Lecture 14

• IR & 1H NMR Practice Problem (Lec 13)• Column Chromatography of Plant Pigments• Get Lecture Problem 5, due next class

This Week In Lab:• Ch 7 PreLab Due• Quiz 4• Ch 5 Final Report Due

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

2. This compound has the formula C5H10O. Determine its structure by using thefollowing spectral data.

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Chapter 9Column Chromatography of Plant Pigments

A two-day experiment

Day One - Extraction & Chromatography of Plant Pigments

Day Two - UV/Vis Analysis of Plant Pigments

Extraction of Plant Pigments

• Obtain spinach leaves

• Grind up leaves with acetone, petroleum ether and CaCO3

• Transfer to a separatory funnel

• Extract (similar to Ch 5!)

• Organic layer contains plant pigments - to be separated via column chromatography

Column Chromatography of Plant Pigments

• Pack column

• Load sample (plant pigment solution/organic layer) to column

• Run column & collect fractions in tared flasks

**NEVER let the column to dry**Always have fresh mobile phase in the

column

• TLC the fractions

See video on column prep in class.

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http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/D-CC-e.htm

Getting the column ready

Column ChromatographyOf Plant Pigments:

Step 1

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Running the column & collecting fractions

http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/D-CC-e.htm

What the column will looklike - the colored bandsare the plant pigments!

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http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/D-CC-e.htm

Finishing up &Evaluating the fractions

The different fractionsThat contain the Different pigments

Evaluate by TLC &By UV/Vis

C

C

C

C

C

C

C

C

CH3

CH3

H

H

CH3

H

H

H

CH3

H

CH3

CH2

OH

Vitamin A C20

H30

O

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

CH3

CH3

H

H

CH3

H

H

H

CH3

H

H

H

H

CH3

H

H

H

CH3

H

H

CH3

CH3

CH3

CH3

lycopene C40

H56

-

m.p. 173°C (all trans)

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

C

CH3

CH3

H

H

CH3

H

H

H

CH3

H

H

H

H

CH3

H

H

H

CH3

H

H

CH3

CH3

CH3

CH3

β -carotene C40

H56

- m.p. 183°C (all trans)

Carotenoids

• Hydrocarbons

• Orange/red/yellow pigments in fruits and veggies

• Conjugated systems

• Involved in photosynthesis

CH3

CH3

CH3

CH3

CH3

CH2

CH3

CH3

O

COOCH3

CH2

COOCH2

H

CH2

H3

C

H

H3

C

CH2

CH

Mg

N

NN

N

C

O

H

CH3

CH3

CH3

CH3

CH3

CH2

CH3

CH3

O

COOCH3

CH2

COOCH2

H

CH2

H3

C

H

H3

C

CH2

CH

Mg

N

NN

N

CH3

chlorophyll-a

chlorophyll-b

Chlorophylls

• Porphyrins• Blue/green pigments in plant leaves• Also involved in photosynthesis• Produced by plants in response to sunlight

Flavonoids

• Aromatic compounds• Red, violet, blue, or yellow pigments in plants, fruit, flowers• In fruit and flowers, act as an attractant for insects to distribute pollen and seeds• In leaves, act as sunscreens

OHO

OH O

OH

OH

Luteolin

O

OGly

Anthocyanin