Chapter%2023%20

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Chapter 23Functional Groups

• Pre-AP Chemistry
• Charles Page High School
• Stephen L. Cotton

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Section 23.1 - Introduction to Functional Groups

• OBJECTIVES
• Explain how organic compounds are classified.

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Section 23.1 - Introduction to Functional Groups

• OBJECTIVES
• Identify halocarbons and the IUPAC rules for
  naming halocarbons.

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Section 23.1 - Introduction to Functional Groups

• OBJECTIVES
• Describe how halocarbons can be prepared.

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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

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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.

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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

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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

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Halogen Substituents

• Common namesp.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

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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

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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
• CH4 Cl2 ? CH3Cl HCl

UV light
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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 X1-
• CH3-Cl NaOH ? CH3-OH NaCl

Methanol sodium chloride
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Substitution Reactions

• CH3-I KOH ? CH3-OH KI
• CH3CH2Br NaOH ? CH3CH2OH NaBr

Iodomethane
Methanol
Bromoethane
Ethanol
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Section 23.2Alcohols and Ethers

• OBJECTIVES
• Identify how alcohols are classified and named.

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Section 23.2Alcohols and Ethers

• OBJECTIVES
• Predict how the solubility of an alcohol varies
  with the length of its carbon chain.

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Section 23.2Alcohols and Ethers

• OBJECTIVES
• Name the reactions of alkenes that may be used to
  introduce functional groups.

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Section 23.2Alcohols and Ethers

• OBJECTIVES
• Construct the general structure of an ether and
  describe how ethers are named.

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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)

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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

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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.

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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

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Alcohols

• Common names
• similar to halocarbons, meaning name the alkyl
  group, then followed by the word alcohol
• One carbon alcohol methyl alcohol

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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

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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

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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

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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

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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

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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!

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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

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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

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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

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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)

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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

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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 di-
  Examples on page 735

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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?

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Section 23.3Carbonyl Compounds

• OBJECTIVES
• Identify the structure of a carbonyl group as
  found in aldehydes and ketones.

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Section 23.3Carbonyl Compounds

• OBJECTIVES
• Construct the general formula for carboxylic
  acids and explain how they are named.

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Section 23.3Carbonyl Compounds

• OBJECTIVES
• Describe an ester.

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Section 23.3Carbonyl Compounds

• OBJECTIVES
• Explain how dehydrogenation is an oxidation
  reaction.

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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

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Aldehydes and Ketones

• The CO 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!)

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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

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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

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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

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Aldehydes and Ketones

• Benzaldehyde
• Cinnamaldehyde
• Vanillin
• Methanal (the common name is formaldehyde)
• 40 in water is formalin, a preservative

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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)

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The Carboxylic Acids

• Also have a carbonyl group (CO), 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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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Oxidation- Reduction Reactions

• Benedicts test and Fehlings test are commonly
  used for aldehyde detection Figure 23.19
  p. 745

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Section 23.4Polymerization

• OBJECTIVES
• Describe how addition polymers are formed.

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Section 23.4Polymerization

• OBJECTIVES
• Describe how condensation polymers are formed.

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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

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Polymers from Monomers
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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

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High Density Polyethylene
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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

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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

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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

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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

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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

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Plastic container code system.
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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...

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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...
  

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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...

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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...

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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...

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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...

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What Do the Numbers Mean?

• 7 -- Other
• This is usually a mixture of various plastics,
  like squeeze ketchup bottles, "microwaveable"
  dishes...

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Timeline of Plastics
1862 First man-made plastic 1866 Celluloid
makes its debut 1891 Rayon is discovered 1907
Bakelite is invented 1913 Cellophane causes
the plastics craze
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Timeline of Plastics
1926 PVC is invented 1933 Polyethylene is
discovered 1933 Saran makes its debut 1938
Teflon is discovered 1939 Nylon stockings hit
market 1957 Here comes velcro
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End of Chapter 23