CA1101445A - Producing glycine by the reductive amination of glyoxylic acid - Google Patents
Producing glycine by the reductive amination of glyoxylic acidInfo
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- CA1101445A CA1101445A CA293,786A CA293786A CA1101445A CA 1101445 A CA1101445 A CA 1101445A CA 293786 A CA293786 A CA 293786A CA 1101445 A CA1101445 A CA 1101445A
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- glyoxylic acid
- glycine
- methanol
- ammonia
- hydrogenation
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Abstract
ABSTRACT OF THE DISCLOSURE
Glycine is produced by the reductive amination of glyoxylic acid in a reaction mixture comprising glyoxylic acid, ammonia, water and a water-soluble organic solvent for glyoxylic acid, in an atmosphere Or hydrogen, using a rhodium hydrogenation catalyst.
Glycine is produced by the reductive amination of glyoxylic acid in a reaction mixture comprising glyoxylic acid, ammonia, water and a water-soluble organic solvent for glyoxylic acid, in an atmosphere Or hydrogen, using a rhodium hydrogenation catalyst.
Description
11()1445 PRODUCING GLYCINE BY THE REDUCTIVE
AMINATION OF GLYOXYLIC ACID
This invention reIates to the production of glycine by the reductive amination of glyoxylic acid according to the following reaction:
OHC COOH ~ NH3 + H2 ~NH2CH2COOH ~ H2O
Glycine (glycocoll; aminoacetic acid) is an industrial chemical having important and varied uses. Because of its amphoteric nature, it is used widely as a buffering agent, particularly in pharmaceutical and cosmetic preparations. It also has extensive application as a food-grade antioxidant, as a corrosion inhibitor, in electro-plating, as an additive to saccharin for preventing its bitter aftertaste, and in the manufacture of plastics and polymers.
At the present time glycine is manufactured commercially from ammonia and glycolonitrile by a procedure outlined in U.S. patent 3,813,434. However, this method is complex; involves the use of a toxic reagent (HCN): and leads - to the production of glycine in a reaction mixture from which it is isolated in the pure condition only with difficulty.
It has been proposed to produce glycine directly from glyoxylic acid by the reductive amination of the latter in aqueous solution using a palladium catalyst (Desnuelle et al Bull. Soc. Chim (5) 1, 700-2 (1934); Chemical Abstracts Volume 28 column 6,700 1934). The proposed procedure has the additional advantage of employing as a starting material glyoxylic acid, which is readily available at low cost on the large commercial scale as a product of the controlled, oxidative degradation of cellulose, and especially of paper-making pulp and sludges. (Hearon et al U.S. patent 4,073,804 of - February 14, 1978 for SELECTIVELY SEPARATING OXALIC, TARTARIC, GLYOXYLIC AND ERYTHRONIC ACIDS FROM AQUEOUS SOLUTIONS
--1-- ~r, ,B,.4l . .
)1445 CONTAINING THE SAME~
However, the procedure ~or the reductive amination of glyoxylic acid reported by Desnuelle et al supra, indicates little promise la za ~la-11~1445 for the successful commercial application o~ the procedure, since the glycine product is obtained in a yield of only 8~ of the the-oretical, and can be isolated from the complex reaction mixture only in the ~orm Or a derivative, i.e. the betanaphthylsul~onateO
The reason ~or the lack o~ success in executing the proposed synthetic procedure is evident when it i9 considered t~at numerous ; side reactions leading to the production o~ numerous byproducts can occur when it is attempted to produce glycine by treating gly-oxylic acid with ammonia in an atmo~phere of hydrogen and in the presence o~ a hydrogenation catalyst. Among these are:
The reduction of glyoxylic acid to ~lycolic acid.
The dimerization and trimerization of ~lyoxylic acid.
The autooxidation and reduction of the glyoxylic acid in al-kaline medium by the well known Cannizzaro reaction to produce oxalic acid and glycolic acid.
The reaction of any o~ the foregoing acids with ammonia to rorm ammonium salts o~ varying degrees o~ solubility in the reaction ; medium.
