WO2006131456A1

WO2006131456A1 - Method for recovering valuable substances from flows when concentrating alcoxy-carbonyl-aminotriazin-containing reaction mixtures

Info

Publication number: WO2006131456A1
Application number: PCT/EP2006/062678
Authority: WO
Inventors: Jörg Schneider; Günter Scherr; Rainer Ehrhardt; Andreas Eichfelder; Martin Reif; Stefan Hirsch; Georg Sieder; Thomas Holtmann; Jürgen CIPRIAN; Hermann Ascherl
Original assignee: Basf Aktiengesellschaft
Priority date: 2005-06-06
Filing date: 2006-05-29
Publication date: 2006-12-14
Also published as: DE102005025898A1

Abstract

The invention relates to a method for recuperating valuable substances form a alkoxy-carbonyl-aminotriazine depleted substance flow during concentrating at least one type of alkoxy-carbonyl-aminotriazine in an alkanolic reaction mixture which results from the a alkoxy-carbonyl-aminotriazine production and contains at least one type of a alkoxy-carbonyl-aminotriazine, at least one type of cyclic and/or acyclic carbonic acid ester, at least one type of C1C13-alcanol optionally provided with two oxygen atoms in the form of an ether bond and optionally C1C4-Alkyl and/or hydroxy substituted and at least one type of alkali or alkaline earth, optionally melamine and optionally a catalyst, wherein said substance flow is distilled at a pressure ranging from 0,5 to 5000 mbar and a substance flow containing at least one type of cyclic and/or acyclic carbonic acid ester is obtained.

Description

Process for the recovery of recyclables from streams resulting from the concentration of alkoxycarbonylaminotriazine-containing reaction mixtures

description

The invention relates to a process for the recovery of recyclables from a stream which, in the concentration of an alkanolic, in the production of Alkoxycarbonylaminotriazinen resulting at least one alkoxycarbonylaminotriazine, at least one cyclic and / or acyclic carbonic acid ester, at least one optionally one or two oxygen atoms as ether bond containing and optionally substituted by CrC ₄ alkyl and / or hydroxy-substituted CrCi ₃ alkanol and at least one alkali or Erdalkalialkanolat, optionally melamine and optionally catalyst-containing reaction mixture is obtained.

The preparation of alkoxycarbonylaminotriazines by reacting triazines, for example melamine, with carbonic acid esters in the presence of a base is known, for example, from EP-A 0 624 577. As a rule, melamine is reacted with a carbonic acid ester in the presence of the alkanol on which the carbonic acid ester is based and in the presence of an alkali alkanolate, based on the alcohol underlying the carbonic acid ester, as the base. For treatment, a mineral acid is added to the reaction mixture for neutralization. Suitable acids are phosphoric acid, sulfuric acid and / or hydrochloric acid. The recovery of the alkoxycarbonylaminotriazine is then carried out by extraction with an organic solvent and evaporation of the solvent. Alternatively, after addition of the acid, a solid is isolated by filtration, which is then washed and dried.

From WO-A 03/035628 a process for the preparation of alkoxycarbonylaminotriazines is known in which the reaction mixture is first neutralized for treatment with a preferably aqueous acid. Suitable acids include nitric acid, sulfuric acid, phosphoric acid or mixtures thereof, but also called formic acid. After the addition of the acid to the reaction mixture, an aqueous and an alkanolic phase are formed which are separated from each other. The alkanolic phase contains the alkoxycarbonylaminotriazine. To increase the concentration of alkoxycarbonylaminotriazine, the organic phase is concentrated after the separation of the aqueous phase. A corresponding process for the preparation of a reaction mixture containing alkoxycarbonylaminotriazine is also disclosed in WO-A 2004/054990.

WO-A 2004/041922 discloses a preparation and preparation process for carbamate-melamine-formaldehyde crosslinkers. The treatment is also carried out by addition of an acid, eg. As sulfuric acid, formic acid, oxalic acid, phosphoric acid, hydrochloric acid or mixtures thereof. The resulting salt in the neutralization is removed by filtration and washing with water.

The object of the present invention is to provide a process for the recovery of valuable substances from a stream which results from the concentration of an alkanolic compound in the preparation of alkoxycarbonylaminotriazines.

The object is achieved by a process for the recovery of valuable substances from an alkoxycarbonylaminotriazine-depleted material stream which comprises at least one alkoxycarbonylaminotriazine in an alkanolic, in the production of Alkoxycarbonylaminotriazinen resulting, at least one alkoxycarbonylaminotriazine, at least one cyclic and / or acyclic carbonic acid ester, at least a optionally one or two oxygen atoms containing as ether bond and optionally substituted by C _r C ₄ alkyl and / or hydroxy-substituted d-Ci ₃ alkanol and at least one alkali or Erdalkalialkanolat, optionally containing melamine and optionally catalyst-containing reaction mixture, wherein the stream at is distilled to a pressure in the range of 0.5 to 5000 mbar, wherein a at least one cyclic and / or acyclic carbonic acid ester-containing material flow is obtained.

Preferred alkoxycarbonylaminotriazines are those of the general formula (I)

in which the symbols and indices have the following meaning:

Y ¹ is hydrogen, -C ₄ alkyl optionally substituted by -C ₄ alkyl, dC ₄ alkoxy or halogen-substituted phenyl or a radical of the formula NR ⁵ R ⁶ and R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each independently hydrogen or a radical of the formula COOX or X or selected from the group (-CH ₂ -O) _I -H, (-CH ₂ - O) _I -R, (-CH ₂ -O) _k -CH ₂ -N (Z) -Q and (-CH ₂ -O) _k -CH ₂ -N (Z) -Q, where

k is 0 to 10, preferably 1 to 5, more preferably 1 or 2 and especially 1 and I is 1 to 10, preferably 1 to 5, more preferably 1 or 2 and in particular 1,

R is selected from the group comprising alkyl, cycloalkyl, and alkylaryl, said groups R preferably contain less than 13 carbon atoms and R is preferably a C _r C ₃ alkyl and more preferably methyl or butyl,

Q is a triazine radical of the general formula (II)

is

X is C ₁ -C ₃ -alkyl whose carbon skeleton may be interrupted by 1 or 2 non-adjacent oxygen atoms in ether function and / or may be substituted by hydroxyl or represents C ₃ -C ₆ -alkenyl and

Z is a radical R ¹ , R ² , R ³ , R ⁴ , R ⁵ or R ⁶ , as defined above

and at least one of R ¹ to R ⁴ , or when Y ^{1 is} NR ⁵ R ⁶ , at least one of R ¹ to R ⁶ COOX.

