remember 1c

Question 1

how do we know if smt is a ring opening metathesis polymerisation

Answer 1

• is there a ring the alkene is a part of
• is the metal catalyst a Mo, W, Re or Ta
• remmebrr it can be cis and trans

Question 2

if we see an alkene and a H2 what do we know it is and how do we know which type it is

Answer 2

alkene and H2 means hydrogenation
meaning alkene to alkane

homolytic if we use wilkinsons catalyst Rh(PPh3)3

heterolytic if we use RuCl2(PPh3)3

its a XXX H2 scission mechanism

if H is more H- aka negative the ratr is faster so look if the ligands are P or sigma donors etc

Question 3

how do we draw the product when its just a ZN one

Answer 3

w cut the alkene and just draw a zigzag

then at the points add the R groups in

Question 4

2 double bonds and toluene

Answer 4

ring closing metathesis

aka forming a ring

one double bond still stays tho

Question 5

ROMP how do we know

Answer 5

grubbs catalyst,, aka the Ru Cl2 big one with pentane with 2N’s in it.

Question 6

ROMP or RCM what catalyst do we use

Answer 6

grubbs catalyst,, aka the massive Ru Cl Cl,, pentane 2N’s.

Question 7

the 2nd catalyst and MAO

Answer 7

homo ZN polymerisation

isotactic polym
and enantiomorphic site control

Question 8

if theres a mirror plane in the catalyst itsss

Answer 8

achiral

therefore its enantiomorphic site control

Question 9

catalyst with just CP on top

Answer 9

syndiotopic addition

enantiomorphic site control

Question 10

catalyst with Cp Ph on top

Answer 10

isotactic addition

Question 11

ROMP and stereochem

Answer 11

random stereochem

can be E or Z

Question 12

most times its what type of ZN

Answer 12

its homogenous ZN

Question 13

1st catalyst,, gives what

Answer 13

isotactic addition
chain end stereochemical control

Question 14

H2 addition goes where

Answer 14

on the alkene that isn’t conjugated to a ketone etc

HOMOLYTIC SCISSION HYDROGENATION

Question 15

3rd catalyst aka Cp and Cp Ph on the bottom

Answer 15

homogenous ZN polymerisation
syndiotactic addition

enantiomorphic site addition

Question 16

if its ZN but theres 2 double bonds what do we need to do

Answer 16

form a cyclic ringgggg

Question 17

RCM what is lost

Answer 17

ethylene aka ethene

aka so our ring has total C - 2 leftttt

and we keep one of the double bonds

Question 18

ROMP gives what streochem

Answer 18

random

Question 19

when doing ROMP what should we comment onnn

Answer 19

ring strain reduction being the driving force of the reaction

Question 20

MOA gives the polymer what weight

Answer 20

gives polymer high mw

Question 21

AlEt3 gives polymer what weight

Answer 21

gives polymer low mw

Question 22

alpha TiCl3 and AlEt3 give what reaction

Answer 22

heterogenous ZN polym
syndiotactic bc holes in surface

poor stereochem control so chain end ig

Question 23

toluene means

Answer 23

sme sort of ring reaction

ROMP or RCM

Question 24

in hydrogenation what alkene is hydrogenated

Answer 24

the least hindered one

Question 25

excess H2 in hydrogenation means what

Answer 25

all alkenes are ydyrogenated

Question 26

role of MAO

Answer 26

ensures high lewis acidicty by acting like a counterion

Question 27

mechanism of alkene polymerisation by metallocene catalysts.

Answer 27

Coshee-Arlman

Question 28

Explain why early transition metals in high oxidation states are useful as olefin polymerisation catalysts

Answer 28

Early transition metal ions have low dπ-electron densities (d0 or d1) – hence donation to σ* of the growing alkylide chain is supressed resulting in a low rate of β-elimination. Credit awarded for drawing of β -elimination mechanism

Question 29

rank the alkenes in order of polymerisation reaction rate

Answer 29

sequence arise on steric groups (less bulky alkenes react more rapidly)

Question 30

Wilkinson’s catalyst [Rh(PPh3)3Cl] and suggest an alternative ligand to triphenylphosphine that would increase the rate of reaction.

