CH9: C.A. and Derivatives. Nucleophilic Addition-Elimination at the Acyl Carbon Flashcards
How do acyl chlorides leave
Cl- is a good L.G.
What are the L.G. of:
Esters
C.A.
Amides
Alcohol
Water
Amine
Aldehydes/Ketones vs Esters,C.A., Amides, Acyl chlorides
Aldehydes and ketones have bad L.G. and need acid/base catalysis, the other ones have good L.G.
Rank reactivity
Acyl chloride>Acid anhydride> Ester>Amide
Less reactive groups can be synthesized from more reactive ones
Acid chlorides from C.A.
PCL5, PCL3, SOCL2…they make the OH into a good L.G. (H2O+)
Acyl chloride to acid anhydride
Carboxylate anion salt
Acyl chloride to ester
R-O-H and base, pyrdidine is used to soak HCl
Acyl chloride to amides (1,2,3)
1-NH3
2-NH2R
3-NHRR’
Acid anhydride to ester
ROH
Acid anhydride to amide (1,2,3)
NH3, NH2R, NHRR’
Acid anhydride to C.A.
H2O
Acyl chloride to C.A.
H2O
Are anhydrides good to use
No, lots of waste
Acid anhydride to carboxylate
OH-/H2O
Acyl chloride to carboxylate
OH-/H2O
Sodium carboxylate + Acyl chloride =
Acid anhydride
Acyl chloride + C.A.=
Acid anhydride, must have pyridine
How to make cyclic anhydrides?
Heat the proper dicarboxylic acid
Fischer estrification
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
Acid anhydride to ester
R-OH leads to ester formation and cleavage
Saponification
Base promoted cleavage of esters.Base in water leads to carboxylate and alcohol
Lactones
Cyclic esters formed by gamma (3 out) or s shape (4 out) carbons attacking a carbonyl carbon. They are acid catalyzed.
How to hyrolyze lactones
OH-/H2O reverts it back to an acyclic carboxylate. HA makes C.A, too much reverts back to lactone i.e. acid catalyzed.
Anhydrides to amides
2 moles of NH2R’ Leads to amide and ammonium carboxylate (R’NH2+ -CO2R)
Cyclic anhydride to cyclic imide
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
Amine and C.A. to amide
DCC is used to react with an Amine and C.A. to yield an amide, it creates a good L.G.
Heating of amide with base or acid in water
Base-Forms sodium carboxylate
Acid-Forms carboxylic acid
Amide to nitrile (R t.b.N)
P4O10 or (CH3CO2)2O Phosphorous pentoxide and acetic anhydride
Phosphorous pentoxide
Amide to nitrile
Acetic anhydride
Amide to nitrile
Heating Beta keto carboxylic acids
decarboxylate readily
