摘要:
Trialkylamines and methyl formate are recovered from reaction mixtures obtained in the preparation of trimethylolalkanes by reaction of n-alkanals with from 2.2 to 4.5 moles of formaldehyde in aqueous solution in the presence of from 0.6 to 3 mole of trialkylamine, each quantity based on 1 mole of alkanal, and subsequent hydrogenation in a process wherein the crude reaction mixturea) is heated to from 100.degree. to 200.degree. C., the water present in the reaction mixture is substantially separated off by distillation, together with any excess free trialkylamine, the trialkylamine present in the form of a trialkylammonium formate is freed to form a trimethylolalkane formate, the trialkylamine is distilled off and the trimethylolalkane formate is transesterified with methanol to trimethylolalkane and methyl formate in the presence or absence of a catalytic amount of an alkali metal alkoxide or alkaline earth metal alkoxide, orb) is substantially dewatered, any excess free trialkylamine being removed at the same time, the trialkylamine present in the form of a trialkylammonium formate is separated off by admixing the remaining mixture with methanol and heating the admixture to from 100.degree. to 200.degree. C. to form methyl formate and trialkylamine.
摘要:
A process for preparing hydroxyl-containing polymers and, in particular, a process for preparing polytetrahydrofuran with terminal hydroxyl groups from the corresponding acyloxy-containing polymers by transesterification with alcohols is carried out continuously in at least one stirred vessel, with the foam produced in the transesterification being fed tangentially to a cylindrical container, preferably a cyclone separator, at an adequate velocity to destroy the foam. The liquid phase which separates out is recycled through a line to the at least one stirred vessel.This continuous process is preferably carried out in a cascade of stirred vessels, in which each stirred vessel or a subunit of at least two stirred vessels can in each case be coupled to a cylindrical container, preferably in the form of a cyclone separator.
摘要:
A process for working up a liquid reaction discharge of the cationic polymerization of isobutene, which substantially comprises polyisobutene, unconverted isobutene and, if required, an inert diluent, is described. Problems with foam formation when the unconverted isobutene is being distilled off are avoided if the heated reaction discharge is let down into a flash container and/or not more than 900 m3/h of vapor are expelled per square meter of liquid surface and/or the resulting foam is destroyed, for example in a wet cyclone.
摘要:
A polyisobutene composition having a global maximum of the differential molecular weight distribution curve at a molecular weight Mmax of from 3 500 to 8 000 is described, which comprises at least one local maximum at a molecular weight of from 112 to 560. The isobutene oligomers present act as flow improvers and boiling assistants. They are added to higher molecular weight isobutene polymers, preferably before or in the course of a distillation, for removing unconverted isobutene and/or an inert diluent.
摘要:
A description is given of a process for preparing methyl formate by reacting excess methanol with carbon monoxide under superatmospheric pressure and at elevated temperature in the presence of alkali metal methoxide or alkaline earth metal methoxide as catalyst in a pressure-rated reactor, in which the use of at least two reactor elements, preferably operated in countercurrent, at about 100° C. and a pressure of about 100 bar in combination with a solids-free desalting of the reaction product makes possible very economical, largely trouble-free production of methyl formate in any desired quality and with a very good production capacity.Furthermore, the process for solids-free desalting and apparatuses for carrying out this process are described.
摘要:
A method for manufacturing solid electrolyte capacitors is provided. Pursuant to the method, pores in formed sintered members composed of a valve metal are first nearly filled with manganese dioxide that is produced by pyrolysis of solutions that contain manganese nitrate. Following thereupon, the sintered members are immersed into a dry melt of manganese nitrate that may comprise an additive of manganese dioxide and/or silicon dioxide powder. Subsequently, the members are introduced into a furnace, and heated to approximately 100.degree. C. in dry air. Subsequently, fine drops of water are applied onto the surface of the heated sintered members and the pyrolysis is ended at temperatures of approximately 200.degree. to about 350.degree. C. in a mist of water vapor that flows by.
摘要:
A process for the preparation of highly reactive polyisobutenes is described, in which isobutene is polymerized in the presence of a complex of boron trifluoride and at least one cocatalyst in a liquid organic phase at a reaction temperature of from −60 to −4° C. and water is added in two stages to the organic phase for catalyst deactivation and catalyst extraction.
摘要:
The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid, in which firstly aqueous formic acid is produced by hydrolysis of methyl formate, with the methanol content in the methyl formate having been reduced in advance. The process according to the invention has the special feature that—before the hydrolysis of the methyl formate—the methanol content of the methanol-containing methyl formate is reduced in a distillation column, this distillation column simultaneously being employed for other separation functions during work-up of the formic acid.
摘要:
The invention relates to a process for obtaining anhydrous or substantially anhydrous formic acid in which, during the work-up, a compound of the general formula I where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R3 is hydrogen or a C1-C4-alkyl group, is employed simultaneously as extractant for formic acid and as antifoam for a distillation process.
摘要:
The invention relates to a process for the preparation of anhydrous or substantially anhydrous formic acid. The process has the special feature that a liquid of the general formula I where the radicals R1 and R2 are alkyl, cycloalkyl, aryl or aralkyl groups, or R1 and R2 jointly, together with the N atom, form a heterocyclic 5- or 6-membered ring, and only one of the radicals is an aryl group, and where R3 is hydrogen or a C1-C4-alkyl group, employed as extractant is also employed as washing liquid for the offgases produced in the process.