DK157139B - PROCEDURE FOR PREPARING A MIXTURE OF 2-KETOGULONATE AND 2-KETOGLUCONATE - Google Patents
PROCEDURE FOR PREPARING A MIXTURE OF 2-KETOGULONATE AND 2-KETOGLUCONATE Download PDFInfo
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- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
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Description
1 DK 157159 B1 DK 157159 B
Den foreliggende opfindelse angâr en fremgangsmâde til frem-stilling af en blanding af 2-ketogulonat og 2-ketogluconat. Blan-dingen er nyttig til fremstilling af ascorbin- og erythorbinsyrer. Ascorbinsyre eller vitamin C er pâkrævet i den menneskelige diaet og anvendt i vid udstrækning pâ sâvel tabletform som som et additiv til andre naeringsmidler for at imodegâ dette behov. Erythorbinsyre eller isoascorbinsyre er nyttig som antioxidant til anvendelse i næ-ringsmidler.The present invention relates to a process for preparing a mixture of 2-ketogulonate and 2-ketogluconate. The mixture is useful for preparing ascorbic and erythorbic acids. Ascorbic acid or vitamin C is required in the human diet and widely used in tablet form as an additive to other nutrients to meet this need. Erythorbic acid or isoascorbic acid is useful as an antioxidant for use in nutrients.
2,5-Diketogluconsyre fremstilles let ved bakteriel pâvirk-ning af glucose, idet adskillige arter af Acetobacter og Pseudomonas er nyttige til dette formâl. Japansk patent nr. 14493 (1964) i2,5-Diketogluconic acid is readily prepared by the bacterial action of glucose, several species of Acetobacter and Pseudomonas being useful for this purpose. Japanese Patent No. 14493 (1964) i
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navnet Shionogi and Co., Ltd. beskriver anvendelsen af Pseudomonas sesami til denne fremstilling.the name Shionogi and Co., Ltd. describes the use of Pseudomonas sesami for this preparation.
Tidligere arbejde vedr0rende natriumborhydridreduktionen af 2,5-diketogluconsyre har været indskrænket til fuldstændig re-duktion af sâvel 2-keto- som 5-ketogrupperne til hydroxylgrupper under anvendelse af et stort overskud af natriumborhydrid, og frem-stillingen af 2-ketogulonsyre og 2-ketogluconsyre ved stereoselek-tiv og regioselektiv ikke-katalytisk reduktion har sâvidt vides ikke været rapporteret. Wakisaka, Agr. Biol. Chem. 28,819 (1964), reducerede 2,5-diketogluconsyre i sâvel 2- som 5-ketostillingerne ved pâvirkning med et overskud af natriumborhydrid. De opnâede fire isomere blev angivet som værende D-gluconsyre, D-mannonsyre, L-idonsyre og L-gulonsyre. Ruffs oxidation af den resulterende blanding af disse isomere gav D-arabinose og L-xylose. üdbyttet af D-arabinose som opnâet var st0rre end üdbyttet af L-xylose, hvilket Wakisaka foreslog kunne forekomme ved enten stereospecifik reduktion, ved tilstedeværelsen af isomere eller ved transformationer mellem de forskellige strukturisomere. Det st0rre udbytte af D-arabinose tyder pâ, at reduktion med hydrid til dannelse af de . D-isomere var st0rre end reduktionen til dannelse af L-isomeren, hvilket er i modsætning til den foreliggende fremgangsmâde, som giver ikke blot regioselektiv reduktion ved 5-ketostillingen, men ogsâ stereoselektiv reduktion til dannelse af st0rre mængder af den 0nskede L-isomere af 2-ketogulonsyre. Fuldstændig reduktion af 2,5-diketogluconsyre med et overskud af natriumborhydrid er ogsâ rapporteret af Katznelson, J. Biol. Chem., 204, 43 (1953), som opnâede en "gluconsyre", der mentes at bestâ af fire isomere, som ikke kunne adskilles i hans fors0g. Pâ lignende mâde er fuldstændig reduktion af calcium-2,5-diketogluconat med natriumborhydrid rapporteret af Bernaerts et al., Antonie van Leeuwenhoeck, 37,185 (1971).Previous work on the sodium borohydride reduction of 2,5-diketogluconic acid has been limited to complete reduction of both 2-keto and 5-keto groups to hydroxyl groups using a large excess of sodium borohydride and the preparation of 2-ketogulonic acid and 2- ketogluconic acid by stereoselective and regioselective non-catalytic reduction has so far not been reported. Wakisaka, Agr. Biol. Chem. 28,819 (1964), reduced the 2,5-diketogluconic acid in both 2- and the 5-keto positions by acting with an excess of sodium borohydride. The four isomers obtained were designated as D-gluconic acid, D-mannonic acid, L-idonic acid and L-gulonic acid. Ruff's oxidation of the resulting mixture of these isomers yielded D-arabinose and L-xylose. The yield of D-arabinose obtained was greater than the yield of L-xylose, which Wakisaka suggested could occur either by stereospecific reduction, by the presence of isomers or by transformations between the various structural isomers. The greater yield of D-arabinose suggests that reduction with hydride to form them. D-isomers were larger than the reduction to form the L-isomer, which is in contrast to the present process, which not only provides regioselective reduction at the 5-keto position, but also stereoselective reduction to produce larger amounts of the desired L-isomer of 2-ketogulonic acid. Complete reduction of 2,5-diketogluconic acid with an excess of sodium borohydride has also been reported by Katznelson, J. Biol. Chem., 204, 43 (1953), which obtained a "gluconic acid" meant to consist of four isomers which could not be separated in his experiment. Similarly, complete reduction of calcium 2,5-diketogluconate with sodium borohydride is reported by Bernaerts et al., Antonie van Leeuwenhoeck, 37,185 (1971).
Katalytisk reduktion af 2,5-diketogluconsyre under anvendelse af en Raney-nikkel-katalysator og hydrogen giver if0lge Wakisaka,Catalytic reduction of 2,5-diketogluconic acid using a Raney nickel catalyst and hydrogen gives, according to Wakisaka,
Agr. Biol. Chem. 28, 819 (1964) ringe udbytter af en blanding af 2-ketogulonsyre og 2-ketogluconsyre med 2-ketogluconsyre som hoved-produkt. Dette er u0nsket, hvis man s0ger at anvende blandingen til fremstilling og isolering af den mere værdifulde ascorbinsyre i h0je udbytter. Til dette formai er en blanding indeholdende en st0rre del 2-ketogulonsyre 0nskelig, da 2-ketogulonsyre er precursoren til ascorbinsyre, medens 2-ketogluconsyre er precursoren til erythor-binsyre.Agr. Biol. Chem. 28, 819 (1964), low yields of a mixture of 2-ketogulonic acid and 2-ketogluconic acid with 2-ketogluconic acid as the main product. This is undesirable if one seeks to use the mixture to prepare and isolate the more valuable ascorbic acid in high yields. For this purpose, a mixture containing a major portion of 2-ketogulonic acid is desirable as 2-ketogulonic acid is the precursor of ascorbic acid, while 2-ketogluconic acid is the precursor of erythorbic acid.
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Den katalytiske reduktion af et 5-keto-D-gluconat under anvendelse af ædelmetalkatalysatorer til fremstilling af en blanding af L-idonat og et D-gluconat er ogsâ kendt. Selektiviteten med hensyn til L-idonat forages ved anvendelse af en metalborkatalysator fremstillet ved behandling af et asdelmetaisait med natriumborhydrid, Chen et al., Chem. Pharm. Bull., 18,1305 (1970). Natriumborhydrid-reduktionen af 5-keto-D-gluconsyre er ogsâ blevet beskrevet, J.A.C.S., 76* 3543 (1954), men er ikke-stereoselektiv, hvilket giver omtrent lige store mængder af D-gluconsyre og L-idonsyre.The catalytic reduction of a 5-keto-D gluconate using noble metal catalysts to prepare a mixture of L-idonate and a D-gluconate is also known. The selectivity for L-idonate is forged using a metal boron catalyst prepared by treating a ash metaisai with sodium borohydride, Chen et al., Chem. Pharm. Bull., 18.1305 (1970). The sodium borohydride reduction of 5-keto-D-gluconic acid has also been described, J.A.C.S., 76 * 3543 (1954), but is non-stereoselective, yielding approximately equal amounts of D-gluconic acid and L-idonic acid.
Den foreliggende opfindelse angâr en fremgangsmâde til fremstilling af en blanding af 2-ketogulonat og et 2-ketogluconat, hvilken fremgangsmâde er ejendommelig ved det i krav l's kendetegnen-de del anforte. Den resulterende blanding af 2-ketogulonatet og 2-ketogluconatet kan overfores i ascorbin- og erythorbinsyrer.The present invention relates to a process for the preparation of a mixture of 2-ketogulonate and a 2-ketogluconate, the process of which is characterized by the feature of claim 1. The resulting mixture of the 2-ketogulonate and 2-ketogluconate can be transferred into ascorbic and erythorbic acids.
