Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C253/00—Preparation of carboxylic acid nitriles
  • C07C253/22—Preparation of carboxylic acid nitriles by reaction of ammonia with carboxylic acids with replacement of carboxyl groups by cyano groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
  • C07C31/18—Polyhydroxylic acyclic alcohols
  • C07C31/22—Trihydroxylic alcohols, e.g. glycerol
  • C07C31/225—Glycerol

Definitions

• the invention relates to a process for reacting mono-, di- and triglycerides of the general formula wherein R 1 ' R 2 and R 3 , which may be the same or different, mean aliphatic hydrocarbon radicals having 3 to 23 carbon atoms, which radicals may optionally be substituted by an OH group, or mixtures of such glycerides in the liquid phase with ammonia Obtaining fatty acid nitriles of the formula R 3 (R 1 , R 2 ) -CN and glycerol by passing gaseous ammonia, optionally with the addition of inert gas, at elevated temperatures and in the presence of catalysts.
• Fatty acid nitriles which are important intermediates for the production of amines, are preferably produced by technical processes from the corresponding fatty acids and ammonia in the presence of suitable catalysts.
• This synthesis which has been known for a long time, can be carried out both in the liquid phase in a temperature range from 250 to 350 ° C. and in the gas phase in a temperature range from 320 to 380 ° C.
• Suitable catalysts for the reaction in the liquid phase are e.g. Zinc oxide or manganese acetate, for the gas phase for example aluminum oxide or bleaching earth.
• Suitable catalysts for this are, for example, metal oxides or calcium nitrate (cf. Japanese patent publications 70-35524 and 71-21846 and 71-6614).
• the fatty acid nitrile can then be obtained in a known manner from the fatty acid amides by dehydration in a second stage.
• a process is known from Japanese Patent Publication 72-26921 in which natural fats can be converted into fatty acid amides by reaction with aliphatic amines. wherein the resulting glycerol is removed from the equilibrium by the presence of boric acid as the glycerol boric acid ester.
• GB-A 416 613 and 451 594 describe a process for the reaction of hydroxy fatty acids or fatty acids, obtained from natural fats, with ammonia to give fatty acid nitriles in the gas phase at temperatures of 300 to 450 ° C. in the presence of oxidic dehydration catalysts, in particular in the presence of alumina.
• oxidic dehydration catalysts in particular in the presence of alumina.
• glycerides can be used directly, although they cannot be evaporated under the specified conditions.
• Examples 3 of GB-A 416 631 and Examples 7 and 14 of GB-A 451 594 show such reactions of castor oil, palm kernel fat and coconut oil with ammonia at temperatures from 350 to 400 ° C. in the presence of bauxite.
• glycerol there is no evidence of the whereabouts of glycerol. Refinements have shown that the glycerol is completely decomposed by thermal cleavage under the conditions of this process.
• the task was therefore to develop a one-step process by which it is possible to obtain glycerol in high yield in addition to the fatty acid nitrile from glycerides in economically justifiable reaction times.
• R j , R 2 and R 3 which may be the same or different, are saturated or mono- or polyunsaturated hydrocarbon radicals having 3 to 23 carbon atoms, which radicals can optionally be substituted by an OH group, or mixtures of such glycerides in liquid phase with ammonia to obtain fatty acid nitriles of the formula R 3 (R ,, R 3 ) -CN and glycerol by passing gaseous ammonia, optionally with admixture of inert gas, at elevated temperatures and in the presence of catalysts, which is characterized by that the glyceride with an ammonia stream of at least 200 I / kg glyceride and hour, at temperatures of 220 to 300 ° C, in the presence of lead, zinc, cadmium, tin, titanium, zirconium, chromium, antimony
• the starting materials for the process according to the invention are mono-, di- and triglycerides of the general formula that is, in this formula, one or two fatty acid residues can be replaced by H.
• the fatty acid residues R 1 CO-, R z CO- and R 3 C0- are derived from fatty acids with 3 to 23 carbon atoms.
• the aliphatic hydrocarbon radicals R 1 , R 2 and R 3 can be straight-chain or can be branched one or more times. They can represent saturated chains or can also have one or more multiple bonds, preferably double bonds. If appropriate, these radicals can be substituted with an OH group.
