Abstract: Near infrared absorbers which have a molecular extinction coefficient of 200,000 or more and are represented by the formula (I) ##STR1## wherein each of Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4, Y.sup.5, Y.sup.6, Y.sup.7 and Y.sup.8 is hydrogen, an alkyl group, alkoxyl group or alkylthio group; each of A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.5, A.sup.6, A.sup.7 and A.sup.8 is hydrogen, halogen, a nitro group, alkyl group, aralkyl group, alkenyl group, alkynyl group, alkoxyl group, aryloxy group, alkylthio group or arylthio group; and Met represents two hydrogen atoms or a metal, are useful for the production of optical display and recording materials.

Abstract: Near infrared absorbers which have a molecular extinction coefficient of 200,000 or more and are represented by the formula (I) ##STR1## wherein each of Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4, Y.sup.5, Y.sup.6, Y.sup.7 and Y.sup.8 is hydrogen, an alkyl group, alkoxyl group or alkylthio group; each of A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.5, A.sup.6, A.sup.7 and A.sup.8 is hydrogen, halogen, a nitro group, alkyl group, aralkyl group, alkenyl group, alkynyl group, alkoxyl group, aryloxy group, alkylthio group or arylthio group; and Met represents two hydrogen atoms or a metal, are useful for the production of optical display and recording materials.

Abstract: A method for preparing a halogenated alkoxyphthalocyanine represented by the formula (7) ##STR1## wherein R.sup.3 to R.sup.6 may be different and each of them is a secondary alkyl group, X is a halogen atom, n is the number of X and in the range of from 1 to 4, and Met is two hydrogen atoms, a divalent metal atom, or a trivalent or a tetravalent metallic derivative, which comprises the step of reacting a metal or a metallic compound with one to four kinds of raw materials selected from the group consisting of phthalonitriles represented by the following formula (1) and diiminoisoindolines represented by the following formula (2) ##STR2## wherein R.sup.1 is a secondary alkyl group, X is a halogen atom, and each of p and q is 0 or 1, but in at least one raw material, p or q is 1, and halogenated alkoxyphthalocyanine prepared by said method.

Abstract: Near infrared absorbers which have a molecular extinction coefficient of 200,000 or more and are represented by the formula (I) ##STR1## wherein each of Y.sup.1, Y.sup.2, Y.sup.3, Y.sup.4, Y.sup.5, Y.sup.6, Y.sup.7 and Y.sup.8 is hydrogen, an alkyl group, alkoxyl group or alkylthio group; each of A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.5, A.sup.6, A.sup.7 and A.sup.8 is hydrogen, halogen, a nitro group, alkyl group, aralkyl group, alkenyl group, alkynyl group, alkoxyl group, aryloxy group, alkylthio group or arylthio group; and Met represents two hydrogen atoms or a metal, are useful for the production of optical display and recording materials.

Abstract: A process for preparing piperonal which comprises the steps of reacting 1,2-methylenedioxybenzene with an N-alkylformanilide and a condensing agent comprising one or more compounds selected from the group consisting of phosgene, phosphorus oxychloride, phosphorus oxybromide, thionyl chloride, thionyl bromide, sulfuryl chloride, sulfuryl bromide, phosphorus trichloride, and phosphorus pentachloride, and then hydrolyzing the resulting reaction product.