Stasch P-Block Metals

Question 1

what group are group 12 often compared to (due to similar ionic radius, mainly ionic properties)

Answer 1

Alkaline earth metals

Question 2

Which is the least reactive - organomagnesium, organozinc or organolithium?

Answer 2

organozinc (gives it better FGT)

Question 3

How would you form organozinc complexes?

Answer 3

direct synthesis // salt metathesis // redox-transmetallation

Question 4

What is the Simmons-Smith reaction?

Answer 4

diiodomethane and Zn(Cu) react to make a carbenoid which is reacted with an alkene to make a cyclopropane

Question 5

what is the Reformatsky reaction?

Answer 5

zinc dust with an a-bromoester to form a zinc enolate that reacts with a ketone to form B-hydroxyesters

Question 6

CdR2 doesn’t react with __ or __ but can react with __

Answer 6

esters ketones acid chlorides

Question 7

HgR2 is of interest for what type of reaction (depending on electronegativity/positivity compared to the other metal)

Answer 7

redox-transmetallation

Question 8

How does mercury poisoning work?

Answer 8

the soft MeHg+X- cation forms strong bonds with nucleophiles such as S containing groups (eg methionine)

Question 9

advantages of organocuprates?

Answer 9

good, soft nucleophiles for substitution reactions. Can react with a range of oxidation states.

Question 10

what sort of mechanism is an RX with a cuprate?

Answer 10

cross-coupling Sn2

Question 11

How do you activate Al metal

Answer 11

grind with AlEt3

Question 12

what aggregation state is preferred for AlR3 compounds

Answer 12

dimeric (3c-2e bonds)

Question 13

What is the Ziegler direct process

Answer 13

INCREASE + ATTACH
synthesis of “more” AlEt3 - combines Al with H2 in presence of AlEt3 then uses the AlH mechanism to combine with alkenes to make more.

Question 14

What is the Aufbau reaction

Answer 14

reacts ethene with AlEt3 to increase chain lengths; attaches oxygens between Al and hydrocarbon chains; hydrolyse the chains to make 3x long alcohols

Question 15

How does the aufbau change when other 1-alkenes are used?

Answer 15

only one insertion of the Al-C bond is possible : eg could be used for catalytic dimerisation of propene to isopropene

Question 16

Can Aufbau work with an acetylene?

Answer 16

yes but stops after one addition

Question 17

what is hydroalumination?

Answer 17

the reverse of B-hydride elimination

Question 18

what isomer are you likely to achieve with hydroalumination to nBuC[triplebond]CH?

Answer 18

cis // and favours anti-Markovnikov product

Question 19

What does Ziegler Natta do?

Answer 19

polymerises ethene and other olefins

Question 20

What is the Code-Arlman mechanism?

Answer 20

creation of long hydrocarbon chains in a specific orientation using metallocene catalysts and ethene

Question 21

What is the role of MAO (MeAlOn) during polymerisation?

Answer 21

alkylating agent, lewis acid, impurity scavenger

Question 22

What is Tebbe’s reagent?

Answer 22

mixed Ti(VI) Al(III) reagent with a bridging methylene group.

Question 23

why is lead so unstable?

Answer 23

it makes weak Pb-C bonds and has poor thermal stability

Question 24

what reaction do organotin reagents undergo with phenyl lithium or alkyl lithiums

Answer 24

transmetallation
(RLi attacks Sn via a 5-CN intermediate)
(PhLi forms SnPh4 and Li complexes)

Question 25

What is Bent’s Rule?

Answer 25

Degree of p character on metal - length of bond to electronegative ligand. If the p character has to be shared the bonds will be shorter

Question 26

What is a hydroelementation?

Answer 26

R3EH can undergo hydrogermanation and hydrostannation reactions with alkenes.

Question 27

Which Pd-catalysed cross-coupling are tin reagents useful in?

Answer 27

Stille

Question 28

What common ER(?) are used in group 15 organometallic?

Answer 28

ER3 or ER5