Über die Struktur der Guaj‐azulen‐sulfosäuren

Abstract

Abstract Sulphonation of guaiazulene ( 1 ) with sulphuric acid in acetic acid anhydride is known to give guaiazulene‐1‐sulphonic acid ( 2 ). It is shown that sulphonation of ( 1 ) with oleum yields the isomers ( 3 ) and ( 4 ), carrying the sulphonic group in position 2 and on the 1‐methylgroup, respectively. The UV. and NMR. spectra of the compounds ( 2 ), ( 3 ) and ( 4 ) and of their conjugate acids ( 6 ), ( 7 ) and ( 8 ) are discussed.