Fremgangsmâden if0lge opfindelsen har uventet vist sig at muligg0re den regioselektive og stereoselektive ikke-katalytiske . . reduktion af 2,5-diketogluconat ved 5-ketostillingen i godt total-udbytte til en blanding af et 2-ketogulonat og et 2-ketogluconat. Forholdet mellem produkterne i den resulterende blanding kan varieres fra ca. 85:15 til ca. 45:55 afhængigt af de betingelser og reagenser der anvendes, soin det vil blive beskrevet udf0rligere i det f0lgende. Af særlig interesse er det, at den omhandlede fremgangsmâde kan give et godt udbytte af en blanding indeholdende overvejende 2-keto-gulonsyre, som i godt udbytte kan overf0res til den mere værdifulde ascorbinsyre. Blandinger indeholdende omtrent lige mængder 2-ketogulonat og 2-ketogluconat er imidlertid nyttige kilder til fremstil-lingen af sâvel ascorbin- som erythorbinsyrer, og fremgangsmâden if0lge opfindelsen giver derfor fordele i form af fleksibilitet til fremstilling af varierende mængder af ascorbin- og erythorbinsyrer.The process of the invention has unexpectedly been found to enable the regioselective and stereoselective non-catalytic. . reduction of 2,5-diketogluconate at the 5-keto position in good total yield to a mixture of a 2-ketogulonate and a 2-ketogluconate. The ratio of the products in the resulting mixture can be varied from approx. 85:15 to approx. 45:55 depending on the conditions and reagents used, as will be described in greater detail below. Of particular interest is that the process of the present invention can yield a good yield of a mixture containing predominantly 2-keto-gulonic acid, which can be transferred in good yield to the more valuable ascorbic acid. However, mixtures containing approximately equal amounts of 2-ketogulonate and 2-ketogluconate are useful sources for the preparation of both ascorbic and erythorbic acids, and the process of the invention therefore offers advantages in the form of flexibility for producing varying amounts of ascorbic and erythorbic acids.
Det i den foreliggende opfindelse anvendte 2,5-diketogluconat kan som nævnt f.eks. være 2,5-diketogluconsyre eller salte af syren. Hensigtsmæssige salte indbefatter de salte, der som modion har et al-kalimetal, et jordalkalimetal, ammonium eller tetraalkylammonium, hvor alkylgrupperne har 1-4 carbonatomer. Nyttige som udgangsmaterialer til fremgangsmâden if0lge opfindelsen er ogsâ de hidtil ukendte normal-alkylestere af 2,5-diketogluconsyre, hvori alkylgruppen har 1-4 carbonatomer. Som anvendt i beskrivelsen og kravene indbefatter udtrykkene 2,5-diketogluconat, 2-ketogulonat og 2-kétogluconat de frie syrer og hensigtsmæssige alkylestere og salte deraf som hfsfikrevet i det foreaâende. 2.5-Diketoaluconsvren οσ salte deraf 4As mentioned, the 2,5-diketogluconate used in the present invention can e.g. be 2,5-diketogluconic acid or salts of the acid. Suitable salts include those salts which, as a counterion, have an alkali metal, an alkaline earth metal, ammonium or tetraalkylammonium, wherein the alkyl groups have 1-4 carbon atoms. Also useful as starting materials for the process of the invention are the novel normal alkyl esters of 2,5-diketogluconic acid, wherein the alkyl group has 1-4 carbon atoms. As used in the specification and claims, the terms 2,5-diketogluconate, 2-ketogulonate and 2-ketogluconate include the free acids and appropriate alkyl esters and salts thereof as described hereinbefore. 2.5-Diketoalucone Acid οσ salts thereof 4
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kan freins tilles pâ enhver i teknikken kendt mâde. Almindeligvis fremstilles 2,5-diketogluconatet som calciumsaltet i vandig opl0s-ning ved fermentering under anvendelse af metoder, der er velkendte i fermenteringsindustrien, se f.eks. japansk patent nr. 14493, og det kan anvendes direkte som udgangsmaterialet ved fremgangsmâden if0lge opfindelsen. 2,5-Diketogluconatet kan ogsâ fremstilles ved fermentering i nærværelse af andre ioner, sâsom natrium, og det resulterende natrium-2,5-diketogluconat kan ligeledes anvendes direkte som udgangsmateriale. Ved en alternativ metode fremstilles 2.5- diketogluconatet pâ konventionel mâde som calcium-2,5-diketo-gluconatet, og det overf0res i den 0nskede forbindelse ved tilsætning af et sait, der kan udfælde calcium og give 2,5-diketogluconat i opl0sning med den 0nskede modion. Sâledes kan f.eks. natrium- eller ammonium-2,5-diketogluconat fremstilles ved tilsætning af natrium-eller ammoniumcarbonat, som det passer sig, til en opl0sning af calcium-2,5-diketogluconat fremstillet ved fermentering. Calcium-, udfældes som calciumcarbonat, hvilket efterlader 2,5-diketogluconatet i opl0sning med natrium- eller ammoniummodioner. De frie syrer kan ogsâ neutraliseres med et hensigtsmæssigt hydroxid eller et andet sait. Om 0nsket kan 2,5-diketogluconatet isoleres, renses og genopl0ses.freins can be allowed in any manner known in the art. Generally, the 2,5-diketogluconate is prepared as the calcium salt in aqueous solution by fermentation using methods well known in the fermentation industry, see e.g. Japanese Patent No. 14493, and it can be used directly as the starting material in the process of the invention. The 2,5-diketogluconate may also be prepared by fermentation in the presence of other ions, such as sodium, and the resulting sodium 2,5-diketogluconate may also be used directly as a starting material. In an alternative method, the 2.5-diketogluconate is prepared in a conventional manner as the calcium-2,5-diketogluconate and it is transferred into the desired compound by the addition of a site capable of precipitating calcium to give 2,5-diketogluconate in solution with the Wanted counterion. Thus, e.g. sodium or ammonium 2,5-diketogluconate is prepared by adding sodium or ammonium carbonate, as appropriate, to a solution of calcium 2,5-diketogluconate prepared by fermentation. Calcium precipitates as calcium carbonate, leaving the 2,5-diketogluconate in solution with sodium or ammonium ions. The free acids can also be neutralized with an appropriate hydroxide or other site. If desired, the 2,5-diketogluconate can be isolated, purified and redissolved.
De normal— alkylestere af 2,5-diketogluconsyre, hvori alkyl-gruppen har 1-4 carbonatomer, er hidtil ukendte forbindelser, der er nyttige som udgangsmaterialer ved fremgangsmâden if0lge opfindelsen. Esterne kan fremstilles ved opvarmning af en opl0sning af 2.5- diketogluconsyre eller et passende sait deraf i den hensigts-mæssige normale alkanol ved 50°C til 100°C i nærværelse af en katalytisk mængde af en stærk syre, sâsom koncentreret svovlsyre, saltsyre, p-toluensulfonsyre og lignende, under dannelse af den tilsvarende alkyl-2,5-diketogluconat-5,5-dialkylacetal. Egnede salte af 2,5-diketogluconsyre indbefatter alkalimetal-, jordalkali-metal-, ammonium- og tetraalkylammoniumsalte, i hvilke hver alkyl-gruppe i tetraalkylammoniumionen har 1-4 carbonatomer. Acetalen hydrolyseres derpâ med vandig syre ved en temperatur pâ mellem ca. -10°C og 30°C til tilvejebringelse af den 0nskede alkylester af 2/5-diketogluconsyre. Egnede syrer indbefatter vandig saltsyre, tri-fluor eddikesyre, svovlsyre, sulfonsyre-ionbytterharpikser og lignende. Alkyl-2,5-diketogluconat-5,5-dialkylacetal-mellemprodukterne er ogsâ hidtil ukendte forbindelser. En foretrukken acetal og ester, der opnâs ved hydrolyse deraf, er methyl-2,5-diketogluconat-5,5- 5The normal alkyl esters of 2,5-diketogluconic acid, wherein the alkyl group has 1-4 carbon atoms, are novel compounds useful as starting materials in the process of the invention. The esters can be prepared by heating a solution of 2.5-diketogluconic acid or a suitable site thereof in the appropriate normal alkanol at 50 ° C to 100 ° C in the presence of a catalytic amount of a strong acid such as concentrated sulfuric acid, hydrochloric acid, p. -toluenesulfonic acid and the like, to give the corresponding alkyl-2,5-diketogluconate-5,5-dialkyl acetal. Suitable salts of 2,5-diketogluconic acid include alkali metal, alkaline earth metal, ammonium and tetraalkylammonium salts in which each alkyl group of the tetraalkylammonium ion has 1-4 carbon atoms. The acetal is then hydrolyzed with aqueous acid at a temperature of between ca. -10 ° C and 30 ° C to provide the desired alkyl ester of 2/5-diketogluconic acid. Suitable acids include aqueous hydrochloric acid, trifluoroacetic acid, sulfuric acid, sulfonic acid ion exchange resins and the like. The alkyl 2,5-diketogluconate-5,5-dialkyl acetal intermediates are also novel compounds. A preferred acetal and ester obtained by hydrolysis thereof is methyl 2,5-diketogluconate-5.5
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dimethylacetal og henholdsvis methyl-2,5-diketogluconat.dimethyl acetal and methyl 2,5-diketogluconate, respectively.
