exp 1 post lab

Question 1

Primary Components of Coffee Beans (4)

Answer 1

1. Cellulose
2. Organic Acid
3. Tannins
4. Alkaloids

Question 2

CELLULOSE

• ___ component of plants
• most _____ ____ ____ in earth
• solubility?
• remains _____ in hot _____ water after ____-_____ ______

Answer 2

• major
• most abundant organic polymer in earth
• water-insoluble
• undissolved in hot distilled water after solid-liquid extraction

Question 2

ORGANIC ACID

• solubility
• contains??
• will be ____ in hot _____ water after ___-____ extraction
• _____ and ____ ____ in nature

Answer 2

• water-soluble
• acidic functional groups (carboxylic acid)
• dissolved in hot distilled water after solid-liquid extraction
• acidic and positively charged

Question 2

How to deprotonate organic acids? + makes them what charge?

Answer 2

addition of Na2CO3 (makes them neutral charged)

Question 2

How to protonate organic acids? + makes them what charge?

Answer 2

addition 10% HCl (makes them positive charge)

Question 2

ALKALOIDS

• a group of _____ _____ _____ products that contain _____ or _____ _____ _____ atoms in a _____ _____ or in _____ _____chain
• commonly used as (3)
• derived from _____ _____
• nitrogen exist as _____ or _____ _____
• polarity?

Answer 2

• highly diverse natural
• one or more basic nitrogen atoms
• heterocyclic ring
• aliphatic side chain

1. drugs
2. stimulants
3. poison

• amino acids
• secondary or tertiary amine
• low polarity

Question 2

STEPS in ISOLATION of ALKALOIDS from COFFEE BEANS (5)

Answer 2

1. Solid-liquid extraction through mixing of coffee beans and hot dH2O (alkaloids remain in hot dH2O afterward)
2. Enhancement of water solubility of alkaloids through addition of 10% HCl, thus alkaloids become positively charged

*lagay sa separatory funnel with organic solvent (LIQUID-LIQUID EXTRACTION)

3. Conversion of alkaloid salt to molecular form through addition of 10% Na2CO3 to make the alkaloid BASIC (neutral charged)
4. (LIQUID-LIQUID EXTRACTION) Extraction with organic solvent like dichloromethane/ethyl acetate (mag ddisolve na si alkaloids dito kasi neutralized na)

• addition of salt to organic layer for removal of excess water

5. Removal of organic solvent from alkaloids by evaporation

Question 2

How much caffein per gram of Arabica coffee beans?

Answer 2

8 - 12 mg caffeine

Question 2

PROPERTIES OF ALKALOIDS (6)

• insolubility
• structure
• solubility (3)
• polarity
• acidity or basicity
• melting point

Answer 2

1. Slightly soluble in water, but salts formed on reaction with acids that become freely soluble in water
2. Most are crystalline solids tho few are AMORPHOUS
3. Free alkaloids are soluble in (3) ether, chloroform, and weakly polar organic solvents
4. Some alkaloids are nonpolar because they lack Oxygen in their structure
5. Basic in nature
6. High melting point

Question 2

Solubility of alkaloids become more soluble in water as temperature ____

Answer 2

increases

Question 2

CAFFEINE

• what functional groups are present (2)
• solubility?
• the major ____ found in coffee beans
• most popular _____ substance

Answer 2

• amide and amine
• slightly soluble in water
• alkaloid
• psychoactive

Question 3

The degree of basicity of alkaloids depend on?? (2)

Answer 3

• its structure
• presence and location of other function groups

Question 3

In 1st step, what is left in the residue and decantate

and which is thrown away

Answer 3

RESIDUE: cellulose (THROWN AWAY)

DECANTATE: tannins, organic acids, alkaloids, and water

Question 3

REMEMBRANCE for structure of alkaloids?

Answer 3

Nitrogen in a ring

Question 3

why is HOT DISTILLED WATER used in step 1?

why is BOILING CHIPS added?

Answer 3

to increase solubility of alkaloids since they are insoluble in water at room temperature

increase rate of boiling

Question 3

OBJECTIVE OF SOLID-LIQUID EXTRACTION

Answer 3

extract as much as solute possible using a LIMITED quantity of solvent

as such, solvent must be able to dissolve the solute of interest

Question 3

1st LIQUID-LIQUID EXTRACTION (step 3) vs 1nd LIQUID-LIQUID EXTRACTION (step 4)

in terms of kung san si alkaloids

Answer 3

1st: si alkaloids nasa aq layer

2nd: si alkaloids nasa organic layer

Question 3

BOILING CHIPS

• size
• solubility
• material composition
• has ___ inside which provide ____ to trap __ and provide ___ where ___ of the solvent ___ can form
• ensure ___ ____

Answer 3

• small
• insoluble
• porous stones made of CALCIUM CARBONATE or SILICON CARBIDE
• pores
• cavities
• air
• space
• bubble
• vapor
• even boiling

Question 3

Does addition of boiling chips affect amount of alkaloids extracted?

Answer 3

no

Question 3

Purpose of adding HCl in Step 2?

Answer 3

increase solubility of alkaloids in water since the polar difference will increase

Question 3

Purpose of adding Na2CO3 in step 3?

