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What are alkaloids?
Naturally occurring compounds which are characterized by a basic nitrogen usually present in heterocyclic ring—pyrrole, pyridine, pyrrolidine, quinoline, or isoquinoline—but may also be present in an aliphatic side chain.
What are the wide applications of alkaloids?
They have wide applications in the field of pharmacology, medicine, and toxicology.
What is the major alkaloid found in tea leaves?
Caffeine is the major alkaloid found in tea leaves.
What are the properties of caffeine?
Caffeine is a diuretic and a cardiac, respiratory, and psychic stimulant.
What is the solubility of caffeine in hot water?
Caffeine is known to be soluble in hot water.
What is the solubility of caffeine in dichloromethane?
Caffeine is considerably more soluble in dichloromethane than in water.
How can the solubility of caffeine in water be enhanced?
Its solubility in water can be enhanced by addition of dilute strong acids.
What is solubility?
Solubility is the ability of two or more substances to form a homogeneous mixture spontaneously, without undergoing any chemical reaction.
What happens when a pure solid or liquid dissolves?
When a pure solid or liquid dissolves, the ions or molecules making it up get separated.
What is the basis for the rule of thumb "like dissolves like"?
The solubility behavior of substances depends chiefly on their polarity, which is the basis for the convenient rule of thumb "like dissolves like."
What is the mechanism of solid-liquid extraction?
The desired substance is initially present as part of a solid mixture and is separated from that mixture by extracting it once or several times with an appropriate solvent.
What is gas-liquid chromatography?
Gas-liquid chromatography is a technique used to separate and analyze volatile compounds in a mixture.
The mixture is vaporized and passed through a column containing a stationary phase. The different compounds in the mixture interact differently with the stationary phase and are separated as they travel through the column. The separated compounds are detected and identified based on their retention time and other properties.
What is liquid-liquid extraction?
It is a process used to separate two immiscible liquids by shaking them together and allowing them to separate into layers based on their densities.
What determines the concentration of a solute in each layer during liquid-liquid extraction?
The concentration of a solute in each layer is determined by the distribution coefficient (K), which is a constant characteristic of the solute at a given temperature and specific solvent pair.
What is the purpose of using water in liquid-liquid extraction?
Water is usually one of the liquids used in this extraction because it is polar and can dissolve many ionic and polar substances.
What type of organic solvent is typically used in liquid-liquid extraction?
The other liquid used in liquid-liquid extraction is usually a weakly polar or nonpolar organic solvent that is immiscible with water.
How can organic substances be extracted from aqueous mixtures using liquid-liquid extraction?
Since most organic substances are more soluble in organic solvents than in water, they may be extracted from aqueous mixtures by shaking the liquid mixture with the extracting solvent in a separatory funnel.
What is extraction?
Extraction is the process of separating a desired compound from a mixture using a solvent.
What is a separatory funnel?
A separatory funnel is a laboratory apparatus used for separating two liquids with different densities.
What is the purpose of shaking the liquid mixture with the extracting solvent in a separatory funnel?
Shaking breaks the organic solvent into small globules, thereby increasing the surface for contact of the organic and aqueous mixtures, hastening the transfer of the desired solute to the solvent layer where it is more soluble.
How are the layers separated in a separatory funnel?
After standing, the layers are separated by draining the lower layer through the stem/stopcock.
How do you determine which of the two layers is the organic layer in a separatory funnel?
To determine which of the two layers is the organic layer, a small portion of the bottom layer is allowed to drop on a watch glass containing water.
What precautions should be taken when using a separatory funnel?
A separatory funnel is fragile and expensive and should be handled with utmost care.
What is the test used to detect the presence of alkaloids?
The test used to detect the presence of alkaloids is through its complexation reaction with Wagner's reagent (aqueous Kl/!2), which is confirmed by a reddish-brown coloration.
What is the proper way to dispose of the aqueous layers in the isolation of alkaloids from tea?
The proper way to dispose of the aqueous layers in the isolation of alkaloids from tea is to discard them into the sink.
What are the applications of alkaloids?
Alkaloids have wide applications in the field of pharmacology, medicine, and toxicology.
What are the different compounds that alkaloids occur as salts of in plants?
Alkaloids occur as salts of inorganic and organic plant acids in complex mixture with water-insoluble compounds (e.g., gums, proteins, mineral salts, tannins, lipids, and resins).
