3 | Product description
BÜCHI Labortechnik AG
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Operation Manual Rotavapor® R-300
3
Product description
3.1
Description of function
The Rotavapor® R-300 is a rotary evaporator with the aid of which single-stage
distillation can be carried out quickly without unduly stressing the product. The basis
of the process is the evaporation and condensing of solvents in a rotating evaporating
flask under vacuum. Distillation under vacuum is more efficient and gentler on the
product.
The product is heated in the evaporating flask by the heating bath. The rotary drive
unit evenly rotates the evaporating flask. Rotation increases the surface area of the
liquid which leads to an increased evaporation rate. This also constantly mixes the
product which prevents localized overheating and delayed evaporation.
The vapor passes from the evaporating flask through the vapor duct into the cooling
section (cooling condenser). There, the thermal energy of the vapor is transferred to
the coolant fluid so that the vapor re-condenses. The resulting solvent is collected in
the receiving flask and can then be reused or properly disposed of.
Distillation under vacuum
Distillation capacity depends on the following factors:
Temperature of the heating bath
Pressure in the evaporating flask
Rotation speed of the evaporating flask
Size of the evaporating flask
Pressure in the evaporating flask:
a low pressure (below atmospheric) reduces the
boiling point of the solvent. A lower boiling point means the solvent does not have to
be heated as much. Distillation under vacuum is more efficient and gentler on the
product.
Vacuum control:
a stable vacuum adapted to the application prevents undesirable
solvent emissions and bumping (boiling) of the product. Control of the vacuum is car-
ried out by two means: the BUCHI VacuBox measures the current vacuum in the dis-
tillation system. The BUCHI VacuBox is connected to the BUCHI Interface I-300 or
I-300 Pro. The BUCHI Interface is used to display the current readings and control the
components of the distillation system. See also Chapter 5.17 "Assembling the BUCHI
distillation system", page 42.
Heating bath temperature, coolant temperature and vapor temperature:
to
ensure optimum distillation, it is important to make sure that the temperature
difference between the coolant and the heating bath is at least 40 °C. The tempera-
ture of the rising vapor should be mid-way between the heating bath temperature and
the coolant temperature. See also Chapter 6.2.3 "Adjusting distillation conditions",
page 60.
