Transcript Chapter 26 Functional Groups and Organic Reactions

Chapter 26
“Functional Groups and
Organic Reactions”
Charles Page High School
Dr. Stephen L. Cotton
Section 26.1 - Introduction to
Functional Groups
 OBJECTIVES:
–Define a functional group, and
give several examples.
Section 26.1 - Introduction to
Functional Groups
 OBJECTIVES:
–Describe halocarbons, and
the substitution reactions they
undergo.
Functional Groups
 Most
organic chemistry involves
substituents
–often contain O, N, S, or P
–also called “functional groups”they are the chemically functional
part of the molecule, and are the
non-hydrocarbon part
Functional Groups
 Functional
group - a specific
arrangement of atoms in an
organic compound, that is
capable of characteristic chemical
reactions.
–What is the best way to classify
organic compounds? By their
functional groups.
Functional Groups
 The
symbol “R” is used to
represent any carbon chains or
rings
 Important:
Table 26.1, page 774 -shows some of the major
categories, and their functional
groups - KNOW THESE.
 Table 26.2, p. 775 - alkyl groups
Halogen Substituents
 Halocarbons - class of organic
compounds containing covalently
bonded fluorine, chlorine,
bromine, or iodine
–General formula: R-X
 Naming?
Name parent as normal,
add the halogen as a substituent (or
prefix) - Examples on page 774
Halogen Substituents
 The
more highly halogenated the
compound is, the higher the b.p.
(see Table 26.3, page 775)
 Few halocarbons found in nature
–but, readily prepared and used
–halothane (Fig. 26.3, p.776) and
also the hydrofluorocarbons
Substitution Reactions
 Organic
reactions often much
slower than inorganic reactions
–must break strong covalent
bond
–trying to find new catalysts to
use
 Substitution - an atom (or group
of atoms) replaces another atom
or group of atoms
Substitution Reactions
 A halogen
(shown as “X”) can
replace a hydrogen to make a
halocarbon:
R-H + X2  R-X + HX
 Sunlight is often a sufficient catalyst:
UV light
CH4 + Cl2

CH3Cl + HCl
Substitution Reactions
 Treating
benzene with a halogen?
Page 776
 Halogens on carbon chains are
readily displaced by hydroxide ions
(OH1-) to make an alcohol + a salt:
R-X + OH1-  R-OH + X1CH3-Cl + NaOH  CH3-OH +
NaCl
Substitution Reactions
CH3-I + KOH  CH3-OH + KI
Iodomethane
Methanol
CH3CH2Br + NaOH  CH3CH2OH + NaBr
Bromoethane
Ethanol
Section 26.2
Alcohols and Ethers
 OBJECTIVES:
–Describe the structures and
naming of alcohols and
ethers.
Section 26.2
Alcohols and Ethers
 OBJECTIVES:
–Define an addition reaction,
and give several examples.
Section 26.2
Alcohols and Ethers
 OBJECTIVES:
–Compare the properties of
alcohols and ethers.
Alcohols
 Alcohols
- a class of organic
compounds with an -OH group
–The -OH functional group in
alcohols is called a “hydroxyl”
group; thus R-OH is the formula
 How
is this different from the
hydroxide ion? (covalent bonding with
the carbon- not ionic with a metal like bases)
Alcohols
 Arranged
into categories according
to the number of R groups
attached to the carbon with the
hydroxyl
–1 R group: primary alcohol
–2 R groups: secondary alcohol
–3 R groups: tertiary alcohol
 Note drawings on page 778
Alcohols
 Both
IUPAC and common names
 For IUPAC:
–drop the -e ending of the parent
alkane name; add ending of -ol,
number the position of -OH
–parent is the longest chain that
contains the carbon with the
hydroxyl attached.
Alcohols
 The hydroxyl is given the
lowest position number
 Alcohols containing 2, 3, and 4
of the -OH substituents are
named diols, triols, and tetrols
respectively
–Examples on page 779
Alcohols
 Common names:
–similar to halocarbons,
meaning name the alkyl
group followed by the word
alcohol
–One carbon alcohol = methyl
alcohol
Alcohols
 More
than one -OH substituents
are called glycols (ethylene glycol?)
