Alcohols, Phenols

1
Alcohols, Phenols Ethers

• Alcohol Structure and Properties
• Alcohol Nomenclature
• Classification of Alcohols
• Reactions of Alcohols
• Phenols
• Ethers
• Thiols

2
Alcohols and phenols

• Alcohols
• When a Hydrogen on a carbon is replaced by an
  OH- (hydroxyl group), the molcule becomes an
  alcohol.
• R - OH
• Phenols
• A hydroxyl group bound to an aryl (benzene)
  group.
• Ar - OH

3

• Both can be viewed as a substituted water
• There are 3 types of alcohols
• primary 1o
• secondary 2 o
• tertiary 3o

O
O
O
H
H
H
R
H
Ar
4
Classification of alcohols

• Based on what's bound to the C-OH group.

H
H
H-C-H
Methyl
Primary, 1o
R-C-H
OH
OH
H
R
Tertiary, 3o
R-C-R
Secondary, 2o
R-C-R
OH
OH
5

• Primary (1?) Alcohol The OH is attached to a
  primary carbon.
• CH3CH2OH Ethanol or Ethyl alcohol
• CH3
• CH3CHCH2CH2OH 3-methyl-1-butanol or
• isopentyl alcohol

6

• Secondary (2?) Alcohols The OH is attached to a
  secondary carbon.
• CH3CHCH3 2-propanol or
• OH isopropyl alcohol
• CH3CH2CHCH3 2-butanol
• OH

sometimes called sec-butyl alcohol
7

• Tertiary (3?) Alcohols The OH is attached to a
  tertiary carbon.
• 2-methyl-2-propanol or t-butyl alcohol

C
H
3
C
H
C
C
H
3
3
O
H
8
Naming alcoholsThe IUPAC System

• Find the longest chain containing OH.
• Drop -e fromname of alkane and replace with -ol.
• Number chain so it contains the hydroxyl group
  with the lowest number.
• Indicate position on parent chain of the hydroxyl
  group.
• Name and number any side chains or other groups.

9
Example
C - C - C - C - O - H
Base contains 4 carbon - alkane name is
butane - remove -e and add -ol alcohol name -
butanol OH is on the first carbon so
- 1-butanol
10
Examples

• C-C-C-C-C-OH
• \______ 1-pentanol
• C-C-C-C-C-C-C-C
• OH C
• \____
  6-methyl-2-octanol
• C-C-C-C-C-Cl
• OH C
• \________ 5-chloro-3-hexanol

11
More examples
C - C - C - C - C - C - Cl
C C - OH C
12
More examples
C - C - C - C - C - C - Cl
C C - OH C
4-(2-chloroethyl)-2-heptanol
13
More examples
14
More examples
4-methylcyclohexanol
15
Naming alcohols

• When an alcohol contain 2 or 3 OH groups
• Use name of alkane with modified ending.
• numbers indicate the position of each OH.
• OH ending Example
• 2 diol 1,2-ethanediol
• (antifreeze)
• 3 triol 1,2,3-propanetriol
• (glycerol)

16
Common names

• For the simplest alcohols, common names are
  often used.
• Name carbon chain with a -yl ending
• Add the name alcohol to the end
• IUPAC Name Common Name
• methanol methyl alcohol
• ethanol ethyl alcohol
• 2-propanol isopropyl alcohol
• 2-methyl-2-propanol tert-butyl alcohol

17
Physical Propertiesof the Alcohols

• The hydroxyl group (OH) on the carbon chain
  creates a polar area in the molecule.
• ? ? -
• -C - O
• ?
• H
• The oxygen forms polar bonds with both the
  carbon and the hydrogen.

18
Solubility of alcohols
-C - O

• This part of the molecule has water - like
  properties
• Alcohols are capable of hydrogen bonding with
  other alcohols or with water.