• Preferred starting materials for the process according to the invention are, above all, natural fats, which are mixtures of predominantly triglycerides and small proportions of diglycerides and monoglycerides, these also mostly representing mixtures and various types of fatty acid residues in the abovementioned range, in particular those with 8 or more carbon atoms , contain.
• Examples include vegetable fats, such as olive oil, coconut fat, palm kernel fat, babussu oil, palm oil, peanut oil, rapeseed oil, castor oil, sesame oil, cotton oil, sunflower oil, soybean oil, hemp oil, poppy oil, avocado oil, cottonseed oil, wheat germ oil, corn oil, pumpkin seed oil, vegetable oil, grape seed oil, grape seed oil , also animal fats, such as beef tallow, pork fat, knock fat, mutton tallow, Japanese tallow, whale oil and other fish oils and cod liver oil. Uniform tri-, di- and monoglycerides can also be used, be it that they have been isolated from natural fats or obtained synthetically.
• Examples include: tributyrin, tricapronin, tricaprylin, tricaprinin, trilaurin, trimyristin, tripalmitin, tristearin, triolein, trielaidin, trilinoliin, trilinolenin, monopalmitin, monostearin, monoolein, monocaprinin, monolaurinoloin, monoleurinoloin, monoleurinoloin, monoleurinolein, monoleurinolein, monoleurinoleinolomine, monoleininoleininomein, monoleinininolein, monoleinineinolein, monoleinininolein, monoleinininolein, monoleininininolein, monoleinininolein, monoleinineinolein, monoleininoleinomein, monoleinininoleinolein, monoleurinoleinineinomein,
• the rapid removal of the glycerol from the reaction zone means that a certain minimum amount of ammonia is passed through the reaction mixture. This is at least 200 per kg glyceride and hour, preferably at least 400 per kg glyceride and hour. There is no upper critical limit with regard to the ammonia flow to be passed, the quantitative upper limit is determined at best by economic considerations and is for this reason about 1000 preferably about 800 ammonia per kg glyceride and hour. Up to 30%, preferably up to 15%, based on the amount of ammonia passed through, of inert gas, for example nitrogen, can advantageously be added to the amount of gas passed through.
• inert gas for example nitrogen
• the reaction temperature is kept in the range between 220 and 300 ° C., preferably 230 to 290 ° C., during the entire course of the reaction.
• the temperature is preferably allowed to rise from the beginning to the end of the process. This can be done continuously or in stages, in particular in the form of a temperature program.
• a preferred temperature program is that the reaction initially takes place in the temperature range from about 220 to 240 ° C. until about 30 to 70% of the theoretically expected amount of glycerol has been discharged from the reaction vessel, that the temperature is then raised in the course of about half to Gradually or continuously increased for 5 hours until a temperature range of about 270 to 400 ° C. is reached, and the reaction then ends in this temperature range.
• the end of the reaction can be recognized from the fact that no more liquid phase passes into the receiver.
• Alkylcarboxylic acids preferably alkylbenzenecarboxylic acids and alkylnaphthalenecarboxylic acids, which carry one or more alkyl radicals each having 1 to 23, preferably 1 to 12, carbon atoms,
• the salts used as catalysts in the process according to the invention can be obtained by reacting the free acids with the corresponding metal oxides by known processes.
• the free sulfonic acids can be obtained from the known sulfonation processes or from the corresponding alkali sulfonates, for example via ion exchangers.
• the catalysts mentioned can be added directly in the form of the salts mentioned. However, the corresponding metal oxide and the corresponding carbon or sulfonic acid can also be added individually to the reaction mixture, the catalyst forming in situ during the reaction.
• the catalysts mentioned are used in the process according to the invention in amounts of from 0.5 to 75% by weight, in the case of batchwise operation preferably from 1 to 25% by weight and in particular from 1 to 10% by weight, in the case of continuous operation in amounts of preferably 5 to 75% by weight, in particular 10 to 30% by weight, based in each case on the glyceride used, is added.
• the respective glyceride or glyceride mixture is placed in a suitable reaction vessel, for example a stirred kettle, together with the catalyst described above.
• a suitable reaction vessel for example a stirred kettle
• the total amount of catalyst or a partial amount can be initially introduced, the remaining part then being added in portions or continuously during the reaction.