We now have discovered, and it is the essence o~ the present invention, that the foregoing problems may be overcome and glycine produced directly from glyoxylic acid in yields o~ up to about 97%
by weight by reductive amination carried out with a colloidal rho-dium catalyst in a reaction medium comprising a mixture of water and selected water-soluble solvents employed in amounts predetermined to maintain the reactants and reaction products in solution, and to inhibit the occurrence of undesirable side reactions, in partic-ular the Cannizzaro reaction.
In its broad aspect, the hereindescribed process comprises ~orming a mixture of glyoxylic acid, ammonia and water together with a selected water-soluble organic solvent used in amount su~-ficient to insure the solubility of the intermediate reaction pro-ducts during the progress o~ the reaction and the separation of the desired glycine product at its conclusion.
AMINATION OF GLYOXYLIC ACID
This invention reIates to the production of glycine by the reductive amination of glyoxylic acid according to the following reaction:
OHC COOH ~ NH3 + H2 ~NH2CH2COOH ~ H2O
Glycine (glycocoll; aminoacetic acid) is an industrial chemical having important and varied uses. Because of its amphoteric nature, it is used widely as a buffering agent, particularly in pharmaceutical and cosmetic preparations. It also has extensive application as a food-grade antioxidant, as a corrosion inhibitor, in electro-plating, as an additive to saccharin for preventing its bitter aftertaste, and in the manufacture of plastics and polymers.
At the present time glycine is manufactured commercially from ammonia and glycolonitrile by a procedure outlined in U.S. patent 3,813,434. However, this method is complex; involves the use of a toxic reagent (HCN): and leads - to the production of glycine in a reaction mixture from which it is isolated in the pure condition only with difficulty.
It has been proposed to produce glycine directly from glyoxylic acid by the reductive amination of the latter in aqueous solution using a palladium catalyst (Desnuelle et al Bull. Soc. Chim (5) 1, 700-2 (1934); Chemical Abstracts Volume 28 column 6,700 1934). The proposed procedure has the additional advantage of employing as a starting material glyoxylic acid, which is readily available at low cost on the large commercial scale as a product of the controlled, oxidative degradation of cellulose, and especially of paper-making pulp and sludges. (Hearon et al U.S. patent 4,073,804 of - February 14, 1978 for SELECTIVELY SEPARATING OXALIC, TARTARIC, GLYOXYLIC AND ERYTHRONIC ACIDS FROM AQUEOUS SOLUTIONS
--1-- ~r, ,B,.4l . .
)1445 CONTAINING THE SAME~
However, the procedure ~or the reductive amination of glyoxylic acid reported by Desnuelle et al supra, indicates little promise la za ~la-11~1445 for the successful commercial application o~ the procedure, since the glycine product is obtained in a yield of only 8~ of the the-oretical, and can be isolated from the complex reaction mixture only in the ~orm Or a derivative, i.e. the betanaphthylsul~onateO
The reason ~or the lack o~ success in executing the proposed synthetic procedure is evident when it i9 considered t~at numerous ; side reactions leading to the production o~ numerous byproducts can occur when it is attempted to produce glycine by treating gly-oxylic acid with ammonia in an atmo~phere of hydrogen and in the presence o~ a hydrogenation catalyst. Among these are:
The reduction of glyoxylic acid to ~lycolic acid.
The dimerization and trimerization of ~lyoxylic acid.
The autooxidation and reduction of the glyoxylic acid in al-kaline medium by the well known Cannizzaro reaction to produce oxalic acid and glycolic acid.
The reaction of any o~ the foregoing acids with ammonia to rorm ammonium salts o~ varying degrees o~ solubility in the reaction ; medium.
We now have discovered, and it is the essence o~ the present invention, that the foregoing problems may be overcome and glycine produced directly from glyoxylic acid in yields o~ up to about 97%
by weight by reductive amination carried out with a colloidal rho-dium catalyst in a reaction medium comprising a mixture of water and selected water-soluble solvents employed in amounts predetermined to maintain the reactants and reaction products in solution, and to inhibit the occurrence of undesirable side reactions, in partic-ular the Cannizzaro reaction.
