27 Organic Chemistry I: Formulas, Names, and Properties.

27Organic Chemistry I: Formulas, Names,

and Properties

2

Chapter Goals

Saturated Hydrocarbons1. Alkanes and Cycloalkanes

2. Naming Saturated Hydrocarbons

Unsaturated Hydrocarbons 3. Alkenes

4. Alkynes

Aromatic Hydrocarbons5. Benzene

6. Other Aromatic Hydrocarbons

7. Hydrocarbons: A Summary

3

Chapter Goals

Functional Groups8. Organic Halides

9. Alcohols and Phenols

10.Ethers

11.Aldehydes and Ketones

12.Amines

13.Carboxylic Acids

14.Some Derivatives of Carboxylic Acids

15.Summary of Functional Groups

4

Chapter Goals

Fundamental Classes of

Organic Reactions16.Substitution Reactions

17.Addition Reactions

18.Elimination Reactions

19.Polymerization Reactions

5

Saturated Hydrocarbons

• Hydrocarbons are chemical compounds that contain only C and H atoms.

• Saturated hydrocarbons contain only single or sigma () bonds.– There are no double or triple bonds in these

compounds.

• The primary source of hydrocarbons is petroleum and natural gas.

6

Alkanes and Cycloalkanes

• The simplest saturated hydrocarbons are called alkanes.• Methane, CH4, is the simplest alkane.• The alkanes form a homologous series.

– Each member of the series differs by a specific number and kind of atoms.

C

H

HH

H or CH4

7


• The alkanes differ from each other by a CH2 or methylene group.

• All alkanes have this general formula.CnH2n+2

• For example ethane, C2H6 , and propane, C3H8 , are the next two family members.

8


• Isomers are chemical compounds that have the same molecular formulas but different structures.

• Two alkanes have the molecular formula C4H10.

– They are a specific type of isomer called structural isomers.

9


• Three alkanes have the formula C5H12.

– There are three structural isomers of pentane.

CH3

CH2

CH2

CH2

CH3

n-pentane

10




CH3

CH2

CH2

CH2

CH3 CH3

CH C

H2

CH3

CH3

n-pentane 2-methylbutane

11




12


• There are five isomeric hexanes, C6H14.You draw them!

CH3

CH2

CH2

CH2

CH2

CH3

n-hexane

13


• There are five isomeric hexanes, C6H14.

CH3

CH

2

CH2

CH

2

CH2

CH3CH3

CH C

H2

CH2

CH3

CH3

n-hexane 2-methylpentane

14



CH3

CH

2

CH2

CH

2

CH2

CH3CH3

CH C

H2

CH

2

CH3

CH3

CH3

CH

2

CH C

H2

CH3

CH3n-hexane 2-methylpentane 3-methylpentane

15



CH3

CH2

CH2

CH2

CH2

CH3CH3

CH C

H2

CH2

CH3

CH3

CH3

CH2

CH C

H2

CH3

CH3

CH3

CCH2 CH3

CH3

CH3

n-hexane 2-methylpentane 3-methylpentane

2,2-dimethylbutane

16



CH3

CH

2

CH2

CH

2

CH2

CH3CH3

CH C

H2

CH

2

CH3

CH3

CH3

CH

2

CH C

H2

CH3

CH3

CH3

CCH

2 CH3

CH3

CH3

CH3

CH C

H CH3

CH3

CH3

n-hexane 2-methylpentane 3-methylpentane

2,2-dimethylbutane 2,3-dimethylbutane

17


• The number of structural isomers increases rapidly with increasing numbers of carbon atoms.

• The boiling points of the alkanes increase with molecular weight.

18


• Cyclic saturated hydrocarbons are called cycloalkanes. – They have the general formula CnH2n.

• Some examples are:

CH2

CH2

CH2

CH2

CH2

cyclopentane

19




CH2

CH2

CH2

CH2

CH2CH2

CH2 CH2

CH2

CH2

CH2

cyclopentane cyclohexane

20




21

Naming Saturated Hydrocarbons

• The International Union of Pure and Applied Chemistry (IUPAC) names for the first 12 "straight-chain" or "normal" alkanes are given in this table.