 ** Examples on page 779 **
 Phenols - compounds in which a
hydroxyl group is attached directly
to an aromatic ring. Cresol is the
common name of o, m, and p
isomers of methylphenol
Properties of Alcohols
 Much
like water, alcohols are
capable of hydrogen bonding
between molecules
–this means they will boil at a
higher temp. than alkanes and
halocarbons with a comparable
number of atoms
Properties of Alcohols
 Alcohols
are derivates of water; the
-OH comes from water, and thus
are somewhat soluble
 Alcohols of up to 4 carbons are
soluble in all proportions; more than
4 carbons are usually less soluble,
because…?
Properties of Alcohols
 Many
aliphatic alcohols used in
laboratories, clinics, and industry
–Isopropyl alcohol (2-propanol) is
rubbing alcohol; used as antiseptic,
and a base for perfume, creams,
lotions, and other cosmetics
 Ethylene glycol (1,2-ethanediol) commonly sold as antifreeze
Properties of Alcohols
 Glycerol
(1,2,3-propanetriol) - used
as a moistening agent in cosmetics,
foods, and drugs; also a
component of fats and oils
 Ethyl alcohol (ethanol) used in the
intoxicating beverages; an
important industrial solvent
Properties of Alcohols
 Denatured
alcohol- means it has
been made poisonous by the
addition of other chemicals, often
methyl alcohol (methanol, or wood
alcohol). As little as 10 mL of
methanol has been known to cause
permanent blindness, and 30 ml
has resulted in death!!!
Addition Reactions
 Carbon-carbon
single bond is not
easy to break
 In double bonded alkenes, it is
easier to break a bond
 Addition reaction- substance is
added at the double or triple bond
location, after it is broken
Addition Reactions
 Addition
of water to an alkene is a
hydration reaction - usually occurs
with heat and an acid (such as HCl
or H2SO4 acting as a catalyst)
 Note sample at bottom of page 781
for the formation of ethanol from
ethene + water
Addition Reactions
 If
a halogen is added in an addition
reaction, the result is a halocarbon
that is disubstituted - top page 782
 The addition of bromine is often
used as a test for saturation - p.782
 Addition of a hydrogen halide? called monosubstituted halocarbon
Addition Reactions
 Addition
of hydrogen to produce an
alkane is a hydrogenation reaction,
which usually involves a catalyst
such as Pt or Pd
–common application is the
manufacture of margarine from
unsaturated vegetable oils
(making them solid from a liquid)
Addition Reactions
 The
hydrogenation of a double
bond is a reduction reaction,
which in one sense is defined as
the gain of H
 Bottom- page 782, ethene is
“reduced” to ethane; cyclohexene is
“reduced” to cyclohexane
Ethers
 A class
of organic compounds in
which oxygen is bonded to 2
carbon groups: R-O-R is formula
 Naming? The two R groups are
alphabetized, and followed by ether
 Two R groups the same? Use the
prefix diExamples on page 783
Ethers
 Diethyl
ether is the one commonly
called just “ether”
–was the first reliable general
anesthetic
–dangerous- highly flammable,
also causes nausea
 ethers are fairly soluble in water
 Note the LINK on page 784
Section 26.3
Carbonyl Compounds
 OBJECTIVES:
–Distinguish among the
carbonyl groups of aldehydes,
ketones, carboxylic acids, and
esters.
Section 26.3
Carbonyl Compounds
 OBJECTIVES:
–Describe the reactions of
compounds that contain the
carbonyl functional group.
Aldehydes and Ketones
 Review:
–alcohol has an oxygen bonded to
a carbon group and a hydrogen
–ether has an oxygen bonded to
two carbon groups
 An
oxygen can also be bonded
to a single carbon by a double
bond
Aldehydes and Ketones
 The
C=O group is called the
“carbonyl group”
–it is the functional group in both
aldehydes and ketones
 Aldehydes - carbonyl group
always joined to at least one
hydrogen (meaning it is always on
the end!)
Aldehydes and Ketones
 Ketones
- the carbon of the
carbonyl group is joined to two
other carbons (meaning it is
never on the end)
 Structures - middle of page 785
Aldehydes and Ketones
 Naming?
–Aldehydes: identify longest chain
containing the carbonyl group, then
the -e ending replaced by -al, such
as methanal, ethanal, etc.
