
 The
poor solubility in water due to the lack of polar and
hydrogen bonds
melting and boiling points tend to be very low
 The boiling points increase as the length of the parent
chain increases
C’s  gases @ SATP
5-20 C’s  liquids (some very viscous) @SATP
20 + C’s  solids @ SATP
1-5
Hydrocarbons (CnH2n+2)
Additional Characteristics
• As the number of carbons in the parent
chain increase:
– The state of matter at STAP moves from gas to
liquid to solid
– The melting and boiling points increase
– The density increases
• Popular fuel source (Methane, propane,
octane, etc.)
• Source for plastics
Boiling points of the first 10 unbranched alkanes.
Comparison of Properties of Organic
and Inorganic Compounds
Property
Solubility in inorganic
solvent (water)
Solubility in organic
solvent (toluene)
Conductivity
Flammability
Volatility
Melting Point
Boiling Point
Organic
Inorganic
Comparison of Properties of Organic
and Inorganic Compounds
Property
Organic
Inorganic
Solubility in inorganic
solvent (water)
Generally not soluble
soluble
Solubility in organic
solvent (toluene)
Generally soluble
Not soluble
Conductivity
Non-conductive
conductive
Flammability
Generally flammable
Not flammable
Volatility
More volatile
Not volatile
Melting Point
Low
High
Boiling Point
Low
High
Ways of depicting formulas and models of an alkane.
Depicting cycloalkanes.
H
H
C
H C
H
C H
H
H C
C H
H C
C H
H
H
cyclobutane
cyclopropane
H
H
Alcohols (R-OH)
Physical Properties
Polarity of
functional
group
 OH
is very polar
 As the parent chain grows, its non-polar nature become
more influential
 Small alcohols are more polar than larger ones
Hydrogen
bonding
 Alcohols
Solubility in
Water
 The
Melting &
Boiling
Points
 Due
experience hydrogen bonding with other
alcohols and water
capacity to form hydrogen bonds make alcohols
extremely soluble in water.
 The solubility decreases as the number of carbons
increase
to the strength of hydrogen bonds most alcohols
have higher melting & boiling points than similar alkanes.
 Most alcohols are liquids at SATP
Some molecules with the alcohol functional group.
Alcohols
Additional Characteristics
• Alcohols are extremely flammable
• Most alcohols are poisonous
– Methanol can cause blindness or death.
– Ethanol is consumed in moderate quantities. Excessive
consumption may cause blindness or death.
– Yeast ferment sugars to produce ethanol and carbon
dioxide
• Antifreeze, cosmetics, foods, medical preparations,
solvents, antiseptics, etc.
• Biological compounds – cholesterol, retinol, etc.
Ethers (R-O-R2)
Physical Properties
Polarity of
functional group
 The
C-O bond is less polar than the O-H
 Ethers are less polar than alcohols
 The bent shape around the O aids in the dipoledipole force strength
Hydrogen
bonding
 There
Solubility in
Water
 Ethers
Melting & Boiling
Points
 Much
is no hydrogen bonding in ethers
 Ethers can accept hydrogen bonds from water
are usually soluble in water
 The solubility decreases as the size of the alkyl
groups grows
lower than comparable alcohols
 Higher than similar hydrocarbons
Ethers
Additional Characteristics
• Ethers are extremely flammable
• Have been used as anaesthetics
– “ether” – ethoxyethane
– More recent anaesthetic
(1-methoxypropane) has fewer side effects.
Amines (R-NH2)
Physical Properties
Polarity of
functional
group
 C-N
and N-H bonds are polar
 Amines are usually polar
Hydrogen
bonding
 The
Solubility in
Water
 Low
Melting &
Boiling
Points
 The
presence of one or more N-H bonds allows hydrogen
bonding
molecular weight amines are soluble in water (<4 C)
 The solubility decreases as the number of carbons
increase
boiling points of primary and secondary amines (N-H
bonds present) are greater than tertiary amines (no N-H
bonds)
Amines
Additional Characteristics
• Widely found in nature. They are often
toxic. Many medical applications.
• Low molecular weight amines have a “fishy”
smell while others are responsible for
odours associated with decay.
• Amines act as weak bases. Adding an acid
produces a salt. So, add lemon to fish to
remove fishy odour.
Aldehydes (R-COH) & Ketones
Physical Properties
Polarity of
functional
group
 C=O
is polar
Hydrogen
bonding
 No
Solubility in
Water
 Low
Melting &
Boiling
Points
 Lower
O-H bonds so no hydrogen bonding between
aldehydes and ketones
 The O atom can accept hydrogen bonds from water
molecular weight aldehydes and ketones have high
solubility
 The solubility decreases as the number of carbons
increase
than comparable alcohols
 Higher than corresponding alkanes
Some common aldehydes and ketones.
methanal
(formaldehyde)
used to make
resins in plywood,
dishware,
countertops;
biological
preservative
ethanal
(acetaldehyde)
narcotic product of
ethanol
metabolism; used
to make perfume,
flavors, plastics,
other chemicals
benzaldehyde
artificial almond
flavoring
2-butanone
2-propanone
(methyl ethyl
(acetone) solvent for
fat, rubber, plastic, ketone) important
solvent
varnish, lacquer;
chemical feedstock
Aldehydes & Ketones
Additional Characteristics
• Aldehydes have a strong pungent odour while ketones
smell sweet. As the size of the aldehyde increases the
odour becomes more pleasant (i.e. cinnamon)
– Odours in nature may be used to communicate between insects pheromones
• Since they are polar, they are used as polar solvents. The
non-polar alkyl chain permits their use as non-polar
solvents too.
