摘要:
In an improved process for preparing 4-pentenates by isomerization, where isomeric pentenates are treated at elevated temperatures with zeolites and 4-pentenates are distilled out of the reaction mixture, the improvement comprises using pentenates in mixture with alkanols.
摘要:
Pure acrylic acid is stored and/or transported by a process in which the pure acrylic acid is stored and/or transported as liquid aqueous solution at ≦15° C.
摘要:
Supported silver catalysts which contain one or more alkali metals are prepared in a two-stage process by doping a basic catalyst which contains silver in metallic form and may also contain lithium with the heavy alkali metal sodium, potassium, rubidium and/or cesium using an impregnating solution which contains the heavy alkali metal and one or more nitrates of the general formulaR.sup.+ NO.sub.3.sup.-wherein R.sup.+ is an ammonium, hydrazinium, C.sub.1 -C.sub.12 -monoalkylammonium, C.sub.2 -C.sub.12 -dialkylammonium, C.sub.3 -C.sub.12 -trialkylammonium or C.sub.4 -C.sub.12 -tetraalkylammonium cation.
摘要翻译:含有一种或多种碱金属的负载型银催化剂通过掺杂含有金属形式的银的碱性催化剂并且还可以使用重质碱金属钠,钾,铷和/或铯来包含锂,通过两步法制备。 含有重质碱金属和一种或多种通式为R + NO 3 - 的硝酸盐的浸渍溶液,其中R +是铵,肼,C1-C12-单烷基铵,C2-C12-二烷基铵,C3-C12-三烷基铵或C4-C12 四烷基铵阳离子。
摘要:
A method is described of stabilizing (meth)acrylic esters against unwanted free-radical polymerization, in which the mixture to be stabilized has added to it a polymerization inhibitor mixture comprising at least one nitroxyl radical and/or at least one organic compound having at least one nitroso group, and at least one p-phenylenediamine.
摘要:
A process for preparing pure (meth)acrylic acid or a (meth)acrylate starting from a crude (meth)acrylic acid, which comprises the following stages: A: treating the crude (meth)acrylic acid with at least one compound which is able to remove aldehydes, to give an aldehyde-free crude (meth)acrylic acid; B: subjecting the aldehyde-free crude (meth)acrylic acid to imprecise distillation, to give a low-boiling fraction comprising (meth)acrylic acid and acetic acid and a high-boiling fraction comprising (meth)acrylic acid and high boilers; C: isolating a pure (meth)acrylic acid from the high-boiling fraction and, if desired, D: esterifying the low-boiling fraction comprising (meth)acrylic acid and acetic acid that is obtained in stage B by means of one or more alkanols, to give an esterification mixture comprising one or more (meth)acrylates, one or more acetic esters, and one or more alkanols.
摘要:
In a process and an apparatus for the continuous preparation of alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid with alkanols having from 1 to 5 carbon atoms in a homogeneous, liquid, solvent-free phase at elevated temperature and in the presence of an acid esterification catalyst, in which the (meth)acrylic acid, the alkanol and the catalyst are fed to a reaction zone, the water formed is removed by rectification during a residence time as constituent of a mixture comprising alkanol in a rectification unit superposed on the reaction zone, the distillate thus obtained is separated into an organic phase comprising alkanol and an aqueous phase comprising water, the organic phase is returned to the rectification unit, the reaction mixture is discharged from the reaction zone and conveyed into a distillative separation zone comprising further rectification units and in the latter the alkyl (meth)acrylate formed is separated off.
摘要:
A catalyst for decomposing dinitrogen monoxide which is pure or present in gas mixtures comprises metallic silver applied to an alumina carrier with a BET surface area of from 5 to 25 m.sup.2 /g.
摘要:
The process for the esterification of (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and the (meth)acrylate to be formed are separated off by distillation and an oxyester-containing bottom product is formed and is separated off, and (a) in the bottom product separated off, the oxyesters present are cleaved, if required after the addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, directly in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, and the cleavage products are removed, a cleavage residue remaining, or (b) the oxyesters are first removed by distillation from the cleavage product separated off, a distillation residue remaining, and the oxyesters removed are cleaved, if required after addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, and the cleavage products are removed, a cleavage residue remaining, is carried out in such a way that the cleavage residue obtained in step (a) or the cleavage residue obtained in step (b) is hydrolytically cleaved together with the resulting distillation residue in the presence of water and acids or bases.
摘要:
The disclosure is a process for preparing (meth)acrylic esters by reacting (meth)acrylic acid with C4-C6-alkanols in the presence of a strong inorganic acid or of a C4-C6-monoalkyl ester of a polybasic strong acid as catalyst, which comprises removing the unconverted alkanol from the resulting reaction mixture by distillation and thereafter removing the catalyst from the resulting mixture.
摘要:
In a process for esterifying (meth)acrylic acid with an alkanol in the presence of an acidic esterification catalyst, in which unconverted starting compounds and the (meth)acrylates to be formed are separated off by distillation and an oxyester-containing bottom product is formed, the bottom product is separated off and is heated in the presence of an acid to 150-250.degree. C. and the pressure is adjusted so that the cleavage products formed under the abovementioned conditions from the oxyesters contained in the bottom product evaporate directly. The process can be carried out in the presence of molecular oxygen. Mineral acids, for example sulfuric acid or phosphoric acid and/or alkanesulfonic or arylsulfonic acids, for example methanesulfonic acid or p-toluenesulfonic acid, can be added to the bottom product.