Number of carbon atoms in chain Name

1 Methane

2 Ethane

3 Propane

4 Butane

5 Pentane

6 Hexane

22

Number of carbon atoms in chain Name

7 Heptane

8 Octane

9 Nonane

10 Decane

11 Unidecane

12 Dodecane


23


• Other organic compounds are named as derivatives of the alkanes.

• Branched-chain alkanes are named by the following rules.

1. Choose the longest continuous chain of carbon atoms which gives the basic name or stem.

24


2 Number each carbon atom in the basic chain, starting at the end that gives the lowest number to the first group attached to the main chain (substituent).

3 For each substituent on the chain, we indicate the position in the chain (by an Arabic numeric prefix) and the kind of substituent (by its name).

The position of a substituent on the chain is indicated by the lowest number possible.

The number precedes the name of the substituent.

25


4 When there are two or more substituents of a given kind, use prefixes to indicate the number of substituents.di = 2, tri = 3, tetra = 4, penta = 5, hexa = 6, hepta = 7, octa =

8, and so on.

5 The combined substituent numbers and names serve as a prefix for the basic hydrocarbon name.

6 Separate numbers from numbers by commas and numbers from words by hyphens. Words are "run together".

26


• Alkyl groups (represented by the symbol R) are common substituents.

– Alkyl groups are fragments of alkanes in which one H atom has been removed for the connection to the main chain.

– Alkyl groups have the general formula CnH2n+1.

• In alkyl groups the -ane suffix in the name of the parent alkane is replaced by -yl.

– A one carbon group is named methyl.

– A two carbon group is named ethyl.

– A three carbon group is named propyl.

27

Unsaturated Hydrocarbons

• The three classes of unsaturated hydrocarbons are:

1. alkenes and cycloalkenes, CnH2n

2. alkynes and cycloalkynes, CnH2n-2

3. aromatic hydrocarbons

28

Alkenes

• The simplest alkenes contain one C=C bond per molecule. – The general formula for simple alkenes is CnH2n.

• The first two alkenes are:– ethene, C2H4

29

Alkenes

• The simplest alkenes contain one C=C bond per molecule. – The general formula for simple alkenes is CnH2n.

• The first two alkenes are:– and propene, C3H6

30

Alkenes

• Each doubly bonded C atom is sp2 hybridized.

• The sp2 hybrid consists of:– two bonds (single bonds) and– one and one bond (double bond)

31

Alkenes

• The systematic naming system for alkenes uses the same stems as alkanes.

• In the IUPAC system, the -ane suffix for alkanes is changed to -ene. – Common names for the alkenes have the same stem but use

the suffix -ylene is used.

• In chains of four or more C atoms, a numerical prefix shows the position of the lowest-numbered doubly bonded C atom. – Always choose the longest chain that contains the C=C bond.

32

Alkenes

• Polyenes contain two or more double bonds per molecule.

• Indicate the number of double bonds with suffixes: – -adiene for two double bonds.

– -atriene for three double bonds, etc.

• The positions of the substituents are indicated as for alkanes.

• The position of the C=C bond(s) is/are given the lowest number(s) possible.

33

Alkenes

CC

CC

CC

H

H H

H

H

H

H

H

H

H

1,3-hexadiene

34

Alkenes

CC

CC

CCH

H H

H

H

H

H

H

1,3,5-hexatriene

CC

CC

CCH

H H

C

C

H

H

H

H

H H

H

HH

2,3-dimethyl-1,3,5-hexatriene

CC

CC

CC

H

H H

H

H

H

H

H

H

H

1,3-hexadiene

35

Cycloalkenes

• Cycloalkenes have the general formula CnH2n-2.

• Examples are:• cyclopentene

C C

CC

C

HH

H

HH

H

H

H

36

Cycloalkenes

• cyclohexene

C

CC

C

CCH

HH H

H

H

H

HH H

37

Cycloalkenes

• cycloheptene

C C

C

CCC

CH

HH

H HH

HH

HHHH

38

Alkynes

• Alkynes contain CC bonds.

• The simplest alkyne is C2H2, ethyne, or acetylene.

– Alkynes with only one C C bond have the formula CnH2n-2.

• Each carbon atom in a C C bond is sp hybridized.

– Each sp hybrid contains two bonds and two bonds.