In its broad aspect, the hereindescribed process comprises ~orming a mixture of glyoxylic acid, ammonia and water together with a selected water-soluble organic solvent used in amount su~-ficient to insure the solubility of the intermediate reaction pro-ducts during the progress o~ the reaction and the separation of the desired glycine product at its conclusion.
-2-The reaction mixture is su~jected to the action ofgaseous hydrogen in the presence of a colloidal rhodium hydrogenation catalyst at pressures ranging from substantially atmospheric pressure to pressures of the order of 3,000 pounds per square inch, and at temperatures varying from just above the freezing point of the reaction mixture to 40C. The reaction is permitted to proceed until the theoretical amount of hydrogen has been absorbed by the system, which occurs usually in from 1 to 16 hours.
At the conclusion of the reaction, the catalyst is removed by filtration, the filtrate concentrated, and a suitable precipitating solvent such as methanol added. Thereupon the glycine separates as a white precipitate which may be separated from the mother liquor by filtration.
In accordance with one broad aspect, the invention relates to the process for the production of glycine which - comprises: a) forming a reaction solution of glyoxylic acid, ammonia, water and a water-soluble organic solvent, l) the ammonia being used in an amount of at least 2 mols of ammonia per mol of glyoxylic acid, 2) the solvent being used in an amount sufficient substantially to dissolve the glyoxylic acid, ammonia and water; the intermediate reaction products of glyoxylic acid with ammonia; and the glycine product, b) hydro-genating the solution in an atmosphere of hydrogen in the presence of a colloidal metallic rhodium hydrogenation catalyst for a time sufficient to convert a substantial proportion of the glyoxylic acid to glycine, and c~ separating the glycine product from the resulting reaction mix~ure.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
The starting material for the hereindescribed process for the production of glycine comprises glyoxylic acid ~OHCCOOH) 11~1445 which, as is well known, under some conditions exists as the hydrate, dihydroxy acetic acid ~HO~2CHCOOH~. Either of these - materials is suitable as a starting material for the present process and each is comprehended herein under the term "glyoxylic acid". As noted above, this compound is potentially available in very large quantities and at low cost as a product of the oxidative conversion of cellulosic pulps to ; various products including glyoxylic acid.
In carrying out the reductive amination, the glyoxylic acid is placed in an aqueous mixture containing in addition to itself ammonia, water, and a water-soluble organic solvent for the glyoxylic acid.
The ammonia may be employed either as aqueous ammonia or as liquid ammonia. In view of its capacity for forming salts with both the glyoxylic acid starting material and the glycine product, it is employed in an amount equal to at least two mols of ammonia for each mol of glyoxylic acid. Preferably from 2-4 mols of ammonia are added for each mol of glyoxylic acid which thereby is n -3a-` L~;
converted to va~ious known intermediate reaction products of gly-oxylic acid and ammonia.
A variety o~ water-soluble organic solvents may be used in con~unction with the water in order to achieve the purpose of main-taining the reactants, the intermediate products and the glycine end product all in solution during the course o~ the reaction.
Such solvents additionally sbould be nonreactive toward the gly-oxylic acid and the glycine, low boiling, of reasonable cost, and recoverable and recycleable at the conclusion of the reaction.
Solvents fulfilling the foregoing criteria comprise 1,4-diox-ane, tetrahydro~uran, piperidine, and the water miscible lower aliphatic alcohols, i.e~ methanol, ethanol, the propanols and ter-tiary butanol. Of these, methanol is a preferred solvent because of its availability, low cost, and efficient action.
As noted, the ratio of water-soluble orFanic solvent to water is predetermined to keep the reactants and reaction products in solution and promote the conversion of the ~lyoxylic acid to gly-cine. When methanol is used as the or~anic solvent, a solvent mixture comprising about 60% methanol and 40~ water gives satis~
~actory results. More broadly stated, from about 40 to about 70~
by wei~ht methanol preferably is employed with reference to the total weight of the methanol-water sol~ent rnixture~
Also included in the reaction mixture is a suitable hydro-genation catalyst. ~e have discovered that of the usual group of such catalysts, including ruthenium, rhodium, nickel, palladium, platinum and osmium, only rhodium is effective in producing high yields of glycine.
