Premium Laboratory Equipment Reflux Condenser Buyer’s Guide Understanding the ① Why refluxing? Air cooled: Reflux condensers with air co- ④ Water consumption and co- oling are available in different versions. In oling costs. Refluxing is one of the most common wor- low-priced systems, heat exchange with air cooled reflux system king methods for organic synthesis. Many the ambient air takes place only on the Extrapolated, an average of 150 liters of chemical reactions only take place under outer surfaces of the glass column. Thus, water flow through a water cooled reflux heat or are accelerated by an increased re- the column must be accordingly high to condenser per hour (Fig. 2 Diagram Water action temperature. Reflux condensers are be able to dissipate heat to the environ- consumption in comparison). Fortunately, used to prevent the solvent of a reaction ment. The much more elaborately desig- many laboratories have installed recircula- Increased requirements on safety and sustainability in the mixture from evaporating even when it is ned reflux condenser system Findenser™ ting chillers or central water recirculating chemical laboratory have been the trigger for the heated for extended periods of time. is equipped with a finned aluminum jacket, systems to reduce the enormous water consumption during refluxing. However, development of new reflux condensers without water which multiplies the heat exchanger surfa- ② Air cooled or water cooled. ce in a compact way. even cooling the coolant has a negative cooling. With the Findenser™, Heidolph offers an What is the difference? impact on the energy balance. efficient, air cooled reflux system, too. The refluxing principle is as simple as it is What are the advantages and disadvantages of reflux ingenious: The boiling vapor from the so- ③ Safety in the laboratory has lution in the flask rises vertically upwards condensers? What are the general aspects to consider many facets. in the glass column, condenses on the when buying one? cooling surfaces and drops back into the If you have ever witnessed how fast a hose flask as liquid condensate. Cooling inside can come off a water cooled reflux con- 150 150 The Heidolph 'Reflux Condenser Buyer’s Guide' answers a reflux condenser takes place according denser and the immense damage caused the most important questions you may have. For all other to the heat exchanger principle. The follo- by such a flooding in a laboratory building 90 wing applies for the cooling surfaces: the you will appreciate an air cooled laborato- 50 matters, the Heidolph Customer Support will be glad to larger the surface, the better the cooling ry condenser as a true alternative. In the 11 Litres of water Litres 0 provide advice. behavior. worst case, laboratory equipment worth thousands of dollars can be destroyed ™ Water cooled: In a predominant number overnight. After all, roughly 2.5 liters per Bath of cases, tap water is used as coolant. Like minute are flowing through a water cooled Toilet Flush a water sheath, it flows around the reflux reflux system. In addition, the lack of any Findenser List of contents column on the inside of which the boiling tubing – as in air cooled reflux condensers Dishwasher Cycle Water Condenser (1 hr) vapor rises. Convexities on the inner side – means that there is no risk of the tubing Washing Machine Cycle walls of the column or cooling coils enlarge coming into contact with hotplates (leaka- the cooling surface. (Fig. 1 Functional prin- ges) and furthermore entails a simple set- Why refluxing? ciple of a water cooled reflux condenser) up and less space that is required in the Fig. 2 Diagram: Average water consump- ① fume hood. tion of common household appliances Air cooled or water cooled. ② compared to the Findenser™ and the wa- What is the difference? ter cooled reflux condenser ③ Safety in the laboratory has many facets. ④ Water consumption and cooling costs. ⑤ An as wide as possible range of applications. An as wide as possible range The best is to test: solvent volume. ⑤ ⑥ of applications. ⑦ Essential: accurate temperature control. These common solvents are already suc- Traditional, air cooled reflux condensers cessfully used with the Findenser™ for Suitable for all types of ambient conditions. ⑧ have a significantly narrower range of chemical synthesis without any apprecia- Good price/performance ratio. ⑨ applications as water cooled devices. ble volume loss: This lies in the nature of physics, be- Hydrocarbons: e.g. pentane, hexane, cause their low cooling capacity makes cyclohexane, heptane them unsuitable for highly volatile, low- Chlorinated solvents: e.g. dichlorometha- boiling solvents - and this applies to the ne (DCM), chloroform vast majority of common solvents used Alcohols: e.g. methanol, ethanol, iso- for syntheses. You should therefore pay propanol attention to the application range when Aromatic hydrocarbons: e.g. toluene, selecting your reflux condenser. xylene, benzene Although the Findenser™ is also air co- Miscellaneous: Methyl tert-butyl ether oled, it offers an excellent cooling capaci- (MTBE), acetone, tetrahydrofuran (THF), ty thanks to its highly thermally conducti- ethyl acetate, acetonitrile, dimethyl furan ve aluminum cooling fins and is therefore (DMF) and others suitable for around 95 % of all chemical The top limit for the boiling temperature Fig. 1 Water cooled reflux system syntheses. is 155 °C / 311 °F. In case of doubt, please ask the Heidolph Customer Support. 2 3 ⑥ The best is to test: solvent ⑧ Suitable for almost all am- volume. bient conditions. The volume too is a determining factor for The higher the ambient temperature, the solvent loss during refluxing. Traditional, worse the performance. Compared to wa- air cooled reflux condensers are in many ter cooled models, the ambient tempera- cases not efficient enough for larger vo- ture plays an important role in air cooled lumes. At high volatility, too much, if not reflux condensers. For this reason and of all, of the solvent is lost relatively quickly. course also for safety reasons, we gene- Even the air cooled Findenser™ – despite rally recommend to perform refluxing in its significantly higher cooling capacity - the fume hood. This ensures reproducibi- Safety in the lab: Findenser™ (on the right sometimes reaches its limits. To be on the lity and the room temperature is no longer side) takes less space in the fume hood safe side, carry out a test under real condi- an issue. tions with highly volatile solvents like ether before the actual test; always work in the ⑨ Good price/performance fume hood while doing so. ratio. ⑦ Essential: accurate tempera- Simple reflux condensers can already ture control. be bought at little money. However, you should always put the running expenses Many tests have shown that the Finden- for water and cooling energy into relation ser™ works with particular efficiency if the to the costs of acquisition. Especially the temperature is accurately controlled. The safety aspect should not be underestima- control temperature set at the hotplate ted. In the event of flooding, the damage should be 10 – 15 °C / 50 – 59 °F above caused is a thousand times higher. A precise temperature control of the re- the boiling point of the solvent used. If it is action is only possible by means of use too high or if it strongly fluctuates, the sol- of an external temperature sensor vent can boil over and the sample can be damaged. This is why, for your next reflux Any questions? reaction, you should not only pay attention Contact us: to a suitable reflux condenser but also to Heidolph Instruments GmbH & Co. KG the heat source you are using. Do you pre- fer magnetic stirrers with a digital display +49 9122 9920-0 or with interface for a digital contact ther- [email protected] mometer. For further information, please contact the Heidolph Customer Support. Further links: Heidolph Magnetic Stirrers Heidolph Findenser™ 4.