In this case, dC ₄ -alkyl z. For example, methyl, ethyl, propyl, isopropyl, butyl, sec-butyl or tert-butyl.

Optionally substituted by C 1 -C ₄ alkyl, C 1 -C ₄ alkoxy or halogen-substituted phenyl are, for. As phenyl, 2-, 3- or 4-methylphenyl, 2-, 3- or 4-ethyl phenyl, 2,4-dimethyl-phenyl, 2-, 3- or 4-methoxyphenyl, 2-, 3- or 4 Ethoxyphenyl, 2,4-dimethoxyphenyl, 2-, 3- or 4-fluorophenyl or 2-, 3- or 4-chlorophenyl. Ci-Ci ₃ -alkyl, whose carbon skeleton may be interrupted by 1 or 2 non-adjacent oxygen atoms in ether function and / or substituted by hydroxy, means z. Pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, octyl, 2-ethylhexyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, isotridecyl, 2-methoxyethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 4-methoxybutyl, 2- or 4-ethoxybutyl, 3 , 6-dioxaheptyl, 3,6-dioxaoctyl, 3,7-dioxaoctyl, 4,7-dioxaoctyl, 2- or 3-butoxypropyl, 2- or 4-butoxybutyl, 2-hydroxyethyl, 2- or 3-hydroxypropyl, 2- or 4-hydroxybutyl, 3-hydroxybut-2-yl. (The above designations isooctyl, isononyl, isodecyl and isotridecyl are trivial terms and are derived from the alcohols obtained by the oxo process - see Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A1, pages 290 to 293, and Vol. A10, pages 284 and 285.)

C ₃ -C ₆ alkenyl means z. B. AlIII, methallyl, ethallyl, 2-, 3- or 4-penten-1-yl or 2-, 3-, 4- or 5-hexen-1-yl.

Optionally, one or two non-adjacent oxygen atoms containing as ether bond and optionally by C _r C ₄ alkyl and / or hydroxy-substituted d- Ci ₃ alkanol are, for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert Butanol, pentanol, isopentanol, neopentanol, tert-pentanol, hexanol, 2-methylpentanol, heptanol, octanol, 2-ethylhexanol, isooctanol, nonanol, isononanol, decanol, isodecanol, undecanol, dodecanol, tridecanol, isotri- decanol, 2- Methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 2- or 3-methoxypropanol, 2- or 3-ethoxypropanol, 2- or 3-propoxypropanol, 2- or 4-methoxybutanol, 2- or 4-ethoxybutanol, 3 , 6-dioxaheptanol, 3,6-dioxaoctanol, 3,7-dioxaoctanol, 4,7-dioxaoctanol, 2- or 3-butoxypropanol, 2- or 4-butoxybutanol, ethane-1,2-diol, propane-1,2 -diol, propane-1,3-diol, 3-oxa-5-hydroxypentanol, 3,6-dioxa-8-hydroxyoctanol, 3-oxa-5-hydroxy-2,5-dimethylpentanol or 3,6-dioxa-8 -hydro xy-2,5,8-trimethyloctanol.

Particular preference is given to optionally containing one or two non-adjacent oxygen atoms as ether bond and optionally C 1 -C ₄ -alkyl and / or hydroxy-substituted C 1 -C ₃ -alkanol selected from ethanol, propanol, isopropanol, butanol, isobutanol, sec- Butanol, tert-butanol, pentanol, isopentanol, neopentanol, tert-pentanol, hexanol, 2-methypentanol and heptanol.

Butanol, isobutanol, sec-butanol and tert-butanol are very particularly preferred.

A cyclic carbonic acid ester is a carbonate of the general formula (III)

in the

L is ethylene, 1,2- or 1,3-propylene or 1,2-, 1,4-, 2,3- or 1,3-butylene.

Acyclic carbonic acid esters are z. For example, diaryl carbonate, dialkyl carbonate, arylalkyl carbonate and dialkenyl carbonate. The acyclic carbonic acid ester is preferably selected from carbonates of the general formula (IV)

Z ¹ O-CO-OZ ² (IV)

in the

Each of Z ¹ and Z ² is independently alkyl, cycloalkyl and aryl. Preferably, the radicals Z ¹ and Z ² contain less than 13 carbon atoms. More preferably, Z ¹ and Z ^{2 are} C _r C ₈ alkyl and especially methyl or butyl.

Preferred dialkyl carbonates are dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate and methyl butyl carbonate.

Preferred arylalkyl carbonates are methyl phenyl carbonate or butylphenyl carbonate.

Suitable diaryl carbonates are, for. As diphenyl carbonate, di- (para-tolyl) carbonate, di (α-naphthyl) carbonate or di (ß-naphthyl) carbonate.

A preferred dialkenyl carbonate is diallyl carbonate.

Particularly preferred carbonic acid esters are dimethyl carbonate, diethyl carbonate, dibutyl carbonate, methylbutyl carbonate, diphenyl carbonate, propylene carbonate or mixtures thereof.

Suitable alkali or Erdalkalialkanolate z. As lithium, sodium, potassium, magnesium or calcium salts of the above-specified alkanols. The use of alkali metal methanolates, especially sodium methoxide, is preferred. The alkali metal or alkaline earth metal alkoxide can be used either in solid state or in dissolved or suspended form.