The catalyst is used in catalytic amount in the ~orm of par-ticles o~ the elemental material. As is usual, it preferably is employed in a finely divided (colloidal) form deposited on a suit-able carrier such as alumina or carbon.
The reactants are placed in a pressure vessel equipped or associated with means for vigorous stirring and a~itation as well ~4~
; as for the introduction o~ hydrogen gas under conditions predster-- mined to maintain the desired pressure within the reactorO Depen-ding upon the cataly~t employed and the other condit~ons of the reaction, pressures from atmospheric pressure to two or three thousand pounds per square inch may be employed. In the usual case, a pressure of from about 20 to about 60 pounds per square ;nch is adequate.
The reaction does not demand high temperatures. Broadly, temperatures of from just above the ~reezing temperature of the mixture to about 40C., preferably from about 15C. to about 30C.
are optimumO More elevated temperatures favor the production of undesired byproducts of the character discussed above.
The reaction is carried on to completion, usually as noted by the failure of the system to absorb a further quantity of hydrogenO
This time is somewhat variable depending upon the other conditions of reaction. In general, however, a reaction period of from 1 to 16 hours suf~ices to complete the reaction. Longer reaction per-iods may be employed where desired, as in order to adapt the re-action to plant operating schedules.
The process of the invention is illustrated by the following examples.
EXAMPLE I
A 500 ml. pressure bottle containing 20 ml. methanol (practical grade) and 0.20 g. 5a~ rhodium on carbon was shaken with 30 psig hydrogen for 20 minutes. A 100 ml. graduated cylinder maintained at 20C~ with an ice bath was filled with 30 ml. methanol and then 10 ml. liquid am~onia, followed by adding 5 ml. 38.8~ glyoxylic acid (2~506 ~ O~ lOOa/a glyoxylic acid), diluted with water to 25 ml. and added dropwise over a period of 10 minutes~
The resulting mixture then was poured into the pressure bottle containin~ the methanol-suspended catalystO
The system was hydrogenated at 45 psi and 20 to 25C~ for 7.50 hours, i.e. to completion of reduction. The catalyst was ~5~
14gS
.
removed by filtration. The filtrate after evaporation to 10 ml.
under reduced pressure at 50C. was precipitated by the addition - of 90 ml. methanolO After standing for six hours the mixture was filtered and the resultant white solid (glycine) dried in an oven at 100C. for 1.00 hours. It weighed 2.4567 ~. (96.7% of theory).
Its identity as glycine was eqtablished by its melting point of 232 -3Co, its mixed melting point of 232-5C, with known glycine, paper chromatography, and its sweet taste.
This example illustrates the reductive amination of glyoxylic acid to glycine in various solvent systems.
Glyoxylic acid solution (2~00g) derived from the oxidative degradation of cellulosic papermill pulp and containing 50.1% by weight glyoxylic acid; 0.100 g. of 5% rhodium on carbon catalyst, distilled water, ammonia and a selected water ~oluble organic sol-vent were placed in a 500 ml. Parr bottle and hydrogenated at 25 to 1l0 psig at room temperature (18-22C) until the theoretical - amount of hydrogen was absorbed by the system.
At the end of the hydrogenation, the catalyst was removed by filtration and the light yellow filtrate was concentrated to about 10 ml. under reduced pressure at 45-50C. The resulting thick con-centrate then was mixed with 90 ml. methanol and stirred for five minutes. After standing for 16 hours ~overnight) the glycine pro-duct was collected as a white precipitate on a filter and oven dried at 100C. to constant weight. In each case the glycine product has a meltin~ point of 229-233C. and a mixed melting point with a known sample of glycine of 230-233C. The composition of the solvent system employed, the reaction conditions and the results from each run are summarized in Table 1 below.
