摘要:
2-Nitro-3-aminopyridine is prepared by(a) reacting 3-aminopyridine with phosgen COCl.sub.2 or urea H.sub.2 NCONH.sub.2 to give N,N'-di-(3-pyridyl)-urea,(b) nitrating and N,N'-di-(3-pyridyl)-urea with nitric acid or with a mixture of nitric acid and sulfuric acid to give N,N'-di-(2-nitor-3-pyridyl)-urea, and(c) hydrolyzing said N,N'-di-(2-nitro-3-pyridyl)-urea to give 2-nitro-3-amino-pyridine.N,N'-di-(3-pyridyl)-urea and N,N'-di-(2-nitro-3-pyridyl)-urea, which are formed in the course of the reaction as intermediates are new compounds.The end product of the process, 2-nitro-3-aminonpyridine, is an intermediate in various specialized fields.
摘要:
Carbamoyl chlorides derived from secondary aliphatic amines having alkyl groups which are branched in the 1-position are prepared by passing phosgene at an elevated temperature into the corresponding, initially taken--if appropriate dissolved in an inert solvent--secondary aliphatic amines having alkyl groups which are branched in the 1-position.The reaction products are intermediates in various specialized fields, particularly in the plant protection sector.
摘要:
p-Hydroxyphenylacetic acid is prepared by reduction of p-hydroxymandelic acid with HI in the presence of red phosphorus. According to a preferred embodiment, the reaction is carried out in one vessel in which the mandelic acid is prepared in situ from phenol and glyoxylic acid.
摘要:
Thiochloroformates are prepared by reaction of mercaptans with phosgene in the presence of carboxylic acid amides and/or urea derivatives as catalysts in amounts smaller than hitherto known for this application. The amounts range from about 0.02 to 0.2 mol %, relative to the corresponding starting mercaptan. Despite the small amounts of catalyst the reaction proceeds as with the use of larger catalyst amounts; however, work-up is simplified and the product yields are increased in most cases.
摘要:
Phenylacetic acid and the simple derivatives thereof are prepared by catalytic hydrogenation of mandelic acid and its appropriate derivatives in the presence of a noble metal catalyst in aqueous solution which is free from mineral acid, especially free from hydrochloric acid.
摘要:
p-Tert.butylbenzotribromide and the derivatives thereof which is halogen-substituted at the nucleus are prepared under side chain halogenation conditions by bromination of p-tert.butyltoluene and its derivatives substituted at the nucleus by halogen. Practically no undesired bromination in the nucleus or at the tert.butyl radical takes place.By partial saponification of the benzotribromide the corresponding benzoyl bromide is obtained. Further saponification of the latter or complete saponification of the benzotribromide yields p-tert.butylbenzoic acid and derivatives thereof which are halogen substituted at the nucleus, the esters of which can be used in pharmacology.
摘要:
A process for the preparation of chloroformic acid aryl-esters and cyclic carbonates of aryl compounds containing at least two phenolic hydroxy groups wherein aromatic compounds containing one or more hydroxy groups linked to an aromatic nucleus, are reacted with phosgene in the presence of catalytic amounts of N,N-disubstituted acid amide either under pressure or without pressure while removing the hydrogen chloride continuously from the reaction mixture. This improved process results in almost quantitative or very high yields of pure products and avoids problems such as disposal of waste water.
摘要:
Process for preparing carboxylic acid chlorides by reaction of carboxylic acids or carboxylic anhydrides with phosgene at temperatures of from 0.degree. to 180.degree.C in the presence of a catalyst, wherein 0.01 to 10 weight percent, calculated on the carboxylic acid or the carboxylic anhydride, of trisubstituted phosphine oxides or trisubstituted phosphine sulfides or reaction products of these compounds with phosgene and/or acids or acid anhydrides or mixtures of these compounds are used as catalyst.
摘要:
Anhydrous organic solutions of alkali metal arylates are prepared by dissolving an alkali metal arylate or reacting an arylhydroxy compound with alkali metal hydroxide in a ketone immiscible or incompletely miscible with water at room temperature and removing the water from the solution, if any, by azeotropic distillation with reflux.
摘要:
Diphenyl ethers are prepared by Ullmann reaction of alkali metal phenolates with halobenzenes in the presence of basic copper carbonate and/or copper salts of lower aliphatic carboxylic acids as catalysts. These special catalysts have a better catalytic activity than other copper catalysts known for the Ullmann reaction.The diphenyl ethers prepared or obtainable according to the invention are mainly intermediates in diverse fields such as pharmaceuticals or plant protecting agents.