Alkenes, Alkynes, and Aromatic Compounds - Youngstown State

29 Pages·2002·0.26 MB·English

Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 1/29
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

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 2/29
Section 2.1 Introduction and Nomenclature of Alkenes

(cid:190) Ethene = (Ethylene), CH =CH
2 2

(cid:190) IUPAC Rules
(cid:190) Start numbering from the end that gives the double bond the
lowest number.
(cid:190) Indicate position of double bond(s) by numbers.
(cid:190) Use the ene ending
(cid:190) Indicated number of double bonds by prefixes (ene, diene,
triene, tetraene, etc.)

(cid:190) Examples

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 3/29
(cid:190) Geometric Isomers
(cid:190) No free rotation (π-bonds)
(cid:190) Experimental observations

(cid:190) cis isomers vs. trans isomers

(cid:190) Examples
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 4/29
Section 2.2 π-Bonds
2
(cid:190) Bonding: sp hybridization for 3 σ-bonds to the three atoms
bonded to each carbon
(cid:190) p orbital for π-bond
z
(cid:190) Typical C=C bond distance (i.e., 1.34 Å) and thus shorter than
the C-C distance (i.e., 1.54 Å)
(cid:190) slightly shorter C-H distance than alkanes

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 5/29
Section 2.3 Physical Properties
(cid:190) Almost identical to Alkanes of same MW
(cid:190) Van der Waals forces
(cid:190) Slightly higher Mp and Bp
(cid:190) Smell (turpentine like)
(cid:190) Density
(cid:190) Solubility
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 6/29
Section 2.4 Chemical Properties: Addition Reactions
(cid:190) Addition reaction (generic)
(cid:190) π-bonds weaker than σ-bonds

(cid:190) Hydrogenation: Addition of H or D (Pt catalyst)
2 2

(cid:190) Addition of Cl or Br (X )
2 2 2

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 7/29
(cid:190) Addition of HX ((HF) HCl, HBr (HI))
(cid:190) Halide Influences
(cid:190) Markovnikov Addition

(cid:190) Addition of Water (Hydration)
+
(cid:190) H Catalyst
(cid:190) Markovnikov

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 8/29
Section 2.5 Addition Polymers
(cid:190) Definition of Addition Polymers
(cid:190) No loss of mass
(cid:190) Rapid chain growth
(cid:190) π-bond opening
(cid:190) “Generic” Synthesis Reaction
(cid:190) typical monomers are CH =CH-R
2

(cid:190) Role of Catalysts
(cid:190) Speed reaction but aren’t themselves consumed
(cid:190) Highly reactive species
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 9/29
(cid:190) Reversibility of Reactions
(cid:190) Polymerization under low temperatures/high pressures
(cid:190) i.e., monomer (liquids or gasses) -> polymer (solids)

(cid:190) Depolymerizations (unraveling) at high temperatures
(cid:190) i.e., polymer -> monomer

(cid:190) Molecular Weights and Molecular Weight Distributions
(cid:190) High average Molecular Weights
(cid:190) Distributions rather than discrete weights

(cid:190) Linear Chains vs. Branched Chains
2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University
Chemistry 1506 Dr. Hunter’s Class Section 2 Notes - Page 10/29
(cid:190) Examples
(cid:190) Polyethylene, PE, Synthesis
(cid:190) CH =CH , R = H
2 2

(cid:190) Poly(vinyl chloride), PVC, Synthesis
(cid:190) CH =CH-Cl, R = Cl
2

2000-2002, Dr. Allen D. Hunter, Department of Chemistry, Youngstown State University