)1445 :
System Or the Solvent (ml) : Type of Organic Organic Solvent H20 Solvent N Type o~ NH3 Dioxane 20 (ml) 45 (ml) 2.00 (ml) Liquid NH3 Tetrahydrofurane 10 50 25000 28% aqueous ~olution Piperidine 15 50 35. 28% aqueous solution t-Butanol 20 5 5- Liquid NH3 Methanol 25 5 10.00 Liquid NH3 : Ethanol 15 60 20.00 28% aqueous . solution Table 1 (Cont) Type of Hydrogen-Organic Solventation Time Glycine Yield %
. _____ (hours) Dioxane 7.50 o.7066 69.6 Tetrahydrofurane7050 0.8009 78.9 Piperidine 8.50 o.5967 58.8 t-Butanol 5.00 o.6483 63,8 Methanol 3.25 0.9740 95.9 ~: Ethanol 16.00 0.9350 92.1 -6a-`~ .
EXAMPLE III
This example illustrates the comparative inapplicability o~
platinum and palladium catalysts and hence the selective character o~ the hydro~enation catalyst employed in the reductive amination of glyoxylic acid to glycine by the hereindescribed process.
2.00 g. o~ 40.14~ ~lyoxylic acid solution, 25 ml. water, 10 ml. 28~ aqueous ammonia and 45 ml. ethanol were mixed at room temp-erature with 0.100 g. of the selected catalyst. The resulting mix-ture was placed in a 500 ml. Parr bottle and hydro~enated with agitation at 40 psig and room temperature until the theoretical amount o~ hydrogen was absorbed by the system.
The catalyst was filtered of~ and the light yellowish to white filtrate was concentrated to about 10 ml. under reduced pressure at 45-50co The resulting thick concentrate then was mixed with 90 ml. methanol, stirred for 5 minute~ and permitted to stand for 16 hours. The precipitated glycine product, if produced, was col-lected on a filter and oven dried to constant weightO
The conditions and results from e~ch experiment are shown in Table 2 below.
Completed Hydro-genation Time Glyc;ne Yield Type of Catalyst (hour~ ) Note~
5% Pt/Alumina 30 0~3288 40~4 M.p. and (White) mixed m.p.
with glycine at 230-233C
5% Pd/Alumina 0.50 0.2100 25.8 M~po203~l~
mixed mOp.
with glycine 206 ~209 Acid taste EXA~lPLE IV
This example illu~trates the relatively low yield of glycine obtained using colloidal nickel as a catalyst.
At the conclusion of the reaction, the catalyst is removed by filtration, the filtrate concentrated, and a suitable precipitating solvent such as methanol added. Thereupon the glycine separates as a white precipitate which may be separated from the mother liquor by filtration.
In accordance with one broad aspect, the invention relates to the process for the production of glycine which - comprises: a) forming a reaction solution of glyoxylic acid, ammonia, water and a water-soluble organic solvent, l) the ammonia being used in an amount of at least 2 mols of ammonia per mol of glyoxylic acid, 2) the solvent being used in an amount sufficient substantially to dissolve the glyoxylic acid, ammonia and water; the intermediate reaction products of glyoxylic acid with ammonia; and the glycine product, b) hydro-genating the solution in an atmosphere of hydrogen in the presence of a colloidal metallic rhodium hydrogenation catalyst for a time sufficient to convert a substantial proportion of the glyoxylic acid to glycine, and c~ separating the glycine product from the resulting reaction mix~ure.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
The starting material for the hereindescribed process for the production of glycine comprises glyoxylic acid ~OHCCOOH) 11~1445 which, as is well known, under some conditions exists as the hydrate, dihydroxy acetic acid ~HO~2CHCOOH~. Either of these - materials is suitable as a starting material for the present process and each is comprehended herein under the term "glyoxylic acid". As noted above, this compound is potentially available in very large quantities and at low cost as a product of the oxidative conversion of cellulosic pulps to ; various products including glyoxylic acid.
In carrying out the reductive amination, the glyoxylic acid is placed in an aqueous mixture containing in addition to itself ammonia, water, and a water-soluble organic solvent for the glyoxylic acid.
The ammonia may be employed either as aqueous ammonia or as liquid ammonia. In view of its capacity for forming salts with both the glyoxylic acid starting material and the glycine product, it is employed in an amount equal to at least two mols of ammonia for each mol of glyoxylic acid. Preferably from 2-4 mols of ammonia are added for each mol of glyoxylic acid which thereby is n -3a-` L~;
converted to va~ious known intermediate reaction products of gly-oxylic acid and ammonia.
