Ch. 13 Unsaturated Hydrocarbons
Markovnikov's rule
in the addition of HX or H2O to an alkene, hydrogen adds to the carbon of the double bond having the greater number of hydrogens
Positional Isomers
same carbon arrangement but different hydrogen arrangement due to placement of double bonds CH2=CH-CH2CH3 (1-butene) CH3-CH=CH-CH3 (2-butene)
Ethene
simplest alkene C2H4 CH2=CH2 common name: ethylene
Benzene
simplest aromatic hydrocarbon; C6H6
Hydrohalogenation
an addition reaction with hydrogen halide; alkene + H-Cl ---> chloroethane
Cycloalkenes
1 or more double bond in a ring CnH2n-2
Alkene Chemical Reactions
1. combustion (review chapter 12; replace alkane with alkene) 2.hydrogenation 3.halogenation 4.hydrohalogenation 5.hydration
Physical Properties of Alkenes
1. soluble in nonpolar solvents 2. insoluble in water 3.density lower than water 4. melting points are lower than alkanes with same number of carbons
Copolymer
2 different monomers are present; saran wrap vinyl chloride + 1,1-dichloroethene ---> saran wrap
Alkynes
C(triple bond)C; CnH2(n)-2
Propene
C3H6 CH2=CH-CH3 common name: propylene
Alkenyl groups
CH2= methylene (methylidene) CH2=CH- vinyl (ethenyl) CH2=CH-CH2- allyl (2-propenyl)
Chlorobenzene
Cl attached to benzene; single substitution
Polyethylene
HDPE LDPE (high and low density)
Halogenation with aromatic hydrocarbons
[bromination or chlorination] with catalyst FeBr3 benzene + Br2 ----> benzene with Br attached + HBr
Beta-carotene is an example of what?
a terpene
Hydrogenation Reaction
addition reaction with H2; requires a catalyst R=R + H2 ---> R-H R-H MAKES ALKANES
Hydration reaction
addition reaction with H2O (H-OH); requires small amount of H2SO4 (acid) as catalyst ethene + H-OH ---> an alcohol (in this case ethanol)
Addition Reactions
atoms or groups of atoms are added to EACH C of a double bond
Fluorobenzene
benzene with F attached; single substitution
Alkylation (Fridedel-Crafts)
catalyst - AlCl3
Pheromones
compound used by insects and some animals to transmit a message to other members of its species
Terpenes
compound with "C" skeleton is composed of 2 or more 5-carbon isoprene structural units
Fused-ring aromatic hydrocarbon
contains 2+ rings fused together
Delocalized bond
covalent bond in which electrons are shared among more than 2 atoms
Polymerization
creates polyethylene, polypropylene, poly vinyl chloride (PVC), teflon and polystyrene
Ortho-
double substituent on 1 and 2
Unsaturated Hydrocarbons
have at least one double bond; can be double or triple
AlkENEs
have one or more double bonds; CnH2n
Which addition reactions are symmetrical?
hydrogenation and halogenation
Which addition reactions are unsymmetrical?
hydrohalogenation and hydration
Isopropylbenzene
isopropyl group attached to benzene; single substitution
Polymer
larger molecule formed by the repetitive bonding together of many smaller molecules
addition polymer
monomers add together
Unsaturated polymers
more flexible than saturated polymers
Polyisoprene
natural rubber
Functional Group
part of a molecule where the reactivity occurs; unsaturated hydrocarbon functional group: C-C multiple bonds
What are the two naturally occurring alkenes?
pheromones and terpenes
Halogenation Reaction
review ch. 12; addition reaction with halogen alkene + halogen ---> dihalogenated alkane
Monomer
the smaller molecule in a polymer that repeats
Aromatic Hydrocarbons
unsaturated cyclic hydrocarbon which does not readily under go addition reactions