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orgchem lab > Isolation of Caffeine from Dried Tea Leaves > Flashcards

Isolation of Caffeine from Dried Tea Leaves Flashcards

1
Q

It is an alkaloid and has base characteristics

A

Caffeine

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2
Q

Caffeine has the ____________, a framework that plays an important role in living systems

A

Purine Ring System

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3
Q

Caffeine is also known as:

A

1,3,7-trimethylxanthine

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4
Q

Caffeine is odorless, has a bitter taste and is ______________

A

Highly Soluble in Hot Water

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5
Q

What is the boiling point of Caffeine? (in celsius)

A

178°C

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6
Q

What is the melting point of Caffeine?

A

235-238°C

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7
Q

Caffeine acts as a ________ - are medications designed to increase the amount of water and salt expelled from the body as urine

A

Diuretic

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8
Q

Caffeine also ________ metabolism

A

stimulates

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9
Q

Caffeine also contributes to an increase in ____________ levels in the blood

A

Dopamine

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10
Q

Caffeine is also a ________ present in tea, coffee, cocoa, cola nuts and beverages.

A

stimulant

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11
Q

small doses of this chemical (blank) can** increase alertness** and reduce drowsiness and fatigue.

A

50-200 mg

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12
Q

Caffeine also affects blood circulation because the heart is stimulated and blood vessels are _____________ (vasodilation)

A

Relaxed

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13
Q

Large doses of caffeine (of over ________) can result in insomnia, restlessness, headaches, and muscle tremors.

A

over 200 mg

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13
Q

Continued, heavy use of caffeine may bring on (blank)

A

Physical Dependence

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14
Q

It is consists primarily of cellulose (the principal structural material of all plant cells)

A

Composition of Tea Leaves

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15
Q

Cellulose is insoluble in water, thus, can be separated from caffeine by ______________

A

Hot Water Extraction

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16
Q

It is a colored polyphenolic compounds of high molecular weight (500-3000 g/mol) that have acidic behavior.

A

Tannins

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17
Q

Tannins are ________ complex substances.

A

Water Soluble

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18
Q

It is responsible for astringency, color, and some flavor in tea.

A

Tannins

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19
Q

TRUE OR FALSE:

As much as 5% by weight of the leaf material in tea
plants consists of caffeine.

A

TRUE

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20
Q

It allows soluble components to be removed from solids using a solvent.

A

Solid-Liquid Extraction

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21
Q

Application of this unit operation include obtaining oil from oil seeds or leaching of metal salts from ores.

A

Solid-Liquid Extraction

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22
Q

They are readily soluble in hot water and is separated from tea leaves.

A

Caffeine and Tannins

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23
Q

It involves using a **liquid solvent to remove a liquid component ** from a liquid mixture.

A

Liquid-Liquid Extraction

24
Q

It is known as **partitioning **

A

Liquid-Liquid Extraction

25
Q

**TRUE OR FALSE: **

In Liquid-Liquid Extraction, the component dissolves preferably in the solvent.

A

True

26
Q

What are the applications of Liquid-Liquid Extraction?

A
  • Removal of Vitamins from Aqueous Solutions
  • Aromatic Compounds from Crude Oil Fractions *(in chemical and mining industries and in the downstream recovery of fermentation products)
27
Q

TRUE OR FALSE:
Frequently, one of the solvents is water or an aqueous
mixture (aqueous phase) and the other is a non-polar
organic liquid (organic phase).

A

TRUE

28
Q

Liquid-Liquid Extraction comprises of two steps:

A

Mixing phase and phase separation

29
Q

The solubility of caffeine in water is _______ ?

A

2g/100 g of cold water

30
Q

The solubility of caffeine in dichloromethane is ______ ?

A

14g/100g

31
Q

A procedure by which two liquids with different boiling points can be separated.

A

Distillation

32
Q

Powerful technique for separating the component substance from a miscible fluid mixture by means of selective** evaporation** and **condensation. **

A

Distillation

33
Q

What are the parts of Separatory Funnel?

A
  • Stopper
  • Teflon Stopcock
  • Separatory Funnel Body
34
Q

**PROCEDURE (Solid-Liquid Extraction) **

  1. What labels do you need to write in a 125 mL Erlenmeyer Flask?
A

Flask 1: Aqueous Layer
Flask 2: Organic Layer

35
Q
  1. What measurements of the chemicals you need to place in a 250mL beaker with a watch glass?
A
  • 10.0 grams of dried tea leaves
  • 6.25 grams of sodium carbonate
  • some boiling chips
36
Q
  1. Pour ________ mL of Distilled Water into the beaker.
A

87.5

37
Q
  1. Turn hotplate to ____. Heat the mixture to boiling for 10 minutes. (Start time when mixture starts to boil).
A

300°C

38
Q
  1. ________ the liquid into a 250-mL Erlenmeyer Flask. Make sure that no solid particles will be included in the supernatant liquid.
A

Decant

39
Q
  1. Cool the __________ to room temperature.
A

Aqueous Extract

40
Q

PROCEDURE (Liquid-Liquid Extraction)

  1. Pour the cooled aqueous extract into a 125mL separatory funnel in the _______
A

fumehood

41
Q
  1. Extract the solution with ________ of __________ . Mix by inverting the mixture in a rocking motion repeatedly. Take care not to shake the funnel too vigorously. (5 shakes by 5 sets)
A

15 mL of CH2CL2

42
Q
  1. How many minutes you should let it stand the Separatory Funnel until the layers separate?
A

About 5 minutes

43
Q
  1. Drain the CH2CL2 layer into a 125mL Erlenmeyer Flask #?
A

Flask #1

44
Q
  1. What you should do next after draining the CH2CL2 in the Erlenmeyer flask?
A
  • Repeat steps 2 and 3 using another 15mL of CH2CL2
  • Combine the two CH2CL2 layers.
45
Q
  1. Add a small amount of __________ to the pooled extract, and swirl the mixture for a few seconds.
A

Sodium Sulfate

46
Q

PROCEDURE (Distillation):

  1. Filter the dichloromethane extract through a _________ into a ____________
A

cotton plug; 250mL distillation flask.

47
Q
  1. What you should do after filtering the dichloromethane?
A

Assemble a distillation set-up

48
Q
  1. ________ the evaporating dish to room temperature and weigh.
A

Cool

48
Q
  1. Evaporate the dichloromethane to dryness over a ___________
A

Hot water bath

49
Q
  1. Distill the dichloromethane and collect about ________. Take note of the _______
A

50mL; BP Range

49
Q
  1. Transfer the remaining solution to a _____________
A

pre-weighted evaporated dish.

50
Q
  1. Collect the ____________ of caffeine into a labeled vial and submit to your lab instructor
A

greenish-white crystals.

51
Q

What is the solubility of caffeine in water?

A

2.17g/100mL water at 25C

52
Q

What is the solubility of caffeine in a chloroform?

A

18.18g/100mL chloroform at 25C

53
Q

The __________ is an expression of the relative preference of the solute for the solvents.

A

Distribution coefficient

54
Q

What is the equation of a substance in each layer?

A

C1/C2 = Kd

55
Q

What does C1 stands for?

A

Concentration of solute in layer 1

56
Q

What does C2 stand for?

A

Concentration of solute in layer 2

orgchem lab (9 decks)

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