orgo 1 exam 3

can be HBr, HI

markovnikov

add Cl to most sub side

remove double bond

check if chiral

if chiral = stereo

CARBOCATION CAN REARRANGE = RING EXPANSION

the H goes to the less sub side, the carbocation goes to the most sub side, CHECK if rearrangement needed, then the Cl Attacks it.

wherever there is a chiral center, related or not, ALWAYS STEROCHEM

can be cat H2SO4 H2O

markovnikov

add OH to most sub side

remove double bond

check if chiral

if chiral = stereo

CARBOCATION CAN REARRANGE

wherever there is a chiral center, related or not, ALWAYS STEROCHEM

markovnikov

add OCH3 to most sub side

remove double bond

check if chiral

if chiral = stereo

CARBOCATION CAN REARRANGE

wherever there is a chiral center, related or not, ALWAYS STEROCHEM

can be iPrOH or EtOH

markovnikov

add OH to most sub side

remove double bond

check if chiral

if chiral = stereo

NO CARBOCATION

wherever there is a chiral center, related or not, ALWAYS STEROCHEM

ANTI markovnikov

add OH to LEAST sub side

remove double bond

check if chiral

if chiral = stereo

NO CARBOCATION

wherever there is a chiral center, related or not, ALWAYS STEROCHEM

double bond → add H and B
then → change B into OH

DONT FORGET STEREOCHEM

Anti on double bond

stereochem!!!!! ONLY on chiral

Add across the double bond

OH goes to MORE substituted carbon (Markovnikov)

Br goes to LESS substituted carbon

ANTI addition (opposite sides)

NO CARBOCATION

• hv (light) → makes :CH₂ (carbene)

• carbene adds across double bond

👉 You take the double bond and turn it into a triangle

This is SYN addition

So:

• both new bonds form from the same side

• Because carbene can come from:

  • front

  • back

  👉 gives 2 stereoisomers

Or CHCl3 NaOH

• You have a ring with a double bond

• A tiny triangle piece (:CCl₂) comes in

• It “snaps” onto the double bond

• Now you get a 3-membered ring attached

• forms :CCl₂ (dichlorocarbene)

👉 adds across double bond → makes:

• cyclopropane

• with 2 Cl on the SAME carbon

• forms :CCl₂ (dichlorocarbene)

👉 adds across double bond → makes:

• cyclopropane

• with 2 Cl on the SAME carbon

---

🔥 Key idea:

👉 both Cl stay on the same carbon

Or CH₂I₂ + Zn(Cu)

makes :CH₂ carbene

What to do:

• find the double bond

• draw a triangle across it

Stereochemistry:

• SYN addition again

• so:

  • front attack → one product

  • back attack → another

STEREOCHEM ON CHIRAL

or Cl2

alkyne to an alkene

add 1 Br to each alkene carbon

trans

no wedge or dash

1 equiv Br2 or Cl2 starting w/ alkene

alkene to alkane

add 1 Br or Cl to each alkane carbon

wedge /dash if chiral

still anti addition

w/ no peroxides (no ROOR)

markov

alkyne to alkane

add two Brs to same carbon

no cis/trans

• Is it HBr?

• Are peroxides (ROOR) present?

• How many equivalents? w/ Alkyne

• How many equivalents? w/ Alkene

• Is it HBr?

  • Yes → continue

  • No → ignore peroxide idea

• Are peroxides (ROOR) present?

  • Yes → ANTI-Markovnikov

  • No → Markovnikov

• How many equivalents? w/ Alkyne

  • 1 → alkene NO wedges/dashes, add only 1 Br

  • 2 → alkane NO wedges/dashes, add two Br same carbon

• How many equivalents? w/ Alkene

  • 1 → alkane Possible wedges/dashes if chiral, add 1 Br

1. alkyne to alkane - mark, ADD 2 Brs!

2. alkene to alkane - mark, chiral? wedges dashes

Type of H	Structure	pKa (approx)
strong acid (protonated O)	O+-H	~ -2 to 0
carboxylic acid	C=O-OH	~ 4–5
ammonium (R₃NH⁺)		~ 9–11
phenol	benzene ring–O-H	~ 10
alcohol	R–OH	~ 16
water	H₂O	15.7
terminal alkyne	RC≡CH	~ 25
amine (R–NH₂)		~ 35–40
alkane		~ 50