Separation and Isolation
40 Questions
3 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the most challenging operation in phytochemical research?

  • Identification of chemical properties of functional groups
  • Purification of plant extracts
  • Separation of alkaloids from other plant constituents
  • Isolation and purification of plant constituents (correct)

    • Which method is used to separate the components of volatile mixtures?

  • Fractional distillation (correct)
  • Fractional crystallization
  • Adsorption chromatography
  • Sublimation

    • What is the main limitation of exploiting chemical properties of functional groups for separation?

  • It is a time-consuming process
  • It can only be used for alkaloids
  • It can only be used for acids
  • It might not fractionate components of the same class (correct)

    • Which modern equipment employs low pressures with a strict control of temperature?

    <p>Sublimation equipment</p> Signup and view all the answers

    What is the purpose of fractional crystallization?

    <p>To separate components of the same class</p> Signup and view all the answers

    What is the advantage of sublimation in phytochemistry?

    <p>It can be used for the purification of crude extracts</p> Signup and view all the answers

    What is the application of fractional distillation in phytochemistry?

    <p>Isolation of the components of volatile oils</p> Signup and view all the answers

    What is typically used on a laboratory scale to separate minor components of a mixture in a pure state?

    <p>Gas chromatography</p> Signup and view all the answers

    What is the basis of fractional liberation of a mixture of alkaloid salts in aqueous solution?

    <p>Basicity of the salts</p> Signup and view all the answers

    What is the purpose of shaking the mixture with an organic solvent after each addition of alkali in fractional liberation?

    <p>To separate the liberated bases</p> Signup and view all the answers

    What is the principle behind the separation of organic acids by fractional liberation?

    <p>Differences in solubility of acids in water-immiscible solvents</p> Signup and view all the answers

    What is the advantage of using derivatives in fractional crystallization?

    <p>Enhanced differences in solubility of the components</p> Signup and view all the answers

    What is the characteristic of a mixture that makes it suitable for separation by fractional crystallization?

    <p>Differences in solubility of the components in a particular solvent</p> Signup and view all the answers

    What is the significance of fractional crystallization in traditional isolations?

    <p>It is still a valuable method for resolving intractable mixtures</p> Signup and view all the answers

    What is the fundamental principle of adsorption chromatography?

    <p>Selective adsorption of substances on the surface of solids</p> Signup and view all the answers

    What is the purpose of using charcoal in solution separation?

    <p>To decolorize and clarify solutions</p> Signup and view all the answers

    What is the result of filtration after using charcoal for solution separation?

    <p>A colourless solution</p> Signup and view all the answers

    What is the role of powdered calcium carbonate in Tswett's original experiment?

    <p>To act as a substrate for the adsorption of pigments</p> Signup and view all the answers

    What is the outcome of the percolation process in Tswett's original experiment?

    <p>Pigments are separated into distinct bands</p> Signup and view all the answers

    Which pigments are accumulated in distinct, characteristically coloured bands near the top of the column?

    <p>Xanthophyll and the chlorophylls</p> Signup and view all the answers

    What is the characteristic of the pigments that accumulate lower down in the column?

    <p>Less strongly adsorbed on the calcium carbonate</p> Signup and view all the answers

    What is the primary purpose of allowing more of the pure solvent to percolate through the column?

    <p>To separate the constituents into distinct bands</p> Signup and view all the answers

    Why is the use of a different solvent sometimes more efficient?

    <p>Because it makes the substances less strongly adsorbed</p> Signup and view all the answers

    What happens to the lower bands as percolation continues?

    <p>They reach the bottom of the column and disappear</p> Signup and view all the answers

    What is the term used to describe the process of desorption in chromatography?

    <p>Elution</p> Signup and view all the answers

    What is the solution obtained through the process of elution called?

    <p>Eluate</p> Signup and view all the answers

    What is the origin of the term 'chromatography'?

    <p>From the experiments of Tswett on the separation of coloured compounds</p> Signup and view all the answers

    What is the primary goal of chromatography?

