Question

Stearolic acid (C18H32O2), a fatty acid, yields stearic acid (18:0) when subjected to catalytic hydrogenation, and undergoes oxidative cleavage with ozone to yield nonanoic acid and nonanedioic acid. What is the structure of stearolic acid?

Answer 1

Structure of stearolic acid (C₁₈H₃₂O₂) :

----

Degree of unsaturation of stearolic acid = (2C+2 -H)/2

                                                                = (2 x 18 + 2 - 32)/2

                                                                = 3

Among 3 degrees of unsaturation, one arises from the carboxylic acid group. Other two could be either due to two double bonds or one triple bond or two rings or 1 double bond and a ring.

Ozonation of the stearolic acid gives two carboxylic acids.   The name of the products of ozonation suggest that the products has 9 carbon atoms in their structures. This is only possible if the compound has a triple bond in its structure.

Catalytic hydrogenation of triple bond gives single bond and stearolic acid converts to stearic acid.