Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
  • C07C319/14—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C319/00—Preparation of thiols, sulfides, hydropolysulfides or polysulfides
  • C07C319/14—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides
  • C07C319/20—Preparation of thiols, sulfides, hydropolysulfides or polysulfides of sulfides by reactions not involving the formation of sulfide groups

Definitions

• the present invention comprises a process which can preferably be carried out continuously and which is suitable for the large-scale production of aqueous alkali metal or
• Alkaline earth methioninate solutions is suitable, which directly z. B. used as a feed additive or
• Amino acids or their salts can be used.
• the method is particularly suitable for the production of methioninate solution.
• Substitutes such as methionine hydroxy analog (MHA) are used worldwide as a feed additive for the MHA.
• Methionine as one of the first limiting amino acids in the animal growth process and its various
• the commercially available sodium methioninate solution has a concentration of 40% by weight methionine and, in contrast to the substitute MHA, corresponds to the solid methionine in terms of its biological value, compared on an equimolar basis.
• the excess of saponification agent (DE 31 05 006 C) can be separated off in the form of calcium carbonate, but must be disposed of as waste salt which is hardly usable or must be returned to the reusable hydroxide form by complex additional steps such as burning and quenching.
• sodium hydroxide solution is used alone, the excess must either (DE 31 04 997 A) in the form of the sodium carbonate formed or (EP 2S3 740) after neutralization of the sodium carbonate with sulfuric acid in the form of the sodium sulfate then formed.
• the accumulation of salt, as well as the elaborate salt separation, but also the risk of undesired salt residues remaining in the product solution form the disadvantages of these procedures.
• Methioninamide can be prepared in a known manner by hydrolysis of methiononitrile, which in turn can be obtained by direct synthesis from the usual starting materials methyl mercaptopropionaldehyde (MMP), hydrocyanic acid or ammonium cyanide and ammonia.
• MMP methyl mercaptopropionaldehyde
• hydrocyanic acid or ammonium cyanide ammonia.
• MMP and HCN are first formed in a customary manner from MMP and HCN in a 500 ml pressure vessel and this is converted to methionine nitrile by subsequently introducing an excess of condensed NH 3 . After relaxing and cooling from 60 ° C to 10 ° C, this (cf.
• the object is therefore a process for the preparation of methionine or its salt or precursors such as methionine nitrile or amide, the process starting directly from the basic chemicals already mentioned and to be able to be carried out on an industrial scale even without isolating the intermediate stages.
• the process should be economical and, in particular, be able to be carried out continuously, the excess ammonia and the ketone used being to be recovered and reused as largely as possible without loss.
• the process which can preferably be carried out continuously or partly continuously, but also batchwise, comprises a total of 5 or 6 main process steps:
• Crude methioninate solution such as B. post-reaction, cleaning step or evaporation to the desired final concentration.
• the Tiemann variant has the advantage in the present case that the relatively high heat of reaction of the cyanohydrin formation can initially be intercepted. This enables a more precise setting of the reaction temperature of the subsequent likewise exothermic aminonitrile formation, in particular in the case of a continuous procedure.
• MMP-cyanohydrin is formed spontaneously from MMP and liquid or gaseous hydrocyanic acid at pH 5-9 and temperatures up to 50 ° C, but is preferably carried out at pH 5.5 - 7.5 and temperatures between 20 and 30 ° C. If necessary, the pH value is kept in the target range by adding small amounts of base.
• organic bases such as amine compounds, for example triethylamine or pyridine
• inorganic bases such as alkali or alkaline earth metal hydroxides or cyanides, such as NaOH or NaCN, in particular in the form of their aqueous solutions.
• the reactants should be used approximately equi olar. An excess of aldehyde should be avoided if possible, since it leads to by-products and degradation products in the subsequent reaction stages or in the end product.
• the MMP-CH production can be carried out from MMP and gaseous or liquid hydrocyanic acid both in batches, for example in a stirred tank, and particularly advantageously continuously in a tube or loop reactor or in a combination of both in the manner explained above.
• the thorough mixing of the reactants with simultaneous pH and temperature control are prerequisites for an optimal implementation of this process step.
• the yields detected using customary analysis methods, such as HPLC or TLC, were 99.9 7.
• the crude MMP-cyanohydrin obtained can, just as in approximately equimolar mixtures of MMP and HCN, or any mixture of crude MMP-cyanohydrin and MMP / HCN, such as, for example, in the case of incompletely formed
• MMP-CH is formed in the cyanohydrin stage, is reacted with ammonia or ammonia / water mixtures to give the crude MMP aminonitrile.