Preferred solvents / diluents in this case are, in particular, the alcohols specified above, alone or as a mixture with one another. It can however, other known and customary inert diluents are also used.

Catalysts which may be included in the reaction mixture are catalysts which are used to prepare the alkoxycarbonylaminotriazine. Such catalysts are z. Phase transfer catalysts such as described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A19, pp. 239-248. Further catalysts may be metal salts or complexes, preferably oxides, chalcogenates, carbonates or halides of the alkali metals, alkaline earth metals or transition metals. Particular mention should be made here of lithium chloride, magnesium chloride or sodium carbonate.

The stream to be treated according to the invention is obtained when concentrating a reaction mixture containing at least one alkoxycarbonylaminotriazine. In addition to the components obtained in the preparation of the at least one alkoxycarbonylaminotriazine, the components to be treated may also contain further components which are introduced into the reaction mixture by means of treatment steps to be carried out concentrating. Thus, for example, it is possible that in the reaction mixture additionally water or a polar extractant from an extraction is included, which is carried out for the removal of ionic or polar components from the reaction mixture.

Furthermore, water can be present in the reprocessed material stream which is supplied to the reaction mixture by neutralization with an aqueous mineral acid, for example nitric acid, sulfuric acid or phosphoric acid, preferably nitric acid.

In the case of a pH adjustment by adding an acid or a base, the corresponding ions of the acid or of the base may also be contained in the reaction mixture. The pH adjustment can be made with any mineral or organic acid if the pH in the reaction mixture is to be lowered. Preferred are organic acids and particularly preferred is formic acid. For example, when using formic acid, H ₃ O ⁺ and formate ions are included in the reaction mixture. If the pH is to be increased, the pH adjustment can be made with any base. Preferred as the base is ammonia water. In the use of ammonia water are respectively NH ₄ ⁺ -, and contain OH ^"ions in the reaction mixture.

Concentration of the reaction mixture comprising at least one alkoxycarbonylaminotriazine can be carried out by thermal or mechanical processes. Suitable thermal processes for concentration are, for example, evaporation, distillation, rectification, drying, preferably spray-drying, or crystallization. Suitable mechanical processes are, in particular, membrane separation processes, for example pervaporation or permeation, and filtration, if the at least one alkoxycarbonylaminotriazine is present as a suspension. The methods for concentration can each be used individually or in combination. It is also possible to use any further suitable method of concentration known to the person skilled in the art. Preferred methods of concentration are distillation and spray drying.

When concentrated by distillation or spray drying, the material stream to be treated according to the invention is obtained as vapor stream.

Recyclables that are to be recovered from the reprocessed material stream, in particular the cyclic and / or acyclic carbonic acid esters. These are removed according to the invention by distillation from the stream. If higher alkanols are contained in the stream, they are separated together with the carbonic acid esters from the stream. For example, when methanol and butanol are contained in the reaction mixture, the butanol is generally separated from the material stream by distillation together with the carbonic acid esters.

The concentration of the organic, alkoxycarbonylaminotriazine-containing phase by distillation can be continuous or discontinuous.

For continuous distillation, it is possible to use conventional continuous evaporators known to the person skilled in the art. Suitable evaporators for continuous distillation are z. B. circulation evaporator, such as Robert self-circulation evaporator, high-speed evaporator with oblique evaporator tubes, forced circulation evaporator with external evaporator bundle, circulation evaporator with chambers divided in chambers or forced circulation evaporator with horizontal radiator. Other suitable continuous evaporators are z. B. falling film evaporator, thin film evaporator or Kestner evaporator.

Furthermore, the concentration of the organic phase can be carried out by distillation in a column. The heating to the evaporation temperature can take place at the bottom of the column or in a heat exchanger located outside the column. Suitable columns are z. B. packed columns, packed columns or tray columns. Suitable packings, fillers or trays are all packs, random packings or trays known to the person skilled in the art. A discontinuous concentration by distillation can, for. B. done in a stirred tank. In this case, the distillation can also be carried out in the container in which the reaction is carried out to Alkoxycarbonylaminotriazin. Preferably, the concentration is carried out by distillation in an additional stirred tank.

In both the continuous and the batch process, the alkoxycarbonylaminotriazine-containing product stream is obtained as the liquid phase and a vapor stream containing at least one alkanol, carbonate and optionally water. When using a polar extractant different from water when carrying out an extraction, the vapor is contained either in the vapor instead of the water or additionally in the polar extractant.

The concentration of the organic, alkoxycarbonylaminotriazine-containing phase by distillation results in a particularly preferred embodiment to a product stream containing 45-60 wt .-% alkoxycarbonylaminotriazine.

Depending on the desired product stream, however, it is also possible to obtain by distillation a product stream which contains a smaller or a larger proportion of alkoxycarbonylaminotriazine.

In a further process variant, it is possible to provide spray drying in addition to concentrating the alkoxycarbonylaminotriazine-containing phase by distillation or instead of concentrating by distillation as a further process step. Spray-drying produces powdery alkoxycarbonylaminotriazine.

The spray drying is preferably carried out in a spray dryer as it is known in the art. Thus, for example, commercially available spray dryers with atomizing disk, single-fluid nozzle or two-fluid nozzle can be used for the spray-drying. The operation can be done depending on the design in DC or in countercurrent. Preference is given to using a two-substance nozzle in which the liquid phase containing at least one alkoxycarbonylaminotriazine is atomized without pressure using a stream of nitrogen. The nitrogen stream in this case has a pressure in the range from 1 to 10 bar, preferably in the range from 2 to 5 bar and particularly preferably in the range from 2.5 to 5 bar. The nitrogen is preferably used as recycle gas.