• Antiseptics, disinfectants (Formaldehyde), resins, dyes,
preservatives (Aldehyde)
• Hormones in biology – testosterone, progesterone,
cortisone
• Solvents, medication
Carboxylic acids (R-COOH)
Physical Properties
Polarity of
functional
group
 Polar
due to C=O and O-H bonds
Hydrogen
bonding
 Strong
Solubility in
Water
 Low
Melting &
Boiling
Points
 The
hydrogen bonding
molecular masses are very soluble (<4C – miscible
in water)
 The solubility decreases as the number of C’s increase
melting and boiling points for carboxylic acids are
very high due to the hydrogen bonding.
 Higher than corresponding alcohols
Some molecules with the carboxylic acid functional group.
methanoic acid
(formic acid)
an irritating
component of ant
and bee stings
benzoic acid
calorimetric
standard; used in
preserving food,
dyeing fabric, curing
tobacco
butanoic acid
(butyric acid)
odor of rancid butter;
suspected component
of monkey sex
attractant
octadecanoic acid
(stearic acid)
found in animal fats;
used in making candles
and soap
Carboxylic acids
Additional Characteristics
• Carboxylic acids often have unpleasant odours
– butanoic acid smells like stale sweat
• Sour taste in many foods & plants – vinegar, spoiled wine,
rhubarb, citrus fruits
• By-product of anaerobic respiration in muscles – lactic acid
• Industrial processes – dyes, tanning, rubber recycling, etc.
• Food preservatives, Vitamin C, ASA
• The OH does not behave like a base. The two O’s have high
electronegativities and carry the H’s electron allowing the H
ion to dissociate.
Boiling & Melting Points
Alcohol
Alkane
CH3CH2CH2CH2OH
0
CH3CH2CCH3
0
=
Aldehyde
CH3CH2CH2COH
=
Ketone
=
Carboxylic acid
0
CH3CH2CH2CH
CH3CH2CH2CH3
b.p. 165.5 oC
m.p. -4.5 oC
High
b.p. 117.2 oC
m.p. -89.5 oC
b.p. 79.6 oC
m.p. -86.3 oC
b.p. 75.7 oC
m.p. -99 oC
b.p. -0.5 oC
m.p. -138.4 oC
Low
Esters (R-COO-R2)
Physical Properties
Polarity of
functional
group
 Usually
polar due to C=O and C-O bonds
 Polarity is reduced with increased number of C atoms
Hydrogen
bonding
 No
Solubility in
Water
 The
Melting &
Boiling
Points
 The
O-H bonds, there fore they don’t form hydrogen bonds
with other esters
C=O bond can accept hydrogen bonds from water,
therefore low molecular mass esters are soluble
 Esters with chains greater than 3 or 4 are not soluble
melting and boiling points for esters are low due to
the lack of hydrogen bonding.
 They are usually volatile liquids at SATP
Some lipid molecules with the ester functional group.
cetyl palmitate
the most common
lipid in whale
blubber
lecithin
phospholipid found in all cell membranes
tristearin
typical dietary fat used as an
energy store in animals
Esters
Additional Characteristics
• Esters often have pleasant odours
– Low molecular mass esters have very pleasant
odours and are used in soaps, perfumes,
cosmetics, air fresheners, etc.
– Natural esters are responsible for the scents in
flowers & fruits. (Pg 64 Table 2)
• Food – lipids and dietary fats are esters
(triglycerides)
Amides (R-CONHR2)
Physical Properties
Polarity of
functional
group
 Polar
due to C=O,C-N and N-H bonds
 Similar physical properties to carboxylic acids
Hydrogen
bonding
 Since
Solubility in
Water
 Amides
Melting &
Boiling
Points
 Primary
primary amides have two N-H bonds they have
stronger hydrogen bonding than carboxylic acids
 Secondary amides also experience hydrogen bonding
are soluble in water
 The solubility decreases as the non-polar alkyl chain
increases in size
amides have much higher melting and boiling
points than carboxylic acids
 Many primary amides are solids at SATP
Amides
Additional Characteristics
• Amides such as acetaminophen are analgesics
(pain killers)
• Urea is a common amide found in urine and
fertilizers
Polymers
• Long chain molecules made of small
repeating units
• Can be made by addition reactions
(adding molecules) or condensation
(splitting something out and joining the
pieces.
• Building polymers….
Crosslinking
• Some polymers make bridges across
chains rather than just adding to chains.
These are “cross-linked” polymers.
• Some cross-links are covalent bonds and
are permanent. Some links are made
with intermolecular forces and can be
broken more easily (like the alginate
worms).
Making Slime
PVA (poly vinyl alcohol)
glue molecule
Borax molecule
PVA (poly vinyl alcohol)
glue molecule