A variety o~ water-soluble organic solvents may be used in con~unction with the water in order to achieve the purpose of main-taining the reactants, the intermediate products and the glycine end product all in solution during the course o~ the reaction.
Such solvents additionally sbould be nonreactive toward the gly-oxylic acid and the glycine, low boiling, of reasonable cost, and recoverable and recycleable at the conclusion of the reaction.
Solvents fulfilling the foregoing criteria comprise 1,4-diox-ane, tetrahydro~uran, piperidine, and the water miscible lower aliphatic alcohols, i.e~ methanol, ethanol, the propanols and ter-tiary butanol. Of these, methanol is a preferred solvent because of its availability, low cost, and efficient action.
As noted, the ratio of water-soluble orFanic solvent to water is predetermined to keep the reactants and reaction products in solution and promote the conversion of the ~lyoxylic acid to gly-cine. When methanol is used as the or~anic solvent, a solvent mixture comprising about 60% methanol and 40~ water gives satis~
~actory results. More broadly stated, from about 40 to about 70~
by wei~ht methanol preferably is employed with reference to the total weight of the methanol-water sol~ent rnixture~
Also included in the reaction mixture is a suitable hydro-genation catalyst. ~e have discovered that of the usual group of such catalysts, including ruthenium, rhodium, nickel, palladium, platinum and osmium, only rhodium is effective in producing high yields of glycine.
The catalyst is used in catalytic amount in the ~orm of par-ticles o~ the elemental material. As is usual, it preferably is employed in a finely divided (colloidal) form deposited on a suit-able carrier such as alumina or carbon.
The reactants are placed in a pressure vessel equipped or associated with means for vigorous stirring and a~itation as well ~4~
; as for the introduction o~ hydrogen gas under conditions predster-- mined to maintain the desired pressure within the reactorO Depen-ding upon the cataly~t employed and the other condit~ons of the reaction, pressures from atmospheric pressure to two or three thousand pounds per square inch may be employed. In the usual case, a pressure of from about 20 to about 60 pounds per square ;nch is adequate.
The reaction does not demand high temperatures. Broadly, temperatures of from just above the ~reezing temperature of the mixture to about 40C., preferably from about 15C. to about 30C.
are optimumO More elevated temperatures favor the production of undesired byproducts of the character discussed above.
The reaction is carried on to completion, usually as noted by the failure of the system to absorb a further quantity of hydrogenO
This time is somewhat variable depending upon the other conditions of reaction. In general, however, a reaction period of from 1 to 16 hours suf~ices to complete the reaction. Longer reaction per-iods may be employed where desired, as in order to adapt the re-action to plant operating schedules.
The process of the invention is illustrated by the following examples.
EXAMPLE I
A 500 ml. pressure bottle containing 20 ml. methanol (practical grade) and 0.20 g. 5a~ rhodium on carbon was shaken with 30 psig hydrogen for 20 minutes. A 100 ml. graduated cylinder maintained at 20C~ with an ice bath was filled with 30 ml. methanol and then 10 ml. liquid am~onia, followed by adding 5 ml. 38.8~ glyoxylic acid (2~506 ~ O~ lOOa/a glyoxylic acid), diluted with water to 25 ml. and added dropwise over a period of 10 minutes~
The resulting mixture then was poured into the pressure bottle containin~ the methanol-suspended catalystO
The system was hydrogenated at 45 psi and 20 to 25C~ for 7.50 hours, i.e. to completion of reduction. The catalyst was ~5~
14gS
.
removed by filtration. The filtrate after evaporation to 10 ml.
under reduced pressure at 50C. was precipitated by the addition - of 90 ml. methanolO After standing for six hours the mixture was filtered and the resultant white solid (glycine) dried in an oven at 100C. for 1.00 hours. It weighed 2.4567 ~. (96.7% of theory).
Its identity as glycine was eqtablished by its melting point of 232 -3Co, its mixed melting point of 232-5C, with known glycine, paper chromatography, and its sweet taste.
This example illustrates the reductive amination of glyoxylic acid to glycine in various solvent systems.
