Information About Distillation Settings; Rotary Speed Of Evaporator Flask; Temperature Difference Between Hot Bath And Vapor; Temperature Difference Between Vapor Temperature And Coolant - Heidolph LABOROTA 4000eco Mode D'emploi

INFORMATION ABOUT DISTILLATION SETTINGS

Using a rotary evaporator for thermal cracking of substances some basic consideration
should be made to achieve the best results possible. Optimize settings as described
below:
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Rotary speed of evaporator flask

Raise distillation speed by raising rotational speed. This methods cuts distillation time and
protects the substances handled.
26

Temperature difference between hot bath and vapor

This temperature difference should at least be 20 K to reach adequate distillation speed. If
acceptable by thermal stability of the substances handled, you even may raise
temperature difference.
Rule of thumb: double temperature to double distillation speed.
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Temperature difference between vapor temperature and coolant

This temperature difference should be no less than 20 K to guarantee adequate
condensation. Low temperature difference, effectiveness of solvent recovery drops.
Choose an as high as possible temperature difference in particular for high-boiling
substances.
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Solvent data

Examples for using reference table and nomogram:
This reference table details substance data needed for distillation, whereas the nomogram
reflects relationship between pressure and boil temperature of some solvents. Go by the
Clausius-Clapeyron equation and plot 1/T against log p.
28.1 At boil temperature of 40°C
At the vacuum controller: in column "vacuum for boil temperature" use the "Set Vac"
nominal value as depicted for 40°C.
28.2 At boil temperatures deviating from 40°C
On temperature axis of the nomogram mark boil temperature needed.
Draw a line to the right and determine intersection with the solvent line.
From this intersection draw a straight line down to determine the vacuum pressure needed
for this particular application.

28.3 Solvents not depicted

The following items might help in determining the right vacuum pressure:
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