Technical Details
The Ethos MicroSYNTH is a refined, professional system designed for synthetic chemistry applications. It combines:
- a microwave cavity for generating the microwave field,
- sensors to monitor reaction parameters for feedback-based process control, and
- sophisticated process control software.
Each component works in harmony with the appropriate Milestone reactor, and the result is convenience, safety, and effective reaction processing in a bench-top microwave instrument.
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Hardware
Advanced engineering and state-of-the-art electronics are at the heart of the Ethos MicroSYNTH labstation.
The all-steel chassis of the Ethos MicroSYNTH allows easy access into the microwave cavity through the downward-opening door and through the top of the cavity. This unique approach facilitates the use of a variety of reaction vessels, as well as top-loading batch reactors and ordinary reflux glassware, all in the same microwave labstation (see Accessories). Milestone supports the way you do your chemistry now, and provides maximum flexibility for the ways you may want to work in a microwave field.
The Ethos MicroSYNTH has a properly designed multimode cavity that is homogeneous in its distribution of the microwave field, and is free of "hot spots." Only a multimode cavity can support a comprehensive range of reaction vessels, allowing single or multiple (simultaneous) reaction processing, all under identical reaction conditions. A multimode cavity also supports easy scale up of reactions, an important consideration for parallel synthesis, medicinal chemistry, and process development. Multimode cavities provide maximum flexibility.
The Ethos MicroSYNTH is the only microwave labstation with a dual-magnetron design. With an installed maximum power of 1,600 watts, the two magnetrons deliver a maximum 1,000 watts of controlled power. The magnetrons work in conjunction with a patented premixing chamber in the rear of the cavity where the output of the two magnetrons is combined, and a pyramidal mode stirrer that produces a homogeneous, forward-projected microwave field. The result is completely homogeneous reaction conditions.
The Ethos MicroSYNTH labstation incorporates a continuously variable high-voltage power supply that regulates the output power of the magnetrons. Unlike a traditional pulsed power supply, which regulates the "average delivered power" by varying the full power duty cycle, a continuous power supply provides an average delivered power that is identical to the power delivered at any given instant. A continuous power supply provides superior reaction control by only delivering a well defined energy to the reaction mixtures. A continuous power supply also facilitates the controlled excitation of electrodeless plasma lamps inside the cavity as well as inside the reaction vessels.
The Ethos MicroSYNTH labstation incorporates a series of features designed to safeguard the instrument and its operators. The synthetic organic chemist can explore the benefits of microwave technology with confidence in the performance and safety of the instrument.
- The rugged chassis is constructed of stainless steel to ensure dimensional stability and multimode tuning of the large cavity.
- Every metal surface inside the cavity is coated with five layers of baked-on PTFE to provide durability when exposed to a wide range of laboratory vapors.
- The patented movable door provides a measure of safety in response to over-pressures inside the cavity. The door can move outward on spring loaded pistons to release any over pressure and then reclose to secure the cavity containment.
- Redundant micro switches instantaneously shut down the magnetrons whenever the cavity door is opened. It is impossible for operators to be exposed to the microwave field by opening the cavity door.
- Additional microwave leakage sensors and reactor proximity switches are installed in the top of the chassis for additional safety when the labstation is configured for operation with batch reactors or for use with reflux reactions. All openings through the cavity are microwave safe, designed to prevent any operator exposure to the microwave field.
The Ethos MicroSYNTH has a motor-driven, variable speed magnetic stirring mechanism installed under the floor of the cavity. Using appropriate stir bars (Teflon coated, glass coated, Weflon) of various dimensions, homogeneity of the reaction chemistry is enhanced in either single reaction vessels or in multiple reactors, simultaneously. Magnetic stirring in our advanced vessel technology extends the flexibility of the multimode cavity design.
For combinatorial chemistry applications, the MicroSYNTH is built with a special back-mounted rotating motor that allows the CombiCHEM rotor to tumble samples, guaranteeing sample homogeneity.
The labstation control functions and process software are located in a compact, separate module, the Ethos MicroSYNTH Lab Terminal. A proprietary instrument interface orchestrates two-way communication with the instrument, while Milestone's easyWAVE software provides simplified process monitoring and control. The result is accurate, reproducible reaction conditions, all with the click of a mouse.
Reaction Parameter Monitoring
The Ethos MicroSYNTH labstation incorporates a variety of advanced sensor technologies to monitor reaction parameters and to use that information for feedback-based process control. The dynamic parameter sensors, combined with Milestone's easyWAVE process control software, ensure accurate parameter monitoring, precise control of defined reaction conditions, and reproducibility in developed methods.