H
R
O
R
O
H
H
O
H
H
R
O
H
O
R
O
H
H
R
19

• Solubility
• Alcohols have higher boiling and melting points
  than similar hydrocarbons. Alcohols can be
  soluble in water.
• Size Solubility in water
• C1 - C4 Highly soluble
• C5 - C7 Moderately soluble
• C8 and above Slightly soluble/insoluble

20
Melting and boiling points

• Higher than for other classes covered so far.
• Name Formula MP
  BP
• methanol CH3OH -97 65
• ethanol CH3CH2OH -224 78
• 1-propanol CH3CH2CH2OH -126 97
• 1-butanol CH3(CH2)2CH2OH -90 118
• 1-hexanol CH3(CH2)4CH2OH -52 158
• 1-octanol CH3(CH2)6CH2OH -16 194

21
Important alcohols
CH3OH

• methanol
• Synonyms Methyl alcohol, wood alcohol
• Uses Common solvent. Used in
  perfumes, other smelly stuff.
• Important industrial starting
  material.
• Toxicity Most poisonous of the
  alcohols. Can cause blindness and death.
• Other Colorless, odorless, liquid.

22

• WHY IS METHANOL SO TOXIC??
• Humans and other primates have liver enzymes
  that oxidize primary alcohols to compounds called
  aldehydes.
• Example Ethanol is oxidized to acetaldehyde

H
liver
C
O
C
H
C
H
O
H
3
2
CH3
23

• This acetaldehyde is in turn oxidized to acetic
  acid, a normal constituent of cells. Acetic acid
  can be further oxidized to CO2 and water.

O
O
O
C
O
C
H
C
C
H
C
2
3
3
O
H
H
24

• Similarly, our liver enzymes attack methanol
  when it enters our system and oxidize it to its
  aldehyde, methanal (formaldehyde)

O
C
H
O
H
C
3
H
H
25

• It is the formaldehyde that is so toxic.
• Formaldehyde reacts rapidly with the components
  of cells. It causes proteins to be coagulated
  (like cooking an egg.)
• It is especially devastating to the optic
  nerves. Less than 2 teaspoons can cause
  blindness.
• 2 tablespoons will often cause death.

26
Ethanol IVs

• The antidote for methanol poisoning has long
  been ethanol, administered intravenously.
• Ethanol preferentially loads up the liver
  enzymes. Since they are tied up oxidizing
  ethanol, they cant oxidize methanol to the
  dangerous formaldehyde.
• Therefore, unoxidized methanol is gradually
  excreted from the body.

27

• Methanol production
• Made by heating wood in the absence of air
• - destructive distillation - wood alcohol
• Preparation from carbon monoxide
• CO 2H2 CH3OH

400oC, 200atm metal catalysts
28
CH3CH2OH

• ETHANOL
• Synonyms Ethyl alcohol, grain alcohol
• Uses Common solvent in flavors
  medicines.
• Industrial starting material.
• Found in alcoholic beverages.
• Toxicity Can be ingested at low levels.
• Other Colorless, odorless, liquid.

29

• Ethanol production
• Fermentation
• - action of yeast on sugars
• - a waste product of yeast metabolism
• - complex biochemical process
• Preparation from ethene
• CH2 CH2 CH3CH2OH

steam, 325oC catalyst
30

• Ethanol was originally made from fruits or
  cereal grains. (Most often grapes or barley.)
• The sugars in fruits and grains are oxidized
  (fermented) by yeast cells to form ethanol and
  carbon dioxide.
• C6H12O6 2 CH3CH2OH 2 CO2
• Yeast on grapes, etc.. Early Mesopotamia
  origins.

31

• When the concentration of ethanol gets up to 12
  - 18, the yeast die off, settle to bottom of
  container, leaving alcoholic beverage. (Actually,
  theres still lots of the little buggers alive,
  they just quit multiplying.
• To get higher percentage, the beverage is
  filtered and distilled.
• Proof 2 X percentage
• Why is it called proof ?

32

• Ethanol is also toxic. It generally acts as a
  depressant.
• A pint of pure ethanol, rapidly ingested, would
  kill most people.
• Excessive ingestion over a long period of time
  leads to deterioration of the liver and loss of
  memory.
• Oxidation to aldehyde is one cause of hangover.

33

• 2-PROPANOL
• Synonyms isopropyl alcohol
• rubbing alcohol
• Uses disinfectant and astringent
• dry gas, industrial solvent
• Toxicity pretty toxic if ingested. Wont kill
  you, just make you wish you were dead.
• Other colorless, slight odor, liquid

34

• The lower alcohols have a mild antiseptic
  action.
• Ethanol and isopropyl alcohol are often used to
  clean skin before injection, drawing of blood, or
  minor surgery.

