CERIUM(IV) AMMONIUM NITRATE AS A CATALYST IN ORGANIC SYNTHESIS

Prepared By:-

MOHD UMAR KHAN

En. No. GD 5010

Roll No.6020097

CONTENTS

INTRODUCTION MECHANISTIC PATHWAYS APPLICATIONS CONCLUSION REFERENCES

INTRODUCTION

Commercially available , use as one-electron oxidants

Low toxicity , inexpensive Reasonably soluble in many organic media Air- stable, easily handled, experimental simplicity Current goal is use of catalytic amounts of CAN Superior to manganese triacetate for the generation

of radicals

MECHANISTIC PATHWAYS

Various pathways are involved and different intermediates are formed

I. Generation of radical and radical- cation species

II. Reduction of Ce(IV) to Ce(III)

III. Concomitant regeneration of Ce(IV) by an external oxidant

IV. Lewis acid catalysis

APPLICATIONS (A) OXIDATION OF ALCOHOLS oxidation of some primary or secondary benzylic alcohols to the

corresponding aldehydes or ketones in the presence of the NaBrO3

THE YIELD OF THE REACTIONS IS HIGHLY IMPROVED

• THE AEROBIC CATALYTIC OXIDATION OF BENZYLIC AND ALLYLIC ALCOHOLS USING A CATALYTIC SYSTEM COMPOSED OF CAN AND 2,2,6,6-

TETRAMETHYLPIPERIDINYL-1-OXYL (TEMPO)

Milder conditions and in shorter time with efficient yields

.

(B)OXIDATION OF ACTIVE METHYLENE COMPOUNDS

Direct transformation of diethyl malonate into diethyl ketomalonate by molecular oxygen

Optimal reaction conditions involved bubbling oxygen through a solution of the reactants in acetic acid-acetonitrile

MECHANISM

(C) REACTIONS INVOLVING THE GENERATION OFCARBON-CARBON BONDS

Most essential maneuver in synthetic organic chemistry. The CAN- induced generation of C-C bonds has been for some time an

important aspect of the synthetic application of Ce(IV) species

(a)Allylation of carbonyl compounds with allyltrimethylsilane:-

(D)ALLYLATION OF 1,3-DIOXO COMPOUNDS

• 1,3-Diketones, such as diethyl malonate, can also be converted to the corresponding monoallylated products in 74–98% yields under the same conditions

(E)REMOVAL OF PROTECTING GROUPS

An efficient reagent for removal of commonly used protecting groups

Markó et al. applied CAN as a catalyst in the deprotection of acetals to give the parent ketones

(F) SYNTHESIS OF BENZOTHIAZOLES

CAN catalyzes the reaction between o-mercaptoaniline and aromatic aldehydes at room temperature to give 2-arylbenzothiazoles

The mechanism of this transformation involves CAN acting both as a Lewis acid and as an oxidant

MECHANISM

CONCLUSION

Excellent, multipurpose catalyst that can be used to promote a wide range of synthetically relevant reactions that go well beyond its traditional role as an oxidant

The reactions are characterized by their experimental simplicity and mild reaction conditions.

Reactions may proceed via processes initiated by a one-electron oxidation, or alternatively CAN may act as a Brønsted acid catalyst, or as a Lewis acid

Low cost and air stability of CAN may make it a useful alternative to the expensive

REFERENCES

Ho, T. L. Synthesis 1978, 936. Kim, S. S.; Jung, H. C. Synthesis 2003, 2135 Ho, T. L. Synth. Commun. 1979, 9, 237. Zeng, X.-F.; Ji , S.J.; Wang, S.-Y. Tetrahedron 2005, 61, 10235. Aggarwal, V. K.; Vennall, G. P. Synthesiett. 2009, 19, 4501. Al - Qalaf, F.; Mekheimer, R. A.; Sadek, K. U. Molecules 2008, 13,

2908. More, S. V.; Sastry, M. N. V.; Yao, C.-F. s 1998, 1822. Sujatha, K.; Shanthi, G.; Selvam, N. P.; Manohara, S.; Perumal, P. T.; Rajendran, M.

Bioorg. Med. Chem. LGreen Chem. 2006, 8, 91. Shaabani, A.; Maleki, A. Chem. Pharm. Bull. 2008, 56, 79

.