Chapter 11: Alkenes, Alkynes, and Aromatic Compounds

Chemistry 506Dr. Hunter’s ClassChapter 11.1

Chemistry 506: Allied Health Chemistry 2

Chapter 11: Alkenes, Alkynes, and Aromatic Compounds Hydrocarbons with Multiple Bonds

Introduction to General, Organic & Biochemistry, 5th Edition by Bettelheim and March: Chapter 11, Pages 353-390

Outline Notes by Dr. Allen D. Hunter, YSU Department of Chemistry, 2000.

Outline

11A Section(s)11.1/2/4 Introduction and Nomenclature of Alkenes......

11B Section(s)11.3 -Bonds......

11C Section(s)11.5 Physical Properties......

11D Section(s)11.6 Chemical Properties: Addition Reactions......

11E Section(s)11.7 Addition Polymers......

11F Section(s)11.8 Alkynes......

11G Section(s)11.9/10 Aromatic Hydrocarbons......

11H Section(s)18.2 Amino Acids having Simple Aromatic Side Chains......

11I Section(s)11.11 Aromatic Reactions......

11J Section(s)11.12 Fused Ring Aromatics......

11K Section(s)11.13 Heterocyclics (Not covered in detail)......

11A Section(s) 11.1/2/4Introduction and Nomenclature of Alkenes

Ethene = (Ethylene), CH2=CH2

IUPAC Rules

Start numbering from the end that gives the double bond the lowest number.

Indicate position of double bond(s) by numbers.

Use the ene ending

Indicated number of double bonds by prefixes (ene, diene, triene, tetraene, etc.)

Examples

Geometric Isomers

No free rotation (-bonds)

Experimental observations

cis isomers vs. trans isomers

Examples

11B Section(s) 11.3-Bonds

Bonding: sp2 hybridization for 3 -bonds to the three atoms bonded to each carbon

pz orbital for -bond

Typical C=C bond distance (i.e., 1.34 )

slightly shorter C-H distance than alkanes

11C Section(s) 11.5Physical Properties

Almost identical to Alkanes of same MW

Van der Waals forces

Slightly higher Mp and Bp

Smell (turpentine like)

Density

Solubility

11D Section(s) 11.6Chemical Properties: Addition Reactions

Addition reaction (generic)

-bonds weaker than -bonds

Hydrogenation: Addition of H2 or D2 (Pt catalyst)

Addition of Cl2 or Br2 (X2)

Addition of HX ((HF) HCl, HBr (HI))

Halide Influences

Markovnikov Addition

Addition of Water (Hydration)

H+ Catalyst

Markovnikov

11E Section(s) 11.7Addition Polymers

Definition of Addition Polymers

No loss of mass

Rapid chain growth

-bond opening

“Generic” Synthesis Reaction

typical monomers are CH2=CH-R

Role of Catalysts

Speed reaction but aren’t themselves consumed

Highly reactive species

Reversibility of Reactions

Polymerization under low temperatures/high pressures

i.e., monomer (liquids or gasses) -> polymer (solids)

Depolymerizations (unraveling) at high temperatures

i.e., polymer -> monomer

Molecular Weights and Molecular Weight Distributions

High average Molecular Weights

Distributions rather than discrete weights

Linear Chains vs. Branched Chains

Examples

Polyethylene, PE, Synthesis

CH2=CH2, R = H

Poly(vinyl chloride), PVC, Synthesis

CH2=CH-Cl, R = Cl

Polypropylene, PP, Synthesis

CH2=CH-CH3, R = CH3

Polystyrene, PS, Synthesis

CH2=CH-C6H5, R = C6H5

Poly(methyl methacrylate), PMMA, Synthesis

CH2=C(CH3)(CO2CH3)

Teflon Synthesis

CF2=CF2

Rubber (Polyisoprene) Synthesis

CH2=CH-CH=CH2

11F Section(s) 11.8Alkynes

Carbon-Carbon Triple Bonds

sp hybridized

Very Short CC Bond distance (i.e., 1.20  ), much shorter than the C=C distance (i.e., 1.34 ) and the C-C distance (i.e., 1.20 )

