orgo 3

Question 1

Pi bonds are ___ than sigma bonds

Answer 1

weaker

Question 2

Electrophile

Answer 2

electron loving, like lewis acids, electron poor, delta positive

Question 3

electrophile examples

Answer 3

HCl, HBr, H2O, H3O+, X2, H2, Hg(OAc)2, BH3, OsO4

Question 4

nucelophile

Answer 4

electron rich, lewis base

Question 5

carbocation

Answer 5

electrophilie, lewis acid, C with only 6 ve- and + charge, trigonal planar, 1 unhybridized P orbital, can be primary, secondary, tertiary

Question 6

hydrohalogenation

Answer 6

adding H
1. Form a new bond netween nucelophile and electrophile which forms carbocation, this is the slowest and rate determining step

2. Form 2nd bond between carbocation and new nucleophile

Question 7

Bond dissociation energy-

Answer 7

• BDE- energy required to break a bond into 2 radicals (odd # e-) gas phase

Question 8

Carbon stability rank

Answer 8

3>2>1*

Question 9

Hyperconjugation

Answer 9

bonded pair share-ish over the carbocation

Question 10

regioselectivity

Answer 10

depends on stability of carbocation; will select pathway that stabilizes aka positive charge can be delocalized

Question 11

Markovnikov’s rule

Answer 11

H adds to the carbon of the double bond that has more hydrogens, aka the more stable carbocation structure (3* is best)

Question 12

Hydration

Answer 12

reactions with H2O, usually have H2SO4 as a catalyst, use H3O+ in step 1 (rate determining)

Question 13

carbocation rearrangement

Answer 13

1,2-methyl shift or 1,2-hydride shift- forms a more stable carbocation

Question 14

Halogenation

Answer 14

addition of halogens

Question 15

Bromination

Answer 15

test for alkenes, bc bromine is red, if the solution goes from red to clear it means there’s an alkene (double bond) if it stays red it means alkane (no d bond), this doesn’t work with benzene rings

Question 16

why are CL2 and Br2 good neutrophiles?

Answer 16

because the bonds between them Cl-Cl are weak and their anion are strong and stable Cl-

Question 17

Br anti orientation

Answer 17

this will only work if the 2nd Br comes from the anti direction to bond with C and make the compounds TRANS, geometry is important in these rxns, called stereoselectivity

Question 18

the H and halogens of HX reactions with alkene are always on _____ carbons

Answer 18

neighboring

Question 19

in lab you would see more _______ (orienattion)

Answer 19

equatorial

Question 20

Oxymercuration Reduction

Answer 20

with mercuric acetate (Hg(OAc)2 and H2O
The addition of HgOAc and H2O must be TRANS
There is no rearrangement with mercuric acetate

Question 21

is there rearrangement with Hg(OAc)2?

Answer 21

NO

Question 22

The addition of HgOAc and H2O must be

Answer 22

TRANS

Question 23

Hydroboration oxidation

Answer 23

use BH3 and H2O2 and NaOH, ends up with OH on the lesser Carbon
Boron adds to the less substituted carbon because of steric strain and electronegativity

Question 24

in hydroboration the -OH ends up where?

Answer 24

lesser carbon

Question 25

oxidation with OsO4 is always what

Answer 25

syn: same side making CIS

Question 26

Ozonolysis

Answer 26

• cleaves double bond with O3, DB becomes a carbonyl group either ketone or aldehyde

Question 27

reduction

Answer 27

the addition of H2 with common catalysts like Pt, Pd, Ru and Ni

1. H2 and alkene are absorbed onto metal surface
2. 1 H gets bonded to the alkene making a new C-H bond
3. 2nd H gets bonded to alkene making 2nd C-H bond and alkene is released from metal

Question 28

∆H for alkene hydrogenations

Answer 28

all ∆H are negative and exothermic, as double bond becomes more substituted (more stable) ∆H gets less negative (smaller negative number)

Question 29

If you start off with an achiral material and an achiral environment product will

Answer 29

not be optically active it will be a racemic mixture, or have enantiomers so individual molecules are chiral but total is not
For halogenations reactions: SAY “+ ENANTIOMER” OR “IS RACEMIC”

Question 30

for halogenation reactions make sure you write

Answer 30

BOTH enantiomers or write “PLUS ENANTIOMER” OR “RACEMIC MIXTURE”

Question 31

If you start off with something that is chiral

Answer 31

product can be chiral or achiral

Question 32

If you start off with an achiral material in a chiral environment

Answer 32

you can selectively make a chiral product