35
Other Important alcohols

• 1,2-ethanediol
• Ethylene glycol
• Used in antifreeze/coolant
• Starting material for polyester
• 1,2,3-propanetriol
• Glycerol
• Used in hand lotions and cosmetics
• Backbone of fats

36
Reactions of alcohols

• Dehydration
• Removal of a water to produce an alkene.
• OH
• R-CH2-CH-R R-CC-R H2O
• Oxidation
• Conversion of an OH to a O.
• R-CH2-OH R-C (aldehyde)
• OH
• R-CH-R R-C-R (ketone)

H, heat
O
oxidizing agent
H
O
oxidizing agent
37

• In these oxidation reactions the carbon forms
  stronger ties to the oxygen.
• The carbon cant do this if it does not have a
  bond to a hydrogen that it can free up.
• Tertiary alcohols will not oxidize.

O
H
NO REACTION
C
H
C
C
H
C
H
3
2
3
C
H
3
38
Phenols

• Alcohol-like compounds that have the hydroxyl
  group bound to a benzene ring

phenol
hexachlorophene
o-phenylphenol
39
Phenols

• Common in nature
• Example, lignand - made of phenols
• - dietary fiber
• - holds cell walls
• together in plants
• Uses for phenols
• natural flavorings of tea and coffee
• synthetic flavorings and odors
• antiseptics
• cosmetics
• health aids

40
Ethers and thiols

• Ethers
• Contain two alkyl or aryl groups bound to
• an oxygen.
• Thiols
• Similar to alcohols but have a sulfur instead of
  an oxygen.

41
Ethers

• Compounds where both sides of the oxygen is bound
  to an alkyl or aryl group
• R - O - R
• Properties
• much less polar than alcohols
• not soluble in water
• lower MP and BT than alcohols
• chemically inert
• all are very flammable

42
Naming ethers

• Common names
• Just name the groups attached to oxygen and then
  add the generic name ether.
• If both groups are the same, just the prefix
  di-.
• CH3-O-CH3 dimethyl ether
• CH3-O-CH2CH2 ethyl methyl ether
• This system is still very popular.

43
Naming ethers

• IUPAC system.
• Identify the longest carbon chain and use it as
  the base name, -ane ending.
• Name the shortest carbon chain with an -oxy
  ending.
• Number location of ether bond on long chain so
  that it is as low as possible.
• Use other IUPAC rules for naming substituents.

44

• CH3-CH2-CH2-O-CH3
• 1-methoxypropane
• CH3-CHCl-O-CH3
• 1-chloro-1-methoxyethane
• CH3-CH2-CH-CH3
• O-CH2-CH2-CH3
• 2-propoxybutane

45

• Ethers have no hydrogen attached to their oxygen.
  Therefore they are incapable of inter-molecular
  hydrogen bonding.
• This is why ethers have such low boiling points.
• The name Ether is from Arabic meaning spirit
  because the liquid always disappeared quickly.

46

• Diethyl ether is best known ether. Its vapors
  act as a CNS depressant (anesthetic).
• Side Effects Nausea, vomiting, respiratory
  arrest.
• Ether vapors form an explosive mixture with air.

47
BANG
48
Ethers

• Used as anesthetics
• diethyl ether - first general anesthetic
• halogenated ethers - common anesthetics
• Penthrane - CH3-O-CF2CHCl2
• Enthrane - CHF2-O-CF2CHFCl
• Special hazard
• Many ethers will form peroxides
• if they sit too long.
• They can then explode

49

• Hospitals buy only fresh ether and only small
  amounts. Containers kept tightly closed and away
  from strong light.

50
Thiols

• Similar to alcohols but contain a sulfur rather
  than an oxygen.
• R-S-H
• Less polar than alcohols
• - less hydrogen bonding
• Lower melting and boiling points
• - compared to alcohols of the same
• number of carbon

51
One common property
Smell!
52
Thiols

• methanethiol
• odor added to natural gas
• 1-propanethiol
• odor in garlic and onions
• trans-2-butene-1-thiol
• skunk odor
• Thiols have some of the strongest odors of
• all chemicals

53
Thiols

• Some biologically significant thiols
• CH2 - CH - CH2 British Anti-Lewisite (BAL)
• OH SH SH Treatment for Hg poisoning
• H-S-C-CH-COOH Cysteine. An amino acid
• NH2 Important to
  protein
• structure

54
Thiols

• When oxidized, thiols can form R-S-S-R links.
  These are referred to as disulfide links.