Nâr der anvendes et alkalimetal-2,5-diketogluconat som udgangsmateriale, foretrækkes natriumsaltet. Natriumsaltet har vist sig at være et særligt 0nskeligt udgangsmateriale til fremstilling af blandinger af et 2-ketogulonat og et 2-ketogluconat indeholdende 2-ketogulonatet som hovedproduktet, hvorved ascorbinsyresyntesen lettes. Et foretrukkent jordalkalimetal-2,5-diketogluconat er calciumsaltet. Nâr tetraalkylammoniumsalte anvendes, er tétraméthylammonium at foretrække pâ grund af prisen og tilgængeligheden. Et foretrukkent alkylester-udgangsmateriale er methyl-2,5-diketogluconatWhen an alkali metal 2,5-diketogluconate is used as the starting material, the sodium salt is preferred. The sodium salt has been found to be a particularly desirable starting material for preparing mixtures of a 2-ketogulonate and a 2-ketogluconate containing the 2-ketogulonate as the main product, thereby facilitating the synthesis of ascorbic acid. A preferred alkaline earth metal 2,5-diketogluconate is the calcium salt. When tetraalkylammonium salts are used, tetramethylammonium is preferred because of its cost and availability. A preferred alkyl ester starting material is methyl 2,5-diketogluconate
En opl0sning af 2,5-diketogluconatet bringes i kontakt med et alkalimetalborhydrid. Reaktionen udf0res foretrukkent i vandig opl0sning, eventuelt indeholdende organiske medopl0sningsmidler, sâsom, men ikke begrænset til, alkoholer med 1-4 carbonatomer, alkandioler med 2-4 carbonatomer, acetonitril, dimethylsulfoxid og dimethylformamid. Methanol er et foretrukkent medopl0sningsmid-del. Koncentrationen af 2,5-diketogluconat er ikke kritisk, men ligger foretrukkent mellem 5 og 20 vægt%. Koncentrationen af 2,5-diketogluconat dannet ved fermentering er almindeligvis beliggende i dette omrâde og giver derved en hensigtsmæssig vandig opl0sning af udgangsmaterialet til anvendelse ved fremgangsmâden if0lge opfin- delsen. Nâr der anvendes en alkylester som udgangsmateriale, kan reaktionen udf0res i vandfri opl0sningsmidler, sâsom alkanoler, specielt methanol, dimethylsulfoxid og dimethylformamid. I aile tilfælde er det ikke n0dvendigt, at 2,5-diketogluconatet er fuldstændig opl0st i opl0sningsmidlet, forudsat at en væsentlig del af udgangsmaterialet er i opl0sning.A solution of the 2,5-diketogluconate is contacted with an alkali metal borohydride. The reaction is preferably carried out in aqueous solution, optionally containing organic co-solvents such as, but not limited to, alcohols of 1-4 carbon atoms, alkanediols of 2-4 carbon atoms, acetonitrile, dimethylsulfoxide and dimethylformamide. Methanol is a preferred co-solvent. The concentration of 2,5-diketogluconate is not critical, but is preferably between 5 and 20% by weight. The concentration of 2,5-diketogluconate formed by fermentation is generally located in this range thereby providing an appropriate aqueous solution of the starting material for use in the process of the invention. When an alkyl ester is used as the starting material, the reaction can be carried out in anhydrous solvents such as alkanols, especially methanol, dimethyl sulfoxide and dimethylformamide. In all cases, it is not necessary that the 2,5-diketogluconate be completely dissolved in the solvent, provided that a substantial portion of the starting material is in solution.
Alkalimetalborhydridet kan anvendes enten i opl0sning eller pâ fast form. Det foretrukne borhydrid til anvendelse ved fremgangsmâden if0lge opfindelsen er natriumborhydrid. Det har vist sig, at anvendelsen af natriumforbindelsen, specielt nâr den anvendes med natrium-2,5-diketogluconatet som substrat, f0rer til store forholds-mængder 2-ketogulonat i produktblandingen. Anvendelsen af andre alkalimetalborhydrider har vist sig at give noget lavere mængder 2-ketogulonat, og ved valg af reagenser kan der dannes blandinger med forhold 2-ketogulonat : 2-ketogluconat pâ 85:15 til 45:55.The alkali metal borohydride can be used either in solution or in solid form. The preferred borohydride for use in the process of the invention is sodium borohydride. It has been found that the use of the sodium compound, especially when used with the sodium 2,5-diketogluconate as a substrate, leads to large proportions of 2-ketogulonate in the product mixture. The use of other alkali metal borohydrides has been found to yield somewhat lower amounts of 2-ketogulonate, and when selecting reagents, mixtures with ratios of 2-ketogulonate: 2-ketogluconate can be formed at 85:15 to 45:55.
Dette muligg0r nogen fleksibilitet ved anvendelse af disse blandinger til opnâelse af enten ascorbinsyre eller erythorbinsyre.This allows some flexibility in using these mixtures to obtain either ascorbic acid or erythorbic acid.
Der kan opnâs gode udbytter af en blanding af et 2-ketogulonat og et 2-ketogluconat ved anvendelse af mellem ca. 0,8 ca.Good yields of a mixture of a 2-ketogulonate and a 2-ketogluconate can be obtained using between 0.8 approx.
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1,1 ækvivalenter af alkalimetalborhydridet pr. mol 2,5-diketogluco-nat. Ved et ækvivalent alkalimetalborhydrid menes der den st0kiome-triske mængde, der er n0dvendig til at overf0re 5-ketogruppen i 2,5-diketogluconatet til hydroxyl. Dette kan ogsâ udtrykkes som 0,8 til 1,1 ækvivalenter hydridion. 1 mol alkalimetalborhydrid indeholder fire ækvivalenter hydridion, og den mængde reagens, der kræves, kan tilsvarende udtrykkes som 0,200 til 0,275 mol alkalimetalborhydrid. Hvis alkalimetalborhydridet anvendes i mængder min-dre end ca. 0,8 ækvivalenter pr. mol 2,5-diketogluconat til selektiv reduktion af 2,5-diketogluconatet vil udbyttet af blandingen af 2-ketosyrer imidlertid være tilsvarende lavere. Ved fremgangsmâden ifolge opfindelsen tilsigtes det at opnâ de optimale totaludbytter af den onskede produktblanding. Beskrivelsen og kravene omhandler derfor en fremgangsmâde til udovelse af denne fremgangsmâde, hvori kun en del af 2,5-diketogluconatet omsættes, og uomsat udgangsmate-riale kan derefter recirkuleres til yderligere reaktion.1.1 equivalents of the alkali metal borohydride per mole of 2,5-diketogluconate. By an equivalent alkali metal borohydride is meant the stoichiometric amount needed to transfer the 5-keto group in the 2,5-diketogluconate to hydroxyl. This can also be expressed as 0.8 to 1.1 equivalents of hydride ion. 1 mole of alkali metal borohydride contains four equivalents of hydride ion and the amount of reagent required can be similarly expressed as 0.200 to 0.275 mole of alkali metal borohydride. If the alkali metal borohydride is used in amounts less than approx. 0.8 equivalents per However, for the selective reduction of the 2,5-diketogluconate, the yield of the mixture of 2-keto acids will be correspondingly lower. The process of the invention aims to achieve the optimum total yields of the desired product mixture. Therefore, the disclosure and claims disclose a method for practicing this process in which only a portion of the 2,5-diketogluconate is reacted and unreacted starting material can then be recycled for further reaction.
Under omsætningen af 2,5-diketogluconatet med alkalimetalborhydridet skal oplosningens pH holdes storre end 5, foretrukkent mellem 6 og 10,5. Nâr 2,5-diketogluconsyre anvendes som udgangs-materiale, skal pH helst indstilles til over 5 for tilsætningen af alkalimetalborhydridet. pH for en vandig oplosning af natrium-eller calcium-2,5-diketogluconat fremstillet ved fermentering er sædvanligvis mindre end 5, og pH skal derfor helst indstilles tilsvarende til en værdi st0rre end 5 f0r tilsætning af borhydridet. Dette kan g0res ved tilsætning af en vilkârlig base, men det fore-trækkes at anvende en natriumforbindelse, sâsom natriumcarbonât eller natriumhÿdroxid. Alternativt kan pH indstilles samtidig med borhydridtilsætningen ved opl0sning af borhydridet i en basisk opl0sning, sâsom natriumhydroxid, sa at ved tilsætning af den basiske borhydridopl0sning indstilles den vandige opl0snings pH straks til en værdi h0jere end 5. I dette tilfælde skal der helst ved tilsætning af et lille overskud i forhold til den krævede st0kiometriske mængde gives mulighed for, at en lille del af borhydridet kan dekomponere ved de sure betingelser, f0r pH er blevet indstillet til over 5.During the reaction of the 2,5-diketogluconate with the alkali metal borohydride, the pH of the solution should be kept greater than 5, preferably between 6 and 10.5. When 2,5-diketogluconic acid is used as the starting material, the pH should preferably be adjusted to above 5 for the addition of the alkali metal borohydride. The pH of an aqueous solution of sodium or calcium 2,5-diketogluconate produced by fermentation is usually less than 5, and the pH should therefore preferably be adjusted correspondingly to a value greater than 5 before the addition of the borohydride. This can be done by the addition of any base, but it is preferred to use a sodium compound such as sodium carbonate or sodium hydroxide. Alternatively, the pH may be adjusted simultaneously with the borohydride addition by dissolving the borohydride in a basic solution, such as sodium hydroxide, so that when the basic borohydride solution is added, the aqueous solution pH is immediately adjusted to a value higher than 5. In this case, preferably by adding a small excess of the required stoichiometric amount allows a small part of the borohydride to decompose under the acidic conditions before the pH has been adjusted to above 5.