• DE-OS 20 06 979 teaches a process which is identical in the essential conditions, but which is carried out in continuously operated stirred tanks, the focus of this invention being on the partial recycling of a NH 3 -rich and still AN-containing water phase obtained after phase separation on the crude aminonitrile lies in the reaction vessel. This is to reduce the amount of salt in the subsequent acid saponification.
• the partial recycling of the product already formed severely limits the economic value of this procedure, in particular to the acid saponification sought there.
• the DN + DNMA portion assumes a justifiable small value of ⁇ 2 mol 7. of the Cya ⁇ hydrins used with AN yields of> 98 mol ', in each case with respect to the converted aldehyde, if one with a molar ratio of NH 3 / CH or NH3 / aldehyde of at least 4: 1, in particular 5: 1 to 15: 1 and used NH 3 concentrations of> 50% by weight -7., Advantageously 55-85% by weight -7. and in particular over a molar ratio NH 3 / H 2 0 of 1.5, at temperatures above 40 ° C but not above 80 ° C and at reaction times of at least 5 but not over 60 min.
• the reaction is preferably ended at the latest when 2 7. d. Th. (Mol-7. Or MMP + CH) to DN + DNMA, otherwise the DS content in the end product will be too high.
• the reaction is carried out within the limits so that the DN + DNMA content is as low as possible.
• a preferred embodiment of the present The process step is the use of 5-8 eq NH 3 with a concentration of 55-85% by weight, in particular 60-80% by weight -7. in the temperature range between 50 and 70 ° C with reaction times of 10 to 50 min and the resulting system pressure. Within this range, the DN + DNMA content can even be reduced to ⁇ 1 mol 7.
• the conditions selected here enable continuous operation with yields above 96 7. which is essential for large-scale production.
• a pure tubular reactor or a combination of loop and tubular reactor can be used for the process, the tubular reactor should have a multiple of the residence time of the loop reactor, since the dinitrile formation can thereby be kept smaller.
• the process described here is also characterized in that, instead of fresh ammonia / water, the ammonia recovered from the later recycling stages or corresponding ammonia / water mixtures can be used.
• Crude aminonitrile / water / ammonia mixtures can either be used directly for the subsequent hydrolysis or after decompression to normal pressure or a pressure which is between the system pressure prevailing in the aminonitrile stage and normal pressure. When the pressure is released, part of the excess NH 3 can be recovered from the amino nitrile stage at this point.
• Aminonitrile hydrolysis methioninamide formation:
• the imidazolidinones are also converted into methionine in the subsequent saponification at a higher temperature, but the IM1 and MMP content in particular lead to losses in the final yield and possibly to purity problems.
• the aldehyde regression and the IM1 formation can be significantly reduced by keeping the temperature and the alkali content low, thereby increasing the selectivity of the overall reaction sequence.
• a process as described in patent DE 27 53 829 for the production of ⁇ -amino acids in which the entire amount of alkali required for aminonitrile saponification, i.e. essentially 1 eq hydroxide, is already added to the crude aminonitrile mixture and the saponification is carried out in one step in the present case to rather worse results.
• the hydrolysis of crude aminonitrile can be carried out both batchwise and preferably continuously, in the first case z. B. ß in a stirred reaction.
• a simple reaction tube but better a loop reactor, in particular a combination of a loop reactor and reaction tube, can be used.
• the pressure in this stage is not critical and can be freely selected depending on the procedure. However, the system pressure which arises in the given procedure is preferably used.
• Amino acid amide hydrolysis methioninate formation:
• the solution thus obtained can be used directly for the subsequent saponification with alkali or alkaline earth hydroxide.
• the hydroxide content already set in the previous hydrolysis stage is increased by adding further hydroxide equivalents, so that the resulting hydroxide content has a ratio of 0.95 to 1.1 eq, preferably 1.0 to 1.05 eq, based on the amount used MMP corresponds.
• the saponification temperature should be at least 85 ° C., preferably at least 90 ° C., but generally above 100 ° C., in particular 110-140 ° C. As a rule, 200 ° C is not exceeded.
• the amide concentration is advantageously 10 to 35% by weight, preferably ⁇ 30% by weight and in particular ⁇ 25% by weight, with a concentration ⁇ 25% by weight at a saponification temperature> 160 ° C. is preferred.
• the system pressure corresponding to the selected temperature is set from 1 to several bar, possibly also combined with simultaneous evaporation of the reaction solution.
• the reaction time is at least 10 but a maximum of 90 min, preferably 20-40 min in the case of alkali metal hydroxide or up to 180 min in the case of alkaline earth metal hydroxide.
