A
Kugelrohr (
GermanGerman is a West Germanic language, thus related to and classified alongside English and Dutch. It is one of the world's major languages and the most widely spoken first language in the European Union. Around the world, German is spoken by approximately 105 million native speakers and also by...
for "ball tube") is a short-path
vacuum distillationVacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...
apparatus typically used to distill relatively small amounts of compounds with high
boiling pointThe boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
s (usually greater than 300
°CCelsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
) under greatly reduced pressure.
"Short path" refers to the short distance that the vapors of the distillate needs to travel, which helps reduce losses, and speed up collection of the distillate. Distilling under vacuum is used to prevent the compound being distilled from charring due to atmospheric
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
, as well as to allow the distillation to proceed at a lower temperature.
The apparatus consists of an electric heater with a digital thermostat, and two or more bulbs connected with
ground glass jointGround glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...
s.
Discussion
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A
Kugelrohr (
GermanGerman is a West Germanic language, thus related to and classified alongside English and Dutch. It is one of the world's major languages and the most widely spoken first language in the European Union. Around the world, German is spoken by approximately 105 million native speakers and also by...
for "ball tube") is a short-path
vacuum distillationVacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...
apparatus typically used to distill relatively small amounts of compounds with high
boiling pointThe boiling point of an element or a substance is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
s (usually greater than 300
°CCelsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
) under greatly reduced pressure.
Design
"Short path" refers to the short distance that the vapors of the distillate needs to travel, which helps reduce losses, and speed up collection of the distillate. Distilling under vacuum is used to prevent the compound being distilled from charring due to atmospheric
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
, as well as to allow the distillation to proceed at a lower temperature.
The apparatus consists of an electric heater with a digital thermostat, and two or more bulbs connected with
ground glass jointGround glass joints are used in laboratories to quickly and easily fit leak-tight apparatus together from commonly available parts. For example, a round bottom flask, Liebig condenser, and oil bubbler with ground glass joints may be rapidly fitted together to reflux a reaction mixture...
s. The compound to be distilled is placed in the last bulb. The other bulbs can be used to collect the distillates sequentially; when they are collecting the desired fraction, the bulb is cooled with ice to aid condensation. A motor drive is used to rotate the string of bulbs to reduce bumping and give efficient distillation.
See also
- Distillation
Distillation is a method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
- Short path distillation
- Vacuum distillation
Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure causing evaporation of the most volatile liquid...
Gallery
Image:Short path distillation apparatus.svg| A simple short path vacuum distillation apparatus can be used for bulb-to-bulb distillation.