Koch-acid

H-acid, l-hydroxy-3,6,8-ttisulfonic acid, which is one of the most important letter acids, is prepared as naphthalene is sulfonated with sulfuric acid to ttisulfonic acid. The product is then nitrated and neutralized with lime to produce the calcium salt of l-nitronaphthalene-3,6,8-ttisulfonic acid, which is then reduced to T-acid (Koch acid) with Fe and HCl modem processes use continuous catalytical hydrogenation with Ni catalyst. Hydrogenation has been performed in aqueous medium in the presence of Raney nickel or Raney Ni—Fe catalyst with a low catalyst consumption and better yield (51). Fusion of the T-acid with sodium hydroxide and neutralization with sulfuric acid yields H-acid. Azo dyes such as Direct Blue 15 [2429-74-5] (17) and Acid... 

Koch acid [117 2-0] 8-nitronaphthalene- 1,3,6-trisulfoni c acid iron... 

Many of the premetallised direct dyes are symmetrical structures in the form of bis-1 1 complexes with two copper(II) ions per disazo dye molecule. Scheme 5.12 illustrates conversion of the important unmetallised royal blue Cl Direct Blue 15 (5.43), derived from tetrazotised dianisidine coupled with two moles of H acid, to its much greener copper-complex Blue 218 (5.44) with demethylation of the methoxy groups as described above. Important symmetrical red disazo structures of high light fastness, such as Cl Direct Red 83 (5.45), contain two J acid residues linked via their imino groups. Unsymmetrical disazo blues derived from dianisidine often contain a J acid residue as one ligand and a different coupler as the other, such as Oxy Koch acid in Cl Direct Blue 77 (5.46), for example. 

Fig. 13.50. Formation of Koch acid via nitration and reduction steps.

Derivation Fusion of l-naphthylamine-3,6,8-trisul-fonic acid (Koch acid) with 30% sodium hydroxide solution at 180C. 

A number of cyclic carbonyl compounds are formed under the conditions of the Reppe reaction or of the Koch acid synthesis. Since the reactions are carried out in the presence of water they can either proceed via... 

Hydroformylation, ring closure reactions and the Koch acid syntheses may be carried out in autoclaves made from stainless steel. If the formation of iron pentacarbonyl has to be completely avoided, silver or copper lined autoclaves may be used. If hydrogen halides or hydrogen halide generating compounds are used, which e.g., is the case in the Reppe carbonylation reactions, stainless steel autoclaves cannot be used due to corrosion. HasteUoy B or Hastelloy C should be used instead. 

Koch acid Komarowdry kiypton 85 kynurenic acid... 

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