Chapter 23 Functional Groups 1l6c35

Chapter 23

“Functional Groups”

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

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 ed to at least one hydrogen (meaning it is always on the end!)

Aldehydes and Ketones  Ketones - the carbon of the carbonyl group is ed 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 ing 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

5-10 percent 5-10 percent

All other resins

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