• the reaction vessel is equipped with a gas inlet device that allows the gas flow to be measured. provided, further with a temperature measuring device, a Heating device and if necessary with a stirrer.
• the reaction vessel is connected to a condensation device which consists of one or preferably a plurality of condensation tanks heated to temperatures of about 60 ° to 120 ° C.
• the ammonia stream is set after the initial temperature has been reached.
• the product mixture emerging into the condensation device consists in the initial phase of higher proportions of crude glycerol.
• the proportion of fatty acid nitrile increases more and more in the course of the reaction, so that essentially pure fatty acid nitrile is discharged in the last part, while the discharge of the crude glycerol has already ended.
• the ammonia stream (to which inert gas can be added, as described above) also ensures that the water of reaction is discharged rapidly over the entire duration of the reaction.
• the escaping gas stream is expediently returned to the reaction after the water carried off has been separated off and, if appropriate, with the addition of fresh ammonia.
• the product mixture discharged collects in the condensation device, this mixture being pre-separated into a fatty acid nitrile phase and a crude glycerol / water phase.
• the final phase separation is expediently carried out after the condensation device has been drained and transferred to a separator, for example a steam separator, at about 60 to 100.degree. Residual glycerin is washed out of the fatty acid nitrile phase with water.
• the crude glycerol isolated from the aqueous phase (for example by distillation) can be purified by known processes (cf. UIImann Encyklopadie der Technischen Chemie, 1956, Volume 7, pages 523 to 524), for example by distillation.
• the process according to the invention makes it possible to produce fatty acid nitriles and glycerol in excellent yields. These yields are at least 93% and reach 96% and more fatty acid nitrile and up to 95% crude glycerol (in each case based on the theoretical yield based on the glyceride used).
• the fatty acid nitrile obtained contains at most up to 2% by weight of free fatty acids and up to 10% by weight, but usually less than 6% by weight of fatty acid amides as by-products.
• fatty acids and fatty acid amides contained in the discharged product mixture are also expediently also converted into fatty acid nitriles by subjecting them to a post-reaction in the presence of ammonia and in the presence of the catalysts defined above, if appropriate before the phase separation.
• the method according to the invention can be designed to be fully continuous in a particularly simple manner.
• the glyceride as described above, is placed in the reaction vessel together with the previously mentioned proportions of catalyst or, optionally, added to an inert, non-volatile solvent, such as paraffin oil.
• the amount of ammonia added should also be at least 2001 / kg glyceride and hour and is normally at higher throughputs than those specified above for the batchwise procedure.
• the process temperatures should advantageously be kept in the temperature range from 220 to 270 ° C., in particular in the temperature range from 230 to 250 ° C.
• the glyceride is then continuously replenished during the reaction.
• Glyceride and catalyst can also be fed continuously in a mixture.
• the fractionation system continuously discharges fatty acid nitrile, glycerol and water, while fatty acid amide and free fatty acid are continuously returned to the process.
• the reaction is first carried out until the crude glycerol is essentially completely discharged (which can be seen in the phase separation since the crude glycerol phase no longer increases), and then the fatty acid nitrile phase obtained from the phase separation does not become that yet
• the portion of fatty acid nitrile discharged is returned to the reactor, the temperature in the reactor being set to a range from 200 ° to 320 ° C. and the ammonia stream to an amount of 5 to 150 I / kg fatty acid nitrile and hour, preferably to 15 to 100 I / kg, is reduced.
• the entire fatty acid nitrile can also be discharged from the reaction, subjected to the phase separation and then introduced into a second reactor (post-reactor), the above-mentioned catalysts being added in the amounts mentioned.
• the aftertreatment then takes place under the same conditions as those mentioned above for the return of a partial amount to the first reaction vessel.
• the fatty acid nitrile has to be worked up by distillation after the after-treatment has ended.
• This aftertreatment method can also be modified such that the entire fatty acid nitrile phase is carried out continuously, for example through a tubular reactor, under the specified conditions.
• the fatty acid nitrile phase obtained can also be in the gaseous state together with ammonia in an amount of 200 to 800 I / kg fatty acid nitrile and hour, preferably 300 to 600 I / kg, and at a temperature of 280 to 400 ° C, preferably at 300 to 380 ° C, continuously passed over a fixed bed of dehydration catalysts.