– The carbon atom will have one single bond and one triple bond.

39

Alkynes

• Alkynes are named like the alkenes except that the suffix -yne is used with the characteristic stem – The alkyne stem is derived from the name of the

alkane with the same number of carbon atoms.

40

Alkynes

• Acetylene is an important industrial chemical. – It is prepared by the reaction of calcium carbide

with water.

sg222s2 CaO HCO H CaC

41

Alkynes

• Acetylene burns in a highly exothermic reaction– The combustion produces temperatures of about 3000°C.– Acetylene is used in cutting torches for welding.

• Alkynes are very reactive – The two bonds are sights of special reactivity.

• Addition reactions, such as hydrogenation, are common.

g2g2g2g22 OH2CO45O H2C

g62g2g22 HC 2H HC

42

Hydrocarbons: A Summary

Carbon Atom Hybridization C uses C forms Example

sp3

tetrahedral4 sp3 hybrids

4 bonds

CH4

sp2

trigonal planar3 sp2 hybrids & 1p orbital

3 bonds

1 bond

C2H4

sp linear2 sp hybrids &

2 p orbitals

2 bonds

2 bonds

C2H2

43

Aromatic Hydrocarbons

• Historically, aromatic was used to describe pleasant smelling substances.

• Now it refers to benzene, C6H6, and derivatives of benzene.– Other compounds that have similar chemical

properties to benzene are also called aromatic.

44

Benzene

• The structure of benzene, C6H6, is:

45

Other Aromatic Hydrocarbons

• Coal tar is the common source of benzene and many other aromatic compounds.

• Some aromatic hydrocarbons that contain fused rings are:

• napthalene

46


• phenanthrene

CC

CC

C

CC

C

CC

C

CC

C

H

H

H

HH

H

H

H

H

H

47


• Many aromatic hydrocarbons contain alkyl groups attached to benzene rings (as well as to other aromatic rings).

• The positions of the substituents on benzene rings are indicated by the prefixes:– ortho- (o-) for substituents on adjacent C atoms– meta- (m-) for substituents on C atoms 1 and 3– para- (p-) for substituents on C atoms 1 and 4

48

Functional Groups

• Functional groups are groups of atoms that represent potential reaction sites.

• Compounds that contain a given functional group usually undergo similar reactions.

• Functional groups influence physical properties as well.

49

Organic Halides

• A halogen atom may replace almost any hydrogen atom in a hydrocarbon.

• The functional group is the halide (-X) group. • Examples include:

– chloroform, CHCl3

CCl Cl

Cl

H

50

Organic Halides

• 1,2-dichloroethane, ClCH2CH2Cl

C CH

Cl

H

H

Cl

HH

C

HHH

51

Organic Halides

• para-dichlorobenzene

Cl

Cl

52

Alcohols and Phenols

• The functional group in alcohols and phenols is the hydroxyl (-OH) group.

• Alcohols and phenols can be considered derivatives of hydrocarbons in which one or more H atoms have been replaced by -OH groups.

• Phenols are derivatives of benzene in which one H has been replaced by replaced by -OH group.

53


• Ethyl alcohol (ethanol), C2H5OH, is the most familiar alcohol.

54


• Phenol, C6H5OH, is the most familiar phenol.

OH

55


• Alcohols are considered neutral compounds because they are only very slightly acidic.– Alcohols can behave as acids but only in the presence

of very strong bases.

• Phenols are weakly acidic.

– Ka 1.0 x 10-10 for phenol

– Although phenols are very weakly acidic, they are also very corrosive.

56


• Alcohols can be classified into three classes:

1. Primary (1°) alcohols like ethanol have the -OH group attached to a C atom that has one bond to another C atom.

CH3

CH2

OH

57


2. Secondary(2°) alcohols have the –OH group attached to a C atom that has bonds to 2 other C atoms.

• For example,2-propanol:

CH3

CH

CH3

OH

58


3. Tertiary (3°) alcohols have the –OH group attached to a C atom that is bonded to 3 other C atoms.

• For example, 2-methyl-2-propanol

CH3 C CH3

OH

CH3

59


• The stem for the parent hydrocarbon plus an -ol suffix is the systematic name for an alcohol.

