Chapter 8 Flashcards
addition reactions are when with one _______ bond is broken and 2 new _________ bonds are formed
pi, sigma
addition reactions are the inverse of what type of reaction?
elimination
Markovnikov’s Rule
predicts that the carbocation will always form on the most stable carbon
hydrohalogenation
- H-X
- creates a carbocation intermediate
- produces an alkyl halide
maokovnikov or anti-maokovnikov: hydrohalogenation
markovinivok
what type of intermediate does an HBr and ROOR (hydrohalogenation) reaction have?
radical
maokovnikov or anti-maokovnikov: HBr/ROOR (hydrohalogenation)
anti-markovnikov
acid-catalyzed hydration
- H2O/H2SO4
- intermediate = carbocation
- product = alcohol
maokovnikov or anti-maokovnikov: acid-catalyzed hydration
mark
oxymercuration-reduction
- Hg(OAC)2, H2O / NaBH4, NaOH
- intermediate = bridged ion
- product = alcohol
maokovnikov or anti-maokovnikov: oxymercuration-reduction
mark
hydroboration-oxidation
- BH3 (or other B) / H2O2, NaOH
- stereochemistry = syn addition
- product = alcohol
syn addition
cis products
maokovnikov or anti-maokovnikov: hydrobromination-oxidation
anti-mark
(OH in least stable position)
hydrogenation
- H2 / Ni, Pt, (or some type of metal catalyst)
- stereochemistry = syn addition
- product = alkenes
HYDROGEN IS JUST ADDED TO MAKE THE CARBONS HAPPY AND HAVE NO DOUBLE BONDS OR IONS
maokovnikov or anti-maokovnikov: hydrogenation
N/A (adding the same thing - hydrogens)
halogenation
- X2
- intermediate = bridged ion
- stereochemistry = anti
- product = vicinal dihalides
vicinal
next to each other in the molecule (1,2)
maokovnikov or anti-maokovnikov: halogenation
N/A (adding the same thing - halides)
halohydrin
- X2 / H2O
- intermediate = bridged ion
- stereochemistry = anti
- product = halohydrin
maokovnikov or anti-maokovnikov: halohydrin
mark
cyclopropanation uses what intermediates?
cabene or carbenoid
Carbenes are reactive intermediates. They are unstable because they violate the _________________
octet rule
4 methods commonly used to introduce carbene intermediates
- CH2
- CHCl3 / tert-butoxide
- N=N-CH2 / hv
- CH2I2 / Zn(Cu)
epoxides are added to double bonds using ______________
peroxy acid
common reagents for epoxidation are _________ and _________
mCAPBA and MMPP(RCO3H)
acid catalyzed ring opening: following protonation of the epoxide the nucleophile will attack the side of the ring with the most _____________ character
positive
base catalyzed ring opening: the strong nucleophile will attack the side of the ring that is _____________ substituted
least
dihydroxylation
adds 2 OH to one double bond (vicinal and syn)
ozonolysis
- O3
- cut the double bond and add an O
reductive workup
- S(CH3)2 or Zn/HOAc
- aldehyde and ketones
oxidative workup
- H2O2
- carboxylic acids and ketones
oxidative cleavage
- KMnO3 / heat
- cut the double bond and add an O and OH
alkyne halogenation
product = tetrahalides
(vicinal halides –> total of 4 halides)
free radical polymerization
alkenes in excess to extend the propagation step almost indefinitely
What is often used when KI, H3PO4 is written?
H-I
Anytime we have a carbocation intermediate you need to look for a _________ or __________ shift
hydride or methyl
_________ cannot have a shift occur
Hg(OAc)
what mechanism as initiation, propogation and termination steps because they have radicals?
hydrobromonation-oxidation
hydrogenation definition
reduction = gains electron density for carbon
markovnikov rule
H tends to go to the least subsidized side and the + goes to the more substituted side
are epoxides reactive?
VERY reactive (due to angle strain)
acidic - ring opening epoxide
more substituted position attacked by a nucleophile (SN1)
basic - ring opening epoxide
less substituted position attacked by a nucleophile (SN2)
carbenes
neutral molecule containing divalent carbon with only 6 electrons in its valence shell
which reactions have a syn addition as part of the mechanism?
- BH3, THF / H2O2, NaOH
- H2, Pd
anti-markovnikov reactions
BH3 and HBr + ROOR