Borhydridet kan tilsættes langsomt portionsvis i l0bet af et tidsrum, f.eks. ved tilsætning af den basiske opl0sning af borhydridet drâbevis under omr0ring af opl0sningen af 2,5-diketogluconatet. Borhydridet sættes foretrukkent til pâ én gang ved reaktionens 7The borohydride may be added slowly portionwise over a period of time, e.g. by adding the basic solution of the borohydride dropwise while stirring the solution of the 2,5-diketogluconate. The boro hydride is preferably added at once to the reaction 7
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start ved en temperatur under 25°C.start at a temperature below 25 ° C.
Reduktionen kan ogsâ udf0res i et str0mningsreaktionssystem, nâr en opl0sning af alkalimetalborhydridet almindeligvis blandes med eller indspr0jtes i den 2,5-diketogluconatet indeholdende str0m.The reduction may also be effected in a flow reaction system when a solution of the alkali metal borohydride is usually mixed with or injected into the 2,5-diketogluconate containing stream.
Den tid, der er n0dvendig til fuldendelse af reaktionen, afhænger af reaktionstemperaturen og tilsætningshastigheden for borhydridet til 2,5-diketogluconatet, men almindeligvis vil reak-tionstiderne være forholdsvis korte, og reaktionen vil være fuld-stændig efter tidsforl0b pâ ca. 10 minutter til ca. 2 timer.The time required to complete the reaction depends on the reaction temperature and the rate of addition of the borohydride to the 2,5-diketogluconate, but in general the reaction times will be relatively short and the reaction will be complete after a period of approx. 10 minutes to approx. 2 hours.
Under tilsætning af alkalimetalborhydridet skal temperaturen af den vandige opl0sning helst holdes ved mellem ca. -30°C og ca. 50°C og foretrukkent mellem -25°C og 25°C. Over 50°C kan der iagt-tages dekomponering af reaktanterne.During the addition of the alkali metal borohydride, the temperature of the aqueous solution should preferably be maintained at between ca. -30 ° C and approx. 50 ° C and preferably between -25 ° C and 25 ° C. Above 50 ° C, decomposition of the reactants can be observed.
Reduktionen kan med fordel udf0res i nærværelse af et bor-kompleksdannende middel, som er opl0st eller dispergeret i reaktionsmediet. Borsyre dannes under reduktionen, og denne kan danne kompleks med 2,5-diketogluconat-udgangsmaterialet. Ved et bor-kompleksdannende middel menes der en vilkârlig forbindelse eller et vilkârligt materiale, som vil inhibere eller forhindre kompleks-dannelsen mellem borsyre og 2,5-diketogluconatet, f.eks. ved for- trinsvis at reagere med eller adsorbere borsyren , men midlet skader ikke reaktionen. Hensigtsmæssige bor-kompleksdannende midler ind- befatter alkalimetalfluorider, ammoniumfluorid og borabsorberende ionbytterharpikser. En række sâdanne harpikser er tilgængelige i handelen. Et særligt nyttigt eksempel pâ sidstnævnte er "Amberiite XE-243" (Rohm and Haas Company, Philadelphia, Pa.). Der mâ være en tilstrækkelig mængde bor-kompleksdannende middel til stede til at danne kompleks med den dannede borsyre. Der mâ sâledes anvendes ca. 4 mol fluorid for hvert mol natriumborhydroxid, der anvendes for at bevirke reduktion. Mængden af ionbytterharpiks, der anvendes, vil sædvanligvis være fra ca. 0,5 til 1 volumen harpiks pr. volumen 2.5- diketogluconatopl0sning i en batchproces, men den anvendte mængde vil n0dvendigvis variere efter den særlige harpiks, der anvendes, og reaktionsbetingelserne.The reduction may advantageously be carried out in the presence of a boron complexing agent which is dissolved or dispersed in the reaction medium. Boric acid is formed during the reduction and it can complex with the 2,5-diketogluconate starting material. By a boron complexing agent is meant any compound or material which will inhibit or prevent the complex formation between boric acid and the 2,5-diketogluconate, e.g. by preferably reacting with or adsorbing the boric acid, but the agent does not damage the reaction. Suitable boron complexing agents include alkali metal fluorides, ammonium fluoride and boron absorbing ion exchange resins. A variety of such resins are commercially available. A particularly useful example of the latter is "Amberiite XE-243" (Rohm and Haas Company, Philadelphia, Pa.). A sufficient amount of boron complexing agent must be present to complex with the boric acid formed. Thus, approx. 4 moles of fluoride for each mole of sodium boron hydroxide used to effect reduction. The amount of ion exchange resin used will usually be from 0.5 to 1 volume of resin per volume 2.5-diketogluconate solution in a batch process, but the amount used will necessarily vary according to the particular resin used and the reaction conditions.
Efter afslutning af den selektive reduktion til dannelse af blandingen af et 2-ketogulonat og et 2-ketogluconat kan uomsat 2.5- diketogluconat recirkuleres til yderligere omsætning, eller det kan effektivt fjernes ved opvarmning med syre eller base.Upon completion of the selective reduction to form the mixture of a 2-ketogulonate and a 2-ketogluconate, unreacted 2.5-diketogluconate can be recycled for further reaction or it can be effectively removed by heating with acid or base.
Hvis det 0nskes at underkaste det uomsatte 2,5-diketogluconat yder-If it is desired to subject the unreacted 2,5-diketogluconate further,
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ligere reduktionsreaktioner, udfores den indledende reduktion fore-trukkent i nærværelse af et bor-kompleksdannende middel, som be-skrevet i det foregâende.like reduction reactions, the initial reduction is preferably carried out in the presence of a boron complexing agent as described above.
Blandingen af 2-ketogulonsyre og 2-ketogluconsyre kan isoleres ved filtrering af reaktionsblandingen og indstilling af filtratets pH til mellem 1,5 og 2 ved tilsætning af syrer, sâsom koncentreret svovlsyre, og frafiltreringog bortkastning af dannet bundfald. 2-Ketogulon- og 2-ketogluconsyrerne kan samles ,ved fjernelse af vandet eller vand-organisk medopl0sningsmiddel, f.eks. ved fryset0rring. Forholdet mellem 2-ketogulonsyre og 2-ketogluconsyre i blandingen kan bestemmes ved væskechromatografi pâ methyl-esterne under anvendelse af en blanding afborsyre (0,6 M) og ammoniumformiat (0,4 M) i vand som den mobile fase med "Aminex Resin" type A-25 (TM. Bio-Rad Laboratories, Richmond, California), 50-100 mesh som den stationære fase eller ved tyndtlagschromatografi under anvendelse af en cellulosebærer.The mixture of 2-ketogulonic acid and 2-ketogluconic acid can be isolated by filtration of the reaction mixture and adjusting the pH of the filtrate to between 1.5 and 2 by the addition of acids such as concentrated sulfuric acid and filtration and disposal of formed precipitate. The 2-ketogulonic and 2-ketogluconic acids can be pooled, by removal of the water or water-organic co-solvent, e.g. by freeze drying. The ratio of 2-ketogulonic acid to 2-ketogluconic acid in the mixture can be determined by liquid chromatography on the methyl esters using a mixture of boronic acid (0.6 M) and ammonium formate (0.4 M) in water as the mobile phase with "Aminex Resin" type A-25 (TM. Bio-Rad Laboratories, Richmond, California), 50-100 mesh as the stationary phase or by thin layer chromatography using a cellulose carrier.
