CHap 10 Flashcards
An alkyl halide is composed of:
an X and H group (addition)
Halogenation is when
two X groups are added through addition
Halohydrin formation is when
an OH and X group are added through addition
Hydroboration-oxidation is when
An H and OH are added through addition (interacting with BH3 or 9-BBN in the first step and H2O2 and OH- in the second)
Hydration and related additions are comprised mainly of
H2O or R-OH
Syn addition occurs in:
Hydroboration
Anti addition occurs in
Halogenation (X-X) and halohydrin (OH and X) formation
Syn and Anti addition occurs in
hydrohalogenation and hydration
Hydro-halogenation is comprised of
an X and H group being added
- The mechanism has two steps
- Carbocations are formed as intermediates
- Carbocation rearangments are possible
- Markinov’s rule is followed (H is boned to less substituated group to form the more stable carbocation)
- Syn and anti addition occur
Hydro-halogenation
- The mechanism has three steps
- Carbocations are formed as intermediates
- CArbocation rearangements are possible
- Markinovs rule is followed
- Syn and anti addition occur
Hydration (addition of H2O and -OH groups)
Hydrohaligenation is different from Hydration in that:
Hydrohaligenation happens in two steps instead of three
- The mechanism has two steps
- Bridged halonium ions are formed as intermediates
- No rearangments can occur
- Anti addition occurs
Halogenation
- The mechanism has three steps
- Bridged halonium ions are formed as intermediates
- no rearangments occur
- Xbonds to less substituated C
- Anti addition occurs
Halohydrin
NBS in DMSO and H2O adds Br in OH the same way that Br2 and H2O would
- The mechanism has a one-step mechanism
- No rearangements occur
- -OH bonds to the less substituated C
- Syn addition of H2O results
Hydroboration-oxidation
Simply adds H and -OH in one step
