Chapter 5: Extraction

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Lecture 3

• Chapter 5 Extraction
• Lecture Problem 1 Due Thursday
• This week in lab
• Ch 4 Recrystallization Melting Point
• Procedures 1 2
• Ch 4 PreLab Due
• Quiz 1
• Next week in lab
• Ch 4 Procedures 3 5
• Ch 5 Extraction, Procedure 1
• Ch 5 PreLab Due Quiz 2

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Chapter 5 Extraction

• Extraction
• Pulling out a component from a mixture
• Used to isolated specific compounds
• Used to purify a compound
• Types Liquid/liquid extraction, solid/liquid
  extraction
• Two day lab
• Procedure 1 Separation of an unknown
  three-component mixture
• Procedure 2 Extraction of caffeine from tea or
  coffee

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Chapter 5 Procedure 1

• Separation of an unknown three-component mixture
• Acidic component (CO2H)
• Basic component (NH2)
• Neutral component

Possible Unknowns
Acids
Separate by acid/base chemistry
Bases
Once separated and dry, take a m.p. of each to
determine the identity. Take melting points the
following week.
Neutrals
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Chapter 5 Procedure 1

• Example Separate these three components

1. Use a flow chart to visualize how the
separation will work. 2. See photos/video.
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Chapter 5 Procedure 1

• Once the separation is complete
• Dry each, weigh and calculate recoveries
  (assume you started with equal amounts of each)
• Take a m.p. of each to determine identities
• Either take an IR of the acidic component OR an
  NMR of the neutral component

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Chapter 5 Procedure 2

• Extraction of caffeine
• 1. Use tea bags (odd desks) or coffee bags
  (even desks)
• 2. Steep tea or coffee bags in hot water
• 3. Extract aqueous solution with dichloromethane
  (CH2Cl2) to
• isolate caffeine
• Purify caffeine by sublimation
• Weigh caffeine.
• Compare caffeine content in tea and coffee with
• hoodmates data reference data.

caffeine
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Chapter 5 Procedure 2

• Extraction of caffeine

For extraction, use a separatory funnel Get a
demo from your TA. A few, smaller extractions
are better than one big extraction. Vent funnel
while shaking. Aqueous layer tea/coffee
solution Organic layer dichloromethane/caffeine
Separatory funnel
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Chapter 5 Procedure 2

• Extraction of caffeine

Vent funnel while shaking. Point away from
face, towards back of hood.
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Chapter 5 Procedure 2

• Once caffeine has been isolated, purify via
• sublimation (heat solid ? gas ? pure solid).
• Weigh the isolated caffeine and calculate the
  amount of caffeine per gram of tea or coffee.
• Compare data with hoodmate reference the data.