Transcript Chapter 23 Functional Groups

Chapter 23
“Functional
Groups”
West Bladen High
School
Section 23.1 - Introduction to
Functional Groups
 OBJECTIVES:
–Explain how organic
compounds are
classified.
Section 23.1 - Introduction to
Functional Groups
 OBJECTIVES:
–Identify halocarbons and
the IUPAC rules for
naming halocarbons.
Section 23.1 - Introduction to
Functional Groups
 OBJECTIVES:
–Describe how
halocarbons can be
prepared.
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 23.1, page 726 -shows some of the major
categories, and their functional
groups - KNOW THESE.
 Table 23.2, p. 727 - alkyl groups
Halogen Substituents
 Halocarbons - class of organic
compounds containing covalently
bonded fluorine, chlorine,
bromine, or iodine
–General formula: R-X (X = halogen)
 Naming?
Name parent as normal,
add the halogen as a substituent (or
prefix) - Examples on page 726
Halogen Substituents
 Common
names…p.726
 The more highly halogenated the
compound is, the higher the b.p.
(see Table 23.3, page 728)
 Few halocarbons found in nature
–but, readily prepared and used
–halothane (Fig. 23.3, p.727) 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?
Examples on Page 729
 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 +
Methanol + sodium chloride
NaCl
Substitution Reactions
CH3-I + KOH  CH3-OH + KI
Iodomethane
Methanol
CH3CH2Br + NaOH  CH3CH2OH + NaBr
Bromoethane
Ethanol
Section 23.2
Alcohols and Ethers
 OBJECTIVES:
–Identify how alcohols are
classified and named.
Section 23.2
Alcohols and Ethers
 OBJECTIVES:
–Predict how the solubility
of an alcohol varies with
the length of its carbon
chain.
Section 23.2
Alcohols and Ethers
 OBJECTIVES:
–Name the reactions of
alkenes that may be
used to introduce
functional groups.
Section 23.2
Alcohols and Ethers
 OBJECTIVES:
–Construct the general
structure of an ether and
describe how ethers are
named.
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
 Aliphatic
alcohols classified 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 730
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 731
Alcohols
 Common names:
–similar to halocarbons,
meaning name the alkyl
group, then followed by the
word alcohol
–One carbon alcohol = methyl
alcohol
Alcohols
 More
than one -OH substituents
are called glycols (ethylene glycol?)
 ** Examples on page 731 **
 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 water in all proportions;
more than 4 carbons are usually
less soluble, because the longer
carbon chain is more nonpolar
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; also
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
 The
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 top of page 734 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 - middle p. 734
 The addition of bromine is often
used as a test for saturation - p.734
 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”
 Top- page 735, 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 735
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
 Alcohol used for fuel in the future?
Section 23.3
Carbonyl Compounds
 OBJECTIVES:
–Identify the structure of a
carbonyl group as found
in aldehydes and
ketones.
Section 23.3
Carbonyl Compounds
 OBJECTIVES:
–Construct the general
formula for carboxylic
acids and explain how
they are named.
Section 23.3
Carbonyl Compounds
 OBJECTIVES:
–Describe an ester.
Section 23.3
Carbonyl Compounds
 OBJECTIVES:
–Explain how
dehydrogenation is an
oxidation reaction.
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 - bottom of page
737
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
23.4, page 738 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
(the common name is:
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)
The 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
 Table 23.6 page 741
The 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.
742
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 743
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 at the top on
page 744
Oxidation- Reduction Reactions
 Methane
can be oxidized in steps
to carbon dioxide (middle p. 744):
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 middle of page 745
 Preparing aldehydes from a
primary 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 –
Figure 23.19 p. 745
Section 23.4
Polymerization
 OBJECTIVES:
–Describe how addition
polymers are formed.
Section 23.4
Polymerization
 OBJECTIVES:
–Describe how
condensation polymers
are formed.
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 747
–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 ® DuPont) 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 (PET)
–Dacron (® DuPont), Fortrel (®
Wellman), Polyesters: permanent
press clothing, tire cords
–Sheets of polyester called Mylar (®
DuPont), 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 (®
DuPont), which is a poor electrical
conductor; makes parts for
electrical fixtures; flame resistant
clothing for race car drivers; flame
resistant building materials
–Kevlar (® DuPont): strong and
flame resistant
Plastic container code system.
CODE
MATERIAL
PERCENT OF
TOTAL
Polyethylene Terephthalate
(PET)
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 (or PETE) 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