2,4,6-TRIIODO-ISOPHTHALAMIC ACID DERIVATIVES, THEIR PREPARATION AND X-RAY CONTRAST AGENTS BASED ON THESE COMPOUNDS

Compounds of the formula wherein R1 is C1-4 alkyl, C1-4 alkyl substituted by OH or C1-2 alkoxy; R2, R3 and R4 are independently each hydrogen or C1-4 alkyl; Z is -A-NHCH3 or when R1 is hydroxy or alkoxy substituted alkyl and/or when R3 is lower alkyl, Z can also be hydroxy-C2-5-alkylamino; R5 is C1-4 alkyl or C1-4 alkyl substituted by OH; n is 1, 2 or 3; and A is: wherein R7 is H or C1-4 alkyl; R8 is H, C1-4 alkyl or C1-4 alkyl substituted by OH or C1-2 alkoxy; or together R7 and R8 form a propylene or hydroxypropylene ring; and m is 0 or 1; or an ester thereof with a C1-C4 alkanol or a physiologically acceptable salt thereof with a base, are valuable as X-ray contrast media.