Lecture 16

• Get Lecture Problem 6• The Synthetics

This Week in Lab:• Ch 9 PreLab Due• Quiz 5• Ch 6 Final Report Due

Next Week:Spring Break!!!

The Condensation Reactions

Experiment 14: Synthesis of 3-Carbethoxycoumarin

Go over mechanisms for transesterifcation & aldol condensation in class

O O O O O O

O

OC2

H5

OHO

7

6

5 4

2

1

Warfarin:

a rat poison

3-Carbethoxycoumarin:

your synthetic goal

Coumarin, the

parent heterocycle:

a flavoring

8

3

The Condensation Reactions

Experiment 16: Synthesis of Creatine

Go over mechanism in class.

C NH2NHN

OH

O

+

NaClNH4OH

H2ON

OH

ONHH2N

creatine

Esterification

Synthesis of estersR O

O

R'

A Typical Esterification (generic example):

R O

O

R'R O

O

H R'OHH+

+ H2O+

• reaction of a carboxylic acid (elec) with an alcohol (nuc)• acid catalyzed• reversible• known as a Fisher Esterification

Esterification

Experiment 80: Synthesis of Aspirin

• Reaction of an alcohol (nuc) with an anhydride (elec)• Similar mechanism to Fisher esterification• Analyses: IR & NMR

Aspirin:• Anti-inflammatory• analgesic (pain killer)• Antipyretic (fever reducer)

OHO OH

salicylic acid

+ OOO

acetic anhydride

H3PO4 OO OH

O+

OHO

acetylsalicylic acid(aspirin) acetic acid

More Esterifications

Experiment 86: Synthesis of Benzocaine

• Fisher esterification reaction• Analyses: IR, NMR & MS

Benzocaine: • Topical local anesthetic for itching and pain caused by sunburn, insect bites, poison ivy, poison oak, minor cuts• Deadens the nerve endings in the skin

NH2

NH2

OH

OCH2

CH3

O

O

CH3

CH2

OH

H2

O

2

1

+

+

H

+

Benzocaine

Fragrant Esters

Analyses: IR, NMR,GC, GC-MS, MS

O

O

n-Butyl AcetateApple scent

(Experiment 81)

O

O

Isobutyl PropionateFragrance of rum(Experiment 82)

O

O

Benzyl acetatePeach scent

(Experiment 83)

O

O

Methyl BenzoateFloral fragrance(Experiment 84)

O

O

Isoamyl acetateBanana scent

(Experiment 87)