USEFUL TO CSIR NET STUDENTS

1. Useful Concept to
•II M.Sc Organic Chemistry,Semester-IV
•III B.Sc –PG Entrance( IIT-JAM & CU-CET)
•CSIR-NET/GATE exam students

2. Out lines of the Topic
• DIBAL-H
• Introduction
• Preparation
• Applications
• Assignment

3. Introduction
• DIBAL can be purchased commercially as a colourless liquid.
• It is more commonly purchased and dispensed as a solution in an organic
solvent such as toluene or hexane.
• It is an electrophilic reducing agent whereas LiAlH4 can be thought of as a
nucleophilic reducing agent.

4. DIBAL-H
1. The diisobutyl aluminium hydride (DIBAL-H) is a
commercially available selective reducing agent.
2. It can selectively reduce esters and nitriles to the
corresponding aldehydes.
3. The reaction is carried out in inert and moisture free
atmosphere

5. Preparation
Preparation of DIBAL by heating of tri isobutyl aluminium
(itself a dimer) to induce beta hydride elimination:
Equation:
(iso-Bu3Al)3 → (i-Bu2AlH)2 + 2 (CH3)2C=CH2
[tri isobutyl aluminium] [DIBAL-H] [Isobutene]

6. B.Sateesh Kumar Lecturer in chemistry GDC(M)-Srikakulam

7. B.Sateesh Kumar Lecturer in chemistry GDC(M)-Srikakulam

8. Mechanism
•The esters are selectively reduced to the corresponding aldehydes at low
temperature.
•The DIBAL-H transfer one hydride to the ester group and forms a tetrahedral
intermediate which is stable at low temperature.
• The hydrolytic work up of the intermediate gives the desired aldehydes .

9. B.Sateesh Kumar Lecturer in chemistry GDC(M)-Srikakulam

10. Appilications-2 :

11. B.Sateesh Kumar Lecturer in chemistry GDC(M)-Srikakulam

12. Assignment-IV
1.Write a short notes on DIBAL-H.
2.Write the any 4 important applications of DIBAL-H.
3.Write the preparation & use of DIBAL-H in organic
synthesis
4.How to distinguish LAH & NaBH4 with DIBAL-H

13. Thank you
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