Blandingen af 2-ketogulonsyre og 2-ketogluconsyre kan let overf0res i ascorbin- og erythorbinsyrer. Blandingen af 2-keto-syrer kan overf0res i methylesterne ved kogning under tilbagesvar ling i methanol i nærværelse af en sur katalysator, sâsom saltsyre eller en sulfonisk ionbytterharpiks i 3 til 24 timer. André estere kan dannes pâ denne mâde under anvendelse af den passende alkohol. Esterne dannes direkte, nâr en alkylester af 2,5-diketogluconsyre er udgangsmateriale til den selektive reduktion. Blandingen af methylestere kan adskilles og koges derpâ under tilbagesvaling i methanol i nærværelse af en base, sâsom natriumbicarbonat, i en inert atmosfære. Ved afk0ling udfælder natriumascorbat og natrium-erythorbat. De râ salte samles ved filtrering, blandes med vand og afioniseres med en kationbytterharpiks, sâsom "Dowex 50" frem-stillet af Dow Chemical Co. Vandet fjernes, og ascorbinsyren og erythorbinsyren omkrystalliseres af methanol/vand til opnâelse af en blanding af ascorbin- og erythorbinsyrer. Qm 0nsket kan ascor-binsyre opnâs ved omkrystallisation fra en 4:1 methanol/vand-opl0s-ning.André hensigtsmæssige opl0sningsmidler eller medopl0sningsmid-ler kan om 0nsket anvendtes.0m 0nsket kan methylesterne af 2-ketogulonsvre og 2-ketogluconsyre adskilles og overf0res i ascor-binsyre henholdsvis erythorbinsyre under anvendelse af de samme betingelser som beskrevet i det foregâende for esterblandingen.The mixture of 2-ketogulonic acid and 2-ketogluconic acid can be easily transferred into ascorbic and erythorbic acids. The mixture of 2-keto acids can be transferred into the methyl esters by boiling under reflux in methanol in the presence of an acidic catalyst such as hydrochloric acid or a sulfonic ion exchange resin for 3 to 24 hours. Other esters can be formed in this way using the appropriate alcohol. The esters are formed directly when an alkyl ester of 2,5-diketogluconic acid is the starting material for the selective reduction. The mixture of methyl esters can be separated and boiled there under reflux in methanol in the presence of a base, such as sodium bicarbonate, in an inert atmosphere. Upon cooling, sodium ascorbate and sodium erythorbate precipitate. The raw salts are collected by filtration, mixed with water and deionized with a cation exchange resin such as "Dowex 50" manufactured by Dow Chemical Co. The water is removed and the ascorbic acid and erythorbic acid are recrystallized from methanol / water to give a mixture of ascorbic and erythorbic acids. If desired, ascorbic acid can be obtained by recrystallization from a 4: 1 methanol / water solution. Other appropriate solvents or co-solvents may be used if desired. ascorbic acid and erythorbic acid, respectively, using the same conditions as described above for the ester mixture.
tt
DK 157139 BDK 157139 B
9 · : > * . r ,* *9 ·:> *. r, * *
Ascorbinsyre kan fremstilles sëlektivt ud fra en blanding af 2-ketogulonsyre og 2-ketogluconsyre. Dette er særlig fordelagtigt, nâr blandingen, indeholdende en haj andel 2-ketogulonsyre, er ble-vet dannet, f. eks. ved natriumborhydridreduktion af natri.um-2,5-diketogluconat. Den ved borhydridreduktionen opnâede blanding af syrer opvarmes i et hensigtsmæssigt organisk oplosningsmiddel, sâsom xylen, til ca. 50-13Q°C, foretrukkent 60-90°C, i nærværelse af en syre valgt blandt saltsyre, hydrogenbromidsyre, svovlsyre og sulfoni-ske ionbytterharpikser. Den foretrukne syre er saltsyre. Efter op-varmning i et tidsrum pâ 3-12 timer, afhængigt af den anvendte tempe-ratur, er lactoniseringen af 2-ketogulonsyren til ascorbinsyre i det vaesentlige fuldstœndig. I denne procès dannes erythorbinsyre ikke, og det er derfor en enkel metode til selektiv fremstilling af ascorbinsyre ud fra blandinger af 2-ketogulonsyre og 2-ketogluconsyre fremstillet ved borhydridreduktion af et 2,5-diketogluconat. Denne syrekatalyserede lactoniseing kan ogsâ anvendes til at overfore ·-blandinger af alkylestrene af 2-ketogulonsyre og 2-ketogluconsyren i ascorbinsyre.Ascorbic acid can be selectively prepared from a mixture of 2-ketogulonic acid and 2-ketogluconic acid. This is particularly advantageous when the mixture containing a shark proportion of 2-ketogulonic acid has been formed, for example, by sodium borohydride reduction of sodium 2,5-diketogluconate. The mixture of acids obtained by the borohydride reduction is heated in an appropriate organic solvent, such as xylene, to ca. 50-13 ° C, preferably 60-90 ° C, in the presence of an acid selected from hydrochloric, hydrobromic, sulfuric and sulfonic ion exchange resins. The preferred acid is hydrochloric acid. After heating for a period of 3-12 hours, depending on the temperature used, the lactonization of the 2-ketogulonic acid to ascorbic acid is substantially complete. In this process, erythorbic acid is not formed and it is therefore a simple method for selectively preparing ascorbic acid from mixtures of 2-ketogulonic acid and 2-ketogluconic acid prepared by borohydride reduction of a 2,5-diketogluconate. This acid-catalyzed lactonization can also be used to transfer mixtures of the alkyl esters of 2-ketogulonic acid and the 2-ketogluconic acid in ascorbic acid.
De efterfolgende eksempler forklarer opfindelsen nærmere.The following examples further explain the invention.
Eksempel 1Example 1
Til en hurtigt omrprt opl0sning af 20 liter filtreret, râ fermenteringsblanding indeholdende 10% calcium-- 2,5-diketogluconat (CgH-yO^, 1,5 H2O, molvægt 238, 0,84 M) ved 0°C (is/vand-bad) blev der sat 42,4 ml 2,2 M NaBH4 i 7 M NaOH (0,93 M H) ved en hastighed pâ 1 ml pr. min. Opl0sningens pH steg hurtigt fra 3,65 til 10,2.To a rapidly stirred solution of 20 liters of filtered crude fermentation mixture containing 10% calcium-2,5-diketogluconate (CgH-yO 1,5, 1.5 H₂O, molar weight 238, 0.84 M) at 0 ° C (ice / water) -bath) 42.4 ml of 2.2 M NaBH 4 was added to 7 M NaOH (0.93 MH) at a rate of 1 ml per ml. mine. The pH of the solution increased rapidly from 3.65 to 10.2.
Den resulterende opslæmning blev filtreret, filtratet indstillet til pH 1,6 med koncentreret H2S04, og det resulterende bundfald blev fjernet ved filtrering og bortkastet. Fjernelse af vand ved fryse-t0rring gav 246 g fryset0rret fast'stof. En del af dette iblev for-estret og analyseret ved væskechromatografi med en indre .-standard til opnâelse af et forhold pâ 78:22 mellem 2-ketogulonsyre og 2-ketogluconsyre i et totaludbytte pâ 79%.The resulting slurry was filtered, the filtrate adjusted to pH 1.6 with concentrated H 2 SO 4 and the resulting precipitate removed by filtration and discarded. Removal of water by freeze-drying gave 246 g of freeze-dried solid. Part of this remained esterified and analyzed by liquid chromatography with an internal standard to obtain a ratio of 78:22 between 2-ketogulonic acid and 2-ketogluconic acid in a total yield of 79%.
En opl0sning af 10 g fryset0rret 2-ketogulon- og 2-keto-gluconsyrer fra ovennavnte reduktion i 50 ml MeOH blev behandlet med 1 g "Dowex 50"(T. M. Dow Chemical Co.) harpiks og kogt under tilbagesvaling i 12 timer. Ved afk0ling blev harpiksen fjernet ved filtrering og de râ methylestere isoleret ved fjernelse af opl0s-ningsmiddel som en olie.A solution of 10 g of freeze-dried 2-ketogulonic and 2-keto-gluconic acids from the above reduction in 50 ml of MeOH was treated with 1 g of "Dowex 50" (T. M. Dow Chemical Co.) resin and refluxed for 12 hours. Upon cooling, the resin was removed by filtration and the crude methyl esters isolated by solvent removal as an oil.
1010
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Anvendelse af produktet:Use of the product:
Den râ blanding af methylestere fra f0r blev anbragt i methanol med 1,5 ækvivalenter NaHCO^ og kogt under tilbagesvaling i en nitrogenatmosfære i 6 timer. Ved afk01ing udfældede natrium-saltene af ascorbin- og erythorbinsyre fra opl0sningen. De râ salte blev isoleret ved filtrering, anbragt i vand og afioniseret med "Dowex 50"-kationbytterharpiks. Ved fjernelse af vand udkrystal-liserede den râ ascorbin/erythorbinsyrerest af methanol/vand til opnâelse af en blanding af ascorbin- og erythorbinsyrer. Omkrystal-lisation af 4:1 methanol/vand gav ascorbinsyre.The crude mixture of methyl ester from before was placed in methanol with 1.5 equivalents of NaHCO 3 and refluxed under a nitrogen atmosphere for 6 hours. Upon decoction, the sodium salts of ascorbic and erythorbic acid precipitated from the solution. The crude salts were isolated by filtration, placed in water and deionized with "Dowex 50" cation exchange resin. Upon removal of water, the crude ascorbine / erythorbic acid residue crystallized from methanol / water to obtain a mixture of ascorbic and erythorbic acids. Recrystallization of 4: 1 methanol / water gave ascorbic acid.