Glyoxylic acid solution (2~00g) derived from the oxidative degradation of cellulosic papermill pulp and containing 50.1% by weight glyoxylic acid; 0.100 g. of 5% rhodium on carbon catalyst, distilled water, ammonia and a selected water ~oluble organic sol-vent were placed in a 500 ml. Parr bottle and hydrogenated at 25 to 1l0 psig at room temperature (18-22C) until the theoretical - amount of hydrogen was absorbed by the system.
At the end of the hydrogenation, the catalyst was removed by filtration and the light yellow filtrate was concentrated to about 10 ml. under reduced pressure at 45-50C. The resulting thick con-centrate then was mixed with 90 ml. methanol and stirred for five minutes. After standing for 16 hours ~overnight) the glycine pro-duct was collected as a white precipitate on a filter and oven dried at 100C. to constant weight. In each case the glycine product has a meltin~ point of 229-233C. and a mixed melting point with a known sample of glycine of 230-233C. The composition of the solvent system employed, the reaction conditions and the results from each run are summarized in Table 1 below.
)1445 :
System Or the Solvent (ml) : Type of Organic Organic Solvent H20 Solvent N Type o~ NH3 Dioxane 20 (ml) 45 (ml) 2.00 (ml) Liquid NH3 Tetrahydrofurane 10 50 25000 28% aqueous ~olution Piperidine 15 50 35. 28% aqueous solution t-Butanol 20 5 5- Liquid NH3 Methanol 25 5 10.00 Liquid NH3 : Ethanol 15 60 20.00 28% aqueous . solution Table 1 (Cont) Type of Hydrogen-Organic Solventation Time Glycine Yield %
. _____ (hours) Dioxane 7.50 o.7066 69.6 Tetrahydrofurane7050 0.8009 78.9 Piperidine 8.50 o.5967 58.8 t-Butanol 5.00 o.6483 63,8 Methanol 3.25 0.9740 95.9 ~: Ethanol 16.00 0.9350 92.1 -6a-`~ .
EXAMPLE III
This example illustrates the comparative inapplicability o~
platinum and palladium catalysts and hence the selective character o~ the hydro~enation catalyst employed in the reductive amination of glyoxylic acid to glycine by the hereindescribed process.
2.00 g. o~ 40.14~ ~lyoxylic acid solution, 25 ml. water, 10 ml. 28~ aqueous ammonia and 45 ml. ethanol were mixed at room temp-erature with 0.100 g. of the selected catalyst. The resulting mix-ture was placed in a 500 ml. Parr bottle and hydro~enated with agitation at 40 psig and room temperature until the theoretical amount o~ hydrogen was absorbed by the system.
The catalyst was filtered of~ and the light yellowish to white filtrate was concentrated to about 10 ml. under reduced pressure at 45-50co The resulting thick concentrate then was mixed with 90 ml. methanol, stirred for 5 minute~ and permitted to stand for 16 hours. The precipitated glycine product, if produced, was col-lected on a filter and oven dried to constant weightO
The conditions and results from e~ch experiment are shown in Table 2 below.
Completed Hydro-genation Time Glyc;ne Yield Type of Catalyst (hour~ ) Note~
5% Pt/Alumina 30 0~3288 40~4 M.p. and (White) mixed m.p.
with glycine at 230-233C
5% Pd/Alumina 0.50 0.2100 25.8 M~po203~l~
mixed mOp.
with glycine 206 ~209 Acid taste EXA~lPLE IV
This example illu~trates the relatively low yield of glycine obtained using colloidal nickel as a catalyst.
3 Freshly prepared activated Raney Nickel 0~20 g; 50.14% by weight glyoxylic acid, 5.00 g; methanol 30 ml; water 40 ml; and llV14~5 liquid ammonia 4.00 ml. in a 500 ml, Parr bottle were shaken with 40 psig of hydrogen at room temperature for 17.00 hours. The total hydrogen absorbed by the mixture was 24.50 psig (theory -24.17 psig).
The catalyst was filtered off and the light green filtrate was evaporated to about 5-10 ml. followed by mixing with 90 ml~
methanol. After 6.0o hours, the precipitate (very light green color) was collected on a filter. The greenish color was not com-pletely removed by washing with ammoniated methanol (ammonia:meth-anol) subsequently the precipitate was dried at 100C to a constantweight of o.8088 g (theory - 2.5408 g). The yield was 31.8% by weight.
