EXERCISE 1

Question 1

most important technique for isolating and purifying organic substances

Answer 1

EXTRACTION

Question 2

plays a very important role in extraction

Answer 2

polarities of two selected solvents

Question 3

EXTRACTION

two solvents must be ____ and they must form two separate phases or layers, for this procedure to work

Answer 3

immiscible

Question 4

solvent where caffeine is more soluble

Answer 4

DICHLOROMETHANE

Question 5

many natural products are present in animal and plant tissues having ____

Answer 5

high water content

Question 6

useful solvent for the extraction and isolation of natural products

Answer 6

water-immiscible organic solvent

Question 7

EXTRACTION

caffeine may be extracted from tea using

Answer 7

dichloromethane

Question 8

EXTRACTION

vanillin can be extracted from vanilla beans using

Answer 8

ethanol

Question 9

EXTRACTION

solvents commonly used

Answer 9

diethyl ether
dichloromethane
hexane

Question 10

instrument used in extraction

Answer 10

separatory funnel

Question 11

in extracting caffeine from aqeous solution, we used what type of solvent

Answer 11

less polar than water

Question 12

why does the mixture separates into two layers?

characteristic of water

Answer 12

bc water is HIGHLY POLAR

Question 13

EXTRACTION

two layers formed

Answer 13

aqueous layer
organic (nonpolar) layer

Question 14

what to do in order to remove water-soluble impurities

Answer 14

water wash is done

Question 15

EXTRACTION

removes highly polar and water-soluble materials (H2SO4, HCl, NaOH, etc.) from the organic layer

Answer 15

water wash

Question 16

EXTRACTION

also helps purify desired organic compound in the original reaciton mixture

Answer 16

water wash

Question 17

EXTRACTION

during shaking, ____ may form

Answer 17

emulsion

Question 18

EXTRACTION

what to do to prevent the formation of emulsion

Answer 18

addition of saturated NaCl soln
gentle stirring
add more dichloromethane

Question 19

EXTRACTION

what to do to identify which layer is organic

Answer 19

get a sample from each layer then add a drop of water; if the drop mixes w the sample, the layer is aqueous; if not, the layer is organic

Question 20

EXTRACTION

dichloromethane is ____ than water

Answer 20

denser

Question 21

EXTRACTION

the combined layer/extracts are dehydrated by adding ____

Answer 21

anhydrous sodium sulfate

Question 22

EXTRACTION

removes excess water from the DCM extract

Answer 22

anhydrous sodium sulfate

Question 23

EXTRACTION

should be avoided so that caffeine will not sublime

Answer 23

too much evaporation

Question 24

EXTRACTION | MUREXIDE TEST

solution

Answer 24

caffeine + conc. HCl + KClO

Question 25

# **EXTRACTION | MUREXIDE TEST** test result

Answer 25

yellow color after steam bath dyring

Question 26

# **EXTRACTION** dried mixture is **moistened** with ____

Answer 26

ammonia (1 drop)

Question 27

# **EXTRACTION** result after adding **ammonia**

Answer 27

pink to purple color

Question 28

# **EXTRACTION** any ____ reacts with **HCl** and **KClO3** upon **exposure** to **ammonia** to **form murexide**

Answer 28

purine

Question 29

# **EXTRACTION** caffeine is an example of ____

Answer 29

purine alkaloid

Question 30

# **EXTRACTION** the **pink to purple color** that is responsible for the **murexide** is called

Answer 30

ammonia purpurate

Question 31

# **CAFFEINE** IUPAC name

Answer 31

1,3,7-trimethypurine-2,6-dione

Question 32

# **CAFFEINE** synonym

Answer 32

1,3,7-trimethylxanthine

Question 33

# **CAFFEINE** molecular formula

Answer 33

C8 H10 N4 O2

Question 34

# **CAFFEINE** physical description

Answer 34

odorless white pwoder w bitter taste

Question 35

# **CAFFEINE** **boiling** point | where it also **sublimes**

Answer 35

178C

Question 36

# **CAFFEINE** **melting** point

Answer 36

235C

Question 37

# **CAFFEINE** solubility in water

Answer 37

poor

Question 38

# **CAFFEINE** density

Answer 38

1.23g/cm

Question 39

# **CAFFEINE** chemical safety

Answer 39

irritant

Question 40

# **CAFFEINE** use

Answer 40

stimulant

Question 41

# **CAFFEINE** structure

Answer 41

3 methyl groups attached in a purine ring