Introduction to Organic and
Biochemistry
(CHE 124)
Reading Assignment
General, Organic, and Biological Chemistry: An Integrated Approach
3rd. Ed. Ramond
Chapter 9
Alcohols, Ethers, Aldehydes, and Ketones
Work Problems
9. 4, 6, 8, 12, 20, 22, 31, 32, 82, 89, 90, 98, 100,
Functional Groups
• Alcohols
- ol
– 1°
– 2°
– 3°
•
•
•
•
•
•
•
Ethers – common names
Thiols – common names
Sulfides – common names
Disulfides – common names
Carbonyls
Aldehydes
-al
Ketones
- one
Naming Alcohols, aldehydes, ketones
• Identify and name longest carbon chain (parent
compound) that contains the hydroxyl group (or
carbonyl for aldehydes or ketones).
• Name parent compound as alkane, then drop -e
add –ol.
• Number carbons so alcohol, aldehyde or ketone
has lowest possible number.
• Name and number side chains.
• For alcohols add -ol
• For aldehydes add –al
• For ketones add -one
Characteristics of Alcohols
• Alcohols have ↑ b.p. than alkanes off similar
molecular weight.
– Due to hydrogen bonding.
• Longer the carbon chain ↑ b.p.
• Alcohols are water soluble, but become less soluble
as carbon length increases.
• Alcohols are classified as:
– 1°
– 2°
– 3°
• Draw on board.
• Ethers, thiols, sufides and disulfides have b.p. lower
than alcohols.
Synthesis of Alcohols
• Nucleophilic substitution
– OH (hydroxyl group) is a group nucleophile and readily
replaces a leaving group (halides ,Cl, F, Br, are good
leaving groups)
• Leaving group an easily replaced atom or group of atoms that is
held to a carbon by a realatively weak covalent bond.
• See p.301 Fig. 9.5 and 9.6
• Hydration of alkenes (C=C)
– In the presence of an acid catalyst, water adds across the
double bond. (Remember Markovnikov’s Rules
• Markovnikov’s Rules states that the hydrogen will add to the carbon
already containing the most hydrogens.
• Asymetric alkenes produce at least 2 different products
• See p. 302 Fig 9.7
Reactions of Alcohols
• Oxidation of alcohols – alcohols are readily
oxidized using K2Cr2O7 (potassium
dichromate)
– 1° alcohol → aldehyde → carboxylic acid
– 2° alcohol → ketones
– 3° alcohol → NO REACTION
• See p. 303 Fig. 9.8
Reactions of Alcohols
• Dehydration of Alcohols
– In the presence of an acid catalyst, produces an
alkene. (C=C)
• When different alkenes are possible, the one favored is
produced from removing hydrogen from the carbon with
the fewer hydrogens.
• See fig. 9.10
Reactions of Aldehydes and Ketones
• Reduction of aldehydes and ketones
– Catalytic hydrogenation uses Pt platinum
catalyst.
• Aldehyde → 1° alcohol
– Methanal (Formaldehyde) → methanol
• Ketone → 2° alcohol
– Propanone → 2- propanol
Oxidation / Reduction in Bioloigical
Systems
• Nicotinamide adenine dinucleotide (NAD+ /
NADH) serves as an electron acceptor or
electron donor in living systems.
– NAD+ oxidized form of Nicotinamide adenine
dinucleotide.
– NADH (also the symbol NADH+H+ is used)
reduced form of Nicotinamide adenine
dinucleotide.
Alcohol dehydrogenase
Ethanol + NAD+ → Acetaldehyde + NADH+H+
Characteristics of Aldehydes and Ketones
• Aldehydes and Ketones have ↓ b.p. than
alcohols of similar molecular weight.
– Due to the inability of aldehydes and ketones to
form H bonds with each other.
• Longer the carbon chain ↑ b.p.
• Short chain aldehydes and ketones are water
soluble, but become less soluble as carbon
length increases.
– Due to polarity of carbonyl and ability of carbonyl
to form H-bonds with water.
Oxidation of Aldehydes
• As shown previously, aldehydes may be
oxidized into carboxylic acids by potassium
dicromate (or other oxidants)
• Benedict’s Reagent
– Used to test for aldehydes.
• Color change from blue to brown – orange
– Uses Cu2+ to oxidize aldehydes without oxidizing
1° or 2°alcohols.
– Used to detect diabetes by monitoring urine for
the presence of glucose
• See p 308 fig 9.13
Reduction of Aldehydes and Ketones
• Aldehydes and ketones can be reduced in the
presence of a Pt catalyst to produce an
alcohol.
– Aldehyde → 1° alcohol
– Ketone → 2° alcohol
• See p. 310 Fig. 9.15
• These reactions are catalyzed in biological
systems by enzymes that use NADH as a
reducing agent.
– E.g. in the synthesis of steroid hormones.
– See p 312 fig 9.16
Alcohols react with aldehydes to form
hemiacetals and ketones to form a
hemiketals.
• Hemiacetals and hemiketals form when
carbohydrates cyclize. Requires and acid
catalyst.
– See p. 313 fig. 9.18 b.