What is the proper way to dispose of the isolate treated with Wagner's reagent in the isolation of alkaloids from tea?
The proper way to dispose of the isolate treated with Wagner's reagent in the isolation of alkaloids from tea is to dispose it to E501.
What is the proper way to dispose of the used Na2SO4 in the isolation of alkaloids from tea?
The proper way to dispose of the used Na2SO4 in the isolation of alkaloids from tea is to dissolve it in water and dispose the solution into the sink.
What is the compound used to detect the presence of alkaloids in the isolation of alkaloids from tea?
The compound used to detect the presence of alkaloids in the isolation of alkaloids from tea is Wagner's reagent (aqueous Kl/!2).
What are the effects of caffeine on the body?
Caffeine is a diuretic and a cardiac, respiratory, and psychic stimulant.
What can enhance the solubility of caffeine in water?
The solubility of caffeine in water can be enhanced by the addition of dilute strong acids.
What type of compounds dissolve in nonpolar solvents?
Nonpolar compounds dissolve in nonpolar solvents.
What type of compounds tend to be more soluble?
Highly polar compounds tend to be more soluble.
What is the meaning of the phrase "like dissolves like"?
Nonpolar compounds dissolve in nonpolar solvents, and highly polar compounds tend to be more soluble in polar solvents because of ion-dipole interaction.
How is the extracted material recovered in solid-liquid extraction?
The extracted material may be recovered by evaporating or distilling off the solvent.
What happens when two immiscible liquids are shaken thoroughly in liquid-liquid extraction?
Any solute initially present in either layer becomes distributed between the two immiscible layers.
What is the concentration of a substance in each layer in liquid-liquid extraction given by?
C1/C2=K, where C1 and C2 are the concentrations of solute in layers 1 and 2, respectively, and K is the distribution coefficient.
What is the distribution coefficient in liquid-liquid extraction?
It is a constant that is a characteristic of the solute and the solvent system.
What is the definition of KC in liquid-liquid extraction?
KC is a constant that is a characteristic of the solute at a given temperature and a specific solvent pair.
What is the purpose of liquid-liquid extraction?
The purpose of liquid-liquid extraction is to obtain the desired substance by the preferential transfer to an extracting solvent in which the desired substance has a higher solubility.
What is the usual composition of the liquid mixture in liquid-liquid extraction?
Water is usually one of the liquids used in this extraction, and the other liquid is usually a weakly polar or nonpolar organic solvent that is immiscible with water.
How is the extraction of organic substances from aqueous mixtures accomplished in liquid-liquid extraction?
This extraction is accomplished by shaking the liquid mixture with the extracting solvent in a separatory funnel.
What is the purpose of shaking the liquid mixture in liquid-liquid extraction?
Shaking breaks the organic solvent into small globules, thereby increasing the surface for contact of the organic and aqueous mixtures.
What is the effect of the shaking process in liquid-liquid extraction?
The shaking process hastens the transfer of the desired solute to the solvent layer where it is more soluble.
How are the layers separated in liquid-liquid extraction?
After standing, the layers are separated by draining the lower layer through the stem/stopcock.
What is the organic layer in liquid-liquid extraction?
To determine which of the two layers is the organic layer.
What is a separatory funnel used for?
It is used to separate two immiscible liquids.
What is the first step in determining which layer is the organic layer in a separatory funnel?
A small portion of the bottom layer is allowed to drop on a watch glass containing water.
What should be done before each use of a separatory funnel?
Check that the stopcock is properly seated and rotates freely.
Why should a clip be attached to the stopcock of a separatory funnel?
This prevents the stopcock from falling out if it is accidentally loosened.
What should be done to vent the mixture in a separatory funnel?
Open the stopper and shake the funnel from side to side.
How should the separatory funnel be supported when not in use?
It should be supported on a ring or proper size and at a convenient height from the bench top.
What should be done if the stopcock of a separatory funnel does not rotate freely?
Call the attention of the laboratory instructor.
What is the purpose of venting the mixture in a separatory funnel?
To release any pressure that may have built up inside the funnel.
What is the consequence of propping up a separatory funnel on its stem?
It can cause the funnel to break.
What is the importance of draining the lower layer through the stem/stopcock in a separatory funnel?
It ensures that only the desired layer is collected.