• A numeric prefix indicates the position of the -OH group in alcohols with three or more C atoms.

• Common names are the name of the appropriate alkyl group plus alcohol.

60


• Alcohols are named using the stem for the parent hydrocarbon plus an -ol suffix in the systematic nomenclature.

• A numeric prefix indicates the position of the -OH group in alcohols with three or more C atoms. – Common alcohol names are the name of the appropriate alkyl group plus the word alcohol.

CH2

CH2

CH2

CH2

CH3

OHCH3

CH C

H2

CH2

CH3

OH

CH3

CH2

CH C

H2

CH3

OH

1-pentanol1-pentyl alcohol



61


• There are several isomeric monohydric acyclic (contains no rings) alcohols that contain more than three C atoms.

• There are four isomeric four-carbon alcohols.

62


• There are eight isomeric five-carbon alcohols.

CH2

CH2

CH2

CH2

CH3

OHCH3

CH C

H2

CH2

CH3

OH

CH3

CH2

CH C

H2

CH3

OH

1-pentanol 2-pentanol 3-pentanol

CH2

CH C

H2

CH3OH

CH3

CH3 C CH2

CH3

CH3

OHCH3

CH C

H CH3

OH

CH3

2-methyl-1-butanol 2-methyl-2-butanol 3-methyl-2-butanol

CH3

CH C

H2

CH

2CH3

OH

3-methyl-1-butanol

CH3 C CH2

CH3

CH3OH

2,2-dimethyl-1-propanol

63


• Polyhydric alcohols contain more than one -OH group per molecule.

CH2

CH CH2

OH

OH

OH

CH2

CH C

H CH C

H CH2OH

OH

OH

OH

OH

OH

glycerin sorbitol

64


• Phenols are usually called by their common (trivial) names.

OH

OH

resorcinol

65



OH

OH

OH

CH3

resorcinol o-cresol

66



OH

OH

OH

CH3

OH

CH3

resorcinol o-cresol m-cresol

67



OH

OH

OH

CH3

OH

CH3

OH

CH3

resorcinol o-cresol m-cresol p-cresol

68


• Because the -OH group is quite polar, the properties of alcohols depend upon the number of -OH groups per molecule and the size of the organic group.

• The boiling points of monohydric alcohols increase with increasing molecular weight.

• The solubility of monohydric alcohols in water decrease with increasing molecular weight.

• Polyhydric alcohols are more soluble in water because of the two or more polar groups (-OH).

69

Ethers

• Ethers may be thought of as derivatives of water in which both H atoms have been replaced by alkyl or aryl groups.

HO

H

water

70

Ethers


HO

H CH3

OH

water an alcohol

71

Ethers


HO

H CH3

OH CH3

OCH3

water an alcohol an ether

72

Ethers

• Ethers are not very polar and not very reactive.

• They are excellent solvents.

• Common names are used for most ethers.

73

Aldehydes and Ketones

• The functional group in aldehydes and ketones is the carbonyl group.

O

R2R1 or H

carbonyl group

74


• Except for formaldehyde, aldehydes have one H atom and one organic group bonded to a carbonyl group.

75


• Ketones have two organic groups bonded to a carbonyl group.

76


• Common names for aldehydes are derived from the name of the acid with the same number of C atoms.

• IUPAC names are derived from the parent hydrocarbon name by replacing -e with -al.

C

O

CH2

CH2

CH2

CH3 H

pentanal orpentyl aldehyde

77




C

O

CH2

CH2

CH2

CH3 HC

O

CCH3

CH3

CH3

H


2,3-dimethylproponal or2,3-dimethylpropionaldehyde

78




C

O

CH2

CH2

CH2

CH3 HC

O

CCH3

CH3

CH3

HC

O

H


2,3-dimethylproponal or2,3-dimethylpropionaldehyde

benzanal orbenzyl aldehyde

79


• The IUPAC name for a ketone is the characteristic stem for the parent hydrocarbon plus the suffix -one.

• A numeric prefix indicates the position of the carbonyl group in a chain or on a ring.

