3 AZAFRIN 28t 



This ester is prepared by the action of bromine and red phosphorous on 

 perhydrocrocet in, conversion of the dibromide into the diol, and esterification 

 with diazome thane. It is a viscous, colourless oil, b.p. 16570.04 mm. 



6:ii-Dimethylhexadecane-2: 15-dione C18H34O2 : 



This compound is prepared from the diester (I)^*^ described above. The 

 diketone is a liquid with a weakly aromatic smell. B.p. i32-i35°/o.05 mm. It 

 forms a disemicarbazone, C20H40O4N6, which separates from ethanol in crystals, 

 m.p. 168°. 



Crocelin Utrabromida C2oH2404Br4: 



This compoimd is obtained from crocetin by the action of bromine dissolved 

 in chloroform^*''. It separates from a mixture of ethanol and ether in yellow 

 crystals, m.p. 103-104° (with decomposition) . It is readily soluble in chloroform, 

 ethanol, ether and acetic acid. 



3. AZAFRIN C27H38O4 



History 



1885 Maisch^*^ is the first to describe the pigment of the roots of Escohedia 



scahrifolia. He names the pigment escobedine. 

 1911 LiEBERMANN^*^ succeeds in isolating escobedine in the crystalline form. 



He proposes a new name, azafrin, for the pigment. 

 1913-16 LiEBERMANN and SchillerI^" and Liebermann and Muhle^^^ 



attempt to elucidate the constitution of azafrin. 

 1931-33 KuHN and co-workers^^^ carry out investigations on azafrin in the 



course of which a structural formula is proposed and proved. 



Occurrence 



Up to the present time, azafrin, has only been found in two South American 

 plants, Escobedia scabrifolia and Escohedia linearis^^^. Most of the pigment is 

 contained in the roots, but some is also present in the stalks. Under the name 

 of "azafran" or "azafranillo", azafrin is used in Paraguay for the colouring of 

 fats. 



Preparation}^^ 



The finely ground material is extracted with benzene or chloroform in an extrac- 

 tion apparatus, the solution is strongly concentrated and set aside in the cold. 

 After about 24 hours the red pigment crystallises out. It is dissolved in 0.1 N 

 alcoholic potassium hydroxide, the solution is filtered, and the pigment is preci- 

 pitated with dilute acetic acid and recrystallised from toluene. From 3 kg of azafran, 

 7.5 g of pure pigment is obtained. 



References p. 2go-2g4. 



