Preparation of perylene-3,4-dicarboxylic anhydrides

A process for the preparation of perylene-3,4-dicarboxylic anhydrides of the formula I ##STR5## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7, R.sup.8 are hydrogen, or one radical to eight radicals are a radical selected from the group consisting of an unsubstituted or substituted carbocyclic aromatic radical, an unsubstituted or substituted heterocyclic aromatic radical, halogen, unsubstituted or substituted C.sub.1 -C.sub.18 alkyl, --OR.sup.9, --CN, --NR.sup.10 R.sup.11, --COR.sup.12, --NR.sup.13 COR.sup.12, --NR.sup.9 COOR.sup.12, --NR.sup.9 CONR.sup.10 R.sup.11, --NHSO.sub.2 R.sup.12, --SO.sub.2 R.sup.12, --SOR.sup.12, --SO.sub.2 OR.sup.12, CONR.sup.10 R.sup.11, --SO.sub.2 NR.sup.10 R.sup.11, --N.dbd.NR.sup.14,--OCOR.sup.12 and --OCONHR.sup.12, where each two adjacent radicals together can form a carbocyclic or heterocyclic ring,

• where R.sup.12 is C.sub.1 -C.sub.18 alkyl, C.sub.6 -C.sub.10 aryl or benzyl which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy or is a five- to seven-membered heterocyclic radical, R.sup.10 and R.sup.11 independently of one another are hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.3 -C.sub.24 cycloalkyl, C.sub.6 -C.sub.10 -aryl or 5- to 7-membered heteroaryl, each of which is unsubstituted or substituted by cyano or hydroxyl groups, or in which R.sup.10 and R.sup.11 together with at least one of the other radicals R.sup.1 to R.sup.8 form a 5- or 6-membered carbocyclic or heterocyclic ring,
• R.sup.9 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.3 -C.sub.24 cycloalkyl, C.sub.6 -C.sub.10 aryl or 5- to 7-membered heteroaryl,
• R.sup.13 is hydrogen, C.sub.1 -C.sub.18 alkyl, C.sub.3 -C.sub.24 cycloalkyl, C.sub.1 -C.sub.4 alkylaryl, each of which is unsubstituted or substituted by cyano, hydroxyl or C.sub.1 -C.sub.4 alkoxycarbonyl groups, is C.sub.6 -C.sub.10 aryl which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy groups, or is a 5- to 7-membered heterocycle, and
• R.sup.14 is the radical of a coupling component or C.sub.6 -C.sub.10 aryl which is unsubstituted or substituted by halogen, C.sub.1 -C.sub.4 alkyl or C.sub.1 -C.sub.4 alkoxy groups, which comprises reacting perylene-3,4:9,10-tetracarboxylic anhydride of the formula II ##STR6## in which R.sup.1 to R.sup.8 have the meaning indicated above, with a sterically hindered amine as a base at elevated temperature.