–Ketones: longest chain w/carbonyl,
then new ending of -one; number it
 propanone, 2-pentanone, 3-pentanone
Aldehydes and Ketones
 Table
26.4, page 786 examples
 Neither can form intermolecular
hydrogen bonds, thus a much lower
b.p. than corresponding alcohols
 wide variety have been isolated from
plants and animals; possible fragrant
odor or taste; many common names
Aldehydes and Ketones
 Benzaldehyde
 Cinnamaldehyde
 Vanillin
 Methanal
(common: formaldehyde)
–40% in water is formalin, a
preservative
Aldehydes and Ketones
 Propanone
(common: acetone)
is a good solvent; miscible with
water in all proportions
 why is it a good substance used
in nail-polish removers? (a
powerful solvent-able to
dissolve both polar & nonpolar)
Carboxylic Acids
 Also
have a carbonyl group (C=O),
but is also attached to a hydroxyl
group (-OH) = “carboxyl” group
 general formula: R-COOH
–weak acids (ionize slightly)
 Named by replacing -e with -oic
and followed by the word acid
 methanoic acid; ethanoic acid
Carboxylic Acids
 Abundant
and widely distributed in
nature, many having a Greek or
Latin word describing their origin
–acetic acid (ethanoic acid) from
acetum, meaning vinegar
–many that were isolated from fats
are called fatty acids
Esters
 General
formula: RCOOR
 Derivatives of the carboxylic acids,
in which the -OH from the carboxyl
group is replaced by an -OR from an
alcohol:
carboxylic acid + alcohol  ester +
water
 many
esters have pleasant, fruity
odors- banana, pineapple, perfumes
Esters
 Although
polar, they do not form
hydrogen bonds (reason: there is
no hydrogen bonded to a highly
electronegative atom!)
–thus, much lower b.p. than the
hydrogen-bonded carboxylic
acids they came from
Esters
 Can
be prepared from a
carboxylic acid and an alcohol;
usually a trace of mineral acid
added as catalyst (because
acids are dehydrating agents)
 Note equation on bottom p. 790
Esters
 Naming?
It has 2 words:
–1st: alkyl attached to single
bonded oxygen from alcohol
–2nd: take the acid name,
remove the -ic acid, add -ate
 example on top of page 791
Oxidation- Reduction Reactions
 All
of the previous classes of
organic compounds are related by
oxidation and reduction reactions
 What is oxidation-reduction?
–Oxidation: the gain of oxygen,
loss of hydrogen, or loss of e-1
–Reduction: the loss of oxygen,
gain of hydrogen, or gain of e-1
Oxidation- Reduction Reactions
 Oxidation
and reduction
reactions (sometimes called
redox) are coupled- one does not
occur without the other
 The number of Oxygen and
Hydrogen attached to Carbon
indicates the degree of oxidation
Oxidation- Reduction Reactions
 The
fewer the # of H on a C-C
bond, the more oxidized the bond
–Thus, a triple bond is more
oxidized than a double bond and a
single bond
 An alkane is oxidized (loss of H) to
an alkene, and then to an alkyne
Oxidation- Reduction Reactions
 Loss
of hydrogen is called a
dehydrogenation reaction
–may require strong heating
and a catalyst
 Note equations on page 791
Oxidation- Reduction Reactions
 Methane
can be oxidized in steps
to carbon dioxide (top page 792):
methane  methanol 
methanal  methanoic acid 
CO2
 the
more reduced (more H) a
carbon compound, the more
energy it can release upon
oxidation
Oxidation- Reduction Reactions
 Alcohols
can also be oxidized
into other products
 “Dr. Al K. Hall  Mr. Al D. Hyde”
 Equations top of page 793
 Preparing aldehydes from a
primaryf alcohol is a problem,
because they are then easily
oxidized to carboxylic acids
Oxidation- Reduction Reactions
 Benedict’s
test and Fehling’s
test are commonly used for
aldehyde detection - margin p.
793
Section 26.4
Polymerization
 OBJECTIVES:
–Define polymer and monomer.
Section 26.4
Polymerization
 OBJECTIVES:
–Name and describe the uses
of some important addition
and condensation polymers.