The spray drying is preferably carried out at a temperature in the range of 50 to 250 ° C, preferably at a temperature of 55 to 150 ° C and more preferably at a temperature in the range of 60 to 100 ⁰ C and at ambient pressure or a Over or under pressure of up to +/- 0.01 MPa, based on the ambient pressure performed.

The powdery product produced during spray-drying can be separated, for example, in a fabric filter of conventional design, such as candle filters, bag filters, bag filters or other filters known to the person skilled in the art, or in a cyclone. As a filter material for a fabric filter is for example polytetrafluoroethylene, silicone or polyester. Preference is given to polyester.

The purification of the nitrogen used as recycle gas is preferably carried out in a scrubber. Any suitable scrubber known to those skilled in the art can be used.

According to the invention, a phase which comprises the cyclic and / or acyclic carbonic acid ester is removed by distillation from the stream of material which is depleted in alkoxycarbonylaminotriazine on the concentration of the alkoxycarbonylaminotriazine. The separation can be carried out continuously or discontinuously.

Before an alkoxycarbonylaminotriazine-depleted material stream depleted in the distillation or spray-drying as a vapor stream is fed to the distillative separation, this can be condensed in a preferred process variant. However, it is also possible to supply the vapor in vapor form to the distillative separation.

If the distillative separation is carried out continuously, this is preferably carried out in a column. Suitable columns are packed columns, packed columns or tray columns. As packages are z. B. ordered packs or knits or knitted fabrics. When using a packed column suitable packing are known in the art and z. B. in Klaus Sattler, thermal separation process, 2nd edition, VCH Verlagsgesellschaft mbH, Weinheim, 1995, pages 226-229 disclosed.

When using a tray column suitable floors are z. B. sieve trays, bubble trays, tunnel trays or crossflow trays.

The stream depleted in alkoxycarbonylaminotriazine can be fed to the column either at the top, in the bottom or via a side feed. Preferably, the vapor stream is fed via a side feed.

As a result of the distillative separation, a substantially water-free mixture of carbonate and alkanol is present at the bottom of the column and a carbonate-free one at the top of the column Mixture of low-boiling alkanols and optionally water and / or polar extractant.

If water and / or polar extractant are present in the substantially carbonate-free mixture withdrawn from the top of the column, an improvement in the alkanol recovery can be achieved by feeding the low-boiling phase withdrawn via the top of the column into a phase separator. In the phase separator, a separation into a substantially alkanol-containing phase and a substantially water and / or polar extraction agent-containing phase takes place. Another advantage of using a phase separator is that the energy requirements for evaporation and condensation are reduced, that the column load is reduced, and further that the carbonate loss is reduced.

The substantially alkanol-containing phase from the phase separator is preferably recycled as reflux into the distillation column. An advantage of the recycling of the alkanolic phase is that the number of separation stages is less than in a column without return from the phase separator and thus the column height can be reduced.

In a further process variant, the stream of alkoxycarbonylaminotriazine-depleted, water and / or polar extraction agent-containing stream - after condensing, when this is obtained in vapor - fed to a phase separator. The phase separator is separated into a substantially organic phase and a phase containing essentially water and / or polar extractant. The essentially organic phase is fed to the distillation column. In the distillation column, a further separation into a carbonate and alkanol-containing bottom product and a low-boiling, alkanol and optionally water and / or polar extractant containing top product.

An advantage over the process variant in which the overhead stream taken from the distillation column is fed to a phase separator is that the amount of feed and the proportion of water and / or the proportion of polar extractant in the feed are greatly reduced and thus a column with a smaller column diameter is used can and the energy requirement is reduced.

Particularly preferred for continuous distillative separation is the process variant in which the power drawn off via the top of the distillation column, water and / or polar extraction agent and low-boiling alkanols containing stream is fed to a phase separator. The reflux ratio in the distillation column is preferably in a range between 0.3 and 2.8 kg / kg. The distillation is preferably carried out in a distillation column with 8 to 18 theoretical plates.

The pressure at which the distillation is carried out is preferably in the range between 0.5 and 2000 mbar, more preferably between 50 and 950 mbar.

In the case of the discontinuous separation by distillation, in contrast to the continuous separation by distillation, no capture of the stream of alkoxycarbonylaminotriazine is carried out, but the individual streams or fractions are distilled off sequentially for concentration. In this case, the distillation column used can be operated as a pure reinforcing column or as a distillation column with reinforcing and stripping section.

If the column is operated as a pure reinforcing column, the feed of the stream depleted in alkoxycarbonylaminotriazine is preferably present as side feed in the bottom of the column. When operating the distillation column as a pure reinforcing column all fractions are withdrawn successively as a distillate. As the first fraction, a mixture of low-boiling alkanol and, if appropriate, water and / or polar extraction agent is taken off as the top product. This mixture is - if water and / or polar extractant is included - separated in a phase separator in an organic and a polar phase. In a preferred embodiment, the organic phase is subsequently fed back to the top of the column. The polar phase is discharged.

As soon as the amount of the polar phase discharged falls below a predetermined value, the distillate is collected in an intermediate container. The water concentration or concentration of polar extractant in the distillate, which is supplied to the intermediate container, is measured. As soon as the concentration of water or polar extractant falls below a predetermined value, the feed to the intermediate container is closed off and the heavy-boiling fraction containing carbonate and high-boiling alkanols is discharged.

If the composition of the distillate stream after separation of the low-boiling fraction already has the required composition, it is of course possible to dispense with the intermediate container and discharge directly the high-boiling fraction. Advantage of the operation of the distillation column as a pure reinforcing column is their low column height. The advantage of operating the distillation column with stripping and enrichment section is the higher recovery rate with respect to the carbonates as well as lower energy consumption and a lower distillation time.

In a preferred embodiment, during operation of the distillation column as a pure reinforcing column, the bottom of the column is passed back into the apparatus, in which the organic phase containing alkoxycarbonylaminotriazine is concentrated by distillation.

