Abstract: The invention provides novel bisazo compounds which is obtained by coupling two molecules of a 2-hydroxynaphthalene-3,6-dicarboxylic acid derivative and a compound having two diazo groups in its molecule, as well as a process for producing the same. The present compounds are superior in resistance to water, chemical agents, solvents, heat and the like.

Abstract: A dichroic dye represented by the formula (I) or (II): ##STR1## wherein the substituents are as described in the specification. The dichroic dyes (I) and (II) exhibit excellent dichroism and can be prepared from 2,2'-ditrifluoromethylbenzidine having no toxicity, such as mutagenicity.

Abstract: Provided are novel dichroic azo dyestuffs, which contain skeletons represented by the following general formula: ##STR1## at one terminals of the long axes of the molecules of the azo dyestuffs, and liquid crystal compositions containing the dichroic azo dyestuffs in forms dissolved in liquid crystals. These dichroic azo dyestuffs have large dichroic ratios and high durability, and their compositions are employed as useful display devices.

Abstract: Azo dyes of the formula ##STR1## and external salts thereof, wherein F is the residue of a monoazo or disazo compound in 1:1 metal complex form or of a trisazo, disazoazoxy or tetrakisazo compound in metal-free or 1:1 metal complex form,each X is independently --NR.sub.2 --Q--NR.sub.3 R.sub.4 or --NR.sub.2 --Q--N.sup..sym. R.sub.5 R.sub.6 R.sub.7,whereinQ is linear or branched C.sub.2-6 alkylene or --NH--CO--CH.sub.2 --,R.sub.2 is hydrogen or C.sub.1-4 alkyl,each of R.sub.3 and R.sub.4 is independently hydrogen; C.sub.1-6 alkyl; C.sub.2-6 alkyl monosubstituted by cyano or hydroxy in the 2-, 3-, 4-, 5- or 6-position; phenyl(C.sub.1-3 alkyl); phenyl(C.sub.1-3 alkyl) having, on the phenyl ring, 1, 2 or 3 substituents selected from chloro, C.sub.1-4 alkyl and C.sub.1-4 alkoxy; C.sub.5-6 cycloalkyl or C.sub.5-6 cycloalkyl substituted by 1, 2 or 3 C.sub.1-4 alkyl groups or --NR.sub.3 R.sub.