An advanced fiber-optic temperature sensor allows direct monitoring of the internal temperature in Milestone reaction vessels. In each of the reaction vessels that accommodates reaction temperature monitoring (a "reference vessel"), the fiber-optic probe is inserted into a thermowell. The thermowell isolates the probe from physical contact with the reaction chemistry, yet intimately positions the probe for good thermal contact with the reaction mixture.
The performance of the temperature probe is traceable to certified temperature standards.
An advanced pressure sensor allows direct monitoring of the vapor pressure inside Milestone reaction vessels. In each of the reaction vessels that accommodates pressure monitoring (a "reference vessel"), a flexible high-pressure line connects the reference vessel with the pressure transducer located in the top of the instrument chassis, external to the microwave cavity.
The pressure sensing mechanism is pneumatic, not hydraulic. The line is not filled with liquid; only the pressure of the vapor above the reaction mixture is monitored directly. Placement of the pressure transducer outside the microwave cavity ensures its accuracy, and prevents any influence from the microwave field.
The performance of the pressure transducer is traceable to certified pressure standards.
An advanced infrared sensor, installed in the side wall of the cavity, monitors the surface temperature of any reaction vessel inside the cavity. This contactless temperature sensor has a focusing lens that narrowly defines the sensor's field of view, and optimizes its response to the variety of vessel materials in Milestone reactors.
Primarily used as a safety feature to limit thermal stress on Milestone reactor systems, the infrared sensor can also be used to monitor and directly control defined reaction conditions in certain reactors. The contactless temperature sensor is particularly convenient when performing reflux reactions or when used with the MultiPREP line of reactors for parallel synthesis.
The QP sensor for solvents is one of a family of sensors for active monitoring and programmed response to vapors inside the cavity. This patented technology responds to the concentration of solvent vapors inside the cavity, and reduces the applied microwave power until the vapors have been cleared from the cavity by the exhaust module. Once the vapors are cleared from the cavity, normal power is again applied and the reaction process continues. By adjusting the response sensitivity of the QP Solvent Sensor, the sensor can be set to respond to: 1) vapors escaping from improperly closed vessels, or 2) vapors escaping from vessels that safely have vented and resealed from an over-pressure inside the vessel. Adjusting the response sensitivity of the QP Solvent Sensor provides optimum operator safety.
EasyWAVE Process Control Software
Milestone's easyWAVE software is the most comprehensive software available for controlling microwave reactions. For the synthetic organic chemist, easyWAVE provides simplified method development, intimate reaction control, and reproducible reaction conditions.
Using a Windows-based user interface, easyWAVE allows the operator to: 1) define the desired reaction conditions, 2) process synthetic reactions under the defined conditions, 3) document sample processing and reaction conditions, and 4) create and use standard methods.
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| You draw it | EasyWAVE does it |
EasyWAVE has a unique facility for easily defining and graphically displaying temperature vs. time or pressure vs. time profiles, with just a few clicks of the mouse. As many as ten separate steps can be defined, describing reaction parameter ramps or plateaus. Once the reaction condition profile has been defined, one more click starts the microwave heated reaction, easyWAVE does the rest. It's that simple.
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| Real time graphic data | Process documentation |
Once started, the heating process will continue uninterrupted, automatically maintaining temperature control to ± 1°C or pressure control to ± 0.1 bar precision through the use of sophisticated PID control algorithms. EasyWAVE dynamically adjusts the delivered microwave power to only deliver enough power to create and maintain the defined reaction conditions.
At any time during the course of a heating process, the operator can intervene and dynamically change any of the defined reaction parameters: extend the run time or add additional steps to the method, change the temperature or pressure profile or change the parameter limits, change the applied power, etc. The effect is instantaneous, without the need to stop the reaction and reload the method.
A special section allows free form text to be entered and saved along with the method information and the graphical reaction run data.
One of the most important functions in easyWAVE is the Solvent Library. The Solvent Library is a practical tool to help predict the resulting reaction pressure based on the target temperature. This information allows one to select and use the correct microwave vessels with the appropriate performance specifications.
The Solvent Library contains physical information on a large number of commonly used solvents. Based on the normal boiling point and the enthalphy of vaporization, a calculation is performed to generate a pressure versus temperature curve, which is then displayed graphically or in tabular form. The Solvent Library can be edited to include additional solvents.
Synthesis: See overview, or continue to fundamentals, resource library, or accessories.
General: Go to the Milestone front page, or send us an inquiry.