Phase Transfer Catalyst
This animation is about phase transfer catalysts and the
way in which they can be used to improve the yields of
certain reactions.
- Dhrubajyoti Samanta
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24/01/11
Master Layout
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Instructions to animator:
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24/01/11
There are a total of 100 green dots and 100 yellow dots.
The green dots stay mostly in the white layer (only 3-5 go to the blue layer).
The yellow dots when not combined with the red dots stay mostly in the blue layer
(only 3-5 dots go to the white layer).
A total of 50 red dots are added of which 40 combine with the yellow dots.
The red dots are initially evenly distributed number wise between the two layers.
When the red dots combine with yellow dots, initially all the combined dots stay in
the blue layer. They slowly move to the white layer also and finally they are
distributed evenly between the two layers.
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Step 1:
Phase Transfer Catalysts are very important catalysts used in organic
reactions involving inorganic reactants.
They become essential because the organic reactants stay largely in the
organic layer while the inorganic reactants stay mostly in the inorganic
or aqueous layer.
Hence, the yield of such reactions remains very low in the absence of a
phase transfer catalyst.
Phase Transfer Catalysts are usually alkylated ammonium compounds
with a few long alkyl chains.
These compounds are soluble in both the organic phase and the
inorganic phase and can freely move from one phase to another.
They also have a property of being able to exchange ions with the
inorganic reactants. Hence they are able to transfer the ions needed
for the reaction to the organic phase where they may react with the
organic reactants.
Hence they bring about a great increase in the yield of reactions of
organic reactants with inorganic ones.
Action
Description of Action
Audio Narration
Display the text in the blue box
Display the text in the blue box one
sentence at a time
*Read the sentences in the box as
they appear*
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Step 2:
An example of a phase transfer catalyst:
(C16H33)(C2H5)3N+Cl-
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Action
Description of Action
Audio Narration
Display the text and the picture
The text in the blue box is displayed
and then the animation in the blue
box is shown.
An example of a phase transfer
catalyst is shown:
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Step 3:
A sample reaction for Phase Transfer Catalyst:
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Action
Description of Action
Audio Narration
The text is displayed first and then
the picture is shown.
An example of a reaction which is
catalyzed by phase transfer
catalysts is shown. We have an
organic compound (1,3 propandiol)
which reacts with an inorganic
compound (sodium sulphide). The
organic compound remains almost
completely in the organic liquid (Di
Chloro Methane) while the
inorganic compound remains
almost completely in the inorganic
liquid (water)
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Display the text and the Picture
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Step 4:
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The Phase Transfer Catalyst (as shown in a previous figure)
exchanges its chloride ions for the sulphide ions and is now able
to transport the sulphide ions from the inorganic phase to the
organic phase where it is needed for the reaction.
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Action
Description of Action
Audio Narration
Display the text and the picture
The text in the blue box is displayed
followed by the picture.
*The text in the blue box is read
out*
Step 5:
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Action
Without Phase Transfer Catalyst
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Description of Action
Audio Narration
The balls keep to their respective
coloured layers (green balls to the
white layer and yellow balls to the
blue layer) with only 5% of the balls
going to the other layer.
The green organic reactant
molecules keep to the white
organic layer and the yellow
inorganic reactant molecules keep
to the blue aqueous layer. Only a
small percentage of the molecules
travel across the interface to the
other layer giving a low yield.
Step 6:
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Action
Description of Action
Audio Narration
Input
Wait for the user to press the
button before adding the red dots
Please press the Add Phase
Transfer Catalyst button to add the
phase transfer catalyst and see the
effect of its addition.
Step 6:
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Action
Description of Action
Audio Narration
With Phase Transfer Catalyst
The red dots are added to the two
liquids and they spread out in equal
numbers in the two liquids. Slowly
the yellow dots start joining with
the red dots. Then slowly the redyellow combined dots spread out
equally into the top layer also.
The phase transfer catalyst is freely
soluble in both the phases and
spreads almost equally among the
two phases. It also exchanges its
chloride ions for the sulphide ions
and is able to transport the
sulphide ions to the organic layer to
a much higher extent than the case
without the catalyst.
Step 6:
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Action
Description of Action
Audio Narration
With Phase Transfer Catalyst
About 80% of the yellow dots
attached to the red dots slowly
change colour to the crème colour
shown above and slowly get equally
distributed between the two
colored layers. As the colour of the
yellow dots change, the colour of
an equal number of green dots also
change slowly to the light green
colour.
The sulphide ions transported to
the organic layer by the phase
transfer catalyst is able to react
with the organic reactant to give
the product. The catalyst is also
able to transport out the hydroxyl
ions formed into the aqueous layer
so that the reaction keeps going
forward.
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Step 6:
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Action
Result
Description of Action
Audio Narration
Narration of the result.
Thus we see that the phase transfer
catalyst is able to carry the sulphide
ions into the organic phase to a
great extent. These sulphide ions
are able to take part in the
reaction.
Thus the addition of phase transfer
catalysts increases the yield of the
reaction greatly.
Phase Transfer Catalysts
- Dhrubajyoti Samanta
DISPLAY AREA
TEXT AREA
24/01/11
Links for further reading
Web Link : http://en.wikipedia.org/wiki/Phase-transfer_catalyst
Book : Phase-transfer catalysis: fundamentals, applications, and
industrial perspectives, 1st Edition, Charles M. Starks, Charles Leonard
Liotta, Marc Halpern, Springer, 1994
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