2. Alkenes Flashcards
how many bonds and of what type are in C=C
1 x sigma
1 x pi
what hybridization does a C=C bond have
sp2
what shape and angle is a C=C bond
120*
planar
how are the 2 orientations of alkenes classified
E and Z
what are the orientation of substituents on an E alkene
Hi priority on opposite sides of the double bond
what are the orientation of substituents on a Z alkene
Hi priority on the same sides of the double bond
what are the cis/trans isomers
Cis = same group on same side of C=C
trans = same group on opposite side of C=C
what are the 2 ways alkenes can be prepared
dehydration of alcohols
dehalogenation of alkyl halides
what reagents and reactants are required in a dehydration reaction of alcohols to form alkenes
conc H2SO4
what reagents and reactants are required in a dehalogenation reaction of alkyl halides to form alkenes
KOH or NaOH(ethanol)
what is sayteffs rule
when >1 alkene can form the maj product is the alkene with the least # of H directly attached to C=C carbons
what are the 3 types of addition reactions that alkenes can undergo
hydrogenation
electrophilic addition
halogenation
what does hydrogenation of alkenes produce
alkanes
what does halogenation of alkenes produce
alkyl halides
what does electrophilic addition of alkenes produce
3 possibilities
alkyl halides/ethers/alcohols
aside from addition reactions what other 2 reactions can alkenes undergo
oxidation
polymerisation
what reagent is involved when an alkene undergoes oxidation
MnO4-
can be with or without acid
what is produced when alkenes undergo oxidation
prodi dihydroxyls
what reagent is involved when an alkene undergoes hydrogenation (addition reaction)
H2/Pt
can also be with Ni instead of Pt
heat
what stereochemistry are the H added in when an alkene undergoes hydrogenation to form alkanes
H added in syn
what reagent is involved when an alkene undergoes addition reaction to form alkyl halides with -Cl
HCl(ether solvent)
to produce with -Br attachment can use HBr
what reagent is involved when an alkene undergoes addition reaction to form ethers
ROH(alcohol)/H+
what reagent is involved when an alkene undergoes addition reaction to form alcohols
H2O/H+
heat
what reagent is involved when an alkene undergoes halogenation (addition reaction)
+ dihalogen
(eg Br2 or Cl2)
what stereochemistry when an alkene undergoes halogenation to form haloalkanes
anti stereochemistry
trans formed
when an alkene undergoes halogenation (addition reaction) what is the nucleophile and what is the electrophile
nucleophile = halide ion
electrophile = halogen
what colour change is observed when Br2 reacts with an alkene
orange to colourless
what colour change is observed when an alkene reacts with MnO4-/H+
purple to colourless
what colour change is observed when an alkene reacts with MnO4- and no H+ catalyst
purple to brown precipitate
what is a hydroboration reaction of alkenes in terms of products produced
produces alcohols
what is a hydroboration reaction of alkenes in terms of reactants and reagents
B2H6/H2O2 and OH-
or
H2O/H+
which reagent is needed for a hydroboration reaction of alkenes to produce a primary alcohol
B2H6/H2O2 and OH-
which reagent is needed for a hydroboration reaction of alkenes to produce a secondary alcohol
H2O/H+
