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: CH4 + Cl2  CH3Cl + HCl UV light

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 + X1- CH3-Cl + NaOH  CH3-OH + NaCl

Substitution Reactions CH3-I + KOH  CH3-OH + KI CH3CH2Br + NaOH  CH3CH2OH + NaBr Iodomethane Methanol 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.

The hydroxyl is given the lowest position number 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 di- Examples 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 Table 26.6 page 789

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. 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 Polypropylene Polystyrene All other resins

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