exp 1 post lab Flashcards
Primary Components of Coffee Beans (4)
- Cellulose
- Organic Acid
- Tannins
- Alkaloids
CELLULOSE
- ___ component of plants
- most _____ ____ ____ in earth
- solubility?
- remains _____ in hot _____ water after ____-_____ ______
- major
- most abundant organic polymer in earth
- water-insoluble
- undissolved in hot distilled water after solid-liquid extraction
ORGANIC ACID
- solubility
- contains??
- will be ____ in hot _____ water after ___-____ extraction
- _____ and ____ ____ in nature
- water-soluble
- acidic functional groups (carboxylic acid)
- dissolved in hot distilled water after solid-liquid extraction
- acidic and positively charged
How to deprotonate organic acids? + makes them what charge?
addition of Na2CO3 (makes them neutral charged)
How to protonate organic acids? + makes them what charge?
addition 10% HCl (makes them positive charge)
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?
- highly diverse natural
- one or more basic nitrogen atoms
- heterocyclic ring
- aliphatic side chain
- drugs
- stimulants
- poison
- amino acids
- secondary or tertiary amine
- low polarity
STEPS in ISOLATION of ALKALOIDS from COFFEE BEANS (5)
- Solid-liquid extraction through mixing of coffee beans and hot dH2O (alkaloids remain in hot dH2O afterward)
- 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)
- Conversion of alkaloid salt to molecular form through addition of 10% Na2CO3 to make the alkaloid BASIC (neutral charged)
- (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
- Removal of organic solvent from alkaloids by evaporation
How much caffein per gram of Arabica coffee beans?
8 - 12 mg caffeine
PROPERTIES OF ALKALOIDS (6)
- insolubility
- structure
- solubility (3)
- polarity
- acidity or basicity
- melting point
- Slightly soluble in water, but salts formed on reaction with acids that become freely soluble in water
- Most are crystalline solids tho few are AMORPHOUS
- Free alkaloids are soluble in (3) ether, chloroform, and weakly polar organic solvents
- Some alkaloids are nonpolar because they lack Oxygen in their structure
- Basic in nature
- High melting point
Solubility of alkaloids become more soluble in water as temperature ____
increases
CAFFEINE
- what functional groups are present (2)
- solubility?
- the major ____ found in coffee beans
- most popular _____ substance
- amide and amine
- slightly soluble in water
- alkaloid
- psychoactive
The degree of basicity of alkaloids depend on?? (2)
- its structure
- presence and location of other function groups
In 1st step, what is left in the residue and decantate
and which is thrown away
RESIDUE: cellulose (THROWN AWAY)
DECANTATE: tannins, organic acids, alkaloids, and water
REMEMBRANCE for structure of alkaloids?
Nitrogen in a ring
why is HOT DISTILLED WATER used in step 1?
why is BOILING CHIPS added?
to increase solubility of alkaloids since they are insoluble in water at room temperature
increase rate of boiling
OBJECTIVE OF SOLID-LIQUID EXTRACTION
extract as much as solute possible using a LIMITED quantity of solvent
as such, solvent must be able to dissolve the solute of interest
1st LIQUID-LIQUID EXTRACTION (step 3) vs 1nd LIQUID-LIQUID EXTRACTION (step 4)
in terms of kung san si alkaloids
1st: si alkaloids nasa aq layer
2nd: si alkaloids nasa organic layer
BOILING CHIPS
- size
- solubility
- material composition
- has ___ inside which provide ____ to trap __ and provide ___ where ___ of the solvent ___ can form
- ensure ___ ____
- small
- insoluble
- porous stones made of CALCIUM CARBONATE or SILICON CARBIDE
- pores
- cavities
- air
- space
- bubble
- vapor
- even boiling
Does addition of boiling chips affect amount of alkaloids extracted?
no
Purpose of adding HCl in Step 2?
increase solubility of alkaloids in water since the polar difference will increase
Purpose of adding Na2CO3 in step 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
Why is salt (anhydrous Na2SO4) added to organic solvent after step 4?
thus salt is also called a?
to remove excess water para ang natira nlng ay solute (alkaloids) and solvent (ethyl acetate)
DRYING AGENT / DESSICANT
Why should vigorous mixing be avoided in liquid-liquid extraction?
tho favourable siya, it may also impair the ease of phase separation through formation of EMULSIONS (bubbles)
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
- 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