• Suitable dehydration catalysts are, for example, aluminum oxide in the form of bauxite or hydrargilite, thorium oxide, zirconium oxide, aluminum phosphate, silica gel, active bleaching earth and the like or mixtures thereof.
• the process according to the invention therefore surprisingly makes it possible not only to obtain fatty acid nitriles in excellent yields and good purity, but also to obtain glycerol in high yields.
• the purity of the fatty acid nitrile obtained can be increased further, so that it is less than 2% by weight, in most cases less than 0.1% by weight of fatty acid amide and less than 1.5% by weight, in most cases contains less than 0.1% by weight of free fatty acids and is otherwise completely free of by-products.
• Fatty acid nitriles are important chemical intermediates that are further processed in particular to form primary amines and quaternary ammonium salts, which in turn can be used in particular as textile auxiliaries, flotation aids and as cationic surface-active substances in many technical processes.
• Glycerin is an important chemical compound that is used, for example, for the production of explosives, as an additive to heat and power transmission fluids, as a moisture-preserving additive to skin creams, toothpastes, soaps, tobacco and the like, as textile auxiliaries, as solvents and in many other fields that Are known in the art, can be used.
• the reaction was carried out in a heatable reactor with a capacity of 800 cm 3 , provided with a gas inlet device, stirrer, internal thermometer and a fractionating column in the form of a glass tube filled with Raschig rings (length 20 cm, diameter 1.5 cm) and one consisting of three feeds connected in series Master system in which the volatile reaction products are condensed.
• a gas inlet device stirrer
• internal thermometer internal thermometer
• a fractionating column in the form of a glass tube filled with Raschig rings (length 20 cm, diameter 1.5 cm) and one consisting of three feeds connected in series Master system in which the volatile reaction products are condensed.
• 495 g of tallow (saponification number 190, acid number 7.6) were introduced together with 5 g of zinc dodecylbenzenesulfonate as a catalyst.
• the apparatus was flushed with nitrogen while heating.
• the nitrogen was then replaced by ammonia gas, 600 l of NH 3 / kg of tallow.
• Tallow fat nitrile obtained in this way was obtained in 93.6% yield (413.7 g), based on theory, at 1.8% by weight amide content and 1.5% by weight tallow fatty acid and pure glycerol after working up with 80.2% (39 , 6 g) yield isolated. (Here and below, the yield values are always to be understood in relation to theory.)
• the total reaction time was 7.5 hours.
• the reaction products discharged into the templates were washed out with water and worked up.
• Tallow fatty nitrile was obtained in a yield of 92.3% (408 g) with an amide content of 0.7 wt .-% and a fatty acid content of 0.5 G ew .-%, and crude glycerol with a yield of 87.7% (44.7 g ) receive.
• the isolated raw glycerol contained 81.2% glycerol, based on the tallow used.
• Example 2 In the described apparatus of Example 1 445 g of technical tallow ( "bleachable tallow") (saponification number 186, acid number 12.6) and 9 g of zinc dodecylbenzenesulfonate were charged and reacted under the reaction conditions of Example 2 with ammonia. The reaction products discharged within 7.5 hours during the reaction were combined and washed out with water glycerol. After separation of the aqueous phase, tallow fatty nitrile could be isolated in 93.0% yield (370.4 g, amide content 0.5% by weight and fatty acid content of 0.3% by weight). Crude glycerol was obtained from the aqueous phase in 97.5% yield (38.5 g). The yield of pure glycerol, according to the OH number of 1683, was 84.0%, based on the tallow used.
• Example 2 In the apparatus described in Example 1, which was equipped here with a 70 cm mirror glass column with Raschig rings for fractionation, 488 g of tallow (saponification number 190, acid number 2.4) and 5 g of zinc toluenesulfonate were added. A weak stream of nitrogen was passed through the reactor during heating. At 190 ° C the changeover to 600 l NHjkg fat h was made. The reaction was carried out at 230 ° C for 3 hours. The mixture was then heated from 230 ° C. to 270 ° C. within half an hour and the temperature was kept at 270 ° C. for a further 3.25 hours.