• the process according to the invention is characterized in that ammonia, ketone and water are taken off together at /> 85 ° C. and / or under a vacuum during and / or after the saponification of the amide.
• the ammonia is advantageously essentially freed from the ketone and the nitrile synthesis (see above).
• the process according to the invention can be used in all methionine syntheses in which methiononitrile is first saponified to the amide in the presence of a ketone, in particular at a temperature below 60 ° C.
• the saponification stage can be carried out batchwise in a stirred pressure reactor, but better continuously, e.g. B. be carried out in a saponification column. With the continuous
• cyanide residues can still occur in the concentrations of several hundred ppm in the raw amino acid salt solutions, it may be necessary to destroy them. According to the invention, this is done by thermal treatment, preferably of the amino acid salt solutions obtained directly, at above 150 ° C. to preferably 200 ° C. and residence times of up to 40 minutes, in particular of at least 10 minutes. In general, treatment is at least 15 minutes at> 160 ° C, at least 7 minutes at> 180 ° C and at least 4 minutes at> 190 ° C.
• DE-OS 33 34 328 From DE-OS 33 34 328 it is known that residual cyanide concentrations can be destroyed by increasing the temperature in an alkaline solution, but DE-OS 33 34 328 relates to the destruction of bound hydrocyanic acid and acrylonitrile in crude acetonitrile, with significantly different temperature and pH values to be considered when converting amino acids.
• the solutions obtained in this way only have a cyanide content of ⁇ 10 ppm, based on 40% by weight. Amino acid content. This means that the permissible limit is clearly undercut.
• the thermal aftertreatment can be at each of the amino acid concentrations obtained from 10-45 wt.7. , but preferably at 15 - 30% by weight. You can both in a downstream step, for example an additional reaction tube, but also during the actual saponification, so z. B. by appropriate temperature increase in the lower part of the saponification column.
• Amino acid requires additional evaporation. This is advantageously carried out at normal pressure or reduced pressure and possibly boiling temperature under conditions which are as gentle as possible, for example using a
• Falling film evaporator The vapors obtained here can be returned to the process elsewhere.
• the quality of the product solutions corresponds to the quality used in the animal feed sector.
• the ammonia used for the aminonitrile formation must be essentially ketone-free, since even small fractions lead to a reduced aminonitrile yield and a clearly measurable aldehyde fraction in the Rohaminonitril and ultimately lead to loss of yield and quality loss in the end product.
• the recycled ammonia should preferably contain less than 25 meq and in particular less than 10 meq ketone with respect to the cyanohydrin and / or the aldehyde. Consequently, this means that the stripped NH 3 / ketone / water mixture cannot be directly recycled, it being irrelevant here whether stripping is carried out before, during or after the amide saponification - the latter two alternatives are, as stated, but preferred . Rather, essentially ketone-free NH 3 must be obtained by a suitable separation operation in the most quantitative yield possible, while the ketone to be recycled may contain both water and NH 3 .
• This separation task could be solved by distillation.
• the vapors coming from the saponification are first taken up in water in an absorption stage and this solution is then fed between the top and bottom, advantageously in the middle to lower region of a distillation column.
• the ketone is, for example, acetone
• the column is separated into practically acetone- and water-free ammonia, which is partially or completely condensed at the top of the column with a suitable reflux ratio and continuously drawn off, and into a 5-30% by weight. 7.
• Acetone and 0- 5 wt. 7 NH 3 -containing aqueous solution in
• This solution can be directly or, if desired, after filtration, if necessary via an adsorbent, such as. B. activated carbon, can be used instead of fresh acetone for aminonitrile hydrolysis. It is advisable to first dilute the solution with water and, if necessary, to add small amounts of acetone until those concentrations are reached which, together with the crude aminonitrile mixture, give the desired target concentrations of acetone or water in the aminonitrile hydrolysis stage. The necessary hydroxide equivalents can be added to the hydrolysis stage either directly by admixing the aqueous ketone solution produced here or by metering in an appropriate alkali hydroxide solution or alkaline earth hydroxide suspension separately.
• an adsorbent such as. B. activated carbon
• the by-product fractions which consist mainly of various pyridine compounds, increase with prolonged recycling have practically no negative influence on the yield of the aminonitrile hydrolysis in the process according to the invention.
• the by-product level can j p but also by continuously discharging smaller fractions z. B. from 1 - 10 Gew.Z the bottom solution from the pressure distillation and supplementing appropriate proportions of fresh solution at a desired level can be kept constant.
• the Ejected portions can either be disposed of or worked again, in particular cleaned of by-products and then reused.
• the process to be carried out under the conditions described above can be technically divided into eleven stages, as shown in the figure, which can preferably be carried out completely continuously, but also optionally partly continuously or discontinuously.