The product had a sweet taste and a melting point and mixed melting point with glycine of 229-230C (theory - 234C.
The catalyst was filtered off and the light green filtrate was evaporated to about 5-10 ml. followed by mixing with 90 ml~
methanol. After 6.0o hours, the precipitate (very light green color) was collected on a filter. The greenish color was not com-pletely removed by washing with ammoniated methanol (ammonia:meth-anol) subsequently the precipitate was dried at 100C to a constantweight of o.8088 g (theory - 2.5408 g). The yield was 31.8% by weight.
The product had a sweet taste and a melting point and mixed melting point with glycine of 229-230C (theory - 234C.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. The process for the production of glycine which comprises:
a) forming a reaction solution of glyoxylic acid, ammonia, water and a water-soluble organic solvent, 1) the ammonia being used in an amount of at least 2 mols of ammonia per mol of glyoxylic acid, 2) the solvent being used in an amount sufficient substantially to dissolve the glyoxylic acid, ammonia and water; the intermediate reaction products of glyoxylic acid with ammonia; and the glycine product, b) hydrogenating the solution in an atmosphere of hydrogen in the presence of a colloidal metallic rhodium hydro-genation catalyst for a time sufficient to convert a substantial proportion of the glyoxylic acid to glycine, and c) separating the glycine product from the resulting reaction mixture.
a) forming a reaction solution of glyoxylic acid, ammonia, water and a water-soluble organic solvent, 1) the ammonia being used in an amount of at least 2 mols of ammonia per mol of glyoxylic acid, 2) the solvent being used in an amount sufficient substantially to dissolve the glyoxylic acid, ammonia and water; the intermediate reaction products of glyoxylic acid with ammonia; and the glycine product, b) hydrogenating the solution in an atmosphere of hydrogen in the presence of a colloidal metallic rhodium hydro-genation catalyst for a time sufficient to convert a substantial proportion of the glyoxylic acid to glycine, and c) separating the glycine product from the resulting reaction mixture.
2. The process of claim 1 wherein the organic solvent comprises methanol.
3. The process of claim 1 wherein the organic solvent comprises ethanol.
4. The process of claim 1 wherein the organic solvent comprises methanol used in an amount of from 40 to 70% by weight, based on the weight of the total methanol-water content of the reaction mixture.
5. The process of claim 1 wherein the hydrogenation of the mixture is effectuated at a pressure of from about 20 to about 60 pounds per square inch.
6. The process of claim 1 wherein the hydrogenation reaction is carried out at a temperature of from about 15°C to about 30°C.
7. The process of claim 1 wherein the organic solvent comprises 40 to 70% by weight methanol, based on the weight of the total methanol-water content of the reaction solution, the hydrogenation catalyst comprises colloidal particles of metallic rhodium, the hydrogenation pressure is from about atmospheric pressure to about 3,000 pounds per square inch and the hydrogenation temperature is from just above the freezing temperature of the reaction solution to about 40°C.
8. The process of claim 1 wherein the organic solvent comprises 40 to 70% by weight methanol, based on the weight of the total methanol-water content of the reaction solution, the hydrogenation catalyst comprises colloidal particles of metallic rhodium, the hydrogenation pressure is from about 20 to about 60 pounds per square inch and the hydrogenation temperature is from about 15 to about 30°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,786A CA1101445A (en) | 1977-12-22 | 1977-12-22 | Producing glycine by the reductive amination of glyoxylic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA293,786A CA1101445A (en) | 1977-12-22 | 1977-12-22 | Producing glycine by the reductive amination of glyoxylic acid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1101445A true CA1101445A (en) | 1981-05-19 |
Family
ID=4110372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA293,786A Expired CA1101445A (en) | 1977-12-22 | 1977-12-22 | Producing glycine by the reductive amination of glyoxylic acid |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1101445A (en) |
-
1977
- 1977-12-22 CA CA293,786A patent/CA1101445A/en not_active Expired
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