Eksempel 2Example 2
En 10%'s vandig opl0sning af natrium-2,5-diketogluconat blev indstillet til et pH pâ 6,1 ved tilsætning af natriumcarbonat, methanol blev tilsat til 50 volumen%, og opl0sningen blev afk01et til mellem -15°C og -25°C. Et ækvivalent natriumborhydrid blev sat til den afk0lede opl0sning, som blev omr0rt i 6 timer ved -15°C til -25°C og ved rumtemperatur natten over. En blanding af natrium-2-ketogulonat og -2-ketogluconat blev isoleret ved udfældning med methanol og filtrering. Analyse af methylestrene ved væskechromato-grafi viste et forhold pâ 78:22 mellem 2-ketogulonsyre og 2-keto-gluconsyre i produktblandingen,A 10% aqueous solution of sodium 2,5-diketogluconate was adjusted to a pH of 6.1 by the addition of sodium carbonate, methanol was added to 50% by volume and the solution was cooled to between -15 ° C and -25 ° C. An equivalent of sodium borohydride was added to the cooled solution, which was stirred for 6 hours at -15 ° C to -25 ° C and at room temperature overnight. A mixture of sodium 2-ketogulonate and -2-ketogluconate was isolated by precipitation with methanol and filtration. Analysis of the methyl esters by liquid chromatography showed a 78:22 ratio of 2-ketogulonic acid to 2-keto-gluconic acid in the product mixture.
Eksempel 3Example 3
Under anvendelse af den i eksempel 2 omhandlede metode blev natriumborhydridreduktion af calcium-2,5-diketogluconat udf0rt ved 0°C ved forskellige pH-værdier. Blandingen af 2-ketogulonat og 2-gluconat som dannet blev analyseret ved væskechromatografi til bestemmelse af forholdet mellem 2-ketogulonsyre og 2-keto-gluconsyre. De opnâede resultater var som f01ger:Using the method of Example 2, sodium borohydride reduction of calcium 2,5-diketogluconate was carried out at 0 ° C at various pH values. The mixture of 2-ketogulonate and 2-gluconate formed was analyzed by liquid chromatography to determine the ratio of 2-ketogulonic acid to 2-keto-gluconic acid. The results obtained were as follows:
Forhold 2-ketogulonsyre: pH Opl0sningsmiddel 2-ketogluconsyre_ 6,37 Vand:methanol (a) 69:31 8,23 Vand:methanol 68:32 8,65 Vand 45:55 (a) 1:1 efter volumenRatio 2-ketogulonic acid: pH Solvent 2-ketogluconic acid_ 6.37 Water: methanol (a) 69:31 8.23 Water: methanol 68:32 8.65 Water 45:55 (a) 1: 1 by volume
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Eksempel 4Example 4
Under anvendlese af den i eksempel 2 omhandlede metode blev der udf0rt natriumborhydridreduktlon af natrium-2,5-diketogluconat i vand:methanol-opl0sning (1:1 efter volumen) holdt ved mellem -15°C og -20°C ved forskellige pH-værdier. Blandingerne af 2-keto-gulonat og 2-ketogluconat som dannet blev analyseret ved væske-chromatografi til bestemmelse af forholdet mellem 2-ketogulonsyre og 2-ketogluconsyre. De opnâede résultater var som f0lger:Using the method of Example 2, sodium borohydride reductone of sodium 2,5-diketogluconate in water: methanol solution (1: 1 by volume) was kept at between -15 ° C and -20 ° C at various pH. values. The mixtures of 2-keto-gulonate and 2-ketogluconate formed were analyzed by liquid chromatography to determine the ratio of 2-ketogulonic acid to 2-ketogluconic acid. The results obtained were as follows:
Forhold 2-ketogulonsyre: pH 2-ketogluconsyre_ 6,10 78:22 8,6o 77:23 8,80 77:23 10,20 71:29Ratio 2-ketogulonic acid: pH 2-ketogluconic acid_ 6.10 78:22 8.6o 77:23 8.80 77:23 10.20 71:29
Eksempel 5Example 5
Under anvendelse af den i eksempel 2 omhandlede metode blev der udf0rt natriumborhydridreduktlon af natrium-2,5-diketogluconat i vand:methanol-opl0sning ved pH mellem 7,9 og 8,6 ved forskellige temperaturer. Forholdet mâlem 2-ketogulonsyre og 2-ketogluconsyre i de resulterende produkter blev bestemt ved væske-chromatografi. De opnâede resultater var som f0lger:Using the method of Example 2, sodium borohydride reductlon of sodium 2,5-diketogluconate in water: methanol solution at pH between 7.9 and 8.6 was carried out at various temperatures. The ratio of target 2-ketogulonic acid to 2-ketogluconic acid in the resulting products was determined by liquid chromatography. The results obtained were as follows:
Forhold 2-ketogulonsyre:Ratio 2-ketogulonic acid:
Temp. °C 2-ketogluconsyre_ 24 77:23 0 80:20 -15 til -20 77:23Temp. ° C 2-Ketogluconic Acid 24 77:23 0 80:20 -15 to -20 77:23
Eksempel 6Example 6
Under anvendelse af den i eksempel 2 omhandlede metode blev der udf0rt natriumborhydridreduktion af natrium-2,5-üiketo-gluconsyre i vand ved 0°C ved et pH pâ 8 med varierende koncentra-tioner af natrium-2,5-diketogluconat. Forholdet mellem 2-ketogulon-syre og 2-ketogluconsyre i de resulterende produkter blev bestemt ved væskechromatografi. De opnâede resultater var som f01ger:Using the method of Example 2, sodium borohydride reduction of sodium 2,5-üiketo-gluconic acid was carried out in water at 0 ° C at a pH of 8 with varying concentrations of sodium 2,5-diketogluconate. The ratio of 2-ketogulonic acid to 2-ketogluconic acid in the resulting products was determined by liquid chromatography. The results obtained were as follows:
12 DK 157139 B12 DK 157139 B
Koncentration af natrium-2,5- Forhold 2-ketogulonsyre: diketogluconat, vægt%_ 2-ketogluconsyre_ 5 75:25 10 79:21 20 56:44Concentration of Sodium 2,5- Ratio 2-ketogulonic acid: diketogluconate, weight% _ 2-ketogluconic acid_ 5 75:25 10 79:21 20 56:44
Eksempel 7Example 7
Reduktionen blev udf0rt under anvendelse af forskellige alkalimetalborhydrider og 2,5-diketogluconater af forskellige modioner. Forholdet mellem 2-ketogulonsyre og 2-ketogluconsyre i de resulterende blandinger blev bestemt ved væskechromatografi. Reaktionsbetingelserne og de opnâede résultater var soin f01ger:The reduction was carried out using different alkali metal borohydrides and 2,5-diketogluconates of different counterions. The ratio of 2-ketogulonic acid to 2-ketogluconic acid in the resulting mixtures was determined by liquid chromatography. The reaction conditions and the results obtained were as follows:
Borhydrid- 2,5-diketo- Temp. Forhold 2-ketogu- ion gluconat °C pH lonsyre:2-ketoglu- _ _ _ _ consyre_Borohydride 2,5-diketo-Temp. Ratio of 2-ketoglucon gluconate ° C pH lonic acid: 2-ketogluconic acid
Ll Li -15 til -20 8,26 48:52Ll Li -15 to -20 8.26 48:52
Na Li -15 til -20 8,06 63:37Na Li -15 to -20 8.06 63:37
Na Na -15 til -20 8,60 77:23Na Na -15 to -20 8.60 77:23
Na K -15 til -20 8,08 64:36 K K -15 til -20 7,97 67:33Na K -15 to -20 8.08 64:36 K K -15 to -20 7.97 67:33
Na Me4N -15 til -20 8,61 63:37Na Me4N -15 to -20 8.61 63:37
Na Ca 0 8,65 45:55Na Ca 0 8.65 45:55
Ll Li '0 8,0 48:52Ll Li '0 8.0 48:52
Ll Na 0 8,0 47:53Ll Na 0 8.0 47:53
NaReach
Li 0 8,0 63:37Li 0 8.0 63:37
Na Na 0 8,0 79:21Na Na 0 8.0 79:21
Eksempel 8Example 8
Reduktionen af calcium-2,5-ketogluconat med 4,4 M natrium-borhydrid i 14 M natriumhydroxid blev udf0rt ved 0°C i vand inde-holdende forskellige medopl0sningsmidler. Forholdet mellem 2-ketogulonsyre og 2-kebogluconsyre i de resulterende blandinger blev bestemt ved væskechromatografi. De opnâede resultater var som f0lger: 13The reduction of calcium 2,5-ketogluconate with 4.4 M sodium borohydride in 14 M sodium hydroxide was carried out at 0 ° C in water containing various co-solvents. The ratio of 2-ketogulonic acid to 2-kebogluconic acid in the resulting mixtures was determined by liquid chromatography. The results obtained were as follows: 13
DK 157139 BDK 157139 B
Forhold vand: Forhold 2-ketogulonsyre:Ratio of water: Ratio of 2-ketogulonic acid:
Medopl0sningsmîddel medopl0sningsmlddel 2-ketogluconsyre_Co-solvent with solvent 2-ketogluconic acid
Ethylenglycol 6:1 72:28Ethylene Glycol 6: 1 72:28
Acetonitril 4:1 76:24Acetonitrile 4: 1 76:24
Dimethylformamid 4:1 72:28Dimethylformamide 4: 1 72:28
Dimethylsulfoxid 6:1 71:29Dimethylsulfoxide 6: 1 71:29
Intet - 77:23Nothing - 77:23
Eksempel 9 15 g isoleret calcium-2,5-diketogluconat blev opl0st i 150 ml vand, og 6,61 g natriumcarbonat blev tilsat ved 0°C under omr0-ring af opl0sningen. Opl0sningens pH steg til 9,57. Der blev sat 0,49 g natriumborhydrid til opl0sningen ved 0°C. Efter omr0ring i 15 minutter blev blandingen filtreret, og filtratet blev ionbyttet med en sur ionbytterharpiks. Efter fryset0rring og dannelse af methylestrene, soin beskrevet i eksempel 1, gav analyse ved vaeskechromatografi et forhold mellem 2-ketogulonsyre og 2-ketoglucon-syre pâ 85:15:Example 9 15 g of isolated calcium 2,5-diketogluconate was dissolved in 150 ml of water and 6.61 g of sodium carbonate was added at 0 ° C with stirring of the solution. The pH of the solution increased to 9.57. 0.49 g of sodium borohydride was added to the solution at 0 ° C. After stirring for 15 minutes, the mixture was filtered and the filtrate was ion exchanged with an acidic ion exchange resin. After freeze-drying and formation of the methyl esters described in Example 1, analysis by liquid chromatography gave a ratio of 2-ketogulonic acid to 2-ketogluconic acid at 85:15:
Eksempel 10Example 10
Til 50 ml 20%'s natrium-2,5-diketogulonat ved 0°C blev der sat 0,8 ml 10%'s natriumhydroxid til indstilling af pH fra 5,15 til 9,70. Der blev straks tilsat natriumborhydridpulver (11,26 mmol, Alfa Products, Danvers, Ma. 01923). Med pH pâ 10,60 efter 10 minutters forl0b blev blandingen indstillet til et pH pâ 7 med koncentreret svovlsyre. Analyse af den reducerede blanding ved HPLC (^minex A-25H-harpiks under anvendelse af 0,5 M NH^HCX^ som elueringsmiddel) viste ren reduktion til en blanding af natrium-2-ketogulonat og natrium-2-ketogluconat i et udbytte pâ 85%.To 50 ml of 20% sodium 2,5-diketogulonate at 0 ° C was added 0.8 ml of 10% sodium hydroxide to adjust the pH from 5.15 to 9.70. Sodium borohydride powder (11.26 mmol, Alfa Products, Danvers, Ma. 01923) was added immediately. With a pH of 10.60 after 10 minutes, the mixture was adjusted to a pH of 7 with concentrated sulfuric acid. Analysis of the reduced mixture by HPLC (³minex A-25H resin using 0.5 M NH ^HCX ^ as eluent) showed pure reduction to a mixture of sodium 2-ketogulonate and sodium 2-ketogluconate in a yield. at 85%.