The preferred process variant in the batchwise distillative separation is that in which the distillation column is operated as a distillation column with a boosting and stripping section. The advantage of this process variant are the higher recovery rates for carbonates than in the operation of the distillation column as a pure reinforcing column.

In operation of the distillation column as a distillation column with reinforcing and stripping section of the apparatus in which the organic, alkoxycarbonylaminotriazine-containing phase is concentrated by distillation, resulting vapor is fed directly as side feed to a distillation column. Within the distillation column, a separation into a low-boiling and a high-boiling fraction takes place. In the distillative separation, a mixture comprising low-boiling alkanol and water and / or polar extractant is first withdrawn as a top product in a forerun. In a preferred embodiment, the feed in a phase separator is separated into an organic and a polar phase. The organic phase is preferably fed again as a feed line to the top of the distillation column and the polar phase is discharged.

As soon as the withdrawn polar phase falls below a predetermined value, the distillate is collected in an intermediate container. In this case, the distillate, which is collected in the intermediate container, in a preferred embodiment is not passed through a phase separator.

As soon as the concentration of water or polar extractant in the distillate falls below a predetermined value, the feed to the intermediate container is sealed off and the heavy-boiling fraction is discharged from the bottom of the distillation column. A reflux into the apparatus, in which the organic, alkoxycarbonylaminotriazine-containing phase is concentrated, then no longer takes place.

The reflux ratio is preferably in the range between 0 and 15 kg / kg. A preferred distillation column in the distillate separation carried out batchwise has between 4 and 10 theoretical plates. The column is - as in the continuous distillation separation - preferably operated at a pressure in the range of 0.5 to 2000 mbar at the top of the column. Particularly preferably, the pressure is between 50 and 950 mbar.

In a further process variant, the distillative separation of the stream depleted in alkoxycarbonylaminotriazine and the concentration of the organic phase containing alkoxycarbonylaminotriazine can be carried out together in a distillation apparatus. For this purpose, the organic, alkoxycarbonylaminotriazine-containing phase is supplied after removal of the salts formed by the neutralization by extraction and / or by ion exchange of a distillation column. The distillation column preferably comprises a reinforcing part and an output part. The feed of the organic, alkoxycarbonylaminotriazine-containing phase is preferably carried out via a side feed.

At the bottom of the distillation column, the concentrated, organic, alkoxycarbonylaminotriazine-containing phase is recovered.

In a preferred embodiment, the bottom product thus obtained is used in a heat exchanger for heating the desalted organic phase, which is fed to the distillation column as feed.

About the top of the distillation column alkanols, optionally low boilers and water and / or polar extractant are withdrawn. In a particularly preferred embodiment, this stream is subsequently fed to a phase separator in which the polar phase is separated from the organic phase. The organic phase is preferably recycled as reflux to the distillation column at its top.

In a particularly preferred embodiment, the distillation column comprises a side take-off, preferably arranged in the stripping section, via which a stream which is preferably vaporous and substantially water-free, comprising carbonate and alkanol, is withdrawn. A particularly preferred position of the side draw is directly above the bottom of the column or directly below the separating internals in the column.

Advantages of this mode of operation lie in the recovery of a large part of the carbonates via side take-off for reuse in the reaction, the reduction of the car- bon. Bonatgehaltes in the product stream and in the recovery of anhydrous high-boiling alkanols, eg n-butanol, on the side offtake.

In a preferred embodiment, the distillation column comprises 8 to 22 theoretical separating stages.

The reflux ratio of the organic phase at the top of the column is preferably in the range between 0.2 and 3 kg / kg.

Also in the embodiment in which the distillation column is directly downstream of the extraction or the ion exchange, the column is preferably operated at a pressure in the range between 20 and 2000 mbar at the top of the column. The preferred range in which the column is operated is between 50 and 950 mbar.

For the separation of possibly still containing salts, the alkoxycarbonylami- notriazine-containing phase after the distillation can be supplied to an ion exchange.

Examples

example 1

In a valve plate column with 22 plates, a diameter of 300 mm, a height of 11 m and a top pressure of 300 mbar 77 kg / h of vapor solution from the distillative concentration of an organic alkoxycarbonylaminotriazine containing phase separated. The power supplied to the valve tray column Brüdenlösung has a temperature of 30 ⁰ C and containing 68.5% n-butanol, 28.89% water, 1, 38% methanol, 0.44% of dibutyl carbonate and 0.4% methyl butyl. The distillation in the valve plate column gives a bottom product with less than 100 ppm water and a top product with less than 100 ppm carbonate. The reflux ratio is 1, 4 kg / kg. The distillation was carried out at a bottom temperature of 88 ° C and a return temperature of 62 ° C. From the valve plate column, a bottoms stream of 27.9 kg / h with a composition of 97.57% n-butanol, less than 100 ppm water, less than 100 ppm methanol, 1.21% dibutyl carbonate and 1, 21% methylbutyl carbonate withdrawn. Furthermore, a top stream of 49.1 kg / h with a composition of 52.24% n-butanol, <45.40% water, <2.17% methanol, <100 ppm dibutyl carbonate and <100 ppm methylbutyl carbonate is withdrawn from the column , Example 2

The apparatus of Example 1 is supplemented by a phase separator in the return. Also, instead of the valve tray column with 22 trays a valve tray column with 16 trays, a diameter of 300 mm and a height of 8.5 m is used. The valve tray column is operated at a top pressure of 300 mbar. The column will be 150.1 kg / h Brüdenlösung from the distillative on concentration of an organic phase containing alkoxycarbonylaminotriazine fed at a temperature of 30 ⁰ C tur. The vapor solution is composed of 68.5% n-butanol, 28.89% water, 1.38% methanol, 0.44% dibutyl carbonate and 0.44% methylbutyl carbonate. By distillative separation in the valve tray column a bottom product with less than 100 ppm of water and a top product is obtained with less than 100 ppm of carbonate. The reflux ratio is 1.4 kg / kg. The bottom temperature at which the distillative separation is carried out, is 88 ° C and the return temperature 62 ° C. 101.5 kg / h bottoms stream having a composition of 98.69% n-butanol, 0.65% dibutyl carbonate, 0.65% methylbutyl carbonate and <100 ppm water and <100 ppm methanol are withdrawn from the valve plate column. Furthermore, a top stream of 48.6 kg / h is withdrawn with a composition of 6.44% n-butanol, <89.3% water, <4.27% methanol, <100 ppm dibutyl carbonate and <100 ppm methyl butyl carbonate.

