Substitution Reactions

Question 1

Stereochemistry of R-OH to R-X

Answer 1

Inversion

Question 2

How to convert R-OH to R-X

Answer 2

SOCl2 and pyridine or PBr3 or Appel = PPh3 and CX4

Question 3

Conversion of R-OH to sulfonate ester stereochemistry

Answer 3

Retention

Question 4

Make tosylates

Answer 4

Tosyl chloride and pyridine

Question 5

Make mesylates

Answer 5

Mesyl chloride and NEt3

Question 6

Make triflates

Answer 6

Triflic anhydride and pyridine

Question 7

Rank sulfonate esters by increasing LG character

Answer 7

OTf > OMS > OTs

Question 8

Ether formation

Answer 8

Alcohol + 1. NaH 2. R-X

Question 9

CN bond formation

Answer 9

azide intermediate = change to good leaving group, NaN3 = inversion
phthalimide + KOH gives phthalimide anion which undergoes SN2 with alcohol then NaOH(aq) for hydrolysis

Question 10

CS bond formation

Answer 10

R-SH + 1. NaOET 2. R-Cl

Question 11

Mitsunobu reaction

Answer 11

One pot reaction, alcohol + NuH (PPh3, DEAD) gives nucleophilic substitution with inversion

Question 12

Polar protic solvent

Answer 12

Water, alcohol, CA, forms H bonds, solvates ions and favours SN1

Question 13

Polar aprotic solvent

Answer 13

Acetonitrile, acetone, DMF, no H bonds, solvates only cations meaning more free anions so more nucleophilic and often SN2

Question 14

Stadinger reaction

Answer 14

Reduces azides to amines, reagents = 1. PPh3 2. H2O