Menthol Dr Javid Hussain 1 Chemical Properties S

Menthol Dr. Javid Hussain 1

Chemical Properties S Chemical Formula: C 10 H 20 O S IUPAC Name: (1 R, 2 S, 5 R)-2 -Isopropyl- 5 -Methylcyclohexanol S Molar Mass: 156. 27 g/mol S Density: 0. 893 g cm-3 2

Chemical Properties S Boiling Point: 212 °C S Melting Point: 36 -38 °C S Solid at room temperature S Waxy, crystalline substance S Clear or White in color S Optically active compound S Only (-) form is found naturally S Present in peppermint oil 3

Medicinal Uses 4

Products Found In 5

Structural Isomers 7

Naturally Occurring Isomers 8

S Index of Hdrogen deficiency (IHD) S Molecular Formula = C 10 H 20 O S Alkane = C 10 H 20× 2+2 S IHD = 22 -20= 2/2 =1 2

S Catalytic Hydrogenation cause no change in the structure S No reaction takes place S Mean molecule is saturated S Cotains no C=C

S Cause no change in the structure S No reaction takes place S Proves that menthol is Saturated S Contain no C=C

Nature of oxygen Formation of ester Shows that nature of oxygen in menthol is alcoholic

Oxidation S Give ketone called Menthone S Shows that Menthol is a secondary alcohol

Reduction S Reduction with HI/P give P. Menthane S Most probably the Menthol will have this skeleton

Formation of Menthol by the reduction of Pulegone

On the basis of all above reaction the structure of menthol was found to be

Synthesis of Menthol

Synthesis 9

Possible Reactions From Menthol 10

Stereochemistry S Examination of menthol structure shows that three chiral centre are present. Thus 8 isomeric forms are possible. S 2 n = 2 3 = 8 S n = number of chiral centres

Acknowledgments 12