Tag Archives: Organic

Electro-Organic Synthesis: A Branch of Green Chemistry

What is Electro-Organic Synthesis? 
In electro-organic synthesis, the electrodes act as “courier” of electrons. The anode which is electron deficient abstracts electron from a substrate, i.e., oxidises it and this is called Anodic oxidation, whereas the cathode which has excess of electrons can transfer an electron to the substrate i.e., reduces it and is called Cathodic reduction.
Some Advantages:
(i) Such synthesis has a green perspective as no reagent is necessary for the redox reactions- the electrons are directly exchanged between the substrate and the inert electrodes like Platinum.
(ii) Such synthesis helps in bringing about “umpolung” in the substrate and allows synthesis of compound from single substrate.
(iii) Since in electrosynthesis, the reactive species react on the electrode surface their “effective volume” is very high for which rates of the reactions are also high.
It Also Has Following Disadvantages:
(i) Multiplicities of the product are the main disadvantage.
(ii) Organic compounds are non electrolytes, i.e., non-conducting. This is overcome by adding supporting electrolytes like Li-salts or tetraalkyl ammonium salts which are appreciably soluble in organic solvents.
The reactions are usually carried out in two ways-
(i) By Potentiostatic technique (i.e. constant energy process)
In this technique the reactions become more chemo-selective and multiplicity of the product is decreased.
(ii) By Galvanostatic technique (i.e. constant current process)
This is easy to carry out but chemo-selectivity is less.

Note: Scientists claim, there is a huge potential in this field to get a Nobel Prize. Using no reagents and no chemical wastage is the main reason for this.
Thanks for reading 🙂

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A Review on Lindlar’s Catalyst

In Short:
Lindlar’s catalyst is Palladium metal partially poisoned with Lead (Pb) to make it chemoselective to certain compounds.
In Details:
Palladium is a powerful reducing agent. So it is less selective and reduces an wide number of organic species. Suppose you want to reduce ethyne to ethane, then Palladium is a great hydrogenation agent to do the work. It will first convert your ethyne to ethene and then ethene to ethane almost instantly. But what if you want the ethene??? This is the idea behind the evolution of Lindlar’s catalyst.
Imagine the surface of Palladium metal with large number of active sites where the organic species binds with it in order to get reduced. What Lindlar has done is that he deactivated some of the active sites by Lead (Pb) therefore made the Palladium metal surface partially poisoned. Now the reduction of ethyne to ethane can be stopped at the ethene level because the ethene produced won’t get the active sites on the palladium surface to further bind and convert to ethane.
Preparation of Lindlars catalyst:
It is prepared by precipitating PdCl2 on CaCO3 and then mixed with Pb(OAc)2. On heating the mixture it becomes Pd-CaCo3-PbO which is Lindlar’s catalyst.
This is a review of Lindlar’s catalyst- A hydrogenation agent.
THANKS FOR READING. 🙂