CH9: C.A. and Derivatives. Nucleophilic Addition-Elimination at the Acyl Carbon

Question 1

How do acyl chlorides leave

Answer 1

Cl- is a good L.G.

Question 2

What are the L.G. of:
Esters
C.A.
Amides

Answer 2

Alcohol
Water
Amine

Question 3

Aldehydes/Ketones vs Esters,C.A., Amides, Acyl chlorides

Answer 3

Aldehydes and ketones have bad L.G. and need acid/base catalysis, the other ones have good L.G.

Question 4

Rank reactivity

Answer 4

Acyl chloride>Acid anhydride> Ester>Amide

Less reactive groups can be synthesized from more reactive ones

Question 5

Acid chlorides from C.A.

Answer 5

PCL5, PCL3, SOCL2…they make the OH into a good L.G. (H2O+)

Question 6

Acyl chloride to acid anhydride

Answer 6

Carboxylate anion salt

Question 7

Acyl chloride to ester

Answer 7

R-O-H and base, pyrdidine is used to soak HCl

Question 8

Acyl chloride to amides (1,2,3)

Answer 8

1-NH3
2-NH2R
3-NHRR’

Question 9

Acid anhydride to ester

Answer 9

ROH

Question 10

Acid anhydride to amide (1,2,3)

Answer 10

NH3, NH2R, NHRR’

Question 11

Acid anhydride to C.A.

Answer 11

H2O

Question 12

Acyl chloride to C.A.

Answer 12

H2O

Question 13

Are anhydrides good to use

Answer 13

No, lots of waste

Question 14

Acid anhydride to carboxylate

Answer 14

OH-/H2O

Question 15

Acyl chloride to carboxylate

Answer 15

OH-/H2O

Question 16

Sodium carboxylate + Acyl chloride =

Answer 16

Acid anhydride

Question 17

Acyl chloride + C.A.=

Answer 17

Acid anhydride, must have pyridine

Question 18

How to make cyclic anhydrides?

Answer 18

Heat the proper dicarboxylic acid

Question 19

Fischer estrification

Answer 19

Acid catalyzed reactions of alcohols and C.A. to yield esters.

Formation is favored by excess C.A. or ester and removal of water.

Esters are good C.A. protecting groups.

Removal with dilute acid

Question 20

Acid anhydride to ester

Answer 20

R-OH leads to ester formation and cleavage

Question 21

Saponification

Answer 21

Base promoted cleavage of esters.Base in water leads to carboxylate and alcohol

Question 22

Lactones

Answer 22

Cyclic esters formed by gamma (3 out) or s shape (4 out) carbons attacking a carbonyl carbon. They are acid catalyzed.

Question 23

How to hyrolyze lactones

Answer 23

OH-/H2O reverts it back to an acyclic carboxylate. HA makes C.A, too much reverts back to lactone i.e. acid catalyzed.

Question 24

Anhydrides to amides

Answer 24

2 moles of NH2R’ Leads to amide and ammonium carboxylate (R’NH2+ -CO2R)

Question 25

Cyclic anhydride to cyclic imide

Answer 25

1) 2 moles amine yields one NH2 and one NH4 group i.e cleaves at the O
2) H3O+ then gets rid of the NH4 group for a C.A.
3) Heating can get rid of H2O and form a cyclic Imide with a very acidic H

Question 26

Amine and C.A. to amide

Answer 26

DCC is used to react with an Amine and C.A. to yield an amide, it creates a good L.G.

Question 27

Heating of amide with base or acid in water

Answer 27

Base-Forms sodium carboxylate

Acid-Forms carboxylic acid

Question 28

Amide to nitrile (R t.b.N)

Answer 28

P4O10 or (CH3CO2)2O 
Phosphorous pentoxide and acetic anhydride

Question 29

Phosphorous pentoxide

Answer 29

Amide to nitrile

Question 30

Acetic anhydride

Answer 30

Amide to nitrile

Question 31

Heating Beta keto carboxylic acids

Answer 31

decarboxylate readily