Organic Chemistry: Extraction Methods

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Questions and Answers

What is a characteristic of the decoction method?

It is suitable for soft plant material.

It uses direct heat. (correct)

It uses gentle heat.

It involves condensation of vapor.

What type of plant material is suitable for digestion?

Soft plant material like leaves and flowers. (correct)

Any type of plant material.

Powdered plant material.

Hard plant material like roots and barks.

What is the purpose of the condenser in reflux extraction?

To heat the solvent.

To recycle the solvent.

To prevent reduction in solvent quantity. (correct)

To separate the solvent from the plant material.

What is an advantage of using a Soxhlet apparatus?

It saves solvent by recycling it over the sample. Signup and view all the answers

Why can't chloroform and ether be used as solvents in decoction?

They are not heat stable. Signup and view all the answers

What is the purpose of the thimble in a Soxhlet apparatus?

To hold the powdered plant material. Signup and view all the answers

What is a characteristic of reflux extraction?

It involves boiling the solvent and recondensing it. Signup and view all the answers

What is an advantage of using a Soxhlet apparatus over other extraction methods?

It is an automatic, continuous method. Signup and view all the answers

What is a disadvantage of extractives being heated during the extraction process?

It leads to the decomposition of carotinoids Signup and view all the answers

In which type of extraction does the plant material come into direct contact with the solvent?

Decoction Signup and view all the answers

What is the main purpose of the Clevenger apparatus?

To extract volatile compounds Signup and view all the answers

What is the term for the process of separating compounds based on their relative solubility in two different immiscible liquids?

Liquid-liquid extraction Signup and view all the answers

In which type of extraction is the extract not required to be filtered?

Soxhlet extraction Signup and view all the answers

What is the purpose of vigorously shaking the solution in liquid-liquid extraction?

To make intimate contact with the solvent Signup and view all the answers

What type of compounds are prone to decomposition during the extraction process?

Thermally labile compounds Signup and view all the answers

What is the name of the apparatus used in Soxhlet extraction?

Soxhlet apparatus Signup and view all the answers

What is the primary purpose of steeping the sample in solvent for 24 hours in percolation?

To ensure complete extraction of active constituents Signup and view all the answers

Which type of solvent is commonly used for the extraction of volatile oil?

Chloroform Signup and view all the answers

What is the advantage of maceration over other extraction methods?

It can be used for heat-sensitive substances Signup and view all the answers

What is the purpose of using water in solvent extraction?

To dissolve alkaloids in salt form Signup and view all the answers

Which method of extraction involves suspending plant material in a solvent over time?

Infusion Signup and view all the answers

What is the primary disadvantage of maceration as an extraction method?

It takes a long time to complete Signup and view all the answers

What is the purpose of using a porous diaphragm in percolation?

To filter the solvent through the plant material Signup and view all the answers

What is the primary advantage of percolation over other extraction methods?

It is easy and cheap to perform Signup and view all the answers

Study Notes

Extraction Methods

Disadvantages of extraction methods:
- Extractives are heated during extraction, which can lead to hydrolysis and decomposition of thermally labile compounds like carotinoids

Reflux and Soxhlet Extraction

Reflux extraction:
- Plant material is placed in a round bottom flask with solvent
- Solvent is heated until boiling point, then vapor is condensed and recycled to the flask
- Condenser is used to ensure complete extraction without reducing solvent quantity
Soxhlet apparatus:
- Powdered plant material is placed in a thimble
- Solvent is boiled and passed through the thimble, extracting the plant material
- Solvent is then recycled back to the flask through siphoning
- Advantages: automatic, continuous, and saves solvent

Distillation

Used for extraction of volatile compounds
Clevenger apparatus is used
Two types of distillation:
- Oil lighter than water (e.g. clove oil)

Liquid-Liquid Extraction

Also known as solvent extraction and partitioning
Separates compounds based on relative solubility in two immiscible liquids
Solution is vigorously shaken to make intimate contact with the solvent
Phases are allowed to separate, and then boiling water is added to allow volatile oils to evaporate and condense

Decoction

Plant material is boiled with solvent (principally water)
Used for heat-stable materials
Hard plant materials like roots, barks, and wood can be used in this method

Digestion

Used gentle heat
Used when moderate elevation of temperature is required
Suitable for soft plant material (leaves, flowers)

Maceration

Plant material is placed in a container and added to solvent
Container is covered and left for 2-4 days at room temperature
Procedure can be repeated multiple times, and solvents are then mixed together
Advantages: can be used for heat-sensitive substances, easy, and cheap
Disadvantages: takes a long time, non-efficient, and extracts small quantities

Non-Continuous Hot Extraction Methods

Infusion:
- Process of extracting chemical compounds or flavors from plant material in a solvent
- Used special container called infusion pot

Continuous Hot Extraction Methods

Reflux extraction and Soxhlet apparatus

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Description

This quiz covers the disadvantages of extractive methods and the reflux Soxhlet extraction process. It highlights the impact of heat on thermally labile compounds and the setup of the extraction apparatus.