Wilkinson’s catalyst – for CSIR NET GATE IIT JAM chemistry exams

October 2, 2017

RhCl(PPh3)3 – Chlorotris(triphenylphosphine)rhodium(I), is known as Wilkinson’s catalyst. It is used as a homogeneous hydrogenation catalyst. It is a square planar 16-electron complex. The oxidation state of Rhodium in it is +1.

wilkinson's catalyst structural formula




Indeed, Wilkinson’s catalyst is a pre-catalyst that is converted to an active form by losing one triphenylphosphine ligand before entering the catalytic cycle. Usually, the solvent molecule fills the vacant site.

Initially, the catalyst activates the molecular dihydrogen by oxidative addition mechanism to give a 18 valence electron dihydrido complex. The oxidation state of Rh is increased to +3. Thus formed dihydrido complex binds to the olefin in the next step with the concomitant loss of solvent or PPh3 ligand. Since the activation of dihydrogen occurs before addition of olefin, this path is referred to as dihydride path .

Now one of the hydrogen undergoes migratory insertion at the double bond. This is a slow step i.e., Rate Determining Step (RDS).

Immediately and finally, the alkane is released rapidly by an irreversible reductive elimination step that completes the catalytic cycle. The oxidation state of Rh is decreased to +1 and the catalyst is regenerated.


Physical Chemistry

April 13, 2017

Physical chemistry deals with the basic principles of physical science involved in chemical systems. It often deals with the macroscopic side of chemical systems; like inter molecular forces, thermodynamic properties, chemical equilibria, reaction kinetics and electrochemical processes.

However modern physical chemistry also deals with the principles of quantum mechanics to help in understanding the chemical phenomena at atomic and molecular level.

On the following page you can find links to topics in physical chemistry.



IIT JEE 2015 solved question paper

October 21, 2016

Find step wise interactive solutions to: IIT JEE 2015 main in chemistry subject at: http://www.adichemistry.com/jee/free/paper/main/2015/index.html. It is also equally helpful to NEET aspirants.


Sample questions:



The ionic radii (in Å) of N3-, O2- and F are respectively:

(1) 1.36, 1.40 and 1.71
(2) 1.36, 1.71 and 1.40
(3) 1.71, 1.40 and 1.36
(4) 1.71, 1.36 and 1.40


The synthesis of alkyl fluorides is best accomplished by :

(1) Free radical fluorination
(2) Sandmeyer’s reaction
(3) Finkelstein reaction
(4) Swarts reaction


August 22, 2016

Factors that influence the reaction rates of chemical reactions include :

1) Concentration of reactants

2) Pressure

3) Temperature

4) Catalyst

5) Nature of reactants

6) Orientation of reacting species

7) Surface area

8) Intensity of light

9) Nature of solvent

According to the collision theory, the rate of a reaction is directly proportional to the number of effective collisions per second between the reactant molecules. Rate of a reaction is directly proportional to the concentration of reactants.

i.e. rate (r) ∝ cn 


c = concentration

n = order of the reaction

or r = kc


k = specific rate

Explanation: The number of collisions and hence the activated collisions between the reactant molecules increase with increase in concentration. Therefore, according to the collision theory, the rate of a reaction should increase with increase in the concentration since the rate is directly proportional to the collision frequency.




Interactive solutions to IIT JEE 2015 chemistry question paper

October 12, 2015

Are you afraid of IIT JEE chemistry paper? Do you want to score more marks in it easily? Just visit interactive solutions page for 2015 MAIN question paper at:


It is a great way of learning concepts step by step. Use modern browsers like firfox or chrome to access the content.


CSIR NET & GATE chemistry study material & free online coaching

May 26, 2015

A great way to improve your score in CSIR NET & GATE exams is possible when you read selected topics along with one textbook from your area of interest. It is very simple and logical.

Adichemistry site is offering such an easy study material & free online coaching to make your life easy while attempting exams at this higher level.

Find more information at:

For study material: http://www.adichemistry.com/common/htmlfiles/csir-gate-chemistry.html

For free online coaching:


This is the best substitute for costly but ineffective offline coaching.


October 30, 2014

Welcome. Good news to chemistry students, who have a strong desire to pursue their dream research with a scholarship at prestigious institutions of India. I launched this web page to cater the needs of aspirants who wish to crack CSIR NET &  GATE exams in chemical sciences.

On this page, you can find CSIR NET chemistry study material and solved previous year model papers, that help in preparation and makes your life easy.

For more information visit: http://www.adichemistry.com/common/htmlfiles/csir-gate-chemistry.html

Electrolysis – Electrolytic cell – Electrodes

May 17, 2014


Electrolysis involves dissociation (lysis) of an electrolyte by using a direct electric current.  In this process, electrical energy is used to carryout a non-spontaneous redox chemical reaction.

The setup used to serve this purpose is known as electrolytic cell.


What is an electrolytic cell?

An electrolytic cell is used to perform electrolysis. It is provided with two electrodes, which are connected to different ends of the DC electric source. The electrode connected to the positive end is referred to as anode and that which is connected to the negative end is referred to as cathode.



Fajan’s rules

May 8, 2014

While it is taught that the chemical bonds are divided broadly into ionic and covalent types, however, in reality, most of the bonds are neither purely ionic nor purely covalent. These terms are used to indicate two extreme cases. The ionic bond refers to complete transfer of electrons from one atom to the other, whereas the pure covalent bond involves equal sharing of electrons. Nevertheless, the nature of chemical bonds in most of the compounds are somewhere in between above said two extremes. 


Read more at: http://www.adichemistry.com/general/chemicalbond/fajan/fajans-rules.html

Aldol reaction

October 15, 2013

The Aldol addition reaction involves the addition of α-carbon of an enolizable aldehyde or ketone to the carbonyl group of another aldehyde or ketone and thus by giving a β-hydroxy carbonyl compound also known as an aldol (indicating both aldehyde and alcohol groups). The reaction is catalyzed more commonly by a base or some times by an acid.

Read more at: http://www.adichemistry.com/organic/namedreactions/aldol/aldol-addition-condensation-1.html