Bonding: 1 -bond and 2 -bonds (px and py)

slightly shorter C-H distance than alkanes or even alkanes

Ethyne = Acetylene, H-CC-H

Physical Properties

Almost identical to Alkanes/Alkenes of same MW

Van der Waals forces

Slightly higher Mp and Bp

Density

Solubility

Nomenclature

yne ending

yne > ene in priority of naming

Examples

Alkyne Reactions

Generic Reaction

Very like Alkenes

Normally Double Addition

Hydrogenation: Addition of H2 or D2 (Pt catalyst)

Addition of X2 (Cl2 or Br2)

Addition of HX (most commonly HCl and HBr)

Markovnikov Addition

Addition of H2O (H+ catalyst)

Markovnikov Addition

Secondary elimination of water from diol

gives carbonyl group (aldehyde or ketone)

11G Section(s) 11.9/10Aromatic Hydrocarbons

Sources

Coal Tar

Coke production

Direct separation

Start of industrial chemistry

Petroleum

multiple processing steps

Uses

Octane enhancers in gasoline

Plastics

Pigments/Dyes

Pharmaceuticals

Aromatic: Properties, Reactivity, C/H Ratios (cf. Alkane/Alkenes/Alkynes)

Substitution Reactions not Addition Reactions (i.e., not like alkenes)

Bonding / Resonance Stabilization

Nomenclature

IUPAC Names

Halobenzenes (X = F, Cl, Br, I)

Nitrobenzene (Z = NO2)

Alkylbenzenes (phenylalkanes)

Common Names (IUPAC)

Phenol(Z = OH)

Aniline (Z = NH2)

Toluene (Z = CH3, methylbenzene)

Benzoic Acid (Z = CO2H)

Multiply Substituted Arenes

Numbering Ring Positions

Ortho, Meta, Para, Ipso

As Side Chains (phenyl groups)

11H Section(s) 18.2Amino Acids having Simple Aromatic Side Chains

Generic AA = H2N-CHR-CO2H

Phenyl Alanine (non-polar)

R = CH2C6H5

PKU

11I Section(s) 11.11Aromatic Reactions

Substitution Reactions

Require catalyst

"Generic"

Z+Electrophiles

Nitration (Z = NO2, HNO3/H2SO4, TNT)

Sulfonation (Z = SO3H, H2SO4/SO3)

Halogenation (X = Cl or Br, Cl2/Fe or Br2/Fe)

11J Section(s) 11.12Fused Ring Aromatics

Polycyclic Aromatic Hydrocarbons, PAHs

Toxicity

Naphthalene (C10H8)

Anthracene (C14H10)

Phenanthrene (C14H10)

11K Section(s) 11.13Heterocyclics (Not covered in detail)

Replace C-H by Heteroatom Groups such as: N, O, S, etc.

Important in Biomolecules

Pyridine (C5H5N)

