Aspects of the present disclosure relate to methods of complexing agent content determination. In at least one aspect, a method includes diluting a first solution with water to form a second solution. The first solution includes a nickel source and a complexing agent. The method includes introducing an indicator with the second solution. The method includes titrating the second solution with a base to provide a color change of the second solution. The method includes calculating a content of the complexing agent of the first solution.

The present invention relates to azo dyes of formula (1), wherein D is a radical of formula (2) or (3), R.sub.1 and R.sub.2 independently denote hydrogen; C.sub.6-C.sub.10aryl which is unsubstituted or substituted by cyano, carboxy, hydroxy, halogen, C.sub.1-C.sub.6alkyl, or C.sub.1-C.sub.6alkoxy; C.sub.1-C.sub.12alkyl which may be interrupted one or more times by —O—, —S—, —NR.sub.4—, —CO—, —COO— or —OOC—, and is unsubstituted or substituted by cyano, carboxy, hydroxy, C.sub.6-C.sub.10aryl, or C.sub.6-C.sub.10aryloxy, which C.sub.6-C.sub.10aryl or C.sub.6-C.sub.10aryloxy is unsubstituted or substituted by cyano, carboxy, hydroxy, halogen, C.sub.1-C.sub.6alkyl, or C.sub.1-C.sub.6alkoxy; R.sub.3 and R.sub.4 are each independently of the other hydrogen, halogen, nitro, cyano, trifluoromethyl, carboxy, C.sub.1-C.sub.6alkyl, C.sub.1-C.sub.6alkoxy, C.sub.1-C.sub.6alkylcarbonyl, C.sub.6-C.sub.10arylcarbonyl, C.sub.1-C.sub.6alkoxycarbonyl, C—C.sub.6alkylsulfonyl, C.sub.1-C.sub.6alkylsulfonylamino or C.sub.1-C.sub.4alkanoylamino; and R.sub.5 is halogen, nitro, cyano, trifluoromethyl, carboxy, C.sub.1-C.sub.6alkyl, C.sub.1-C.sub.6alkoxy, C.sub.1-C.sub.6alkylcarbonyl, C.sub.6-C.sub.10arylcarbonyl, C.sub.1-C.sub.6alkoxycarbonyl, C.sub.1-C.sub.6alkylsulfonyl, C.sub.1-C.sub.6alkylsulfonylamino or C.sub.1-C.sub.4alkanoylamino; and R.sub.6, R.sub.7, R.sub.8 and R.sub.9 independently of each other are hydrogen, hydroxy, halogen, cyano, nitro or C.sub.1-C.sub.4alkanoylamino, and the radicals X independently denote N or C—H, with the proviso that at least one radical X denotes C—H, which are distinguished by their good lightfastness properties.

##STR00001##

The present invention relates to disperse azo dyes of formula ##STR00001##
wherein R.sub.1 is bromo, nitro, cyano, methyl, methoxy or trifluoromethyl; R.sub.2 is hydrogen, chloro, bromo or trifluoromethyl; R.sub.3 is hydrogen, chloro, bromo, methoxy, trifluoromethyl, nitro or cyano; and R.sub.4 is methyl, ethyl, n-propyl, 2-methoxyethyl, methoxycarbonylmethyl or 2-methoxycarbonylethyl;
with the proviso that R.sub.1 is cyano in case R.sub.2 denotes chloro or bromo,
to a process for the preparation of such dyes and to their use in the dyeing or printing of semi-synthetic and, especially, synthetic hydrophobic fibre materials, more especially textile materials.

The invention relates to cleavable chemistry in general, and in particular, to tunable fluorescence using cleavable linkers present in fluorochrome-quencher conjugates.

An azo compound excellent in solubility in solvent and having a high absorbance coefficient is disclosed, as well as an ink containing the azo compound. Such an ink contains a solvent having a relative permittivity at 22° C. and at a measurement frequency of 1 kHz of 3 or less and having a solubility in water at 25° C. of 20 mg/L or less, and an azo compound.

The invention relates to a method for producing aniline or an aniline derivative, in which a solution of aminobenzoic acid in aniline with a mass fraction of aniline in the solution, in relation to the total mass of aminobenzoic acid and aniline, in the region of 20% to 85%, is subject to a thermal decarboxylation at a temperature in the region of 165° C. to 500° C. without the presence of a non-system catalyst, such that the aminobenzoic acid is converted into aniline. The obtained aniline can be converted into derivatives, such as di- and polyamines of the diphenylmethane series.

Disclosed is a mono-azo dichroic dye compound represented by the following Chemical Formula 1, a composition for polarizing plate, a polarizing plate, and an optical device.

##STR00001##

In Chemical Formula 1, Z represents any one selected from the group consisting of CN, COOR.sub.11, indanone and 1,3-dioxoindane, wherein R.sub.11 is any one selected from the group consisting of alkyl groups, aryl groups, and substituted or non-substituted heteroaryl groups. The mono-azo dichroic dye compound shows excellent dichroic properties, and has excellent heat resistance and photo-resistance, and thus may be used advantageously for a dye-based polarizing plate.

Provided is a composition containing a compound of formula (1), and a polymerizable liquid crystal compound or a liquid crystalline polymer compound. n represents 1 or 2; Ar.sup.1, Ar.sup.2, and Ar.sup.3 each represent a 1,4-phenylene group or a divalent sulfur-containing aromatic heterocyclic group; At least one of Art and Ar.sup.2 has a fluorine atom; R.sup.1 represents a single bond or a group selected from —OC(═O)—, —C(═O)O—, —C≡C—, —CH═CH—, —CH═N—, —N═N—, and —N═CH—; R.sup.2 represents an alkylamino group or an alkoxy group; R.sup.3 represents a group selected from an alkanediyl group, an alkanediyloxy group, an alkanediyloxycarbonyl group, and an alkanediylcarbonyloxy group; and R.sup.4 represents a polymerizable group or a hydrogen atom.

R.sup.4—R.sup.3—Ar.sup.1—(—R.sup.1—Ar.sup.2—).sub.n—N═N—Ar—R.sup.2   (1)

Sensors for detecting and distinguishing metals in a sample comprise phenol group-containing azo dyes, the phenol group having one hydroxy involved in reversible metal ion binding and a second hydroxy alkylated to an optically transparent substrate. The sensors have utility for detecting chromium, calcium, magnesium, copper, mercury, nickel, zinc, cobalt, manganese, cadmium, lead, tin, aluminum, potassium, sodium, or arsenic ions in a sample.

Dichroic azo-azomethine dyes of formula (A) or (B), wherein Ar.sup.1 to Ar.sup.10 are specific (hetero)aromatic moieties and L is a linking group, as defined in the present claims, a dichroic dye mixture comprising said azo-azomethine dyes and a process for preparing the dyes are provided. The dyes are well suited for combination with liquid crystal material for use, inter alia, in a light absorption anisotropic element, for example, in a switchable optical device or an optically anisotropic film.

##STR00001##