C

O

CH2

CH2

CH2

CH3 CH3

2-hexanone ormethyl pentyl ketone

80




C

O

CH2

CH2

CH2

CH3 CH3


CH3

CH

2

CH2

CCH2

CH3

O

3-hexanone orethyl propyl ketone

81




C

O

CH2

CH2

CH2

CH3 CH3


CH3

CH2

CH2

CCH2

CH3

O

3-hexanone orethyl propyl ketone

CCH3O

acetophenone ormethyl phenyl ketone

82


• Many aldehydes and ketones occur in nature.

CHCH

COH

cinnamaldehyde

O

CH3

CH3OH

testosterone

83

Amines

• Amines are derivatives of ammonia in which one or more H atoms have been replaced by organic groups (aliphatic or aromatic or a mixture of both).

• There are three classes of amines.

HN

HH

ammonia

84

Amines


• There are three classes of amines.H

NH

HCH3

NH

H

ammonia primary amine

85

Amines


• There are three classes of amines.H

NH

HCH3

NH

H

CH3

NH

CH3


secondary amine

86

Amines


• There are three classes of amines.

HN

HH

CH3

NH

H

CH3

NH

CH3

CH3

NCH3

CH3


secondary amine

tertiary amine

87

Amines

• Aniline is the simplest aromatic amine. It is much less basic than NH3.

• Aniline is a very important industrial chemical.

88

Amines

• Heterocylic amines have one or more N atoms in a ring structure.

• Many are important in living systems.

N

pyridine

89

Amines



N

pyridine

N

N

pyrimidine

90

Amines



N

pyridine

N

N

pyrimidine

N

N

N

N

purine

91

Carboxylic Acids

• Carboxylic acids contain the carboxyl functional group.

• The general formula for carboxylic acids is:– R represents an alkyl or an aryl group

COH

O

R1

COH

O

92

Carboxylic Acids

• IUPAC names for a carboxylic acid are derived from the name of the parent hydrocarbon.

– The final -e is dropped from the name of the parent hydrocarbon

– The suffix -oic is added followed by the word acid.

• Many organic acids are called by their common (trivial) names which are derived from Greek or Latin.

93

Carboxylic Acids

• Positions of substituents on carboxylic acid chains are indicated by numeric prefixes as in other compounds – Begin the counting scheme from the carboxyl

group carbon atom. • They are also often indicated by lower case Greek

letters. = 1st C atom = 2nd C atom = 3rd C atom, etc.

94

Carboxylic Acids

CH C

OH

O

CH3

CH3

2-methylpropanoic acid or-methylpropanoic acid

95

Carboxylic Acids

CH C

OH

O

CH3

CH3


CH3

CH C

H2

COH

OCH3

3-methylbutanoic acid or-methylbutanoic acid

96

Carboxylic Acids

CH C

OH

O

CH3

CH3


CH3

CH C

H2

COH

OCH3

3-methylbutanoic acid or-methylbutanoic acid

CH3 CH C

H2

CH2

COH

O

CH3

4-methylpentanoic acid or-methylpentanoic acid

97

Carboxylic Acids

• Dicarboxylic acids contain two carboxyl groups per molecule.

OH

C C

OHO

O

oxalic acid

98

Nomenclature of Carboxylic Acids• Dicarboxylic acids contain two carboxyl groups per

molecule.

OH

C C

OHO

OOH

CCH2

COH

O O

oxalic acid malonic acid

99

Nomenclature of Carboxylic Acids• Dicarboxylic acids contain two carboxyl groups per

molecule.

OH

C C

OHO

OOH

CCH2

COH

O O

OHC

CH2

CH2

COH

O

O

oxalic acid malonic acid succinic acid

100

Carboxylic Acids• Aromatic acids are usually called by their

common names.

• Sometimes, they are named as derivatives of benzoic acid which is considered to be the "parent" aromatic acid.

101

Carboxylic Acids

OOHOOH

Cl

benzoic acid p-chlorobenzoic acid

102

Carboxylic Acids

OOHOOH

Cl

OOH

CH3

O

OH

O

OH

benzoic acid p-chlorobenzoic acid

p-toluic acid phthalic acid

103

Carboxylic Acids

• Acid strengths of simple carboxylic acids vary little with chain length.

• However, substituents on a carbon atom in the chain can cause large variations in acid strengths .

