addition

Question 1

addition rxn

Answer 1

addign two groups to a double bond which destroys the double bond

Question 2

regiochemistry

Answer 2

where the 2 groups are being installed on the double bond
-only matters when adding two different groups to an unnsymmetric alkene

Question 3

symmetric alkene or adding the same groups

Answer 3

regiochemistry is irrelevant

Question 4

regiochemistry types

Answer 4

mark and anti mark

Question 5

mark

Answer 5

h gets less sub

Question 6

anti mark

Answer 6

h gets more sub

Question 7

stereochem

Answer 7

-syn or anti
-mechanism will explain stereochemistry
-does not matter is there are no stereocenters being made (not 4 unique groups) (here only one product)

Question 8

syn

Answer 8

groups being added on the same side of the plane

Question 9

anti

Answer 9

groups each being added on opposite sides of the plan

Question 10

regio vs stereo

Answer 10

-regio described the order in which they are added / which group is added to which atom
-stereo describe how they are geometrically added to the mocule/ determines that the product is going to look like

Question 11

both carbons sp2

Answer 11

tigronal planar
-must rotate the molecule to do either syn or anti

Question 12

products of syn and anti

Answer 12

each represent a pair of isomers
-4 products total

Question 13

non stereospecific

Answer 13

expect all 4 products
-if stereo specific it would be 2 enan from syn or 2 enan from anti

Question 14

stereochemistry irrelevant

Answer 14

-when there are no stereocenters made
-when there is one stereocenter made but no others int he molecule

Question 15

one stereocenter

Answer 15

2 possible products
-will get racemic mixture (enan pair)

Question 16

if it creates a plane of symmetry

Answer 16

meso
-only need to draw one because there is only one product they will be the same compound

Question 17

meso

Answer 17

are not enantiomers they are just two drawings of same molecule
-choose one
-can have the same group along the plane of symmetry with a dash or a wedge dont have to match
DO NOT WRITE PLUS ENANTIOMER
-can also say D2

Question 18

anti adition

Answer 18

one dashed one wedges

Question 19

hydrogenation

Answer 19

adding h and h across alkene
-regiochemistry irrelevant
-uses a metal catalyst (pt, pd or ni)
-hydrogen interacts with the surface of the metal catalyst which breaks the h-h bond and leaves sinlge h bonds to the metal that are ready to interact with the alkene bond
-will be a syn addition

Question 20

adding hydrogen halide

Answer 20

-2 steps (proton transfer and nucleophilic attack)
-proton transfer gets rid of the double bong leaving a carbo cat and then the halide/nu will attack
-regiochem irrelevant if symmetric
-not symmetrical: make the most stable carbocation, the proton from protonation goes to the less stable carbocat then the halid will attack the carbocation, ending up on the more substituted carbon thus mark
-stereochem (syn or anti) irrelevant bc there is not two stereocenters
-shift may occur after protonation to make the carbocat more stable
-hbr withour roof is still mark

Question 21

hydrogen halide rxn that can be anti mark

Answer 21

ONLY HBR and peroxides (ROOR)
-BR ends up on LESS sub (ANTI)
-Does NOT involve br- (ionic) involves Br as a radical intermediary
-radicals formed by peroxide bonds breaking

Question 22

adding water across a double bond

Answer 22

hydration

Question 23

hydration

Answer 23

can be mark or anti mark
-depends on the reagents

Question 24

mark hydration

Answer 24

-reagent can be water and an acid source or in brackets (h2so4), brakets mean the h is not consumed in the rxn it is a catalyst

Question 25

mark hydration name

Answer 25

acid catalyzed reaction
-because the h is the catalyst and oh is the product

Question 26

acid catalyzed hydration

Answer 26

-first is protonation that will yield carbocation
-nu (h20) attacks
-the product will be CHARGED
-extra step to remove charge and do it by using water as a base (deprotonate w water)
-use reversible arrows bc the product/ equilibrium can be controlled by contorlling the amount of water used
-use dilute acid and more water to favor alcohol, push equilibrium right

Question 27

anti mark addition of oh and h
-hydroboration oxidation
-2 step synthesis

Answer 27

-oh ends up on less substituted (regiochem)
-stereochem= syn rxn
-uses bh3 and THF
-THF will stabalize the empty b orbital of bh3 by donating electron density
-bh3 is an electrophile and looking to fill empty orbitals/ wants electrong so the pi bond attacks it and that will trigger a hydride shift
-adding h and bh2 across the double bond (BH2 goes anti mark because it is bbb) (step 1) then comes oxidation
-step 1= hydroboration
-there is an alkyl shift which places oxy between b and r but stereocenter is preserved
-final product will be an alcohol

Question 28

not creating two stereocenters

Answer 28

-stereochem is irrelevant

Question 29

br-br addition

Answer 29

-regiochemistry irrelevant (same molecule)
-creates two new stereocenters sometimes and results in enantiomers
-anti addition
-the alkene functions as the nu
-br is the electrophile bc it has a partial positive becuase there is a covalent bond btwn br and br that creates a dipole with the pi bond
-alkene attacks the “electron poor” nu
-if water is the solves an oh group will be on the product bc water will act as a nu too
-last step is deprotonation (when water is the solvent)

Question 30

water as solvent for br br

Answer 30

there will be regiochem
-oh goes on the MORE sub c
-halohydrin rxn

Question 31

two oh groups

Answer 31

can be added anti or syn

Question 32

oh oh anti

Answer 32

two steps
-first step involves peroxyacid (RCO3H) to form epoxide
-step two add water like acid catalyst rxn (protonates then form a charged intermediate (not carbocat) and then water attacks)
-water attacks from the back therefore anti

Question 33

oh oh syn

Answer 33

syn dihydroxylation
-KMnO4 cold is often used
-oso4 also
-pair of enantiomers