5d

Question 1

when we add a monomer to a polymer chain what is always the same

Answer 1

the orientation in the way its added
aka the orientation of its addition

Question 2

why is the orienatation of addition aka when we add a monome to the polymer the same

Answer 2

bc the R groups are bulky lowks

Question 3

when we say the orientation of the monomer being added to the polymer is the same

Answer 3

bc all the R groups are pointing the same way

aka in the same direction

Question 4

what is needed to regenerate the TiCl3 VS site

Answer 4

we need migrationnn

aka when the Et leaves with the CH2 CH2 things

Question 5

rates of insertion( Et binding with Ch2 Ch2 ) and migration (removal of Et and CH2 CH2) vary with what

Answer 5

they vary with temp
syndiotacitc under 230k

isotatic above 230k

Question 6

the rate of the growing chain is what

Answer 6

the rate of the growing chain is constant

and the polymer is always attached to the ctatlyst

Question 7

where does the polymerisation occur at

Answer 7

it occurs at the crystal face

aka if theyres lots of edges thats not good and these are seen when the crystal is small

Question 8

whats enantiomorphic site control

Answer 8

this is where the catalyst active site determines the stereochem pf the added monomer

Question 9

what kind of site control does HZNP have

Answer 9

it has enantiomorphic site control

Question 10

how do we terminate the chain formation // reaction

Answer 10

B elimination or H2 reduction (preferred) aka 2Hs come together from 2 diff polymers,, they bind and then leave a VS,, the polymers are now connected

Question 11

what tm are good HZNP metals

Answer 11

the early row ones

Question 12

bonding in happens in beta eliination

Answer 12

2 adjacent groups are removed to go from a sigma to a pi bond

Question 13

how is beta elimination promoted

Answer 13

by adding e- density to the sigma* bond of the ligand

pi bond donated to M ,, M donated electron density to pi* bb

Question 14

early TM and e- density

Answer 14

low in e- density

theyre e- poor

therefore b elimination is slow bc they have little e-

Question 15

PE synthesis uses what type of catalyst

Answer 15

homogenous!!

Question 16

if our monomer is chirall,, what do we need

Answer 16

if our omonomer is chiral that means we need a chiral catalyst to make it a polymer

Question 17

PE to make a polymer,, what do we need

Answer 17

catalyst and MAO

Question 18

why are early tm goof polymerisation catalysts

Answer 18

bc beta elimination is favoured

Question 19

BETA ELIMINATION GIES US WHATTT

Answer 19

IF GIVES US AN ALPHA OLEFINNN

AKA THE DOUBLE BOND IS FIRST

this can act as a substrate aka termination is reversible

Question 20

why is d0 slow whe it comes to beta elimination

Answer 20

its slow bc theres no pi electrons

so elimination is therefore very slow

and elimination occurs from d pi to ligand sigma star bond

Question 21

whats MAO stand for

Answer 21

methyl alumin oxane

Question 22

how is methyl aluminoxane synth

Answer 22

partial hydrolysis of AlMe3

Question 23

what MAO acc made up of //structure

Answer 23

complex mix of linear, branched and 3d network structures

most the Al are 4 coordinate centres

Question 24

what do we need to make MAO

Answer 24

aka partial hydrolysis of AlMe3

so AlMe3 + H20 - CH4 to give like a -Al - O - Al -O with a line going up from each Al

Question 25

heterogenous ZN usessss

Answer 25

TiCl3 and AlEt3

Question 26

homogenous ZN uses

Answer 26

MAO

Question 27

what is AlMe3 in MAO in equilibrium with

Answer 27

its in equilirbrium with free and astrongly associated ALMe3 with oligomers

Question 28

how is MAO used as a cataylsyst in homo ZN p

Answer 28

- halide alkyl exchnage alkylide abstraction AKA CATALYST ACTIVATION acts as a non corrdinating counter ion,, bc if counter ion coordinates,, the lewis acidity of the metal is reduced and its catalytic ability is lowered aka its harder for it to accept an e- pairrr