104

Carboxylic Acids

COH

O

H

CH3

COH

O

OHC

CH2

CH3

O

Compound Name Ka

formic acid

acetic acid

propionic acid

1.8 x 10-4

1.8 x 10-5

1.4 x 10-5

105

Carboxylic Acids

CH2

COH

O

Cl

Compound Name Ka

monochloroacetic acid 1.5 x 10-3

CH3

COH

O

acetic acid 1.8 x 10-5

CH C

OH

O

Cl

Cl dichloroacetic acid 5.0 x 10-2

CC

OH

O

ClCl

Cltrichloroacetic acid 2.0 x 10-1

106

Carboxylic Acids

• The -OH group in the carboxyl group of carboxylic acids, is displaced in many of their reactions.

• The non -OH portion of a carboxylic acid is called an acyl group.

R1C

OH

O

R1C

O

carboxyl group acyl group

107

Some Derivatives of Carboxylic Acids• Four important classes of compounds contain

acyl groups – They are all considered to be derivatives of

carboxylic acids.

• In these structures R's may represent either alkyl or aryl groups.

108

Some Derivatives of Carboxylic Acids

R1C

OC

R1

O O

R1C

Cl

O

acid anhydride acid chloride

109


R1C

OC

R1

O O

R1C

Cl

O

R1C

OR2

O

R1C

NH2

O

acid anhydride acid chloride

ester amide

110

Some Derivatives of Carboxylic Acids• Acid anhydrides are related to their parent acids as

follows:– The word anhydride means without water.

CH3

COH

O

2CH3 O CH3

O O

+ H2O

acetic acid acetic anhydride

111

Some Derivatives of Carboxylic Acids• Acyl halides are much more reactive, and more

volatile, than their parent acids. • They react with water to form their parent acids and a

hydrohalic acid.

CH3

CCl

O

CH3 OH

O

+ HCl

acetyl chloride acetic acid

H2O+

112

Some Derivatives of Carboxylic Acids• Acyl halides are prepared by reacting their parent

acids with PCl3, PCl5, or SOCl2.

• The more volatile acid halide is then distilled out of the reaction mixture.

OOH

+ PCl5

OCl

benzoic acid benzoyl chloride

113

Some Derivatives of Carboxylic Acids• Esters are prepared by heating a carboxylic acid with

an alcohol in the presence of a small amount of an inorganic acid. – The reaction mixture will contain some ester and water, as

well as unreacted acid and alcohol.

CH3

COH

OCH2

OHCH3

+H2SO4

CH3

CO

CH2

CH3

O

+ H2O

ethanoic acid or acetic acid

ethanol orethyl alcohol

ethyl ethanoate orethyl acetate

114

Some Derivatives of Carboxylic Acids• Esters are usually called by their common names. • Many simple esters occur naturally and have pleasant

odors. – Esters are frequently used in fragrances and as artificial

flavors.

CH2

CO

CH2

CH3

O

CH2

CH3

ethyl butanoate or ethyl butyrateodor of pineapples

CH3 OCH2

CH2

CH2

CH2

CH2

CH2

CH2

CH3

O

octyl ethanoate or octyl acetate odor of oranges

115

Some Derivatives of Carboxylic Acids• Fats are solid esters of glycerol and (mostly) saturated

acids at room temperature.

• Oils are liquid esters of glycerol and primarily unsaturated acids at room temperature.

• The "acid" parts of fats and oils usually contain even numbers of C atoms in naturally occurring fats and oils.

– 16 and 18 carbon chains are the most commonly found chain sizes in nature.

116


• Some acids that are found (as their esters) in fats and oils include:

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

COH

O

palmitic acid CH3(CH2)14COOH

117

Some Derivatives of Carboxylic Acids• Stearic acid is often found in beef fat.

CH3

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

CH2

COH

O

stearic acid CH3(CH2)16COOH

118

Some Derivatives of Carboxylic Acids• Triglycerides are the triesters of glycerol.• The common name for triglycerides is tri (acid

stem) plus an -in suffix.– For example, tripalmitin.

119

Some Derivatives of Carboxylic Acids• Waxes are esters of long chain fatty acids and

alcohols other than glycerol.

– Commonly, waxes are derived from monohydric alcohols.

