Wittig

Question 1

Reactants and products

Answer 1

Aldehyde/ketone to alkenes

Question 2

Unstabilised ylides

Answer 2

No conjugated withdrawing group, needs nBuLi/LDA, reacts with aldehydes and ketones, forms Z product

Question 3

stabilised ylides

Answer 3

Has anion stabilising group, NaOEt/NaOH, aldehydes only, forms E product

Question 4

Ylide formation

Answer 4

PPh3 and alkyl bromide

Question 5

Unstabilised ylide mechanism

Answer 5

Ylide and C=O approach perpendicular, large substituents kept apart, forms Z product

Question 6

Stabilised ylide mechanism

Answer 6

Ylide and C=O perpendicular, large subs kept apar and electronegative groups repel, forms E product