摘要:
A process for producing the magnesium salt of 3-nitro-naphthalene-1,5-disulfonic acid by sulfonating naphthalene, nitrating the sulfonation product, and separating the pure magnesium salt of 3-nitronaphthalene-1,5-disulfonic acid, which process comprises:(a) sulfonating naphthalene with liquid SO.sub.3 in the presence of an inert organic solvent at temperatures between -40.degree. and +20.degree. C.;(b) adding to the reaction mixture obtained a mixture consisting of about equal parts of 100% sulfuric acid and fully reacted crude nitration mixture from nitration of a previous nitration charge, separating from the resulting two-phase system the upper organic solvent phase by decanting, and removing from the Armstrong's acid anhydride acid slurry the remainder of organic solvent by distillation, or removing it during or after subsequent nitration, subsequently adding to the residue the amount of nitric acid required for nitration, and then nitrating;(c) adding then firstly water and afterwards, in the absence of the inert organic solvent, at 90.degree. to 120.degree. C., a compound releasing magnesium ions, the amount being such that, per mol of 3-nitronaphthalene-1,5-disulfonic acid, 1.1 to 1.3 mols of magnesium ions are added, and a sulfuric acid concentration of between 40 and 60 percent by weight (relative to the sulfuric acid and water) is maintained; and(d) separating the crystallized magnesium salt of 3-nitronaphthalene-1,5-disulfonic acid at a temperature of between 20.degree. and 70.degree. C., and subsequently optionally washing it with a maximum of 60 percent by weight of sulfuric acid and/or water, and optionally drying the product.
摘要:
A process has been invented for the preparation of aminonaphthalenesulphonic acids by the catalytic hydrogenation of salts of nitronaphthalenesulphonic acids with hydrogen in the presence of Raney nickel catalysts at elevated temperature and pressure, said catalysts comprising a combination of fresh Raney nickel catalyst and Raney nickel catalyst which has already been used in prior hydrogenation or hydrogenations.
摘要:
2-Amino-5-alkyl-phenols, which are suitable as intermediates in the production of crop-protection agents or photographic couplers, can be prepared by subjecting 2-amino-5-alkyl-benzenesulphonic acids or their salts to alkaline hydrolysis.
摘要:
The invention relates to a process for the preparation of 1-amino-8-naphthol-3,6-disulphonic acid (H-acid) as the mono-alkali metal salt from napthylamine-trisulphonic acid isomer mixtures by alkaline hydrolysis under pressure. The separation of the H-acid is effected by utilizing an aqueous sulphuric acid which contains naphthalene- and/or nitronaphthalene- and/or naphthylamine- and/or naphthol- and/or aminonaphthol-mono-, -di-and/or-tri-sulphonic acids.
摘要:
A process has been invented for the preparation of naphthalene-1,3,6-trisulphonic acid by sulphonating naphthalene with sulphuric acid and oleum, characterized in that naphthalene and most of the oleum are simultaneously metered into sulphuric acid or oleum of low concentration, which has been initially introduced, at about 140.degree. to 240.degree. C., the temperature is kept at about 140.degree. to 240.degree. C. for some time, the remainder of the oleum is then added at about 140.degree. to 240.degree. C. and the mixture is then further stirred for some time.Naphthalene-1,3,6-trisulphonic acid is a known important intermediate used, for example, in the preparation of T-acid, H-acid and chromotropic acid.
摘要:
A process for the preparation of o-nitrobenzaldehyde, comprising converting to the corresponding acetals a mixture of nitrated benzaldehyde which contains about 10 to 30% of o-nitrobenzaldehyde and about 70 to 90% of m-nitrobenzaldehyde, removing the o-nitrobenzaldehyde acetal by distillation, and then converting the o-nitrobenzaldehyde acetal to o-nitrobenzaldehyde.
摘要:
The invention relates to an improved process for preparing 3-acyloxy-2-methylbenzoic acids by heating substituted naphthalenes in the presence of alkali metal hydroxides and subsequently acylating.
摘要:
A process is provided for preparing 4-hydroxy-3-nitrobiphenyl from 4-hydroxy-biphenyl by nitrating in the position adjacent to the phenolic hydroxyl group in high selectivity and yield, and the nitric acid used as the nitrating reagent is metered into the reaction system in a specific manner.
摘要:
The invention relates to a process for isolating H acid and K acid in the form of their monoalkali metal salts from acid aqueous solutions which contain these two acids and alkali metal ions and may contain other aminonaphtholdisulphonic acids, in which process H acid monoalkali metal salts are precipitated at elevated temperatures from solutions which contain not only sodium ions but also potassium ions and then precipitating K acid monoalkali metal salts by cooling down the filtrate obtained after separating off the H acid monoalkali metal salts.
摘要:
A process has been invented for the preparation of a mono-alkali metal salt of 1-amino-8-naphthol-3,6-disulphonic acid comprising reacting 1-naphthylamine-3,6,8-trisulphonic acid and/or a salt thereof and/or a naphthylamine-trisulphonic acid isomer mixture and/or salt thereof with an alkali metal hydroxide solution at elevated pressure and elevated temperature and in the presence of an alcohol or alcoholate, and separating out the mono-alkali metal salt by acidification. The process results in the procurement of higher yields of the desired product and in the formation of less by-products.