Butyl 2-[[3-[[(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)amino]carbonyl]-2-hydroxy-1-naphthyl]azo]benzoate

The Pigment Red 208 is an organic compound with the formula C₂₉H₂₅N₅O₅. The IUPAC name of this chemical is butyl 2-[(2Z)-2-[2-oxo-3-[(2-oxo-1,3-dihydrobenzimidazol-5-yl)carbamoyl]naphthalen-1-ylidene]hydrazinyl]. With the CAS registry number 31778-10-6, it is also named as Benzoic acid, 2-(2-(3-(((2,3-dihydro-2-oxo-1H-benzimidazol-5-yl)amino)carbonyl)-2-hydroxy-1-naphthalenyl)diazenyl)-, butyl ester. The other registry number is 71872-62-3. In addition, it is bright red powder with excellent performance of solvent resistance and chemical reagents resistance.

The other characteristics of this product can be summarized as: (1)ACD/LogP: 5.72; (2)# of Rule of 5 Violations: 3; (3)ACD/LogD (pH 5.5): 7; (4)ACD/LogD (pH 7.4): 7; (5)#H bond acceptors: 10; (6)#H bond donors: 4; (7)#Freely Rotating Bonds: 9; (8)Index of Refraction: 1.691; (9)Molar Refractivity: 143.338 cm³; (10)Molar Volume: 374.408 cm³; (11)Polarizability: 56.824×10^-24 cm³; (12)Surface Tension: 57.992 dyne/cm; (13)Rotatable Bond Count: 9; (14)Tautomer Count: 42; (15)Exact Mass: 523.185569; (16)MonoIsotopic Mass: 523.185569; (17)Topological Polar Surface Area: 138; (18)Heavy Atom Count: 39; (19)Complexity: 1030.

Preparation of Pigment Red 208: Stirring 2-amino-benzoicacibutylester, 2mol / L hydrochloric acid and water to dissolve and cooling to 6 °C. Adding 2mol / L sodium nitrite solution under rapidly stirring, stirring, filtering, adjusting the pH = 5 to wait for coupling. Heating 84% 5-(2'-hydroxy-3 '-benzoyl amino)-benzimidazole-2-ketone, 2mol/L sodium hydroxide solution and water to 60 ~ 65 °C and hot filtration to remove insoluble matter. After cooling to below 10 °C, dropping this solution to the above diazo solution and controlling pH = 5 ~ 6.2. Stirring 1h after coupling. heating to boiling, hot filtration, washing and drying to get the crude product.

Uses of Pigment Red 208: It is mainly used in plastic coloring and packaging ink. And it is also used to color PAN puree, cellulose acetate and polyurethane foam puree.

People can use the following data to convert to the molecule structure. 
1. SMILES: O=C(OCCCC)c1ccccc1N\N=C2\c5ccccc5\C=C(/C2=O)C(=O)Nc3ccc4c(c3)NC(=O)N4;
2. InChI: InChI=1/C29H25N5O5/c1-2-3-14-39-28(37)20-10-6-7-11-22(20)33-34-25-19-9-5-4-8-17(19)15-21(26(25)35)27(36)30-18-12-13-23-24(16-18)32-29(38)31-23/h4-13,15-16,33H,2-3,14H2,1H3,(H,30,36)(H2,31,32,38)/b34-25-.