Abstract: Fluorescent dyes which fluoresce a variety of colors are prepared from substituted isoviolanthrone and substituted isoviolanthrone by reductive alkylation with alkyl halides in the presence of zinc.

Abstract: Fluorescent dyes which fluoresce in a variety of colors are produced from substituted and un-substituted 6-ring and 8-ring aromatic diketones by reductive alkylation with alkyl halides in the presence of zinc.

Abstract: A water-immiscible organic fluid is tagged and identified by tagging the organic fluid with between about 0.25 and about 100 ppm of a marker compound having the formula: ##STR1## where the OH groups are either ortho or para to the diazo moieties, and the Xs are the same or different and are selected from C.sub.1 -C.sub.12 -alkyl, Cl, Br, F, NH.sub.2, CN, NO.sub.2, NH(C.sub.1-3 -alkyl) and N(C.sub.1-3 -alkyl).sub.2, and the fluid is identified by extracting the tagged fluid with an alkaline aqueous extractant having a pH above about 12 and containing, based on 100 parts by weight of said extractant, between about 10 and about 60 parts by weight of an organic cosolvent having the formula:R.sup.1 --O--R.sup.2 --NH.sub.2 (II)where R.sup.1 is C.sub.1 -C.sub.3 -alkyl, and R.sup.2 is C.sub.2 -C.sub.6 -alkylene.

Abstract: A polyol ester or poly-alkylene glycol lubricant is tagged by adding to the lubricant a chemical marker which is stable over the temperature cycling range of a refrigerant.In testing for the presence of the marker, a sample of a lubricant is obtained, and the sample is diluted in a sufficient volume of an organic solvent such that subsequent admixture with an aqueous solution will not result in emulsification. The diluted sample is extracted with an aqueous solution appropriate for the marker. Simultaneous with or subsequent to extraction, a chromophoric reaction of the marker is induced, whereby a readily identifiable color is observable.