Forms cross links in proteins which helps give
them the shape they need.
S-S cross links are also used to make stronger
polymers. Latex uses S-S links. Vulcanized
rubber is rubber that has sulfur added.
55
Aldehydes and Ketones

• Structure and Properties
• Nomenclature and Common names
• Sources
• Reactions
• Some Important Aldehydes and Ketones

56
The carbonyl group

• Aldehydes and ketones contain this group.
• \
• C O
• /
• Many other compounds also have a carbonyl.
• Acyl halides acids amides
• carbohydrates esters

57
The carbonyl group

• The group is planer - flat
• R
• \
• C O
• /
• R
• R and R are two different groups. They
• determine what functional group the
• carbonyl is a part of.

All angles are 120o
58
Carbonyl containing compounds

• Formula Family Formula Family
• R-CO Aldehyde R-CO Ester
• H OR
• R-CO Ketone R-CO Amide
• R NH2
• R-CO Carboxylic R-CO Acid
• OH acid Cl chloride

59
Aldehydes and ketones

• Only differ by location of carbonyl.
• R
• \
• CO Aldehyde. CO on end chain
• /
• H
• R
• \
• CO Ketone. CO not on end
• /
• R
• Results in different properties and reactions.

60
Properties

• Moderately polar Due to CO group.
• Boiling points Lower than alcohols and
• Higher than alkanes.
• Solubility Low MW species are
• soluble in water.
• Decreases as they get
• larger.

61
Hydrogen bonding
?-
The carbonyl group is polar.
?
62

• The condensed structural formulas for aldehydes
  often show the carbonyl group as CHO.
• Ex.
• The formula above would be shown as
• CH3CH2CHO

O
C
H
C
H
C
3
2
H
63
Aldehyde nomenclature

• Find longest carbon chain that contains the
  aldehyde group.
• Change ending of base alkane name drop -e,
  change to -al.
• All other branches and groups are named using
  standard IUPAC system.

64
Common Names for Aldehydes

• Sometimes we find aldehydes named after the
  common name of the acid they are related to.
• Ex.

O
O
C
H
C
C
3
H
H
H
M
E
T
H
A
N
A
L
E
T
H
A
N
A
L

F
O
R
M
A
L
D
E
H
Y
D
E
A
C
E
T
A
L
D
E
H
Y
D
E
65
Examples

• CH3CH2CH2CHO
• 
  butanal
• CH3CH2CHBrCH2CHO
• 
  3-bromopentanal
• CH3CH2C(CH3)2CH2CHO
• 
  3,3-dimethylpentanal
• CH3C(CH3)ICH2CHO
• 3-iodo-3-methylbutanal
• CH3CH(CH2I) CH2CHO
• 3-(iodomethyl)butanal

66
(No Transcript)
67
Ketone nomenclature

• Find longest chain that contains CO.
• Must not be at end or it is an aldehyde.
• Use base alkane name
• - drop -e, change to -one.
• Find lowest number to show location of the
  carbonyl, CO.
• Name and number other substitutes as before.

68
Examples

• CH3C(O)CH3
• propanone
• CH3CH2CH(CH3)C(O)CH3
• 3-methyl-2-pentanone
• CH2BrCH2C(O)CH2CH3
• 1-bromo-3-pentanone
• CH3CCl2C(CH2CH3)2C(O)CH2CH3
• 5,5-dichloro-4,4-diethyl-3-hexanone

69
(No Transcript)
70
More examples
O C - C - C - C - C
C - C - C - Cl
Cl
71
More examples
O C - C - C - C - C
C - C - C - Cl
Cl
7,7-dichloro-4-methyl- 3-heptanone
72
More examples
O C - C - C - C - C
C - C - C - Cl
Cl
7,7-dichloro-4-methyl- 3-heptanone
2-methylcyclopentanone
73
Common names for Ketones

• Common names for the ketones are derived from
  names of the groups attached to the carbonyl.
  (Like the ethers.)

