Section a – Organic Natural Products



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Chapter 37 – Natural Products


Section A – Organic Natural Products

Organic compounds found in nature are refer to as natural products. It can be useful to extract these products from their natural source to study them or use them in medicines and other products.

Examples:

1._______________________________________________________________________________

2.________________________________________________________________________________

Once they are isolated they can then be analysed in their pure form, and can often be synthesised in the laboratory.



Section B – Mandatory experiment – To extract clove oil from cloves by steam distillation and to isolate it using solvent extraction

Introduction

Clove oil is a natural product that can be found in cloves. Its main constituent is _______________. Used in ________________ and is an _____________________ used by Dentists. Also used for flavouring and seasoning!



The clove oil CANNOT be extracted from the cloves by normal distillation. This is because the cloves would have to be heated to a very high temperature to make the oil reach boiling point, and this would cause ______________of the useful molecules present. Instead a gentler method of steam distillation followed by solvent extraction is used in this experiment.

Procedure

  1. Water and cloves are put into the reaction flask and set up for stea distillation as shown in the diagram. The reaction mixture should be allowed to undergo steam distillation for about 40 minutes .

How steam distillation works

  • Clove oil and water are immiscible liquids

  • The mixture of immiscible liquids will boil at a ___________________ temperature that either would normally boil on their own.

  • This allows the clove oil to boil without having to heat it to a very high temperature that could cause it to decompose.

  • The oil and steam mixture pass through the condenser, where they condense and are collected at the other end as an emulsion ( small droplets of one liquid in another in which it is not soluble)

The safety outlet allows the steam to have an escape route in case of a __________________

The solvent extraction technique

  1. Some cyclohexane is added to the emulsion from the separating funnel . You will notice that the the _________________ layer will float on top of the emulsion (aqueous layer). *Cyclohexane is not polar and so does not dissolve in water. It is less ____________ than water and so floats on top.

3. A stopper is placed on the funnel and it is inverted several times, with care to open the stopper and release the pressure at regular intervals. * Clove oil is very soluble in cyclohexane and will move into the cyclohexane solvent.

4. The lower aqueous layer is collected in one beaker and the cyclohexane layer is collected in a separate flask.

5. The aqueous layer is put back through steps 2-4 at least 3 times to maximise the extraction of the clove oil from it. The aqueous layer should look less______________ at the end of this solvent extraction technique.

6. Some anhydrous Magnesium sulfate (____________) is added to the cyclohexane layers in the flask and shaken to allow mixing. * Magnesium sulfate acts a drying agent – it reacts with any ____________ remaining in the cyclohexane layer. It will form ___________ as it reacts with any water present. When all the water has been removed it will simply settle as a _____________ to the bottom of the reaction mixture.

7. The contents of the conical flask are filtered to remove any ____________________.

8. The conical flask is heated in a water bath overnight in a fume cupboard. * The volatile cyclohexane ____________________ and leaves the clove oil behind. It is important to heat the mixture gently as otherwise the clove oil might evaporate along with the cyclohexane.

9. The mass of the clove oil isolated can be calculated by subtracting the mass of the clean dry conical flask from the mass of the conical flask with the clove oil

Calculations: Calculate the percentage yield of the clove oil

Example: What is the percentage yiled of clove oil from cloves if 0.8g is extracted from 4g of cloves?

Answer:

Percentage yield = ______________________________ x 100 =



Check your learning of …..Organic Natural Products

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Orange = Im not sure – have to check this

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Know about the various extraction techniques – solvent extraction, steam distillation, etc.










Mandatory experiment: Extraction of clove oil from cloves by steam distillation










Know any two examples of useful organic natural products













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