• Beeswax and carnauba wax are esters of myricyl alcohol, C30H61OH.

120


• Carnauba wax is often used in car waxes.

carnauba wax

C

O

OC25H51

C30H61

121

Some Derivatives of Carboxylic Acids• Dihydric alcohols (2 –OH’s per molecule) can react with

dicarboxylic acids (2 –COOH’s per molecule) to form polyesters.

• Ester linkages are formed at both ends of both molecules to give polymeric esters with very high molecular weights.

C

OH

C

OH

O

O+ C

H2CH2

OHOH

terephthalic aciddicarboxylic acid

ethylene glycoldihydric alcohol

122


CO

CO

O

O

CH2

CH2

O

*

*n

dacron

123

Some Derivatives of Carboxylic Acids• Amides are derivatives of organic acids and primary

or secondary amines. • The functional groups of amides are:

CN

O

R2

H

R1C

N

O

R2

R3

R1orCN

O

H

H

R1 or

124

Some Derivatives of Carboxylic Acids• Amides are also named as derivatives of carboxylic

acids. • The suffix -amide is substituted for -ic acid or -oic

acid.

CN

O

H

H

CH3

CNH2O

ethanamide or acetamide

benzamide

125

Some Derivatives of Carboxylic Acids• When an aryl or alkyl substituent is present on the N

atom, the letter N and the name of the substituent are prefixed to the name of the unsubstituted amide.

CN

O

CH3

H

CH3

CNO

CH3

CH2

CH3

N-ethylethanamide or N-ethylacetamide

N-ethyl-N-methylbenzamide

126

Some Derivatives of Carboxylic Acids• Acetaminophen – “Tylenol” - is an amide.

127

Summary of the Functional Groups

• A summary of the functional groups is:

129

Substitution Reactions

• In a substitution reaction an atom or group of atoms attached to a carbon atom is replaced (substituted for) by another atom or group of atoms. – There is no change in the degree of saturation at

the reactive carbon atom.• Halogenation reactions are an important class of

substitution reactions. – Chlorine reacts with alkanes in free radical

chain reactions (also substitution reactions).

130


• Free radical chain reactions– The halogenation of methane is one example.

heat oruv light

Cl··

···· .2

free radicals

Cl Cl······

··

··

····

131


Cl··

···· .+ H C

H

H··

····. + ··Cl

····

··HH C H

H

H··

······

heat oruv light

free radicals

Cl Cl······

··

··

···· 2 Cl

····

·· .

methyl radical

132


H C

H

H··

····. + Cl Cl····

··

··

··

···· + Cl

····

·· .H C

H

H··

···· Cl···· ····

methyl radical

Cl··

···· .+ H C

H

H··

····. + ··Cl

····

··HH C H

H

H··

······

heat oruv light

free radicals

2 Cl··

···· .Cl Cl····

··

··

··

····

methyl chloride

133


• Free radical chain reactions– Many substitution reactions of alkanes produce

more than one product.

C ClH

H

H

+ Cl Cl C

H

H

ClCl + HCl

134


C ClH

H

H

+ Cl Cl C

H

H

ClCl + HCl

C

H

H

ClCl + Cl Cl C

H

Cl

ClCl + HCl

135


HCl

C

H

Cl

ClCl + Cl Cl C

Cl

Cl

ClCl + HCl

C

H

H

ClCl + Cl Cl C

H

Cl

ClCl +

C ClH

H

H

+ Cl Cl C

H

H

ClCl + HCl

136


• Nitration reaction of an aromatic hydrocarbon replaces an H atom attached to an aromatic ring with a nitro, -NO2, group.

+ 2H SO4HNO2

NO2

137

Addition Reactions

• An addition reaction involves an increase in the number of groups attached to carbon. – The degree of saturation of the molecule is increased.

C C

H

H H

H

+ Cl C CH

Cl

H

HH

Cl2

138

Addition Reactions

• Hydrogenation is a very important kind of addition reaction.– Hydrogenation is used to convert unsaturated fats and oils to

saturated fats or oils.

C C

H

H H

H

+ H C CH

H

H

HH

H2

139

Elimination Reactions

• An elimination reaction involves the removal of groups attached to carbon.– The degree of unsaturation increases.