Example 3

In addition to the apparatus of Example 1, a phase separator is added in the feed to the valve plate column. Instead of the valve tray column with 22 trays according to Example 1, a valve tray column with 20 trays, a diameter of 300 mm and a height of 10 m is used. 233.5 kg / h of vapor solution from the distillative concentration of an organic, alkoxycarbonylaminotriazine-containing phase are fed to the phase separator, the vapor solution being 68.5% of n-butanol, 28.89% of water, 1.38% of methanol, 0 , 44% dibutyl carbonate and 0.44% methyl butyl carbonate. In the phase separator an aqueous phase is separated from the vapor solution, the organic phase is fed to the valve plate column. The distillative separation in the valve bottom column results in a bottom product with less than 100 ppm of water and a top product with less than 100 ppm of carbonate. The reflux ratio is 1, 7 kg / kg. The bottom temperature in the column is 88 ° C, the return temperature 62 ° C. 135.1 kg / h bottoms stream having a composition of 98.5% n-butanol, 0.7540% dibutyl carbonate, 0.7393% methyl butyl carbonate, less than 100 ppm water and less than 100 ppm methanol are withdrawn from the valve plate column. Continue to be 49.8 kg / h overhead stream with a composition of 51.12% n-butanol, <44.59% water, <4.29% methanol, <100 ppm dibutyl carbonate and <100 ppm methyl butyl carbonate withdrawn. The overhead stream is then combined with the aqueous phase from the phase separator. After combining the overhead stream with the aqueous phase from the phase separator, the stream is composed of 28.0738% butanol, 68.63% water, 3.28% methanol, 0.02% methylbutyl carbonate and <100 ppm dibutyl carbonate.

Example 4

On a reaction vessel, in which the production of alkoxycarbonylaminotriazines NEN, a valve tray column with 10 valve trays, a diameter of 250 mm and a height of 5 m is placed. The head pressure in the valve tray column is 300 mbar. In the reaction vessel 1327.4 kg of a reaction mixture having a composition of 62.29% n-butanol, 21, 86% water, 1.07% methanol, 2.34% dibutyl carbonate, 0.43% methylbutyl carbonate and 21.01% Alkoxycarbonylami - notriazine submitted. Subsequently, the reaction vessel is heated to a temperature of 88 ° C. The resulting vapor is fed to the attached valve tray column. At the top of the valve plate column, a mixture of methanol and n-butanol / water is first withdrawn and separated by means of a phase separator into an organic and an aqueous phase. The organic phase is added as a feed back to the column. The aqueous phase is discharged. The aqueous phase is composed of 89.09% water, 4.4% methanol and 6.52% n-butanol. After the aqueous phase separated from the phase separator falls below a mass flow of 5 kg / h, which was reached after 11 h, the distillate is collected in an intermediate container without passing it through the phase separator. The distillate collected in the intermediate tank contains 4.19% water, 0.02% methanol, 95.74% butanol and 0.06% butylmethyl carbonate. The reflux ratio is 10 kg / kg. After falling below the H ₂ O concentration in the distillate of 100 ppm after about 6 h in the intermediate run is switched from intermediate to main run and the carbonate-containing butanol with a reflux ratio of 0.1 kg / kg recovered. The high boilers thus obtained are composed of 99.12% n-butanol, 0.36% dibutyl carbonate, 0.52% butylmethyl carbonate. The distillation in the reaction vessel is stopped by monitoring the temperature in the reaction vessel in the presence of a product solution containing 50% alkoxycarbonylaminotriazine. The recovery rates are 70.7% for butanol, 6.8% for dibutyl carbonate and 54.1% for butyl methyl carbonate. The concentration of further components possibly contained in the individual material streams are each less than 0.01%. Example 5

On a reaction vessel, a valve tray column with 15 valve plates, a height of about 7.5 m and a diameter of 180 mm is placed. The valve tray column is operated at a top pressure of 300 mbar. In the reaction vessel 663.7 kg of reaction mixture are presented at a temperature of 30 ⁰ C. The reaction mixture is composed of 62.29% n-butanol, 21, 86% water, 1.07% methanol, 2.34% dibutyl carbonate, 0.43% methylbutyl carbonate and 12.01% alkoxycarbonylaminotriazine. The reaction mixture introduced in the reaction vessel is heated. In a forerun, first a mixture of methanol and n-butanol / water is taken off as top product and separated by means of a phase separator into an organic and an aqueous phase. The organic phase is added as a feed back to the column. The aqueous phase is discharged. The aqueous phase is composed of 89.09% water, 4.41% methanol and 6.50% n-butanol. After 12.5 h, the withdrawn aqueous phase falls below a mass flow of 5 kg / h. From this point on, the distillate is collected in an intermediate container without passing it through the phase separator. The reflux ratio is 10 kg / kg. After the H ₂ O concentration in the distillate falls below 100 ppm, the carbonate-containing butanol solution from the bottom of the valve plate column is no longer returned to the reaction vessel, but discharged. The distillative separation is terminated as soon as the concentration of alkoxycarbonylaminotriazine in the reaction vessel is 50%. While the carbonate-containing butanol solution is discharged, the reflux ratio is 0.1 kg / kg. The discharged carbonate-containing butanol solution is composed of 98.47% n-butanol, 0.96% dibutyl carbonate and 0.57% butyl methyl carbonate. The distillate runs until the end of the distillation time in the intermediate container. The distillate collected in the intermediate tank is composed of 4.49% water, 0.03% methanol, 95.42% n-butanol and 0.06% butyl methyl carbonate. The distillation is stopped by monitoring the temperature in the reaction vessel as soon as the alkoxycarbonylaminotriazine concentration in the reaction vessel is 50%. The recovery rates are 68.3% for butanol, 17.7% for dibutyl carbonate and 57.8% for butyl methyl carbonate. Concentrations of other substances that occur in the individual material streams are each less than 0.01%.