Question 29

describe the alkyl halid exchange MAO does

Answer 29

Cp2 ZN Cl2 MAO gives Cp2 Zn Me Cl alkylide association Cp2 Zn Me Vssss and u have a Mao - Cl - Mao

Question 30

what makes active catalysts a powerful lewis aciddd

Answer 30

when they have an active siteeee bc this allows them to accept e- theyre cationic and have 14e-

Question 31

what must counterions do accc

Answer 31

they needddd to interact so that the lewis acidity of the catalyst isngt reduced MAO is the counterionnnn

Question 32

homogenous isotatic synthesis of PP requires what

Answer 32

a well controlled insertion of monomer onto the polymer chain obvs well controlled bc its isotactic aka we want all of it to be the same

Question 33

to make the addition of the monomer onto the polymer well controlled and isotactic what matters

Answer 33

the symmetry of the complex atttt the metal site is important aka it has to be ZnCl2 Cpph Cpph not just Cp

Question 34

without MAO what happens

Answer 34

thw activity is lpwwww its less reactive maybe bc lewis acidity decreases and therefore cant accept an e- pair

Question 35

whats more reactive,, HOMO and MAO or hetero

Answer 35

homo is morereactive than heterooo

Question 36

stereochemical contorl of homo mao insertion occurs due to what

Answer 36

ligand design kinda like an enzyme is adding rhe monomers on

Question 37

controlled insertion of an alkene into the polymer using homo MAO is due to what

Answer 37

steric repulsion of R groups aka steric interaction of the alkene monomer and the ligand framework

Question 38

do we need lots or little MAo

Answer 38

we need lots of it

Question 39

early tm have what in terms of b elim

Answer 39

they are bad at beta elim

Question 40

whats a signle site catalyst

Answer 40

catalyst were there are active sites separated on top of a surface and theyre identical

Question 41

whats an example of a sigle site activation catalyst

Answer 41

homogenous ZN

Question 42

what type of single site catalysis ways do we have

Answer 42

chain end stereochemical control enantiomorphic stereochemical control

Question 43

whats chain end stereochemical control

Answer 43

as the chain grows from the metal site, the last monomer ifluences the stereochem of the next monomer its kinda bad bc theres propagation errors,, aka if an error occurs,,, it keeps being made

Question 44

whats enantiomorphic stereochemical cntrol

Answer 44

when the metal site controls the chain growth errors arent propagated

Question 45

how can chain end caused errors be corrected

Answer 45

if u get another error and it cancels it out

Question 46

how are site controlled errors fixed

Answer 46

theyre fixed by themselves

Question 47

what if we wanna make syndiotactic pp in a single site catalyst

Answer 47

we need to insert the monomer in alternating positions at the metal site non chrial catalyst but must have a mirror plane system

Question 48

C4 and C20 alpha olefins are used where

Answer 48

theyre used in deterges, plasticisers etc

Question 49

do we want long chain alpha olefins ior short chain

Answer 49

we want long chain alpha olefins,, the lower ones are recycled

Question 50

to make alpha olefins what do we need a lot of

Answer 50

Al R3 aka aluminium alkyls not very good for industrial scale

Question 51

majority of alpha olefins are made in what way

Answer 51

SHOP shell higher olefin process

Question 52

SHOP has what

Answer 52

many diff reactions that use diff catalysts

Question 53

what reaction occur in HSOP,, aka shell higher olefin process,, aka the most pop way to make alpha oldefins

Answer 53

oligomerisation isomerism metathesis

Question 54

describe oligomerisation in HSOP

Answer 54

- polar solvent used -biphasic reaction( product in diff phase then solvent) - Ni hydrido complex is the active species - 70-140 bar and 80-140*C produces alpha olefinsss

Question 55

isomerisation in SHOP

Answer 55

this places the alpha double bonds at more therodynamically stable positionsin the chain aka more internal posiotions

Question 56

metathesis in SHOP

Answer 56

higher internal olefins are metathesised with lower olefins aka short chain to make fractions with double near chain ends aka cis alkenes with R1 of one alkene and R of the other alkene theyr enot alpha oldefins but theyre still valuable