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