O
O
C
H
C
C
H
C
H
C
H
C
H
C
C
H
3
2
2
3
3
3
Dimethyl ketone
Methylpropyl ketone
74
Synthesis of Aldehydes and ketones

• Industrial Scale
• Fischer-Tropsch Syntheses
• heat
• CO H2 aldehydes and
  ketones
• coke
• coke - high temperature carbon
• acts as a reducing agent.
• Reaction is most often used to form -
• methanal, ethanal and propanone.

75

• Air oxidation of methanol
• Methanol vapors passed over copper metal that
  has been heated in air to form copper oxides.
• air, CuO
• CH3OH H2CO
• heat
• The copper oxides are reduced to copper metal
  while the methanol is oxidized
• to methanal (formaldehyde).
• Also works with
• ethanol to make ethanal
• 2-propanol to make propanone

76

• Laboratory Production
• O
• R-OH aldehyde or ketone
• Most common small laboratory method is -
  oxidation of alcohols.
• Type of alcohol determines product
• primary - aldehyde
• secondary - ketone
• tertiary - no reaction

77
Production of aldehydes and ketones
H R - C - OH Primary - produces aldehyde
H R R - C - OH Secondary - produces
ketone H R R - C - OH Tertiary -
no reaction R
78
Some important aldehydes

• methanal (formaldehyde) - In pure form, this is
  a gas at room temperature.
• A 37 aqueous solution (formalin) is often used
  as a sterilizing agent. It kills microorganisms
  by denaturing their proteins. It is often used
  to preserve tissue.
• Its presence in wood smoke is one of the reasons
  smoking meats helps in their preservation.

79

• ethanal (acetaldehyde) - Used as an intermediate
  in the synthesis of many organic compounds.
• A solvent for things like fingernail polish.

80

• Most notable as the oxidation product of ethanol.
  It is the formation of acetaldehyde that is
  thought to be the major factor in discomfort
  resulting from alcohol consumption.
• Easily crosses placenta - results in fetal
  alcohol syndrome.
• The use of Antabuse (disulfiram) in alcoholics
  blocks the oxidation of acetaldehyde and makes
  drinking even small amounts of alcohol extremely
  painful and nauseating

81
Some other familiar aldehydes.

• benzaldehyde oil of almonds.
• vanillin oil of vanilla beans

82
Some important ketones

• propanone (acetone) - a common solvent, it is
  the most important of the ketones.
• It is miscible in water and will dissolve most
  organic compounds.
• It is the major ingredient in finger nail polish
  remover.
• It is also one of the products of fat
• metabolism in diabetics that results in
  ketosis. In fact, it is the smell of acetone on
• a persons breath that indicates high levels of
  ketone bodies.

83

• butanone methyl ethyl ketone
• MEK
• another common solvent
• 2-octanone mushroom flavoring

84
Reactions of aldehydes

• Oxidation reactions - aldehydes
• Conversion of aldehydes to carboxylic acids

H R-CO
OH R-CO
O
Tollens Test for aldehydes
85
Reactions ofaldehydes and ketones

• Reduction reactions - conversion to alcohols
• - H2 addition reaction

R H
\
CO H2
R - C - OH /

R
R
Pt

• Aldehydes result in primary alcohols.
• Ketones form secondary alcohols.

86

• The carbonyl group is susceptible to attack
  because of its polarity.

Positive species attack here.
?-
O
C
?
Negative species attack here.
87

• Because the carbonyl group is like a little
  magnet just begging to be attacked, many polar
  compounds do just that.
• These reactions are normally addition reactions
  where the attacking compound ends up as part of
  the molecule.

88
Other addition reactions ofaldehydes and ketones
R X
\
CO HX
R - C - OH /
R
R

• Addition of HX
• Addition of H2O
• Addition of ROH

H
R OH
\
CO H2O
R - C - OH /
R
R
H
89
(No Transcript)
90
(No Transcript)
91
(No Transcript)
92
(No Transcript)
93

• See the discussion covering these addition
  reactions on page 432-438 in text.
• The hemiacetal and acetal reactions will be
  covered again when we get to the chapter on
  carbohydrates.
• Since sugars are poly hydroxy aldehydes and
  ketones, they are capable of reacting internally
  where one of the OH's adds to a carbonyl group
  further up the chain.

94
(No Transcript)
95
Intramolecular cyclization

• Cyclization. The preferred geometry of a hexose
  is a cyclic, closed-ring structure.
• Remember - chains can bend and rotate.