Polyhydroxy-alkyl-3,5-disubstituted-2,4,6-triiodocarbanilates

A compound of the formula:

• ##STR28## wherein X and Y are each selected from the group consisting of lower alkoxy, lower alkoxy-(lower alkoxy), lower acylamino, lower acylamino-(lower alkyl), lower acylamino-(lower acylamino), N-(lower alkyl)-lower acylamino, lower alkylsulfonamido, N-(lower alkyl)-lower alkylsulfonamido, 3,3-bis-(lower alkyl)-ureido, lower perfluoroacylamino, carbamyl, N-(lower alkyl) carbamyl, N,N-di-(lower alkyl) carbamyl, lower alkoxy-(lower acylamino), lower alkoxyalkoxy-(lower acylamino) functions and ester, acetal or ketal derivatives of hydroxy, hydroxy-lower alkyl, hydroxy-(lower alkoxy) and hydroxy-lower acylamino functions and Z.sub.p is selected from the group consisting of ester, acetal and ketal derivatives of a monovalent residue of a polyol selected from the group consisting of cyclic polyols, acylamino polyols and alkyl glycosides, said derivatives containing at least one hydroxyl group in an unprotected form and said monovalent residue containing not more than 7 carbon atoms in its chain or ring.