Til bestemmelse af forholdet mellem 2-ketogulonat og 2-ketogluconat blev det fryset0rrede faste stof fra 5 ml af den reducerede blanding forestret med 15 ml methanol og 0,275 ml koncentreret svovlsyre. Den opnâede methylester blev analyseret ved gas-chromatografi som sit persilvlerede dérivât (fremstillet ved behand-ling med "Tri-Sil/TBT" [Pierce Chemical Company, Rockford, 111. 61105]). Adskillelse pâ en 3%1 s *OV-21O*-s0jle ved 135°C (30 ml pr. min. str0mningshastighed) viste et forhold mellem methyl-2-keto-gulonatsyre og methyl-2-ketogluconatsyre pâ 85:15.To determine the ratio of 2-ketogulonate to 2-ketogluconate, the freeze-dried solid from 5 ml of the reduced mixture was esterified with 15 ml of methanol and 0.275 ml of concentrated sulfuric acid. The methyl ester obtained was analyzed by gas chromatography as its persilvated dérivat (prepared by treatment with "Tri-Sil / TBT" [Pierce Chemical Company, Rockford, 111. 61105]). Separation of a 3% 1 s * OV-21O * column at 135 ° C (30 ml per min flow rate) showed a ratio of methyl 2-keto-gulonate acid to methyl-2-ketogluconate acid at 85:15.
,4 DK 157139 B, 4 DK 157139 B
Eksempel 11Example 11
En 250 ml rundbundet kolbe med 5,0 g (19,8 mol) methyl- 2,5-diketogluconat-5,5-dimethylacetal, 150 ml vand og 3 ml 6 N saltsyre blev omr0rt ved 80°C i 45 minutter, afk0let,og den vandige opl0sning blev passeret gennemen sbjle indeholdende 40 ml "Amberlyst A-21"-ionbytterharpiks (Rohm and Haas Co., Philadelphia, Pa.) .A 250 ml round bottom flask with 5.0 g (19.8 mol) of methyl 2,5-diketogluconate-5,5-dimethyl acetal, 150 ml of water and 3 ml of 6N hydrochloric acid was stirred at 80 ° C for 45 minutes, cooled and the aqueous solution was passed through a beaker containing 40 ml of "Amberlyst A-21" ion exchange resin (Rohm and Haas Co., Philadelphia, Pa.).
Det neutraliserede elueringsmiddel blev derpâ fryset0rret til opnâelse af 2,2 g (100%) methyl-2,5-diketogluconat som et 10st, ustabilt gult pulver, der var homogent if01ge HPLC-analyse ("Aminex A-25"-harpiks under anvendelse af 0,5 M ΝΗ^+Η002 som elueringsmiddel) : IR (KBr) cm”1 3330 (s, OH), 1736 (s, methylester), NMR (D20) S,c 170,00 (s, ester-carbon), 96,86 og 92,84 (singlets, anomere), 73,20 og 71,50 (doublets, -CH-OH), 65,99 (t, -CH2-0-), (53,95 (q, CH3-0).The neutralized eluent was then freeze-dried to obtain 2.2 g (100%) of methyl 2,5-diketogluconate as a 10 pt. Unstable yellow powder homogeneous by HPLC analysis ("Aminex A-25" resin using of 0.5 M + + + 002 as eluent): IR (KBr) cm -1 3330 (s, OH), 1736 (s, methyl ester), NMR (D20) S, c 170.00 (s, ester carbon) ), 96.86 and 92.84 (singlets, anomers), 73.20 and 71.50 (doublets, -CH-OH), 65.99 (t, -CH2-0-), (53.95 (q , CH3-0).
Produktet blev anbragt i 150 ml vand, af7 k0let til 0°C, og pH blev indstillet til 7,5 med 1 N NaOH. Til den hurtigt omr0rte blanding blev der sat 215 mg natriumborhydrid. Efter 1 minuts forl0b blev blandingen f0rt gennem 40 ml af en ion-bytter i en s0jle indeholdende 50% "Dowex 50" og 50% "Amberlyst A-21" harpiks. Filtratet blev koncentreret i vakuum til en fast blanding af methyl-2-ketogulonat og methyl-2-ketogluconat omfattende 3,7 g. Det râ faste stof blev anbragt i 50 ml 95%'s éthanol med 5,99 g natriumbicarbonat og kogt under tilbagesvaling i 4 timer under nitrogen. Efter afk0ling blev reaktionsblandingen afioni-seret med overskud af "Dowex 50" og derpâ koncentreret i vakuum til en gui olie. GLPC-analyse af den per-trimethylsilylerede reak-tionsblanding (ΙδΟ*3, 5 ft 0V-210 s0jle) indikerer et forhold pâ 78:22 mellem ascorbinsyre og erythorbinsyre i et totaludbytte pâ 20% bestemt ved iodtitrering.The product was placed in 150 ml of water, cooled to 0 ° C and the pH adjusted to 7.5 with 1 N NaOH. To the rapidly stirred mixture was added 215 mg of sodium borohydride. After 1 minute, the mixture was passed through 40 ml of an ion exchanger in a column containing 50% "Dowex 50" and 50% "Amberlyst A-21" resin. The filtrate was concentrated in vacuo to a solid mixture of methyl 2-ketogulonate and methyl 2-ketogluconate comprising 3.7 g. The crude solid was placed in 50 ml of 95% ethanol with 5.99 g of sodium bicarbonate and boiled under reflux for 4 hours under nitrogen. After cooling, the reaction mixture was deionized with excess "Dowex 50" and concentrated in vacuo to a crude oil. GLPC analysis of the per-trimethylsilylated reaction mixture (δδ * 3.5 ft 0V-210 column) indicates a ratio of 78:22 between ascorbic acid and erythorbic acid in a total yield of 20% determined by iodine titration.
Eksempel 12Example 12
Til 50 ml 12%'s vandig natrium-2,5-diketogluconat (28,04 mmol) blev der sat 45 ml "Amberlite XE-243" ionbytterharpiks (Rohm & Haas, Philadelphia, Pa. 19105). Blandingen blev omr0rt til 0°C i et isAand-bad.Veddrâbevis tilsætning af 10%'s natrium-hydroxid blev pH indstillet til 10,8. Behandling med 0,265 g natriumborhydrid (7,01 mmol, Alfa Products, Danvers, Ma. 01923) i 10 minutter efterfulgt af indstilling til pH 7 med koncentreret svovlsyre. Omr0ring i 0,5 timer gav efter filtrering af harpiksen 15To 50 ml of 12% aqueous sodium 2,5-diketogluconate (28.04 mmol) was added 45 ml of Amberlite XE-243 ion exchange resin (Rohm & Haas, Philadelphia, Pa. 19105). The mixture was stirred to 0 ° C in an ice-bath. After addition of 10% sodium hydroxide, the pH was adjusted to 10.8. Treatment with 0.265 g of sodium borohydride (7.01 mmol, Alfa Products, Danvers, Ma. 01923) for 10 minutes followed by adjustment to pH 7 with concentrated sulfuric acid. Stirring for 0.5 hours gave after filtration of the resin 15
DK 157139 BDK 157139 B
en reduceret blanding, hvorfra ca. 50% af det oprindeligt tilstede-værende bor var fjernet. Der opnâedes et 90%'s udbytte af en 85:15-blanding af 2-ketogulon- og 2-ketogluconsyrer.a reduced mixture from which approx. 50% of the initially present boron was removed. A 90% yield of an 85:15 mixture of 2-ketogulonic and 2-ketogluconic acids was obtained.
