ch 7 o chem

Question 1

What makes a stable alkene

Answer 1

e (trans)
0  h
  = 
 o h
more substituted (less H)

Question 2

dehydroghalogenation of alkyl halides

Answer 2

you have an alkane and then a base and Hx comes and takes off the alkyl halide and makes it =

Question 3

dehydrogenation of alcohols

Answer 3

alkali + h+, heat, HOH, it takes of the OH and makes a alkene

Question 4

what are the base+solvents for dehydrohalogenation?

what are the bases and how are they made

Answer 4

KOH + EtOH
t-butOK+t-butOH
EtONa+ EtOH

bases are alkoxides , they are alcohols but then u put them

Question 5

rate for E2

how is the LG and H placed in E2

Answer 5

r8= k[base][alkane]

one is in front one is in back on Newman but they are one up and one down

Question 6

what are regioisomers

Answer 6

when the E2 can happen from multiple different places with H then it gives constitutional isomers, regioisomers

Question 7

what are sterioisomers (E2)

Answer 7

when th E2 can give a cis or a trans (wedge and dash for things and then u take out the H so now its one is cis and one is trans)

Question 8

in a cyclohexane thing how do u prepare for E2

Answer 8

make sure LG is axial, chair might beed to be flipped

Question 9

regio and seterioisomers form through the law of zeitozkjhf if…

Answer 9

its a small base being used

ETONa or KOH

Question 10

Hofmann rule

Answer 10

if u use bulky base (t-butOH) for E then it will only use one spot mainly because its so fat

Question 11

which favours e more vs sn

Answer 11

the more substituted the more e2

Question 12

e or s 1 or 2 ?
3º + weak base
3º + strong base

Answer 12

3º + weak base
sn1
3º + strong base
E1

Question 13

how to dehydrate the different alchohols

Answer 13

1º
hardest 
180º and conc h2so4
2º
165-170º and h3po4 (rearranges)
3º
85º and h2so4

Question 14

acidity of the h related to the alkene position

Answer 14

Terminal alkene = not very acidic
middle alkene = medium acidity
no alkene = more acidic

Question 15

to make a terminal alkene you need how many mols of base

Answer 15

1 more than the amount of h your abstracting+you need a step at the end to give a H so its not + charge

Question 16

dehydration vs hydrogenation

Answer 16

dehydration=making double bond

hydrogenation = taking out double bond

Question 17

catalysts for hydrogenation

Answer 17

pt pd Ni (hetero, doesn’t mix with solvent(different phase))

Wilkinson’s catalyst = homo (mixes with solvent)

Question 18

syn vs anti addition

Answer 18

SYN: The things are added cis

ANTI : the things are added grandly

Question 19

is catalytic hydrogenation sin or trans

Answer 19

Adding H gas is added syn

Question 20

for hydrogenation of alkynes how Manny hs do you use

Answer 20

2H2

Question 21

what is semi hydrogenation of alkyne

Answer 21

when it goes from alkyne to alkene

use H2 added syn

Question 22

how to make alkyne to alkene trans

Answer 22

use
Na, NH3 (l) -78ºc
Ni, NH3 (l) -78ºc

Question 23

how to make alcohols from alkenes? (oxymercuration, demurcuration)

Answer 23

step one:
Hg(OAC)2 and THF-H2O
step 2:
NaBH4 and OH

Question 24

hallogen addition

Answer 24

they will be added trans even if it doesn’t seem like it can be. it does a weird thing where it takes one of the halogens that bonds with both c breaking the=
then the other halogen attacks from the back and now they are attatched trans

Question 25

syn dihydroxylation reagents

Answer 25

1)OsO4
2)NaHSO3/H2O
it breaks the = and now there are oh added syn (cis)

Question 26

oxidative cleavage of alkenes

Answer 26

use hot KNO4 OH-, H2o heat or O3, CH2Cl2,-78º
cut = in two look at groups attached to the c on each end of =
if its:
2 R groups: just add o the end with =
1R I H: add o to end with = and replace H with OH (the H is added in a next step with H3O)
2H groups: it will end with O=C=O + h2o

Question 27

oxidative cleavage = of alkynes

Answer 27

reagents:
1) O3, 2) HOAc
or
1)KMnO4, OH-
2)H3O+