What is Lindlar’s catalyst and does Lindlar’s catalyst use ?

Metallic palladium deposited on calcium carbonate with lead acetate and quinoline is known as Lindlar's catalyst and use for reduction of alkynes into cis alkenes.

The reactant alkyne molecules and hydrogen molecules get adsorbed at the surface of metal catalyst. It is chemical adsorption (chemisorption). In this state, the reactants lie very close to each other and so the hydrogen atoms start forming bond with carbon. Two hydrogen atoms are added to two triply bonded carbon atom from the same side of π-bond and a cis or syn addition product is formed. The product alkene now escapes away from the surface of the catalyst. Quinoline occupies the metal surface inhibiting further reduction to be alkanes Quinoline therefore is called catalyst poison and palladium is called deactivated catalyst or poisoned catalyst.

More related Questions:

Why enol form of Beta Dicarbonyl compound more stable than those of monocarbonyl compounds?

Why enol form of phenol is more stable than its keto isomers?

Reactivity order of Pyrrole, Furan and Thiophene towards Electrophilic substitution :

Phenyl group is known to extract negative inductive effect, but each phenyl ring in biphenyl is more reactive than benzene towards Electrophilic substation. Why?

Chloroform is more acidic than fluoroform why?

Fluorine is more electronegative than chlorine even then, p-flurobenzoic acid is weaker acid than p-chlorobenzoic acid explain ? 

Trifluoroethyl carbocation is less stable than trifluromethyl carbocation why ?

Why is the Tropylium carbocation less stable than the tricyclopropylmethyl carbocation?

Arrange the following groups in order of their increasing tendency for nucleophilic addition reactions -COO-, -COOH, -COOCH3, -COCH3, -CHO, -COCI, -CONH2. Justify your answer.

Oxymercuration demercuration hydration procedure is superior to acid- catalysed hydration of most alkenes. Why ?

Out of Acet.yl chloride and acetic anhydride, acetic anhydride is preferred for acylation reactions. Explain why?

Only aldehydes, methyl ketones and cyclic ketones react wilh sodium bisulphite.explain why?

Carbonyl compounds do not undergo nucleophillc substitution reactions.why?

How to calculate radius ratio of square Voids?

The square voids are found in the planes of the close packed structures, whenever three spheres are in contact in such a fashion. The coordination number of square void is four.

Related Questions:

How to calculate radius ratio triangular voids?

How to calculate packing fraction or packing efficiency of two dimensional (2D) hexagonal packing solid atoms?

How to calculate radius ratio triangular voids?

The triangular voids are found in the planes of the close packed structures, whenever three spheres are in contact in such a fashion. Coordination number of triangular void is three. Here three atoms A, B, and C form triangular voids in which equilateral triangle form having angle 60⁰

Where, R= Radius of the (Atoms) sphere, r = maximum radius of a sphere that can be placed inside the void or radius of void.

Why transition metals and their compounds are act as catalyst?

Transition metals and their compounds are known to act as good catalyst due to the following reasons: 

(1) Due to the variable oxidation state, they form unstable intermediate compounds and provide a new path with lower activation energy for the reaction (Intermediate compound formation theory) and hence rate of reaction is increases.

(2) In some cases the finely divided metals or their compounds provide a large surface area for adsorption and the adsorbed reactants react faster due to the closer contact (Adsorption theory).

Some Important Catalytic:

1. TiCl₃ + Al(C₂H₅)₃ Used as Ziegler – Natta catalyst 

2. V2O₅ Converts SO₂ to SO₃ in the contact process for making H₂SO₄

3. MnO₂ Used as a catalyst to decompose KClO₃ to give O₂

4. Fe Used in Haber – Bosch process for making NH₃

5. FeCl₃ Production of CCl₄ from CS₂ and Cl₂

6. FeSO₄ & H₂O₂ Fenton's reagent 

7. PdCl₂ Wacker process for the following conversion 

            C₂H₂ + H₂O + PdCl₂ to CH₃CHO + 2HCl + Pd 

8. Pd For hydrogenation (Phenol to Cyclohexanol) 

9. Pt/PtO Adam catalyst used for reduction 

10. Pt SO₂ to SO₃ contact process 

11. Pt Cleaning car exhaust fumes 

12. Cu In manufacture of (CH₃)₂SiCl₂

13. Cu/V Oxidation of cyclohexanol 

14. CuCl₂ Deacon process or making Cl₂ from HCl 

15. Ni Raney nickel

16. Pt/Rh Ostwald's process. NH₃ to NO

17. Baeyer's reagent - 1% alkaline solution of KMnO₄.

18. Etard's reagent- CrO₂Cl₂ Chromyl chloride.

19. Luca's reagent- Anhydrous ZnCl₂+ concentrated HCl.

20. Barford reagent- Cu(CH₃COOH)₂+ CH₃COOH.

21. Brown catalyst- Nickel Boride.

22. Lindlar's Catalyst- Pd/C use to convert alkynes to cis alkenes.

23. Adkin's catalyst- (CuO.CuCr2O4) or CuO.Cuo.Cr2O3, Copper chromite is use to reduce corboxylic acids into corresponding alcohols 

Related Question:

(1) Although both [Mn(H2O)6]2+ and [FeF6]3- have a d5 configuration and high-spin complexes. But the dilute solutions of Mn2+ and Fe +3 complexes are therefore colorless. Why?

(2) Which of the Complex of the following pairs has the highest value of CFSE?

(3) Colour of Complexes due to charge transfer:

(4) Why violet colour of [Ti(H2O)6]Cl3 disapear (colourless) on heating heating ? 

(5) Why [Ni(CN)4]-2 is colourless while [Ni(H2O)4]-2 although both have +2 oxidation state and 3d*8 configuration ?

(6) Why [FeF6]3– is colourless whereas [CoF6]3– is coloured ? 

(7) Why Fe(CO)5 is colourless while Fe(bipy)(CO)3 is intensely purple in colour ?

(8) Why all the tetrahedral Complexes are high spin Complexes ?

How is base strength related to the availabihty of the electron-pair?

Base strength depends on the ability of the basic site (which always has an unshared electron pair) to accept a proton. This ability depends on the charge in an anion or electron density in a molecular base. For species with an identical charge, dispersal or delocalization of the electrons from the basic site to other parts of the molecule results in decreased electron density and decreased base strength.

Related Questions:

1. What is relative basic strength order 1° amines , 2°amines and 3° amines ? 
2. Explain:Arrange the following in the increasing order of their acid strength : Methyl amine, Dimethyl amine, Aniline, N-methyl aniline (I.I.T, 1988).
3. What is Carbylamine test or Isocyanide test ?
4. What is Hinsberg's reagent and where Hinsberg's test use?
5. Can we prepare aniline by Gabriel – phthalimide reaction?
6. N-Ethyl-N-methyl propanamine does not show optical activity why?
7. What is relative basic strength order 1° amines , 2°amines and 3° amines ? Explain:
8. Amines are more basic than ammonia why?
9. Give an explanation for the fact that Guanidine NH=C(CH3)2 is a stronger base than most of amines?
10. Arrange in correct order of basic Character of aniline, pyrrol, pyridine and piperidine?
11. What is correct basicity order of pyridine, pyridazine, pyrimidine and pyrazine ?
12. Give an explanation for the fact that Guanidine NH=C(CH3)2 is a stronger base than most of amines?
13. Arrange in correct order of basic Character of aniline, pyrrol, pyridine and piperidine?
14. What is correct basicity order of pyridine, pyridazine, pyrimidine and pyrazine ?
15. Why pyridine is more basic than Pyrrole?
16. Why pyrimidine is less basic than pyridine?
17. Imidazole is more basic than pyridine? Why?
18. Biological Important of Imidazole and structure:
19. Pyridine is almost 1 million times less basic than piperidine? Why?
20. Cyclohexylamine amine is the stronger base than Aniline? Why?
21. Tetrahydroquinoline amine is the stronger base than Tetrahydroisoquinoline? Why?