3 p-CAROTENE 145 



P-Apo-4-carotenal C25H34O: 

 CH3 CH3 



C CH3 CH3 CH3 



/\ I I I 



CHj C-CH=CH-C=CHCH=CH-C=CHCH=CHCH=C-CHO 



CHj C'CH3 

 \ / /?-Apo-4-carotenal 



This compound is obtained together with /3-apo-2-carotenal by the oxidation 

 of /5-carotene with potassium permanganate^^^. It has not been obtained in the 

 crystalhne state, but forms a crystalhne oxime and semicarbazone. 



Solvent: Absorption maxima: 



Carbon disulphide about 460 m/z (diffuse) 



Petroleum ether about 442 m// (diffuse) 



y5-Apo-4-carotenal oxime crj-'stallises from methanol in rhombic plates and 

 clusters, m.p. 165°. 



Solvent: Absorption maxima: 



Petroleum ether 408 m/^ 



Ethanol 409 m^ 



Carbon disulphide 456 m/< (slightly diffuse) 



^-Apo-4-carotenal semicarbazone separates from ethanol as a scarlet-red 

 powder, m.p. 217° (with decomposition), sintering above 214°. 



Solvent: Absorption maxima: 



Carbon disulphide 474 m/^ 



Ethanol 445 m/i (broad band) 



P-Apo-4-carotenol CjsHjgO: 

 CHo CH3 



C CH3 CH3 ^^3 



/\ I I I 



CH2 C- CH=CH- C=CHCH=CH- C=CHCH=CHCH=C- CH2OH 



I i . 



CHj C*CH3 



\ / /9-Apo-4-carotenol 



CH2 



This polyene alcohol is formed by the reduction of /5-apo-4-carotenal with 

 isopropyl alcohol and aluminium isopropoxide^^^^ ^-Apo-4-carotenal has so 

 far only been obtained as a viscous oil. 



Oxides of ^-Carotene 



By the oxidation of /^-carotene with monoperphthalic acid, Karrer and 

 JuCKER^^^ obtained a number of oxidation products which are epoxides or 

 References p. 16^-iyo. 

 Carotenoids 10 