    <p>To separate and isolate constituents</p> Signup and view all the answers

    What is the effect of adding a little alcohol to light petroleum in chromatography?

    <p>The bands become wider apart and pass down the column more rapidly</p> Signup and view all the answers

    What is the purpose of the column in chromatography?

    <p>To separate the constituents into distinct bands</p> Signup and view all the answers

    What is the reason for the incomplete separation of constituents during the first adsorption stage?

    <p>Overcrowding of bands near the top of the column</p> Signup and view all the answers

    What is the purpose of allowing more of the pure solvent to percolate through the column?

    <p>To facilitate the separation of constituents</p> Signup and view all the answers

    Why is the use of a different solvent sometimes more efficient?

    <p>Because it allows for less strong adsorption of substances</p> Signup and view all the answers

    What happens to the lower bands as percolation continues?

    <p>They reach the bottom of the column and disappear</p> Signup and view all the answers

    What is the term used to describe the process of obtaining a pigment in a solution through chromatography?

    <p>Elution</p> Signup and view all the answers

    What is the significance of Tswett's experiments on the separation of coloured compounds?

    <p>They gave rise to the term 'chromatography'</p> Signup and view all the answers

    What is the effect of adding a little alcohol to light petroleum in chromatography?

    <p>It makes the bands wider apart and faster-moving</p> Signup and view all the answers

    What is the primary goal of chromatography?

    <p>To separate mixtures into their individual constituents</p> Signup and view all the answers

    What is the role of the column in chromatography?

    <p>To separate the substances based on their adsorption properties</p> Signup and view all the answers

    What is the outcome of the percolation process in chromatography?

    <p>The separation of constituents into distinct bands</p> Signup and view all the answers

    Study Notes

    Separation and Isolation of Constituents

    • Separation and isolation of plant constituents is a challenging task in phytochemical research.
    • The chemical properties of functional groups and moieties can be exploited for separation, but new techniques are constantly being developed to fractionate components of the same class.

    Sublimation

    • Sublimation can be used to isolate or purify materials present in a crude extract.
    • Modern equipment employs low pressures with a strict control of temperature.
    • Example: isolation of caffeine from tea.

    Distillation

    • Fractional distillation is traditionally used for separating volatile mixtures.
    • It has been widely used in phytochemistry for isolating components of volatile oils.
    • However, it is not easy to separate minor components of a mixture in a pure state on a laboratory scale, and gas chromatography is now routinely used.

    Fractional Liberation

    • Some groups of compounds can be fractionally liberated from a mixture.
    • Example: a mixture of alkaloid salts in aqueous solution, treated with alkali, gives first the weakest base in the free state followed by base liberation in ascending order of basicity.
    • Similar scheme can be used for organic acids soluble in water-immiscible solvents.

    Fractional Crystallization

    • A method that exploits differences in solubility of components in a particular solvent.
    • Frequently, derivatives of the components are employed (e.g. picrates of alkaloids, osazones of sugars).
    • Valuable for resolving intractable mixtures.

    Adsorption Chromatography

    • A technique that exploits the phenomenon of selective adsorption.
    • Finely divided solids have the power to adsorb other substances on their surfaces.
    • All substances are capable of being adsorbed, some more readily than others.
    • Example: A light petroleum extract of green leaves is allowed to percolate through a column of powdered calcium carbonate, resulting in separation of pigments.

    Elution

    • The process of desorption is termed elution.
    • The solution obtained is the eluate.
    • Example: using light petroleum containing a little alcohol to percolate through the chromatogram, resulting in wider separation of bands and elution of the pigment.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Pharmacognosy: Separation and Isolation of Constituents PDF

    Description

    Test your knowledge on the separation and isolation techniques used in pharmacognosy to extract and purify plant constituents. This quiz covers sublimation, distillation, fractional crystallization, and adsorption chromatography. Learn how to overcome the challenges of isolating and purifying plant compounds.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser