Exam 3 Flashcards
Fischer Esterification
Creates an ester from Carboxylic acid
Uses: acid
What does the Hoffman elimination do?
Turns an amine into an alkene, and forms the less substituted alkene (anti-Zaitsev) product
What does saponification do?
Hydrolysis of ester under basic conditions to form carboxylate anions
Last step is irreversible
What does hydrolysis of a nitrile in acid (or base) produce?
Carboxylic acid (or carboxylate anion)
What reagents synthesize nitriles?
R-X and CN-
What is the order of decreasing reactivity for the reagents used in Nu Acyl substitution rxns?
Acid chloride > anhydride > ester ~ Carboxylic acid > amide
What reagent is used to convert COOH to acid chloride?
SOCl2 and heat
What reagent is used to convert COOH to an anhydride?
Heat
What reagent is used to convert COOH to an ester?
HOR’ and H+ cat.
What reagent is used to convert COOH to an amide?
NH2R’ and DCC
What reagent is used to convert acid chloride to COOH?
H2O and pyridine
What reagent is used to convert anhydrides, esters, or amides to COOH?
H2O and H+
What reagent is used to convert ester to COOH?
H2O and H+ (or base)
What does the haloform reaction do?
Forms a good LG (which leaves as the haloform)
Forms a carboxylate anion
What three things allow you to preferentially make the kinetic enolate over the thermodynamic enolate?
Strong, BULKY base (LDA) Aprotic solvent (like THF) Low temp (-78 C)
What does Malonic ester synthesis do?
Uses a Malonic ester to synthesize Carboxylic acid and CO2
1-Deprotonate to form enolate
2-Alkylation via R-X
3-Hydrolysis and loss of CO2 (or more if it is bonded to that LG)
What does adetoacetic ester synthesis do?
Makes methyl ketones
Steps are identical to Malonic ester synthesis
What does Aldol reaction do?
Forms C-C bonds using aldehydes or ketones as starting material
1-Form Nu enolate
2-Nu addition
3-Protonation
When can decarboxylation occur?
Whenever a carboxy group is bonded to the alpha carbon of another carbonyl group
What do intramolecular Aldol reactions do?
Form five and six member rings 1-Make enolate 2-Nu attacks 3-New C-C bond forms 4-H2O is lost and pi bond forms
What does the Claisen reaction do?
Makes new C-C bonds between the alpha carbon and carbonyl carbon of two esters via substitution
1-Make enolate
2-Nu addition and loss of LG
3-deprotonation and protonation
What will a 1,6 diester make if it reacts with itself via a Claisen reaction?
A five-member ring
What does a Michael reaction do?
1,4 addition of enolate to beta carbon of alpha, beta unsaturated carbonyl system
1-Enolate forms
2-Enolate attacks BETA carbon
3-Alpha carbon is protonated
What does the Robinson Annulation do?
Forms a six-member ring and three new C-C bonds
1-Michael reaction
2-the other enolate is formed
3-Nu attacks other carbonyl carbon to make ring
4-Beta oxygen gets protonated
5-dehydration and new pi bond forms between alpha and beta carbons (this step is irreversible)
When using a diazonium salt what reagent is used to make phenol?
H2O
When using a diazonium salt what reagent is used to make benzyl chlorides or bromides?
CuCl
CuBr
When using a diazonium salt what reagent is used to make benzyl fluorides?
HBF4
When using a diazonium salt what reagent is used to make benzyl iodides?
NaI or KI
When using a diazonium salt what reagent is used to make benzene?
H3PO2
When using a diazonium salt what reagent is used to make cyanobenzene?
CuCN
How can you selectively make a primary amine?
Gabriel synthesis
What are the steps of reductive amination of aldehydes and ketones?
Replaces C=O by C-H and C-N
1-Nu of NH3 on carbonyl group forming IMINE
2-Oxygen leaves
3-Nitrogen is deprotonated
What does the Hoffman elimination do?
Converts an amine into a quaternary ammonium salt prior to beta elimination
1-make good LG (quat. Ammonium salt)
2-Use strong base to cause anti-periplanar E2 elimination
Is the more substituted or less substituted pi bond formed in the Hoffman reaction and why?
LESS.
The sterics of the bulky N(CH3)3 prevent abstraction of the more hindered hydrogen