C C

CH3CH3

HH

CH3

CH CH

BrBr

CH3

Zn in

acetic acidor ethanol

C C

CH3 H

CH3H

+ ZnBr2

mixture of cis & trans-2-butene

+

140

Elimination Reactions

• Dehydration is an important kind of elimination reaction.

concentrated

2H SO4

C C

H H

HH

H

CH CH

OHH

H+ H O2

141

Polymerization Reactions

• A polymer is a large molecule that consists of a high-molecular weight chain of small molecules.– The small molecules that have been joined to form

the polymer are called monomers.

• Synthetic polymers are a relatively new class of molecules.– The first one, bakelite, was discovered in 1909.– Nylon, which is still extensively used, was

discovered in 1930’s.

142


• Addition polymerization is a large commercial process in the United States.

• Polyethylene is the addition polymer made in the largest quantities in the United States.– Polyethylene is used to make Coke bottles, plastic

bags, etc.

143


• Addition polymerization– Polyethylene formation

CH2 CH2n

ethylene

catalyst* CH2 CH2 *n

polyethylene

144


• Addition polymerization– Teflon is the material used in nonstick frying pans and

other kitchen utensils.

C C

F

F F

F

ncatalyst

C C

F

F F

F

** n

polytetrafluoroethylene or Teflon

tetrafluoroethylene

heat

145


• Formation of rubber– Natural rubber is a polymer made of isoprene (2-

methyl-1,3-butadiene) units that form a unique stereoisomeric structure.

2n

natural rubberisoprene

CH2

C CH

CH2

CH3

CH2

CCH

CH2

CH2

CCH

CH2*

CH3 CH3

*n

146


• Vulcanization of rubber– Natural rubber is a sticky, soft compound when heated

which limited its commercial potential.

• Charles Goodyear discovered in 1839 that heating rubber with sulfur removed the stickiness and made the substance elastic.– This is the basis of modern tire production.

• Vulcanization provides disulfide cross-linking bonds between the isoprene units.

147


• Copolymers– If two different monomers are mixed and the

polymerized, copolymers are formed.

• Styrene butadiene rubber - SBR - is an important copolymer used in tire production.

148


• Copolymers

3

styrenebutadiene

C CC C

H

H

H

H H

H CCH

H

H

+

149


CH2

CC

CH2 CH2

CC

CH2

CH2

CCH2

CC

CH2

**

H

H

H

HH H

H

n

Styrene - butadiene rubber (SBR)

150


• Condensation Polymers– Condensation polymers occur when two molecules

react and eliminate a small molecule.– Molecules eliminated commonly are water and HCl.

• Important condensation polymers include nylon, dacron, and kevlar.– Dacron is used in clothing to make it wrinkle free. – Blood does not clot in contact with dacron thus it is

used in artificial arteries.

151


• Condensation Polymers– Dacron formation

terephthalic acidethylene glycol

CH2

CH2

OHOH

COOH

O OH

+

152


C

O

OCO

OCH2

CH2

CH2

O HCH2

OH n

Dacron is a polyester

+ H2O

153


• Condensation Polymers

• Nylon was first made by Wallace Carothers in the 1930’s.– Nylon is widely used in a variety of commercial

products including stockings, rope, guitar strings, fire-proof clothing.

154


• Condensation Polymers– Nylon 66 formation

OHC

CH2

CH2

CH2

CH2

COH

O

O

NH2

CH2

CH2

CH2

CH2

CH2

CH2

NH2+

adipic acid hexamethylene diamine

155


+ H2ONH2

CCH2

CH

2

CH2

CH

2

CNH

CH2

CH

2

CH2

CH

2

CH2

CH

2

NH

COH

O

O

O

n

Nylon is a polyamide

156

Synthesis Question

• TNT, the explosive ingredient in dynamite, has the correct name of 2,4,6-trinitrotoluene. Draw the structure of TNT.

157

Synthesis Question

CH3

NOO N

NO

2

2

2

TNT or 2,4,6-trinitrotoluene

27Organic Chemistry I: Formulas, Names,

and Properties

27 Organic Chemistry I: Formulas, Names, and Properties.

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Transcript of 27 Organic Chemistry I: Formulas, Names, and Properties.