orgo reaction mechanisms

equally likely b/c both 2° carbocations

Markovnikov

a strong base

• only the alkene reacts

• The products of this reaction are called vicinal dihalides, since the two halogens are vicinal
• (in the vicinity of each other, or on neighboring carbons

• The products of this reaction are called vicinal dihalides, since the two halogens are vicinal
• (in the vicinity of each other, or on neighboring carbons

• This immediately makes a three-membered halonium ring (bromonium, in this case), which can then be attacked by the second halogen atom in the next step.

• once the ring is formed, water comes in to attack it.

• but now water is (+) charged and it needs to be neutral. so another water comes in to deprotonate it.

• we only have one choice of what to deprotonate here. The R does not want to detach.

• Intramolecular reactions like this will make a new ring.

This reaction is helped by the proximity effect – it’s easier for two functional groups to react when they’re already tethered together as part of the same molecule, because they’re a lot more likely to run into each other than two separate molecules are.

• anti-markovnikov

• anti-markov

• If you use DMS (dimethyl sulfide, or CH3SCH3),
• then no further changes are made.

• If you use DMS (dimethyl sulfide, or CH3SCH3),
• then no further changes are made.

1. Initiation: This is when the radicals are created that will go on to perform the reaction. Many, but not all, initiation steps involve starting with 0 radicals and ending up with 2. 

• initiation steps start with ROOR splitting into two RO· radicals.
• 2. propagation: now we have the actual organic molecule that creates the major product. Each propagation steps starts and ends with ONE radical. The SAME radical that exists at the start HAS TO BE RECREATED at the end of the propagation steps.

•  radicals, like carbocations, are sp2 hybridized with trigonal planar geometry,

but they will not rearrange to become more substituted like cc+ will.

3. termination: two radicals combine to form a new bond.

• For all radical reactions, the major product is formed during the propagation steps, and any
• minor products are formed during the termination steps.

1. dihalogenation, halohydrin formation, haloether formation

2. a. hydrogen-halide (HX) addition, acid-catalyzed hydration, oxymercuration-reduction

b. hydroboration-oxidation, free-radical HBR addition

3. hydrogenation

4. ozonolysis

Br2                 ||        Cl2

Br2 / H2O     ||       Cl2 / H2O

Br2 / ROH    ||       Cl2 / ROH

HBr, HI, HCl

H2O, H+  or H2SO4 + H2O

• 1) Hg(OAc)2, H2O, THF 
• 2) NaBH4, -OH

• 1)BH3 
• 2) H2O2, H2O, -OH

• HBR
• ROOR

• H2 
• Pt/C or Pd/C

• 1) O3
• 2) DMS

initiator