Answer 3

since protonated si alkaloids at this step, mas soluble siya sa water (aq layer) than the organic layer.

yung ibang components will dissolve sa organic layer (ethyl acetate/dichloromethane) kaya organic layer ang i-ddispose

after 3 times of shaking (AND addition of organic solvent) the separatory funnel, most likely lahat ng components ASIDE from the alkaloids ay wala na sa aq layer

so need na dagdagan ng Na2CO3 si final aq layer para ma neutralize na yung alkaloid again

+++ nagiging negatively charged si tannins and organic acids so mas soluble sa water pagdating sa step 4

Question 4

Why is salt (anhydrous Na2SO4) added to organic solvent after step 4?

thus salt is also called a?

Answer 4

to remove excess water para ang natira nlng ay solute (alkaloids) and solvent (ethyl acetate)

DRYING AGENT / DESSICANT

Question 5

Why should vigorous mixing be avoided in liquid-liquid extraction?

Answer 5

tho favourable siya, it may also impair the ease of phase separation through formation of EMULSIONS (bubbles)

Question 6

EMULSIONS

• dispersion of _______ _____ liquids which may be due to ____ ____ while the mixture is ______
• traps some of the ____ or _____ of interest that will _____ the solute extracted

Answer 6

• slightly miscible
• rapid shaking
• hot (since nag iincrease solubility ng 2 layers with each other so they should be as INSOLUBLE as possible)
• analyte or solute of interest
• decrease

Question 7

HOW TO PREVENT EMULSIONS (2)

Answer 7

- gently swirl instead (but may diminish contact between the 2 layers, thus decrease the solute that may be extracted) instead: do slightly vigorous shaking and... 1. break/mix/poke the emulsions using a stirring rod 2. add salt or brine solution which lowers solubility of the organic compound in water

Question 8

Why after every shaking of the separatory funnel, the STOPCOCK of the funnel should be opened? + what do u call this process

Answer 8

due to PRESSURE BUIL-UP that intensifies with heat of the hand + ethyl acetate is a very volatile solution "VENTING"

Question 9

DRYING AGENT - usually a ___ - other term - a ____ substance that removes traces of water - water will cause this to ______ into ____ ____, thus, excess drying agent can be removed by _____ with a ____ ____

Answer 9

- salt - dessicant - hygroscopic substance - clump into large particles - filtration with a cotton plug

Question 10

FACTORS governing choice of drying agent (4)

Answer 10

1. possibility of reaction with the solute extracted 2. speed of removal of water from solvent 3. efficiency of the process 4. ease of recovery from drying agent

Question 11

In step 5, why is it possible to remove the organic solvent through evaporation?

Answer 11

ethyl acetate is highly volatile thus evaporates quickly with a low boiling point of 39.8 C

Question 12

the QUANTIFICATION OF ALKALOIDS TRANSFERRED DURING EXTRACTION is governed by the _______ ______

Answer 12

distribution coefficient, Kc

Question 13

Distribution Coefficient, Kc - an expression of the relative____ of the _____ for the ____ ____ in the ___-____ ____ - the ___ of ____ in the ____ ___ over the _____ of the ____ in the ____ layer - an ___ process wherein the ____ in the ______ is allowed to ___ into the ____ + formula and unit

Answer 13

- preference of the solute - 2 solvents in the liquid-liquid extraction - concentration of solute in the organic layer - concentration of solute in the aqueous layer - equilibration - solute in the aqueous layer is allowed to distribute into the organic layer Kc = (C1) / (C2) ; NO UNIT C1: solute concentration in organic layer C2: solute concentration in aqueous layer

Question 14

Interpret the FF: Kc > 1 Kc < 1 Kc = 1

Answer 14

: more solute (more soluble) in the organic layer : more solute (more soluble) in the aqueous layer : solute in organic layer = solute in aqueous layer

Question 15

EXTRACTION EFFICIENCY - the ____ the amount of ___ extracted, the more ____ the ____ - a ____-_____ ____ method is always more ____ than a ___-____ ____ method

Answer 15

- higher - solute - efficient - extraction *if mas madaming solute na transfer sa organic layer than sa natira sa aqueous layer, MAS EFFICIENT yung extraction - multi-step extraction - efficient - single-step extraction *so mas maganda na you extract 3 times or more as possible; ang ginawa sa experiment is 2 times lang tho

Question 16

EXTRACTION EFFICIENCY - when a large batch of solvent is used to extract a solute, how much of the product will be extracted? - the more ____ used, the more ____ will be obtained from the original sample + formula

Answer 16

- 30% lang; yung 70% maririta sa solvent *so mas maganda separate into smaller volumes and multiple extractions - solvent - solute *still better separate the large solvent into multiple extraction parts % Efficiency = (difference in amount between 2 extractions) / (amount extracted in single extraction) x 100

Question 17

5 CHEMICAL TESTS to confirm identity of alkaloid (positive sign of reaction)

Answer 17

1. Dragendorff's Test - Red-brown precipitate 2. Hager's Test - Yellow precipitate 3. Mayer's Test - Cream precipitate 4. Tannic Acid Test - buff-colored precipitate 5. Wagner's Test - Red-brown precipitate

Question 18

5 CHEMICAL TESTS to confirm identity of alkaloid (reagents needed)

Answer 18

1. Dragendorff's Test - 2 M HCL / Dragendorff's reagent 2. Hager's Test - saturated picric acid solution / Hager's reagent 3. Mayer's Test - K2HgI4 / Mayer's reagent 4. Tannic Acid Test - 10% tannic acid solution 5. Wagner's Test - I2 / KI solution / Wagner's reagent