Example 6

1000 g / h of washed reaction mixture were concentrated in a column with a diameter of 0.05 m and a height of 1.5 m. The column comprised a 0.5 m long reinforcement section filled with Rombopak 9M and a split stripping section with 0.5 m Rombopak 9M and 10 bubble trays. The column was with operated at a top pressure of 110 mbar and a bottom pressure of 130 mbar. The refined reaction mixture had a composition of 7.3% nonvolatiles (di- and tri-alkoxycarbonylaminotriazines), 74% n-butanol, 15.4% water, 1.6% methanol, 1.2% dibutyl carbonate, 0.5 % Butyl methyl carbonate and <0.1% dimethyl carbonate. The distillate stream was separated in a phase separator into an aqueous and an organic phase. The reflux ratio of the organic phase was 0.45 kg / kg. From the column was a bottom stream 165 g / h with 48.8% nfA, 47.0% n-butanol, 0.02% water, 0.0% methanol, 7.3% dibutyl carbonate, 0.1% methyl-butyl carbonate and <0.1% dimethyl carbonate subtracted. At the top of the column, an organic distillate stream of 816 g / h with 0.0% nfA, 78.0% n-butanol, 20.6% water, 0.8% methanol, <0.1% dibutyl carbonate, 0.5% Methyl butyl carbonate, <0.1% dimethyl carbonate. Furthermore, an aqueous overhead stream of 17 g / h with 0.0% nfA, 7.3% n-butanol, 90.9% water, 1.8% methanol, <0.1% dibutyl carbonate, <0.1% Me - Thylbutylcarbonat and <0.1% dimethyl carbonate withdrawn. Other substances that occur in the individual streams had a concentration below 0.01%.

Example 7

A column having an upper packing area with a diameter of 900 mm and a lower area with a diameter of 1200 mm, a height of the upper packing area of 16.5 m and a height of the lower area of about 7 m and a total height of about 24 m is operated with 1400 kg / h of neutralized and washed reaction mixture. In the upper packing area are

High-performance metal packing with a specific surface area of approx. 150 m ^{2 /} m ³ . In the lower area there are 4 valve bottoms to break through

Avoid water due to maldistribution or marginalities in the pack in the product.

The column is operated with a top pressure of about 110 mbar and a bottom pressure of about 130 mbar. The washed reaction mixture is at the level of the 8.

Stage supplied with a temperature of 30 ⁰ C. The reaction mixture contains 6.2% nfA, 71.7% n-butanol, 17.0% water, 2.2% methanol, 1, 35% dibutyl carbonate, 1.3%

Butyl methyl carbonate and 0.25% dimethyl carbonate. At the top of a distillate stream is withdrawn, which is separated by a phase separator in an aqueous and an organic phase. The reflux ratio of the organic phase is 0.46 kg / kg. From the column, a bottom stream of 212 kg / h with a composition of 41, 0% nfA, 42.7% n-butanol, 8.9% dibutyl carbonate and 7.4% methylbutyl carbonate withdrawn. The organic distillate stream, which is withdrawn at the top of the column is 1070 kg / h and has a composition of 0.0% nfA, 84.7% n-butanol, 12.4% water, 2.3% methanol, 0, 24% methyl butyl carbonate and 0.32% dimethyl carbonate. nat. The aqueous distillate stream separated in the phase separator is 114 kg / h and has a composition of 0.0% nfA, 4.9% n-butanol, 90.8% water, 4.3% methanol 0.02%, methylbutyl carbonate and 0, 03% dimethyl carbonate. Other substances contained in the individual streams have a concentration below 0.01%. The temperature in the column is in the range between 55 ° C and 80 ° C.

Example 8

A plant whose construction corresponds to the plant in Example 6 but which additionally has a side draw and a condenser below the first bubble tray was operated with 800 g / h of refined reaction mixture. The reaction mixture was added to the column at a temperature of 30 ^° C. and a composition of 7.2% nfA, 72% n-butanol, 17.3% water, 1.4% methanol, 1.1% dibutyl carbonate, 0.4%. Butylmethylcarbonat and <0.1% dimethyl carbonate fed. The distillate stream withdrawn at the top of the column was separated in a phase separator into an aqueous and an organic phase. The reflux ratio of the organic phase was 0.50 kg / kg. From the column a bottom stream of 120 g / h with a composition of 55.3% nfA, 47.0% n-butanol, 0.015% water, 0.0% methanol, 4.8% dibutyl carbonate, 0.2% methylbutyl carbonate and <0.1% of dimethyl carbonate. The phase separator gave an organic distillate stream of 200 g / h with a composition of 0.0% nfA, 78.0% n-butanol, 21.7% water, 1.9% methanol, <0.1% dibutyl carbonate, 1 , 0% methylbutyl carbonate and <0.1% dimethyl carbonate. Furthermore, an aqueous distillate stream of 104 g / h with a composition of 0.0% nfA, 8.0% n-butanol, 90.6% water, 3.0% methanol, <0.1% dibutyl carbonate, <0.1% methylbutyl carbonate and <0.1% dimethyl carbonate. 370 g / h of essentially anhydrous carbonate-containing butanol solution were withdrawn via the side draw. The composition of the butanol solution was 0.0% nfA, 99.0% n-butanol, 0.023% water, <0.1% methanol, 1.1% dibutyl carbonate, 0.4% methylbutyl carbonate and <0.1% dimethyl carbonate. Other components present in the individual streams have a concentration below 0.01%.