Problems: All up to 11.50

Index of Topics and Vocabulary

2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University

Chemistry 506Dr. Hunter’s ClassChapter 11.1

1.20 ...... 13

1.34 ...... 4, 13

4

Acetylene...... 13

Addition...... 15

Addition of HX...... 7

Addition of Water...... 7

Addition Polymers...... 8

Addition reaction...... 6

Addition Reactions...... 18

aldehyde...... 16

alkanes...... 4

alkenes...... 18

Alkenes...... 15

Alkylbenzenes...... 19

Alkyne Reactions...... 15

Alkynes...... 13

Amino Acids having Simple Aromatic Side Chains....22

Aniline...... 20

Anthracene...... 25

Arenes...... 21

Aromatic...... 17

Aromatic Hydrocarbons...... 17

Aromatic Reactions...... 23

Benzoic Acid...... 20

Biomolecules...... 26

Bonding...... 4, 13, 18

Bp...... 5, 13

Br2...... 6, 15

Br2/Fe...... 24

Branched Chains...... 9

CC Bond distance...... 13

C/H Ratios...... 17

C=C bond distance...... 4

C=C distance...... 13

C10H8...... 25

C14H10...... 25

C5H5N...... 26

Carbon-Carbon Triple Bonds...... 13

carbonyl group...... 16

catalyst...... 23

Catalysts...... 8

C-C distance...... 13

CF2=CF2...... 12

C-H distance...... 4, 13

CH2=C(CH3)(CO2CH3)...... 11

CH2=CH2...... 2, 10

CH2=CH-C6H5...... 11

CH2=CH-CH=CH2...... 12

CH2=CH-CH3...... 11

CH2=CH-Cl...... 10

CH2=CH-R...... 8

chain growth...... 8

Chemical Properties: Addition Reactions...... 6

cis isomers...... 3

Cl2...... 6, 15

Cl2/Fe...... 24

Coal Tar...... 17

Coke...... 17

Common Names...... 20

D2...... 6, 15

Density...... 5, 13

Depolymerizations...... 9

diene...... 2

diol...... 16

Double Addition...... 15

Dyes...... 17

Electrophiles...... 23

ene...... 2, 14

ene ending...... 2

Ethene...... 2

Ethylene...... 2

Ethyne...... 13

free rotation...... 3

Fused Ring Aromatics...... 25

gasoline...... 17

Geometric Isomers...... 3

H+ catalyst...... 16

H+ Catalyst...... 7

H2...... 6, 15

H2O...... 16

H2SO4/SO3...... 24

Halide Influences...... 7

Halobenzenes...... 19

Halogenation...... 24

HBr...... 7, 16

H-CC-H...... 13

HCl...... 7, 16

Heteroatom Groups...... 26

Heterocyclics...... 26

HF...... 7

HI...... 7

HNO3/H2SO4...... 23

HX...... 7, 16

Hydration...... 7

Hydrogenation...... 6, 15

industrial chemistry...... 17

Ipso...... 21

IUPAC Names...... 19

IUPAC Rules...... 2

ketone...... 16

Linear Chains...... 9

Markovnikov...... 7

Markovnikov Addition...... 7, 16

Meta...... 21

methylbenzene...... 20

Molecular Weight Distributions...... 9

Molecular Weights...... 9

monomer...... 9

monomers...... 8

Mp...... 5, 13

Naphthalene...... 25

Nitration...... 23

Nitrobenzene...... 19

Nomenclature...... 14, 19

Octane...... 17

Ortho...... 21

PAH...... 25

Para...... 21

PE...... 10

Petroleum...... 17

Pharmaceuticals...... 17

Phenanthrene...... 25

Phenol...... 20

Phenyl Alanine...... 22

phenyl groups...... 21

phenylalkanes...... 19

Physical Properties...... 5, 13

Pigments...... 17

PKU...... 22

Plastics...... 17

PMMA...... 11

Poly(methyl methacrylate)...... 11

Poly(vinyl chloride)...... 10

Polycyclic Aromatic Hydrocarbons...... 25

Polyethylene...... 10

Polyisoprene...... 12

Polymerization...... 9

Polymers...... 8

Polypropylene...... 10

Polystyrene...... 11

PP...... 10

Problems...... 26

Properties...... 17

PS...... 11

Pt catalyst...... 6, 15

PVC...... 10

px...... 13

py...... 13

Pyridine...... 26

pz...... 4

Resonance Stabilization...... 18

Reversibility of Reactions...... 9

Ring Positions...... 21

Rubber...... 12

Secondary elimination of water...... 16

Smell...... 5

Solubility...... 5, 13

sp hybridized...... 13

sp2 hybridization...... 4

Substitution Reactions...... 18, 23

Sulfonation...... 24

Teflon...... 12

tetraene...... 2

TNT...... 23

Toluene...... 20

trans isomers...... 3

triene...... 2

Van der Waals forces...... 5, 13

X2...... 6, 15

yne ending...... 14

Z+...... 23



...... 4



-bond...... 4

-bond opening...... 8

-bonds...... 3, 13

-Bonds...... 4

-bonds weaker than -bonds...... 6



-bond...... 13

-bonds...... 4

2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University

Chemistry 506Dr. Hunter’s ClassChapter 11.1

2000, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University