• Example 4 In the apparatus described in Example 4, 436 g of sunflower oil (saponification number 189, acid number 0.8) and 9 g of zinc dodecylbenzenesulfonate as a catalyst were reacted with ammonia gas (690 I / kg of fat) under the conditions given in Example 4 (6.75 hours reaction time) - h) implemented. After working up 94.6% fatty nitrile (amide content 0.5% by weight, fatty acid content 0.35% by weight) and 91.2% crude glycerol (40.9 g) or, according to the OH number of 1717, 85.6 % Pure glycerin, based on 01 used, obtained.
• ammonia gas 690 I / kg of fat
• fatty acid nitrile and glycerol directly from glycerides is also possible using a continuous procedure.
• a heatable, cylindrical 750 ml glass vessel 192 g of food tallow were placed together with 7.5 g of zinc dodecylbenzenesulfonate.
• the reactor was equipped with a stirrer, internal thermometer, heated dropping funnel and a 70 cm mirror glass column filled with Raschig rings. 600 l of ammonia / kg of fat - h were passed into the reactor from below using a frit at 230 ° C.
• Example 445 g of beef tallow (saponification number 186, acid number 0.8) were introduced together with 9 g of iron dodecylbenzenesulfonate as a catalyst. Starting at 230 ° C, 600 I NH 3 / kg fat ⁇ h were passed through the sebum. The reaction temperature was raised to 290 ° C. in the course of 7.25 hours.
• Example 1 In the apparatus described in Example 1, which, however, was equipped with a direct transition piece from the reactor to the feed system instead of a fractionation unit, 486 g of food tallow (saponification number 187, acid number 0.8) were obtained together with 1% by weight of zinc dodecylbenzenesulfonate on tallow.
• I NH 3 / kg fat. h passed through the reaction material. The temperature was kept at 230 ° C. for 3 hours and after heating (0.5 hours) at 270 ° C. for 1.25 hours. The reaction was complete after a total of 4.75 hours.
• the reaction products discharged into the templates at 230 ° C. and 270 ° C. were each collected and worked up separately.
• the fatty acid nitrile isolated at 230 ° C. had an amide content of 20% by weight. At 270 ° C., an amide content of approximately 9% by weight was observed. The amide content in the entire fatty acid nitrile was 10% by weight.
• Example 1 In the apparatus described in Example 1, which, however, was equipped with a direct transition piece from the reactor to the feed system instead of a fractionation unit, 500 g of tallow (saponification number 189, acid number 0.9) together with 2% by weight of zinc dodecylbenzenesulfonate, based on Tallow. During the reaction, 600 l of NH 3 / kg fat - h were passed through the reaction mixture. The temperature was kept at 230 ° C. for 3 hours and then increased by 10 ° C. and after every half hour by a further 10 ° C. The reaction was complete at 280 ° C. The reaction time was 5.25 hours.
• the entire condensate was in water at 80 ° C in fatty acid nitrile and Glycerin / water separated.
• the isolated fatty acid nitrile had an amide content of 5.3% by weight and a fatty acid content of 0.5% by weight.
• the nitrile yield was 95.2%. After working up, pure glycerol could be obtained with a yield of 91.4%.
• Example 1 500 g of technical tallow (saponification number 191.4, acid number 1.5) were preassigned together with 2% by weight of zinc dodecylbenzenesulfonate, based on tallow.
• 600 l of ammonia per kg of fat and hour were passed through the reaction mixture, the temperature being kept at 230 ° C. for 3 hours and then being raised continuously to 280 ° C. over the course of 2.25 hours.
• the total reaction time was 5.25 hours.
• care was taken to ensure that the temperature gradient between the bottom and the transition was as small as possible.
• the condensate obtained was separated into crude fatty acid nitrile and glycerol by means of water washing.
• the isolated 432.8 g of crude fatty acid nitrile (amide content 6.1% by weight) were placed in a reactor equipped with a gas inlet tube, stirrer, internal thermometer and condensation system, and 2% by weight of zinc dodecylbenzenesulfonate were added. 60 l of ammonia per kg of reaction material were passed through the reaction mixture at 290 ° C. per hour. Water of reaction formed was discharged. The reaction time was 1 hour. After distillation of the reactor contents, 415 g of tallow fatty nitrile (93.1% yield) with an amide content of less than 0.05% by weight and an acid number of 0.1 were present. Pure glycerol (according to OH number) was obtained 47.3 g (91.2% yield).

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