Example 9

A system is operated in accordance with that of Example 7, but below the first bubble tray a side take-off and a condenser are arranged. The column differs from that of Example 7 in that the upper Füllkörperbereich has a height of 13.5 m, the lower column area has a height of about 7 m and the total height of the column is about 20 m. The reaction mixture is fed at the level of the 8th stage via a side inlet of the column. The column is at a top pressure of about 90 mbar and a bottom pressure of about 130 mbar operated. The column is 1400 kg / h of washed reaction mixture having a temperature of 30 ° C and a composition of 7.2% nfA, 72.6% n-butanol, 17.3% water, 1.4% methanol, 1, 1% Dibutyl carbonate, 0.4% butylmethyl carbonate and 0.1% dimethyl carbonate. The withdrawn at the top of the column distillate stream is separated in a phase separator in an aqueous and an organic phase. The reflux ratio of the organic phase in the column is 0.50 kg / kg. From the column, a bottoms stream of 210 kg / h with a composition of 48.0% nfA, 46.4% n-butanol, 4.9% dibutyl carbonate and 0.7% methyl butyl carbonate withdrawn. The distillate stream withdrawn from the phase separator is 314 kg / h and has a composition of 0.0% nfA, 84.5% n-butanol, 12.4% water, 2.6% methanol, 0.06% methylbutyl carbonate and 0.41% dimethyl carbonate. Furthermore, 225 kg / h aqueous distillate stream having a composition of 0.0% nfA, 4.9% n-butanol, 90.2% water, 4.9% methanol and <0.04% dimethyl carbonate are removed via the phase separator. About the side offtake of the column 650 kg / h are withdrawn substantially anhydrous, carbonate-containing butanol solution. The composition of the butanol solution is 0.0% nfA, 98.6% n-butanol, 0.8% dibutyl carbonate and 0.6% methylbutyl carbonate. Other substances that occur in the individual streams have a concentration below 0.01%. The column is operated at a temperature in the range between 47 ° C and 78 ° C.

Non-ascending balances in the above examples are generally caused by measurement inaccuracies.

Claims

claims

1. A process for the recovery of valuable substances from an alkoxycarbonyl aminotriazine-depleted stream comprising at least one alkoxycarbonylaminotriazine in an alkanolic at least one alkoxycarbonylaminotriazine obtained in the preparation of alkoxycarbonylaminotriazines, at least one cyclic and / or acyclic carbonic acid ester in the concentration of at least one alkoxycarbonylaminotriazine , at least one optionally containing one or two oxygen atoms as ether bond and optionally C 1 -C ₄ -alkyl and / or hydroxy-substituted CrCi ₃ alkanol and at least one alkali metal or Erdalka- lialkanolat, optionally melamine and optionally containing catalyst containing reaction mixture, wherein the stream is distilled at a pressure in the range of 0.5 to 5000 mbar, whereby a stream containing at least one cyclic and / or acyclic carbonic acid ester is obtained.

2. The method according to claim 1, characterized in that the distillation is carried out at a pressure in the range of 0.5 to 2000 mbar, preferably from 50 to 950 mbar.

3. The method according to claim 1 or 2, characterized in that the distillation is carried out in a distillation column.

4. The method according to claim 3, characterized in that the column is a packed column, a packed column or a tray column.

5. The method according to claim 3 or 4, characterized in that the distillation column has 8 to 18 theoretical plates.

6. The method according to any one of claims 3 to 5, characterized in that the alkoxycarbonylaminotriazine depleted material stream of the distillation column is fed as a side feed and the at least one cyclic or acyclic carbonic acid ester-containing stream is obtained as bottom draw stream.

7. The method according to any one of claims 1 to 6, characterized in that the depleted alkoxycarbonylaminotriazine material stream is first supplied to a phase senscheider in which a separation into a polar and an organic phase is carried out, and then the organic, the at least one cyclic or acyclic carbonic ester containing phase is fed to the distillation.

8. The method according to any one of claims 1 to 7, characterized in that the overhead obtained in the distillation overhead stream is fed to a phase separator, in which a separation in an organic and a polar, water and / or polar extractant-containing phase is performed.

9. The method according to claim 8, characterized in that the organic phase is recycled to the distillation.

10. The method according to any one of claims 1 to 9, characterized in that a substantially anhydrous, carbonate and alkanol-containing stream is withdrawn as a side draw from the column.

11. The method according to claim 10, characterized in that the withdrawn as a side draw, essentially anhydrous, containing carbonate and alkanol

Stream vapor is taken in the stripping section of the column.

12. The method according to claim 10 or 11, characterized in that the substantially water-free, carbonate and alkanol-containing stream is taken as a side draw vapor directly above the bottom of the column.

13. The method according to any one of claims 1 to 12, characterized in that the depleted in alkoxycarbonylaminotriazine material stream is obtained at a concentration by distillation or spray drying as vapor stream.

14. The method according to claim 13, characterized in that the vapor stream is condensed before it is fed to the separation by distillation.

15. The method according to any one of claims 1 to 14, characterized in that the resulting in the distillation bottoms stream is recycled to the apparatus in which the organic, alkoxycarbonylaminotriazine-containing phase is concentrated.

16. The method according to claim 1, characterized in that the concentration of alkoxycarbonylaminotriazine and the recovery of the valuable substances are carried out in a distillation column.

17. The method according to claim 16, characterized in that the at least one Alkoxycarbonylaminotriazin containing reaction mixture is fed as a side feed to the distillation column and a concentrated, organic, Alko- xycarbonylaminotriazine-containing phase at the bottom and the at least one cyclic or acyclic carbonic acid ester-containing stream as a side take-off of the distillation column incurred.