exp 1 Flashcards
MAIN GOAL of the experiment
isolation of ALKALOIDS form GROUND ARABICA COFFEE BEANS
2 types of extraction used in this experiment
- solid-liquid extraction
- liquid-liquid extraction
Alkaloids are derivatives of?
ammonia
Alkaloids are characterized by the presence of ____ in a ____
basic nitrogen
heterocyclic ring
Alkaloids usually occur as… (2)
Tertiary or secondary amines
due to being derivatives of NH3
EXAMPLES of alkaloids (5)
- pyrrole
- pyridine
- pyrrolidine
- quinoline
- isoquinoline
What makes alkaloids basic?
The nag-i-isang LONE PAIR present in Nitrogen in the alkaloid
What is the alkaloid of interest for the experiment?
CAFFEINE
Does caffeine have HIGH or LOW polarity?
LOW polarity = does not readily dissolve in water at room temperature
Major alkaloid found in tea leaves?
and how much?
Caffeine : 3-5% by weight
Once alkaloids is isolated as a solid, what will be its color?
white / off-white
How to ascertain if the isolated solid from the extraction procedure?
WAGNER’S TEST (a chemical test)
Will caffeine be the only alkaloid will be/possible to be isolated?
NO, there are many other alkaloids aside from caffeine
What other alkaloids can be separated from coffee beans?
Theobromine, theophylline, trigonelline
Why is it possible to isolate alkaloids from such compounds?
Solubility of alkaloids in organic solvents (low polarity) and water
How much CAFFEINE is present in Arabica coffee bean?
1.2 - 1.5% by weight
What is solubility?
Ability of 2 or more to form a HOMOGENOUS mixture spontaneously without a chemical reaction
Which interaction is higher:
solute-solvent
or
solute-solute
solute-solvent (meaning mas mag ddisolve)
Guiding principle of solubility
“like dissolves like”
Solubility is based on what process?
and what does THIS process require and why?
separation of solute molecules from each other to spread amongst solvent molecules
- requires energy to overcome the intermolecular forces in the solute
If alkaloids are not that soluble in water @ room temp, what temperature are they soluble?
high temperature -> hot water
Examples of ORGANIC SOLVENTS (3)
- dichloromethane
- chloroform
- ethyl acetate
How can solubility of alkaloids in water be enhanced?
and why can this happen?
addition of dilute strong acids (gives H+ to alkaloids)
results to a stronger interaction: ion-dipole forces
wherein: ion = positively charged alkaloids
dipole = polar water
What is extraction
laboratory technique for transferring a solute from a solid or liquid into a different solvent or phase
SOLID-LIQUID EXTRACTION vs LIQUID-LIQUID EXTRACTION
SLE: separation of solute from a solid material (coffee bean) by CONTACT WITH low-boiling solvent (water)
LLE: transfer of solute from one liquid component to an EXTRACTING SOLVENT (wherein the solute should have a higher solubility in para makuha ni E.S. yung solute)
What extracting solvent will we use in the experiment?
ethyl acetate
In liquid-liquid extraction, what should you remember?
the 2 liquids that you will use should be IMMISCIBLE
How does the liquid-liquid extraction exactly work?
- mix the container where you will perform the LLE
- the solute should become distributed in the two layers
- a higher amount of solute will go to the layer where it is more soluble in
What is the funnel used in liquid-liquid extraction?
Separatory funnel
What test to determine if what composition is at the bottom layer of the separatory funnel?
WATER TEST
- if nag dissolve: it’s water
- if di nag dissolve: it’s organic solvent
LIQUID-LIQUID EXTRACTION
Aqueous layer VS Organic layer
AL: water
OL: organic solvent
Purpose of DILUTE STRONG ACID and DILUTE WEAK BASE in this experiment
DSA: mixed with water to extract the alkaloids from the coffee bean. thus, alkaloids will become + charged
DWB: used to neutralize the alkaloids
In Wagner’s Test, what confirms the presence of alkaloid in the sample?
reddish brown precipitate
WASTE DISPOSAL
- Filtrate & Decantate (Liquids)
- Wagner’s Test
- Tira-tirang solids
- G704 (non-halogenated org solvents)
- E501
- Dissolve with water + E501