• MMP and HCN base-catalyzed (CAT.) MMP-cyanohydrin is formed, which is then in the aminonitrile reactor 2, together with aqueous ammonia, at a concentration of> 50% by weight. from the absorption and mixing stage 11 is implemented.
• the cyanohydrin reactor 1 and the aminonitrile reactor 2 can also be combined into one stage.
• the crude methionine nitrile / water / ammonia mixture formed is either brought to a lower pressure in a relaxation stage 3 and the NH3 portion released is removed separately (a) or b)), or the crude mixture is passed directly into the subsequent one without releasing the pressure Hydrolysis stage 4 introduced.
• the solution thus formed from ketone, possibly NH 3 and the above-mentioned reaction products in water is simultaneously introduced into the saponification reactor 5 with an appropriate aqueous alkali hydroxide solution or alkaline earth hydroxide suspension (MOH) and reacted there.
• alkaline earth methioninate solution is passed through a filter 7 and, if necessary, then further concentrated in an evaporation stage 8.
• an evaporation stage 6a can also be arranged after the aftertreatment zone 6, the filter 7 then has a lower liquid throughput.
• the vapors discharged from the saponification reactor 5, which contain ammonia, ketone, water and by-product fractions, are, if desired, together with the NH 3 (a)) originating from the expansion stage 3 and the vapors from the evaporation stage 8 or 8a, in an absorption stage 9 taken up in so much water that the NH 3 concentration obtained is at least 20% by weight.
• This solution is then fed into the distillation plant 10.
• the ketone-containing solution obtained there as a distillation sump is passed after filtration (7a) via an adsorption and / or a filter aid or, if appropriate after removal of small portions (waste) into the hydrolysis stage 4.
• the NH 3 obtained as the top product possibly with the NH 3 partial stream (b) obtained from the expansion stage 3, goes to the absorption and mixing stage 11, in which the desired NH 3 concentration is set and, if necessary, small NH 3 losses ( ⁇ -NH 3 ) are added.
• the methioninate solution produced by this process can be used directly as a liquid methionine formulation in the animal feed sector according to DE-OS 31 05 009 or, if desired, for isolating methionine or methionine derivatives by the methods known from the literature.
• An MMP-CH supply line which is connected to a storage vessel, and an ammonia supply line are connected to a heatable flow pipe with internal temperature measurement (pos. 2) and an ammonia supply line, which is connected to an absorption and mixing stage (pos . 11) is connected.
• the flow tube is stirred with an automatic pressure maintaining valve
• Expansion vessel (item 3) connected, the gas space of which is connected via a line to an absorption stage (item 9), and the bottom drain of which leads to the hydrolysis stage (item 4) via a pump.
• the hydrolysis stage can be thermostatted and consists of a loop reactor with a circulating pump and a downstream one
• the loop reactor is still connected on the inlet side via a delivery line and a pump to a storage vessel for aqueous acetone / NaOH solution, and the flow tube is connected via a pressure regulator connected to a collecting vessel.
• the absorption stage (item 9) is an NH 3 absorption system, which is composed of a sump tank with circulation pump and quencher and a bubble cap column attached.
• the column head is supplied from a fresh water tank via the delivery line and pump.
• the sump drain opens into a collecting vessel.
• a supply line with pump and storage vessel is connected to a 250 ml steel autoclave with stirrer, manometer, internal thermometer and heating bath.
• Sodium methionate solution was prepared analogously to Example 19 from 50.0 g (1.76 mol) of 60% ammonia. 39.3 g (0.298 mol) MMP-cyanohydrin, a solution of 2.5 g (0.063 mol) NaOH and 3.6 g (0.062 mol) acetone in 79.6 g (4.42 mol) water and 18.8 g ( 0.235 mol) 50% sodium hydroxide solution. 101.8 g of light brown solution with the following composition were obtained:
• An MMP-CH supply line which is connected to a storage vessel, and an ammonia supply line, which is connected via an intermediate heat exchanger to a.
• Absorption and mixing stage (item 11) is connected.
• the flow tube (item 2) is connected directly to a hydrolysis stage (item 4), which can be thermostatted and consists of a loop reactor with a circulating pump and a downstream flow tube.
• the loop reactor is still connected on the inlet side via a feed line and pump to a storage vessel for aqueous acetone / NaOH solution and on the outlet side via the flow tube and a pressure control to a saponification reactor (item 5).
• the saponification reactor consists of a bubble tray column, the top plate of which is connected via a feed line and a pump
• Sodium hydroxide solution storage container and its head is connected to an absorption stage (item 9) via a pressure maintenance.