Eksempel 13Example 13
Til 50 ml 12%'s vandig natrium-2,5-diketogluconsyre (28,04 mmol) blev der sat 35 ml "Amberlite EX-243" ionbytterharpiks (Rohm & Haas, Philadelphia, Pa. 19105). Blandingen blev omr0rt ved 0°C i et is/vand-bad. Ved drâbevis tilsætning af 10%'s natrium-hydroxid blev pH indstillet til 10,8. Ved tilsætning af 0,212 g natriumborhydrid (5,61 mmol, Alfa Products, Danvers, Ma. 01923), blev der iagttaget en pH-stigning til 11,55. Efter 10 minutters forl0b blev blandingen afskrækket med koncentreret svovlsyre til indstilling af pH fra 11,2 til 7. Efter omr0ring i 0,5 timer blev den delvist reducerede blanding filtreret til fjernelse af harpiksen.To 50 ml of 12% aqueous sodium 2,5-diketogluconic acid (28.04 mmol) was added 35 ml of Amberlite EX-243 ion exchange resin (Rohm & Haas, Philadelphia, Pa. 19105). The mixture was stirred at 0 ° C in an ice / water bath. By dropwise addition of 10% sodium hydroxide, the pH was adjusted to 10.8. By adding 0.212 g of sodium borohydride (5.61 mmol, Alfa Products, Danvers, Ma. 01923), a pH increase to 11.55 was observed. After 10 minutes, the mixture was quenched with concentrated sulfuric acid to adjust the pH from 11.2 to 7. After stirring for 0.5 hours, the partially reduced mixture was filtered to remove the resin.
Til den delvist reducerede opl0sning blev der sat yderligere 10 ml "Amberlite XE-243" harpiks. Efter afk0ling til 0°C blev opl0sningens pH indstillet til 10,8 med 10%'s natriumhydroxid.To the partially reduced solution was added an additional 10 ml of "Amberlite XE-243" resin. After cooling to 0 ° C, the pH of the solution was adjusted to 10.8 with 10% sodium hydroxide.
Der blev tilsat yderligere 53 mg (1,40 mmol) natriumborhydrid.An additional 53 mg (1.40 mmol) of sodium borohydride was added.
Efter 10 minutters forl0b blev der tilsat koncentreret svovlsyre til indstilling af pH til 7. Efter omr0ring i 0,25 timer blev blandingen filtreret. HPLC-analyse viste fuldstændig reduktion af natrium-2,5-diketogluconat til natrium-2-ketogulonat og natrium-2-ketogluconat. Der blev observeret meget lidt borsyre eller mulige overreduktionsprodukter. Ved anvendelse af HPLC-analyse med 2-imidazolidon som indre standard blev der bestemt et 96%'s udbytte af en 85:15-blanding af 2-ketogulonsyre og 2-ketogluconsyre.After 10 minutes, concentrated sulfuric acid was added to adjust the pH to 7. After stirring for 0.25 hours, the mixture was filtered. HPLC analysis showed complete reduction of sodium 2,5-diketogluconate to sodium 2-ketogulonate and sodium 2-ketogluconate. Very little boric acid or possible over-reduction products were observed. Using HPLC analysis with 2-imidazolidone as the internal standard, a 96% yield of an 85: 15 mixture of 2-ketogulonic acid and 2-ketogluconic acid was determined.
Eksempel 14Example 14
Til en hurtigt omr0rt 12%'s vandig opl0sning af natrium- 2,5-diketogluconat (28,04 mmol), afk0let til 0°C i et is/vand-bad blev der sat 2,355 g (56,08 mmol) natriumfluorid. Ved drâbevis tilsætning af 10%'s natriumhydroxid blev pH indstillet fra 4,3 til 10,8. 10 minutter efter tilsætningen af 0,530 g natriumborhydrid (14,02 mmol, Alfa Products, Danvers, Ma. 01923) blev pH indstillet til 7 med koncentreret svovlsyre. HPLC-analyse ("Aminex A-25" harpiks under anvendelse af 0,5 M NH^HŒ^ som eluerings-middel) viste mindre tilstedeværende bor end uden harpiks. Efter omr0ring af blandingen natten over blev der ved filtrering fjernetTo a rapidly stirred 12% aqueous solution of sodium 2,5-diketogluconate (28.04 mmol), cooled to 0 ° C in an ice-water bath, was added 2.355 g (56.08 mmol) of sodium fluoride. By dropwise addition of 10% sodium hydroxide, the pH was adjusted from 4.3 to 10.8. Ten minutes after the addition of 0.530 g of sodium borohydride (14.02 mmol, Alfa Products, Danvers, Ma. 01923), the pH was adjusted to 7 with concentrated sulfuric acid. HPLC analysis ("Aminex A-25" resin using 0.5 M NH 2 H 2 as eluent) showed less boron present than without resin. After stirring the mixture overnight, filtration was removed
16 DK 157139 B16 DK 157139 B
lidt hvidt fast udfældet stof. üdbyttet af 85:15-blandingen af 2-ketogulon- og 2-ketogluconsyre blev bestemt til 90%.a little white solid precipitated. The yield of the 85:15 mixture of 2-ketogulonic and 2-ketogluconic acid was determined to be 90%.
Eksempel 15Example 15
Til en hurtigt omr0rt opl0sning af 55 mmol natrium-2,5-diketogluconsyre i 150 ml H20 ved 0°C og et pH pâ 9,5 blev der sat 12,7 mmol natriumborhydrid i 10bet af 15 minutter. Efter endt tilsætning blev opl0sningens pH indstillet til ca. 7 med 6 N saltsyre og fryset0rret til opnâelse af 16,3 g fast stof. En portion pâ 15,0 g af det fryset0rrede faste stof blev opl0st i 250 ml methanol: vand i forholdet 95:5 med 100 ml "Amberlyst 15" (Rohm and Haas, Philadelphia, Pa. 19105) ionbytterharpiks og kogt under tilbage-svaling natten over. Efter afk01ing blev harpiksen fjernet ved filtrering, filtratet blev passeret gennem 40 ml "Amberlyst A-21" (Rohm and Haas, Philadelphia, Pa. 19105) ionbytterharpiks og kon-centreret i vakuum. Krystaller, som forekom ved henstand, blev fjernet ved filtrering og vasket med acetone, hvilket gav 2,21 g (21%) methyl-2-ketogulonat (smp. 150-154°C, litteraturangivelse 155-157°C), der ved HPLC-analyse og C^^spektroskopi viste sig at være 97% iscmeriskrai.Methyl-2-ketogulonatet kan overf0res i ascorbinsyre ved opvarmning med natriumbicarbonat under nitrogen.To a rapidly stirred solution of 55 mmol sodium 2,5-diketogluconic acid in 150 ml H2 O at 0 ° C and a pH of 9.5 was added 12.7 mmol sodium borohydride for 10bet of 15 minutes. After completion of the addition, the pH of the solution was adjusted to ca. 7 with 6 N hydrochloric acid and freeze-dried to give 16.3 g of solid. A portion of 15.0 g of the freeze-dried solid was dissolved in 250 ml of methanol: 95: 5 water with 100 ml of "Amberlyst 15" (Rohm and Haas, Philadelphia, Pa. 19105) ion exchange resin and boiled under reflux overnight. After decoction, the resin was removed by filtration, the filtrate passed through 40 ml of "Amberlyst A-21" (Rohm and Haas, Philadelphia, Pa. 19105) ion exchange resin and concentrated in vacuo. Crystals present on standing were removed by filtration and washed with acetone to give 2.21 g (21%) of methyl 2-ketogulonate (mp 150-154 ° C, literature 155-157 ° C), which HPLC analysis and C ^^ spekt spectroscopy were found to be 97% ischemic. The methyl 2-ketogulonate can be transferred into ascorbic acid by heating with sodium bicarbonate under nitrogen.
Claims (13)
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Application Number | Priority Date | Filing Date | Title |
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US74950976A | 1976-12-10 | 1976-12-10 | |
US74950976 | 1976-12-10 | ||
US05/843,946 US4159990A (en) | 1976-12-10 | 1977-10-20 | Reduction of 2,5-diketogluconic acid |
US84394677 | 1977-10-20 |
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DK549477A DK549477A (en) | 1978-06-11 |
DK157139B true DK157139B (en) | 1989-11-13 |
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DK (1) | DK157139C (en) |
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- 1977-12-07 AR AR270273A patent/AR218278A1/en active
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