AROMATIC COMPOUNDS 269 



Tyramine. 



OH Tyramine or p-hydroxyphenylethylamine is a base 



formed from tyrosine by putrefaction. It occurs in ergot 

 of which it is one of the active principles. 



The decomposition of tyrosine by putrefaction is ex- 

 actly similar to that of phenylalanine and takes place in the 



following stages : 

 . NHo. 



/OH /OH /OH 



C 6 H 4 < <~C 6 H 4 ( -*C 6 H 4 / - 



\CH 2 .CH 2 .COOH X CH 2 .CH(NH 2 )COOH \CH 2 .CH 2 .NH 2 



p-hydroxyphenyl propionic Tyrosine. Tyramine. 



acid. 



C 



/OH /OH 



H 4 -> C 6 H 4 / - C 6 H 5 .OH. 



-hydroxyphenyl acetic p-cresol. Phenol. 



acid. 



The two following other disubstitution products of benzene occur 

 in nature : 



(1) Cymene, or methylisopropyl benzene, which occurs in numer- 



ous essential oils (p. 312) and can be obtained by 

 heating camphor with phosphorus pentoxide, by 

 heating turpentine with concentrated sulphuric acid 

 and by reducing carvacrol and thymol with phos- 

 phorus pentasulphide. 



It is a colourless liquid which boils at 175-176 



and has a sp. gr. of -8722 at o. It yields p-toluic acid and terephthalic 



acid on oxidation. 



(2) Anethole, or p-methoxyphenylpropylene, is the principal 



constituent of oil of aniseed. It yields p-methoxy- 

 benzoic acid, or anisic acid, on oxidation with 

 chromic acid, but anisic aldehyde or p-methoxy- 

 benzaldehyde on oxidation with bichromate and 

 II sulphuric acid. Anisic aldehyde on reduction 



^ H with sodium amalgam and alcohol is converted 



CH 8 into anisic alcohol. 



