The electrochemical reactor adjusts the spacing through the thickness of the chip. The electrode material can be graphite electrode or copper-nickel electrode, and a sealing ring is used to prevent leakage. The multi-threaded tube-and-tube parallel tree branch structure reduces resistance, and the effect is very good without electrolyte.
Electrolysis provides another method for organic synthesis where anion/cation radical intermediates must be formed. Traditional electrolysis methods are subject to many limitations, such as uneven electric field, heat loss due to heating, and supporting electrolytes must be used. These factors either hinder the efficiency of electrosynthesis or increase the difficulty of separation. The combination of electrosynthesis and micro-reaction technology can effectively overcome the above shortcomings.
Continuous flow electrochemical reactor can be used for the research of electrochemical reaction, electrode, electrolyte and membrane separation.
Electrochemistry has great potential to provide synthetic organic chemists. However, the use of electrochemistry in modern laboratories is usually rare. This is largely due to the lack of suitable equipment that allows non-electrochemical personnel to use "convenient" methods for chemical reactions. In order to make this technique more acceptable as a routine procedure, chemists need a simpler and more user-friendly way to access it.
Past electrochemical technology relied on electrolysis in glass reactors, which resulted in poor reaction control, low selectivity, poor reproducibility and slow reaction rates. Although these systems can be easily set up, they have been reluctant to adopt them for the reasons mentioned above.
In the past 5 years or so, the development of continuous flow electrochemical cells has made it possible to selectively synthesize high reactant-to-product conversion rates, more commonly in single-pass equipment. These devices provide convenient access to electrochemical technology, which is driving its current re-evaluation as a viable and attractive synthesis method.
Basic principles of organic electrosynthesis
During the organic electrochemical reaction, organic molecules are activated by adding or removing electrons on the electrode surface through a heterogeneous process. Electrosynthesis reactions usually require two electrodes (anode and cathode) to be in contact with a solution containing electrolyte. The electrolyte is a salt that provides ions to improve the conductivity of the solution.
Electrochemistry can be performed in many different ways, including potentiostatic mode (controlling the voltage across the electrodes) or constant current mode (controlling the current across the electrodes).
· Several variables can be explored in the development of electrosynthesis methods.
The nature of the electrode
· Applied voltage/current
· Whether the chemical reaction takes place at the anode or the cathode
· Whether the electrodes are simply located on either side of the battery or are separated (for example, separated by an ion permeable membrane)
Advantages of organic electrosynthesis
· The reaction selectivity can be controlled by the potential applied to the working electrode. It means that you can choose an electrophoresis that is the opposite of an electrophoresis with a similar structure. Unlike using redox reagents, the potential can be modified at will
· The reaction speed can be controlled by adjusting the current density or the applied potential
· Like classical organic chemistry, the degree of molecular transformation can be controlled by managing the number of electrons provided (regarding its oxidation state)
· The properties of the electrode and the composition of the electrolyte can be used as reaction parameters to control the selectivity and reaction rate
· Predict the experimental conditions and methods of electrosynthesis
· Since electrolysis is usually carried out at room temperature and atmospheric pressure, the reaction conditions are usually mild.
Continuous flow electrochemical technology
Traditional electrochemical methods involve the use of "beakers". Generally, in the electrochemical literature, the precise description of the device is not properly described. While giving the electrode material, the geometry, position and size will not bring difficulties to the replication experiment. The development of continuous flow electrochemical equipment eliminated many problems of copying experimental procedures and restricted variables to electrode materials and synthesis procedures.
Electrochemistry is a surface phenomenon, which means that a large surface area to volume ratio is required. If we are familiar with flow chemistry in general, this is something we know very well. Compared with batch reactors of equivalent volume, flow reactors have a larger surface area to volume ratio. It is not a big leap to design a flow electrochemical reactor that produces a high surface-to-volume ratio relative to the electrode.
One thing to consider in traditional electrochemical methods is that the distance between the electrodes is greater than that of electrodes of the same flow rate. Larger distances between the electrodes can cause loss of control of the charge passing between the electrodes, resulting in an "electronic gradient". The figure below illustrates this through simple oxidation. A series of electrons in the reaction causes a loss of selectivity.