Chapter 11: Alkenes, Alkynes, and Aromatic...
Transcript of Chapter 11: Alkenes, Alkynes, and Aromatic...
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 1/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506: Allied Health Chemistry 2
Section 2: Alkenes, Alkynes, and Aromatic Compounds
Hydrocarbons with Multiple Bonds
Outline
SECTION 2.1 INTRODUCTION AND NOMENCLATURE OF ALKENES.................................................2
SECTION 2.2 π-BONDS.......................................................................................................................................4
SECTION 2.3 PHYSICAL PROPERTIES .........................................................................................................5
SECTION 2.4 CHEMICAL PROPERTIES: ADDITION REACTIONS .......................................................6
SECTION 2.5 ADDITION POLYMERS ............................................................................................................8
SECTION 2.6 ALKYNES...................................................................................................................................13
SECTION 2.7 AROMATIC HYDROCARBONS.............................................................................................17
SECTION 2.8 AMINO ACIDS HAVING SIMPLE AROMATIC SIDE CHAINS .......................................22
SECTION 2.9 AROMATIC REACTIONS .......................................................................................................23
SECTION 2.10 FUSED RING AROMATICS ..................................................................................................25
SECTION 2.11 HETEROCYCLICS (NOT COVERED IN DETAIL)...........................................................26
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 2/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.1 Introduction 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
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 3/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Geometric Isomers
No free rotation (π-bonds)
Experimental observations
cis isomers vs. trans isomers
Examples
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 4/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.2 π-Bonds
Bonding: sp2 hybridization for 3 σ-bonds to the three atoms
bonded to each carbon
pz orbital for π-bond
Typical C=C bond distance (i.e., 1.34 Å) and thus shorter than
the C-C distance (i.e., 1.54 Å)
slightly shorter C-H distance than alkanes
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 5/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.3 Physical Properties
Almost identical to Alkanes of same MW
Van der Waals forces
Slightly higher Mp and Bp
Smell (turpentine like)
Density
Solubility
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.4 Chemical Properties: Addition Reactions
Addition reaction (generic)
π-bonds weaker than σ-bonds
Hydrogenation: Addition of H2 or D2 (Pt catalyst)
Addition of Cl2 or Br2 (X2)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 7/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Addition of HX ((HF) HCl, HBr (HI))
Halide Influences
Markovnikov Addition
Addition of Water (Hydration)
H+ Catalyst
Markovnikov
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 8/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.5 Addition Polymers
Definition of Addition Polymers
No loss of mass
Rapid chain growth
π-bond opening
“Generic” Synthesis Reaction
typical monomers are CH2=CH-R
Role of Catalysts
Speed reaction but aren’t themselves consumed
Highly reactive species
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
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
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 10/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Examples
Polyethylene, PE, Synthesis
CH2=CH2, R = H
Poly(vinyl chloride), PVC, Synthesis
CH2=CH-Cl, R = Cl
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 11/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
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)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 12/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Teflon Synthesis
CF2=CF2
Rubber (Polyisoprene) Synthesis
CH2=CH-CH=CH2
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.6 Alkynes
Carbon-Carbon Triple Bonds
sp hybridized
Very Short C≡C Bond distance (i.e., 1.20 Å ), much shorter
than the C=C distance (i.e., 1.34 Å) and the C-C distance
(i.e., 1.54 Å)
Bonding: 1 σ-bond and 2 π-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
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 14/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Nomenclature
yne ending
yne > ene in priority of naming
Examples
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Alkyne Reactions
Generic Reaction
Very like Alkenes
Normally Double Addition
Hydrogenation: Addition of H2 or D2 (Pt catalyst)
Addition of X2 (Cl2 or Br2)
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
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)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 17/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.7 Aromatic 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)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 18/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Substitution Reactions not Addition Reactions (i.e., not like
alkenes)
Bonding / Resonance Stabilization
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Nomenclature
IUPAC Names
Halobenzenes (X = F, Cl, Br, I)
Nitrobenzene (Z = NO2)
Alkylbenzenes (phenylalkanes)
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Common Names (IUPAC)
Phenol (Z = OH)
Aniline (Z = NH2)
Toluene (Z = CH3, methylbenzene)
Benzoic Acid (Z = CO2H)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 21/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Multiply Substituted Arenes
Numbering Ring Positions
Ortho, Meta, Para, Ipso
As Side Chains (phenyl groups)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 22/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.8 Amino Acids having Simple Aromatic Side Chains
Generic AA = H2N-CHR-CO2H
Phenyl Alanine (non-polar)
R = CH2C6H5
PKU
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2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.9 Aromatic Reactions
Substitution Reactions
Require catalyst
"Generic"
Z+ Electrophiles
Nitration (Z = NO2, HNO3/H2SO4, TNT)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 24/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Sulfonation (Z = SO3H, H2SO4/SO3)
Halogenation (X = Cl or Br, Cl2/Fe or Br2/Fe)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 25/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.10 Fused Ring Aromatics
Polycyclic Aromatic Hydrocarbons, PAHs
Toxicity
Naphthalene (C10H8)
Anthracene (C14H10)
Phenanthrene (C14H10)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 26/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Section 2.11 Heterocyclics (Not covered in detail)
Replace C-H by Heteroatom Groups such as: N, O, S, etc.
Important in Biomolecules
Pyridine (C5H5N)
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 27/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Index of Topics and Vocabulary
1.20 ................................. 4, 13 1.34 ................................. 4, 13 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 ........................4, 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
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 28/29
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
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
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 29/29
Poly(vinyl chloride) ................ 10 Polycyclic Aromatic
Hydrocarbons ....................... 25 Polyethylene............................ 10 Polyisoprene............................ 12 Polymerization .......................... 9 Polymers.................................... 8 Polypropylene ....................... See Polystyrene.............................. 11 PP .......................................... See 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 π-bond .......................................4 π-bond opening..........................8 π-bonds................................3, 13 π-Bonds .....................................4 π-bonds weaker than σ-bonds ...6 σ-bond .....................................13 σ-bonds......................................4
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University