L9-1

CHEM 110L, Lecture 9 Experiment 6 – Diels Alder Reaction in Water Report due to TA mailbox Monday 6/10 by 5pm

Diels-Alder [4+2] Cycloaddition Reaction

During 1 hr Reflux - Drawer check - 10 points toward lab report & avoid grade drop

• Take everything out of the drawer, wipe out drawer, make sure glassware is clean & intact and there’s nothing extra (personal items, duplicates, etc.). Students are responsible for visually inspecting each piece of glassware, whether or not it was used this quarter. Your TA will not be held responsible for final drawer checks.

- UV-vis spectra of NEM Reaction Work-up = Vacuum filtration, wash w/ cold water Save some crude sample to take Melting Point (not boiling point!) later Mixed Solvent Recrystallization

EDG

EWGΔ

+

EDG

EWG

+ mixture of other products

N

O

O

Δ

HOOH

+ N

O

O

Et

9-anthracenemethanol(NEM)

N-ethylmaleimide

H2O* 25mL RBF(not 15-mL)

Diels-Alder Adduct

Dissolve in minimumamount of hot toluene

Add Et2O drop-wise until slightly cloudy solution after stirring

L9-2

UV-Vis – The General Idea Greater conjugation = lower energy = higher absorbance wavelength (λmax)

Sketch Expected 1H NMR Spectra – use online NMR predictor tool!!

12 Chemical Shift (ppm) 0

12 Chemical Shift (ppm) 0

N

O

OHO

OH

9-anthracenemethanol(NEM) Diels-Alder Adduct

vs.

HO

9-anthracenemethanol(NEM)

N

O

ON-ethylmaleimide

L9-3

Signal (a-o) Integration Splitting Expected

Chemical Shift Observed

Chemical Shift 0.4 3.0 3.2 4.7 4.8 5.3 5H (overlap) 7.1 7.2 7.4 7.7

NO

Oab

OHg fhi

cd

jk

elm

no

L9-4

Signal Observed Shift Expected Shift

50 10 45/47 32 57 46 123-125 125-126 139-142 142’s

NO

Oab

OHghi

cd

jk

elm

no

*

**

*

Use these designations for unlabeled carbons...* = aromatic C's without H'sAmide C=O4o (between c-g)