摘要:
A process for the preparation of 1,3-dichloropropane by reacting bis(3-hydroxypropyl)ether with hydrogen chloride, optionally in the presence of tertiary basic nitrogen compounds or other tertiary aliphatic bases as catalysts, distilling off the 1,3-dichloropropane and the water of reaction and working up the two phases.
摘要:
The invention relates to a novel process for the simultaneous preparation of cyclopropyl alkyl ketones and 4,5-dihydroalkylfurans from 3-acyltetrahydrofuran-2-ones using a metal salt according to the diagram ##STR1## In the reaction, N-alkyllactams and/or N-acylmorpholines which are high-boiling and only slightly miscible with water are used. By charging the solvent, the metal salt and the 3-acyltetrahydrofuran-2-one in a molar excess with respect to the metal salt, heating the mixture to 160.degree. to 220.degree. C. and metering in further 3-acyl-tetrahydrofuran-2-one, the desired products are obtained in high yields. The metal salt can moreover be recovered in a simple manner by washing with water.
摘要:
A process for preparing acetaldehyde diethyl acetal is provided which involves:reacting acetaldehyde with ethanol in the presence of an acid catalyst and in the presence of an entrainer having a boiling point of from 25.degree. to 75.degree. C.
摘要:
A method of manufacturing chlorine-free cyclopropanecarboxylic acid methyl ester is described wherein a first portion of alkali methoxide is added to a high-boiling solvent, followed by a second portion of methoxide with an equimolar portion of 4-chlorobutyric acid. The ester product can be readily hydrogenated catalytically to the corresponding carbinol.
摘要:
A process for producing technically pure, chlorine-free cyclohexadecadiene by purifying the product mixture obtained preferably from the metathesis of cyclooctene by first removing by distillation the low boiling C.sub.6 hydrocarbons and any water that may be present, then treating the sump product with a solution of a strongly alkaline compound at about 100.degree.-250.degree. C. After separation of the thus-formed salts, the thus-pretreated product mixture may be subjected to fractional distillation in the usual way.
摘要:
In a process for recovering pure methylal from methanol-methylal mixtures, which can optionally contain still further compounds, the separation conducted in a rectification device comprising two rectifying columns. In the first rectifying column, the mixture to be separated is rectified under a pressure lower than that in the second column, into a methylal-rich, methanol-poor distillate, and into a practically methylal-free, methanol-rich sump product. The methylal-rich distillate of the first rectification is then separated in a second rectifying column, operated under a higher pressure than the first rectification column, into a compound stream containing methanol and methylal, which is then recycled to the first rectifying column, and into pure methylal as the sump product. In a specific refinement, the first rectification is preferably operated under a pressure of 1-22 bar absolute and the second rectification preferably under a pressure of 9-30 bar absolute, with the second rectification being operated under a pressure which is at least 8 bar higher than that of the first rectification.
摘要:
Cyclopropanecarboxylates of lower alcohols are prepared by esterification of the corresponding cyclopropanecarboxylic acids with the corresponding lower alcohols in the presence of an acid catalyst, while maintaining a considerable stoichiometric excess of the cyclopropanecarboxylic acid with respect to the lower alcohol, keeping the temperature at from 100 to 200° C. and distilling off the cyclopropanecarboxylate together with the water of reaction and small amounts of alcohol. Cyclopropanecarboxylates of lower alcohols are valuable intermediates in the pharmaceutical and agrochemical sectors.
摘要:
A method for the continuous production of esters of thermally unstable acids by the esterification, with or without a catalyst, of the acids with alcohols is provided. The method involves esterification at temperatures of approximately 80.degree. C. to approximately 130.degree. C., essentially in a single reaction zone, to which the acid and an excess of alcohol are continuously supplied and from which a vapor stream containing alcohol and water produced by the esterification reaction are removed, while at the same time removing an ester-rich liquid reaction mixture from the single reaction zone, from which the ester is obtained.
摘要:
Preparation of 4-acylamino-2,2,6,6-tetramethylpiperidines from 4-amino-2,2,6,6-tetramethylpiperidine and acid anhydrides carried out in the presence of carboxylic acids, whereupon the carboxylic acid is eliminated, using water at elevated temperature, from the initially formed carboxylate salt of the 4-acylamino-2,2,6,6-tetramethylpiperidine. In this process, no salt-like by-products arise.
摘要:
A process for the preparation of 5-chloro-2-pentanone starting from a ketal of a levulinic ester, followed by hydrogenation, and then reaction with hydrochloric acid. The process involves first purifying the ketal of the levulinic ester by distillation, making the hydrogenation catalysts for the ketal alkaline, and reacting the 3-(2-methyl-1,3-dioxolan-2-yl)propan-1-ol formed in this hydrogenation with hydrochloric acid to obtain 5-chloro-2-pentanone.