Answer 30

Ph with OMe paraaaaa to the P not meta

Question 31

olefin hydrogenation : how many ways are there and what is the diff

Answer 31

- alkene hydrogenation - homolytic: each get a H: Rhcl (PPh3)3 wilkinsons - heterolytic: one gets both Hs: RuCl2(PPh3)3 with ethanoic benzene forms alkanes from alkenes

Question 32

wilkinsons rate is afcected by

Answer 32

its homolytic hydorgnation aka turning alkenes into alknanes - more E- rich P = more negative H so faster H migration//insertion - steric bulk can increase or decrease rate - depends where the double bond is too,, internal,, trans ,, cis and terminal with terminal hydrogenation being the fastest aka wilkinsons only hydrogenates the most available alkene

Question 33

RuCl2(PPh3)3 aka heterolytic hydrogenation

Answer 33

very active for 1alkenes // alpha olefins RDS = making the hydride complex

Question 34

whats disproportionation in olefin metathesis

Answer 34

its when we metathesis the same alkene and it gives off an ethene

Question 35

ehats cross metathesis in olefin metathesis

Answer 35

where u react two different alkenes and get an ethene as a product

Question 36

whats ADMET

Answer 36

acyclic diene methatheiss

Question 37

whats ROMP

Answer 37

ring open metathesis polymerisation

Question 38

whats RCM

Answer 38

ring closing metathesis

Question 39

whats a carbene

Answer 39

s neutral 2e- donor divalent C

Question 40

schrock alkylidee is what metals

Answer 40

early tm

Question 41

fischer alkylidenes are what metals

Answer 41

later TM

Question 42

ROMP driving force

Answer 42

release of ring strain

Question 43

ROMP metals and catalysts

Answer 43

Mo W Re Ta W Mo Al Re

Question 44

in ROMP what is given out

Answer 44

unsaturated aka double bond polymer and an ethylene aka an ethene

Question 45

how can we make a poly acetylene and what does it look like

Answer 45

just a zigzag of double and single alternating CC bonds. - ZN: but air sensitive - ROMP: makes cis and trans

Question 46

alkene polymerisation can occur from what 2 routes

Answer 46

- radical polymerisation: hight temp and pressure - organometallic catalysis: control of branching, rate, mw etc can have isotactic or syndiotactic

Question 47

do we want branched or unbranched polymers

Answer 47

unbranched they can pack together and have lots of vdw strengthening them

Question 48

whats polypropene

Answer 48

zigzag of double and single bonds,, with Me on every OTHER C

Question 49

polypropene can be what

Answer 49

- isotactic - atactic - syndiotactic

Question 50

what tactilities are useful

Answer 50

syndiotactic and isotactic

Question 51

HeteroZN P what metald and metal alkyls

Answer 51

4-8tm 1-3 metal alkyls

Question 52

heteroZNP: key observations

Answer 52

smaller particles have higher rates larger particles have better isotactic control

Question 53

TiCl3

Answer 53

on the surface every 3rd Ti is missing polymer encapsulates it so polymerisation rates are lowered

Question 54

HeteroZNP reaction mech

Answer 54

Cossee Arlman

Question 55

HeteroZNP below and above 203k

Answer 55

below n203k = syndiotactic above 203k - isotactic

Question 56

heteroZNP is an example of what

Answer 56

enantiomorphic site control stereochem,, errors will not be propagated

Question 57

to terminate heteroZNP what do we do

Answer 57

beta hydride eliination early TM = e- poor so they have slow beta elimination bc donation to sigma star is slow

Question 58

CHIRAL METALLOCENES give what in HOMOZP

Answer 58

chiral = ISOTACTIC.

Question 59

HOMOZNP and termination

Answer 59

need to beta elim,, we use d0 metals bc e- poor so no beta elimination forms an alpha olefin so termination is tmporary as the alkene can reinsert and continue with polymerisation

Question 60

role of MAO

Answer 60

its a weakly coordination anion making the metal a rlly good lewis base meaning it can accept electron pairs generates a M-R using halide alkyl exchange!!!

Question 61

what also affects b elim

Answer 61

temp larger temp = faster b elim