摘要:
The invention relates to a process for the selective liquid-phase hydrogenation of .alpha.,.beta.-unsaturated carbonyl compounds of the formula I, ##STR1## where R.sub.1 is hydrogen or an organic radical, and R.sub.2, R.sub.3 and R.sub.4, independently of one another, are hydrogen or a C.sub.1 -- to C.sub.4 --alkyl group, to saturated carbonyl compounds of the formula II ##STR2## using hydrogen in the presence of a pulverulent palladium and/or rhodium catalyst and in the presence of an organic base. The process is carried out in a packed bubble column reactor (1, 2) with product recycling (11, 17) and circulating hydrogen gas (4, 15, 16). It is particularly suitable for the selective hydrogenation of citral to citronellal.
摘要:
In a process for carrying out an exothermal reaction, selected from the addition reaction of organomagnesium halide compounds to carbonyl compounds and the ensuing hydrolysis of the addition product, a considerable fraction of the heat liberated during the reaction is removed by evaporation of the solvent.
摘要:
In a distillation column for separating a liquid mixture into a plurality of pure fractions, the distillation column being divided into 2 parts, a feed part and a take-off part, in its middle region by a separation effective in the longitudinal direction, the separation consists of two walls with a gas space in between, the distance between the two walls being from 1 to 50 mm, preferably from 3 to 10 mm.
摘要:
A process is proposed for the separation of C5+ cuts by distillation into a low-boiler (A), a medium-boiler (B) and a high-boiler fraction (C) in one or more dividing-wall columns (TK), in which a dividing wall (T) is arranged in the longitudinal direction of the column with formation of an upper, common column region (1), a lower, common column region (6), a feed part (2, 4) with rectifying section (2) and stripping section (4), and a withdrawal part (3, 5) with rectifying section (5) and stripping section (3), with feed of the C5+ cut (A, B, C) into the central region of the feed part (2, 4), discharge of the high-boiler fraction (C) from the bottom of the column, discharge of the low-boiler fraction (A) via the top of the column, and discharge of the medium-boiler fraction (B) from the central region of the withdrawal part (3, 5), wherein the dividing ratio of the liquid reflux at the upper end of the dividing wall (T) is set in such a way that the proportion of high-boiling key components in the liquid reflux over the stripping section (3) of the withdrawal part at the upper end of the dividing wall (T) is from 10 to 80%, preferably from 30 to 50%, of the limit value allowed in the medium-boiler fraction (B), and wherein the heating power in the evaporator at the bottom of the dividing-wall column (TK) is set in such a way that the concentration of the low-boiling key components in the liquid at the lower end of the dividing wall (T) is from 10 to 80%, preferably from 30 to 50%, of the limit value allowed in the medium-boiler fraction (B).
摘要:
An &agr;,&bgr;-unsaturated carbonyl compound of formula (I) where R1 is saturated C1-40-hydrocarbyl or a substituted or unsubstituted aromatic radical containing moiety, and R2, R3 and R4, independently of one another, are hydrogen or a C1- to C4-alkyl group, is selectively hydrogenated in the liquid phase to a saturated carbonyl compound of formula (II) with hydrogen in the presence of a pulverulent palladium and/or rhodium catalyst and in the presence of an organic base, by conducting the hydrogenation in a packed bubble column reactor in which product is recycled and hydrogen gas is recirculated.
摘要:
An improved process for preparing lower unsaturated ketones by reacting the corresponding &agr;,&bgr;-unsaturated alcohols with alkyl acetoacetates in a Carroll reaction in the presence of from 0.1 to 5 mol %, based on the alkyl acetoacetate to be reacted, of an organic aluminum compound as catalyst with elimination and continuous removal by distillation of the alkanol eliminated during the reaction from the alkyl acetoacetate in a reactor system with a fitted fractionation column, wherein A an &agr;,&bgr;-unsaturated alcohol which boils below 140° C. is introduced, in the absence of effective amounts of a solvent, together with the organic aluminum compound into the reaction vessel, B a reaction temperature which is as constant as possible between 170° C. and 250° C. is set under elevated pressure, C at this temperature, the alkyl acetoacetate is metered into the mixture, obtained in A, of the &agr;,&bgr;-unsaturated alcohol and the organic aluminum compound, and D during the reaction the content of alkyl acetoacetate in the reaction mixture is set at a value which is as constant as possible between 0.1 and 10% by weight.
摘要:
A process for producing solids by precipitation in a mixer to form a mixture of solid and liquid, where the starting materials are fed into a mixing apparatus which has essentially a rotationally symmetrical mixing chamber which has a rotor disposed therein and is formed by a peripheral wall and two end walls, and where a) the starting materials are each fed to at least one inlet opening in the peripheral wall of the mixing chamber, and b) the solid-containing mixture which is formed is removed from at least one outlet opening in the peripheral wall of the mixing chamber.
摘要:
Alkenes are prepared by partial hydrogenation of alkynes in the liquid phase over palladium catalysts by a process which comprises A. using a fixed-bed catalyst which is obtainable by heating the preferably metallic carrier in the air, cooling, coating under reduced pressure with metallic palladium, suitable molding and processing to a monolithic catalyst elements and B. adding from 10 to 180 ppm of CO to the hydrogen used for the hydrogenation.
摘要:
Process for the continuous preparation of &agr;- and/or &bgr;-ionone or homologous compounds using concentrated sulfuric acid at temperatures from 20 to 90° C., in the presence of organic solvents or diluents with cooling and by subsequent termination of the reaction by hydrolysis of the reaction mixture with water or dilute sulfuric acid, wherein both the cyclization of pseudoionones and the subsequent hydrolysis of the reaction mixture are carried out in a virtually adiabatic reaction in one or more reaction mixing pump(s) which are connected in series and each of which consists essentially of a rotationally symmetrical mixing chamber formed from a peripheral wall and two end walls and of a mixing rotor made of material inert to sulfuric acid and with rotational drive, where the mixing chamber has at least one inlet opening for each component and one outlet opening for the reaction mixture, and annular channels in fluid connection to one another in the end walls, and wherein the heat of the two reactions is in each case partly or wholly removed with the aid of a downstream heat exchanger.
摘要:
A process for preparing .gamma.,.delta.-unsaturated ketones of the general formula I ##STR1## by reacting an allyl alcohol of the general formula II ##STR2## in which R.sup.1 is H or a hydrocarbon radical having 1 to 20 carbon atoms, with diketene or an alkyl acetoacetate of the general formula III ##STR3## in which R.sup.2 is alkyl having 1 to 4 carbon atoms in an unmodified or modified Carroll reaction in the presence of an aluminum catalyst, wherein aluminum compounds which are stable liquids at room temperature, or a mixture of such aluminum compounds, which comprise at least one radical formed from an alkyl acetoacetate and 1 or 2 alkoxy radicals, or else comprise exclusively radicals formed from alkyl acetoacetates, which are esterified with sec-butanol or isobutanol, or else are esterified with at least two different alcohols, are used as aluminum catalyst. Also claimed are the novel mixtures of aluminum compounds which comprise radicals which are formed exclusively from alkyl acetoacetates and are esterified with at least two different alkanols, and the batchwise and continuous preparation of the liquid aluminum catalysts.