by Class 11, Kendriya Vidyalaya 2, Kalpakkam
What is Electrosynthesis?
• Electrosynthesis in organic chemistry is the synthesis of
chemical compounds in an electrochemical cell.
• The main advantage of electrosynthesis over an ordinary
redox reaction is avoidance of the potential wasteful
other half-reaction and the ability to precisely tune the
• The basic setup:
1)A Galvanic cell
2)A Potentiostat and
Good electrosynthetic conditions use a solvent
and electrolyte combination that minimizes
• Electrodes are selected which provide favorable
electron transfer properties towards the substrate
while maximizing the activation energy for side
• Two basic cell types: undivided cell & divided cell type
• In divided cells the cathode and anode chambers are separated with
a semiporous membrane.
• Divided cell permits the diffusion of ions while restricting the flow of
the products and reactants. This is important when unwanted side
reactions are possible.
• The most well-known electrosynthesis is the Kolbe
• A variation is called the non-Kolbe reaction when a
heteroatom (nitrogen or oxygen) is present at the αposition. The intermediate oxonium ion is trapped by a
nucleophile usually solvent.
• In the so-called Crum Brown–Walker reaction an aliphatic
dicarboxylic acid is oxidized forming the elongated di-acid.
• Amides can be oxidized through a N-acyliminium ion which can be
captured by a nucleophile.
This reaction type is called a Shono oxidation. An example is the αmethoxylation of N-carbomethoxypyrrolidine.
• In the Markó-Lam deoxygenation, an alcohol
could be almost instantaneously deoxygenated
by electroreducing their toluate ester.
• The cathodic hydroisomerization of
activated olefins is applied industrially in
the synthesis of adiponitrile from 2
equivalents of acrylonitrile:
• The Tafel rearrangement (Julius Tafel, 1907) at one time
was relevant to the synthesis of certain hydrocarbons
from alkylated ethyl acetoacetate, a reaction
accompanied by the rearrangement reaction of the alkyl
Research & Development
• Electrochemical expertise in electrosynthesis includes the following
Electrosynthesis of inorganic and organic (including pharmaceuticals) compounds
Batteries and fuel cells
Membrane separation processes including salt splitting
Environmental electrotechnology: water purification; metal recovery; pollutant
destruction; recovery, recycle and reuse
Electrochemical synthesis of inorganic compounds offers several
advantages over conventional synthesis and often provides the only viable
Electrosynthetic processes can often be run under milder operating
conditions with fewer chemical reagents.
Water Electrolysis to produce hydrogen and oxygen
Manufacture of bromine, chlorate, perchlorate, ferrate, etc.
Metals extraction and refining: Al, Na, Mg, Li, etc.
Metal oxides manufacture
• Industrial scale electrochemical processing of organic chemicals : In
practice for almost 100 years. An estimated 120 different processes
– piloted .
At least 60 are now commercial.
Other examples of reactions that can be carried out electrochemically
This technology was based on a polysulfide/bromide system.
The Redox Flow Battery : Form of rechargeable battery in which electrolyte
flows through an electrochemical cell.
On charge, it converts electricity into chemical energy.
The electrolyte, and therefore energy, is stored externally in tanks until the
energy is required when the solution is pumped back into the
electrochemical cell discharging the chemical energy as electrical energy.
Advantages of E.S
• This is one of only a few technologies that can separate energy and
power requirements. Power is determined by the size of the
electrochemical cell whereas the energy is proportional to the size of
the storage tanks.
• Large amounts of energy (up to hundreds of MWh) can be stored
until required with little loss.
• High efficiency conversion from electrical to chemical energy
• Long cycle life with quick response times.
Applications of E.S
• Large (1 kWh - many MWh) stationary applications.
• Load leveling: Store energy during times of low demand
and provide electricity during peak time.
• Storing energy from renewable sources such as wind or
solar to supply power during low generation periods.
• Uninterrupted power supply (UPS), to provide power
when main power fails.
• Electrodialysis (ED) is a very versatile technology for the separation
of difficult mixtures.
• Electrodialysis is an electromembrane process in which ions are
transported through ion permeable membranes from one solution to
another under the influence of a potential gradient.
• The electrical charges on the ions allow them to be driven through
the membranes fabricated from ion exchange polymers.
• Types of Membranes used:
– Ion Permeable Membranes
– Bipolar membranes
• The ion permeable membranes used in electrodialysis are essentially
sheets of ion-exchange resins.
• They usually also contain other polymers to improve mechanical
strength and flexibility.
• The resin component of a cation-exchange membrane would have
negatively charged groups (e.g., -SO3-) chemically attached to the
• Bipolar membranes consist of an anion-permeable membrane and a
cation permeable membrane laminated together.
• When this composite structure is oriented such that the cationexchange layer faces the anode it is possibleto spit water into proton
and hydroxyl ions by imposing a potential field.
• Multiple bipolar membranes along with other ion permeable
membranes can be placed between a single pair of electrodes.
• Salt splitting is a relatively new technology dependent on
the availability of modern membranes.
• Its development has usually been driven by two major
– The first is the desire to produce caustic soda without the coproduction of chlorine.
– The second is the increased cost of disposing of heavily laden
• With the demand for Chlorine predicted to fall down, the need for
using production of NaOH without Chlorine has to be done.
• Electrosynthesis of Sodium Sulphate can be done to give Caustic
• A successful technology for treatment of sodium sulfate wastes will
likely require additional economic incentives such as the
coproduction of a saleable product (for example ammonium sulfate),
or credits for the elimination of a waste stream.
• Technologies for the production of commodity quantities of caustic
will need to rely on very low power costs and an increasing
imbalance in causticchlorine production.
• Modular on-site production of chemicals will facilitate the
implementation of electrochemical technologies.
• Electrosynthesis Company, Inc. specializes in the development of
electrochemical technologies for energy storage systems, fuel cells,
electrodialysis, separations, sensors, synthesis of inorganic and
organic chemicals and recycling of waste streams.
– New method for production of Potassium Ferrate by
electrosynthesis which has reduced its price from $100/g to $2/g.
– New methods for synthesising Caustic Soda without Chlorine as
– Developing large scale energy storage systems using