| http://www.w3.org/ns/prov#value | - e carboxylic acid or sulphonic acid group.DETAILED DESCRIPTION OF THE INVENTIONIt is to be expected that the ethylenic double bond of the new chalcone derivatives (Ia) is in the more thermo-dynamically stable trans form.Carboxyalkoxy radicals R.sub.1 and R.sub.4 are preferably of the formula --O--CH.sub.2).sub.n COOH in which n is an integer equal to or greater than 1 and is preferably 1 to 3.The
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