Buchi Labortechnik AG is celebrating the invention and the 50 year success story of the rotary evaporator. One cannot imagine a modern laboratory without a rotary evaporator as nowadays evaporation and distillation are still the most frequently used separation methods. 50 years ago Buchi invented the first Rotavapor and thus revolutionized the laboratory world. Since then Buchi has improved not only the method of rotary evaporation but has also consequently developed its products to reach high operation safety. Buchi continuously sets new standards for quality and working comfort to support the customers on the highest level.
To see the commencements of evaporation and separation we have to look back 3500 years into the history of mankind towards the Near East. At that time in Persia 'drop by drop separation' was discovered for the production of rose water. The simplest apparatus design for distillation was based on a clay bowl. When the clay bowl was closed with a cover the vapor formed during heating and condensed at the inner surface of the cover to fine droplets. These droplets were collected from time to time by wiping them off with a feather to process them further. This method quickly spread from Persia all over Europe, North Africa and Asia.
Around 2500 years ago, Greek sailors discovered the wool condensator on the high seas. The ship was in distress and the crew had to derive the vital fresh water from salt water. For this purpose they heated sea water and condensed the vapors through wool that was fixed above a pot. The so-called wool condensator became widespread from antiquity until modern times and represented quite a leap in progress compared to the earlier clay bowl-variant.
The realization that fresh water could be obtained from sea water through evaporation came when it was noticed that fog condensed at the sail and fell on the deck of the ship as heavy drops. At this time no specific scientific experiments were carried out to clarify the connection between fluids and vapors. It was not until 350 BC that the basic principles of distillation, evaporation and condensation were investigated by Aristotle, when he described the vital hydrological cycle in nature. Later, in the second century, distillation apparatuses were developed in Egypt by alchemists. They consisted of the four components: heating bath, sample flask, helmet and receiving flask. A helmet-shaped cover with an internal drain channel for the condensate was fixed above a kettle. The rising vapor condensed at the walls of the cover, the condensate accumulated in the lower rim and flew through the spout into a collecting vessel. The so-called 'alembic' was normally made from copper but also from ceramic or glass. This principle in a modernized style is still used today in the rotary evaporators.
Through the 17th and 18th centuries, apparatuses were continually improved with regard to their distillation power. For this purpose water was used as cooling agent for the first time. As to the choice of material, metal was steadily replaced by the more chemical-resistant glass. In the 17th century the Irish physician Robert Boyle, who intensively studied vacuum, carried out the first vacuum distillations to clarify the connection between pressure and boiling point. The invention of the pressure controller as well as improvements to pumps enabled a more specific use of vacuum distillation and led to a more efficient evaporation. At first only bubble apparatuses were used for vacuum distillation. With the emergence of organic chemistry in the mid of the 19th century a veritable innovation explosion took place and the first rectification columns and multi-step distillations were developed.
In 1950 and 1955, scientists CC Draig and ME Volk respectively outlined the idea of the rotating flask to improve the mixing and increase the heat input for a product sparing operating procedure. Additionally, they suggested a condenser for the efficient condensation of the vapors.
Walter Buchi took up the ideas of Draig and Volk and developed the first manufactured rotary evaporator. The first patented instruments were sold 1957 in Basel and introduced to an international public for the first time at ACHEMA in Frankfurt in 1958. It was a resounding success! The Rotavapor Model 1957 featured a spark-free operating induction motor and a powerful glass condenser with cooling coil. For the first time it was possible to control the rotation speed of the motor continuously between 0-240 rpm with a simple preset potentiometer. The condenser was put on the drive unit by means of a standard joint. The design enabled a continuous feeding of liquids during the distillation with a feeding tube and a cock. A water jet pump was used as vacuum source and a waterbath, into which the rotating flask could be partly immersed, was suggested for heating.
For over 20 years the Rotavapor Model 1957 was popular in countless laboratories.