• the bottom part consists of a circulation evaporator.
• the level-controlled bottom drain of the saponification reactor is linked to an aftertreatment zone (item 6) via an intermediate tank and a pump.
• the aftertreatment zone consists of a preheater and a downstream dwell time and is directly connected to a filter (item 7) via a thermostattable line and retention.
• the filter consists of a fine filter, the drain of which leads to an evaporation stage (item 8).
• the evaporation stage is an evaporation system consisting of a falling film evaporator, a downstream condenser and a product collection vessel.
• the absorption stage (item 9) serves as an NH 3 absorption system, which is composed of a sump tank with circulation pump and quencher and a bubble cap column attached.
• the column head is removed via the delivery line and pump supplied to a fresh water tank, while the vapor line from the top of the saponification column (item 5) and the condensate line of the evaporation stage (item 8) flow into the quencher.
• the bottom outlet of the absorption stage (item 9) is connected via a pump to a distillation system (item 10), which serves as a pressure distillation system for the continuous removal of NH 3 from the feed mixture and is designed as a bubble tray column.
• the feed from the absorption stage (item 9) takes place in the middle of the column.
• the bottom part consists of a circulation evaporator which has a level-controlled, coolable outlet and is coupled via this to a collecting vessel, which in turn is followed by the storage container for the aqueous acetone / NaOH solution.
• the head section consists of a condenser with a subsequent collecting vessel, which is connected to the absorption and mixing stage (item 11) via a flow control, which consists of a pressure-stable stirred tank, which is also provided with a liquid ammonia and fresh water supply option.
• the evaporation stage (item 8) obtained an average of 4.69 kg of a yellow-colored aqueous sodium methioninate solution with the following composition:
• the relaxation level (item 3) is a stirred one
• Absorption stage (item 9) and its Bode ⁇ outflow is connected to the hydrolysis stage (item 4) via a pump.
• the filter (item 7) consists of two activated carbon filter columns connected in series, from below are flowed through upwards, so that the outlet of the second column leads into the evaporation stage (item 8).
• Example 23 An average of 1.988 kg (15.02 mol) MMP-cyanohydrin and 2.01 kg (94.4 mol) preheated to 80 ° C ammonia (from Pos 11) each metered in under flow control.
• the set internal temperature was 58 ° C at the pipe inlet and 56 ° C at the pipe outlet, the pressure 14.2 barg, the dwell time 24.6 min.
• the reaction mixture was let down in the expansion stage (item 3) to 0.9-1.0 bar g at 30 ° C. and pumped into the loop reactor (item 4), in which 6.7 kg of an aqueous solution with 6 , 55 parts by weight (7.56 mol) acetone and 1.8 parts by weight -7. (3.02 mol) NaOH from a p -ingeDumot reservoir.
• the temperature in the loop was 26 ° C, in the reaction tube 25 ° C, the total residence time 50 min.

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• 1992
  • 1992-10-20 DE DE4235295A patent/DE4235295A1/de active Pending
• 1993
  • 1993-10-14 JP JP50963594A patent/JP3548574B2/ja not_active Expired - Lifetime
  • 1993-10-14 ES ES93923467T patent/ES2102686T3/es not_active Expired - Lifetime
  • 1993-10-14 AU AU53339/94A patent/AU675989B2/en not_active Ceased
  • 1993-10-14 KR KR1019950701502A patent/KR950704246A/ko not_active Withdrawn
  • 1993-10-14 US US08/416,900 patent/US5672745A/en not_active Expired - Lifetime
  • 1993-10-14 SG SG1996005199A patent/SG47910A1/en unknown
  • 1993-10-14 EP EP93923467A patent/EP0665832B1/de not_active Revoked
  • 1993-10-14 WO PCT/EP1993/002838 patent/WO1994008957A1/de not_active Application Discontinuation
  • 1993-10-14 SK SK511-95A patent/SK51195A3/sk unknown
  • 1993-10-14 CZ CZ95947A patent/CZ94795A3/cs unknown
  • 1993-10-14 RU RU95112467A patent/RU2116294C1/ru not_active IP Right Cessation
  • 1993-10-14 DE DE59306216T patent/DE59306216D1/de not_active Revoked
  • 1993-10-14 CA CA002146644A patent/CA2146644A1/en not_active Abandoned
  • 1993-10-18 TW TW082108635A patent/TW278072B/zh active
  • 1993-10-20 CN CN93120388A patent/CN1040533C/zh not_active Expired - Lifetime
  • 1993-10-20 MY MYPI93002169A patent/MY109335A/en unknown
  • 1993-10-20 MX MX9306515A patent/MX9306515A/es unknown

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