Addition Polymers
 Polymers
are giant molecules,
not small like the ones studied
earlier in this chapter
–examples are plastics
 Polymer- large molecule formed
by the covalent bonding of
smaller molecules called
monomers
Polymers from Monomers
Addition Polymers
 An
addition polymer forms when
unsaturated monomers react to
form a polymer
–ethene will form polyethylene,
shown on page 795
–polyethylene is easy to clean,
chemically resistant- milk bottles,
plastic wrap, refrigerator dishes
High Density Polyethylene
Addition Polymers
 Polypropylene
is a stiffer polymer, used
in utensils and containers
 Polystyrene is formed from styrene
(phenylethene), and is a poor heat
conductor (styrofoam – Dow Chemical)
–molded coffee cups and picnic
coolers, insulates homes
 Polyvinyl chloride (PVC) used for pipes
in plumbing
Addition Polymers
 Polytetrafluoroethene
(PTFE, or
“Teflon”) is very resistant to heat
and chemical corrosion
–found on nonstick cookware;
coating on bearings and
bushings used in chemical
reactors
Condensation Polymers
 Condensation
polymers are
formed by the head-to-tail
joining of monomer units
–usually accompanied by the
loss of water from the
reacting monomers, and
forming water as a product
Condensation Polymers
 Ex:
polyethylene terephthalate (PETE)
–Dacron, Fortrel, Polyesters:
permanent press clothing, tire cords
–Sheets of polyester called Mylar,
used as magnetic tape in tape
recorders and computers, as well as
balloons
–Nylon: carpet, fishing line, hosiery
Condensation Polymers
 Examples:
–aromatic rings form Nomex,
which is a poor electrical conductor;
makes parts for electrical fixtures;
flame resistant clothing for race car
drivers; flame resistant building
materials
–Kevlar: strong and flame resistant
Plastic container code system.
CODE
MATERIAL
PERCENT OF
TOTAL
Polyethylene Terephthalate
(PETE)
20-30 percent
High Density Polyethylene
50-60 percent
Polyvinyl Chloride (PVC)
5-10 percent
Low Density Polyethylene
5-10 percent
Polypropylene
Polystyrene
All other resins
5-10 percent
5-10 percent
5-10 percent
What Do the Numbers Mean?
1 -- PETE (Polyethylene
terephthalate)
•PET is used in the production of
soft drink bottles, peanut butter
jars...
•PET can be recycled into fiberfill
for sleeping bags, carpet fibers,
rope, pillows...
What Do the Numbers Mean?
2 -- HDPE (High-density
polyethylene)
•HDPE is found in milk jugs, butter
tubs, detergent bottles, motor oil
bottles...
•HDPE can be recycled into flower
pots, trash cans, traffic barrier
cones, detergent bottles...
What Do the Numbers Mean?
3 -- V (Polyvinyl chloride)
•PVC is used in shampoo bottles,
cooking oil bottles, fast food service
items...
•PVC can be recycled into drainage
and irrigation pipes...
What Do the Numbers Mean?
4 -- LDPE (Low-density
polyethylene)
•LDPE is found in grocery bags,
bread bags, shrink wrap, margarine
tub tops...
•LDPE can be recycled into new
grocery bags...
What Do the Numbers Mean?
5 -- PP (Polypropylene)
•PP is used in most yogurt
containers, straws, pancake syrup
bottles, bottle caps....
•PP can be recycled into plastic
lumber, car battery cases, manhole
steps...
What Do the Numbers Mean?
6 -- PS (Polystyrene)
•PS is found in disposable hot cups,
packaging materials (peanuts), and
meat trays...
•PS can be recycled into plastic
lumber, cassette tape boxes, flower
pots...
What Do the Numbers Mean?
7 -- Other
•This is usually a mixture of various
plastics, like squeeze ketchup
bottles, "microwaveable" dishes...
Timeline of Plastics
1862 – First man-made plastic
1866 – Celluloid makes it’s debut
1891 – Rayon is discovered
1907 – Bakelite is invented
1913 – Cellophane causes the
plastics craze
Timeline of Plastics
1926 – PVC is invented
1933 – Polyethylene is discovered
1933 – Saran makes it’s debut
1938 – Teflon is discovered
1939 – Nylon stockings hit market
1957 – Here comes velcro