TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation: No general preparation given. Preferred Definitions:    D'=group (ip);    R2 and R3=H;    R1=unsaturated 1-20C alkyl, optionally containing heteroatoms, preferably is formyl;    R5=1-20C alkyl (preferably methyl);    q=1;    P'=group (Ia);    T'=a double nitrogen-nitrogen bond (XXX);    n=1;    P1=bivalent aryl of formula (iii);    R1-R4=H;    m=1;    r and s=0;    A=COOH;    t=1.    SPECIFIC COMPOUNDS - 39 Compounds are disclosed as the compound (I) e.g. (E)-2-cyano-3-(5-((E)-2-(4-ethyl-1,3,5-trimethyl-1H-pyrrol-2-yl)-vinyl)-1-methyl-1H-pyrrol-2-yl)-acrylic acid of formula (I'), 4-(4-ethyl-3,5-dimethyl-1H-pyrrol-2-ylazo)-benzoic acid, 4-(5-formyl-1H-pyrrol-2-ylazo)-benzoic acid, (E)-2-cyano-3-(5-((E)-2-(4-ethyl-1-hexyl-3,5-dimethyl-1H-pyrrol-2-yl)-vinyl)-thiophen-2-yl)-acrylic acid and (E)-2-cyano-3-(7-((E)-2-(4-ethyl-1- hexyl-3,5-dimethyl-1H-pyrrol-2-yl)-vinyl)-2,3-dihydro-thieno(3,4-b)(1,4)dioxin-5-yl)-acrylic acid.    EXAMPLE - About 0.45 g of 4-amino benzoic acid were introduced into a 100 ml flask and suspended in 8 ml of water. About 2 ml of hydrochloric acid at 37% were added to the suspension obtained. About 0.25 g of sodium nitrite in 5 ml of water were added to the solution obtained, cooled to 0 degrees C with an ice bath and kept under magnetic stirring, obtaining a solution comprising a diazonium salt. About 0.36 g of N-methylpyrrole-2-carboxyaldehyde and 3 ml of pyridine were dissolved, separately, in 30 ml of ethanol, in a 50 ml flask. The solution of diazonium salt prepared above was slowly added dropwise to the solution obtained, maintaining the temperature at 0 degrees C to 5 degrees C. At the end of the dripping, the reaction mixture obtained was left to warm up to room temperature (25 degrees C) and kept under stirring for 18 hours. The reaction mixture was then concentrated by evaporation of the solvent at reduced pressure observing the formation of a precipitate which was filtered at reduced pressure obtaining a dark solid. The dark solid obtained was dissolved in 3 ml of acetic acid, precipitated by adding 20 ml of petroleum ether and filtered at reduced pressure obtaining 0.47 g (yield 57%) of 4-(5-formyl-1-methyl-1H-pyrrol-2-ylazo)-benzoic acid as a dark solid.