DE1768658C - Process for the preparation of 2,5-dimethyl-4,5-dihydrofuranol- (3) -one- (4) - Google Patents

Description

3 4

dihydrofuranol- (3) -one- (4) can be obtained. The NMR spectrum (CDCl ₃ ) of the compound shows the following

Sublimation of the product at a bath temperature lowing data:

of 80 ° C under a pressure of 0.005 Torr, δ = 1.45 ppm, 3 H, d; 2.30 ppm, 3 H, s; 4.55 ppm,

1.34 g of sublimed product obtained, which was treated twice with IH, quartet; 7.65 ppm, 1H, s.

a little petroleum ether is washed. 1.27 g of 5 are obtained. The hexanediol- (3,4) -dione- (2-5) used above

(51% of theory) of the compound from F. 77 bis has been prepared as follows: A solution, loading

79 ° C, the purity of which is determined by thin-layer chromatography from 7.16 g (45.2 millimoles) of 2,5-dimethyl

graph or gas chromatography is confirmed. 2,5-dimethoxy-dihydrofuran, 7.9 g (64.5 millimoles)

The hexane potassium chlorate used as starting material above, 0.25 g (1.0 millimole) Osmi τη-

dioI- (3,4) -dione- (2,5) has been prepared as follows: io tetroxyd, 50 ml tetrahydrofuran and 100 ml water,

(a) A mixture of 680 g of pyruvaldehyde in the form is heated for 18 hours at 45 to 50 ° C. The solution of a 50% aqueous solution, 680 g of ethanol is then concentrated to dryness in vacuo and 500 g of glacial acetic acid is added with vigorous stirring in one the residue is heated several times to 45 ° C. with a nitrogen atmosphere of acetic acid ether. The organic extracts are triturated in portions of 600 g of 15 hours within X ¹ It hours, dried over sodium sulfate and then powdered J'lnk is added, the temperature being reduced, whereby 6.9 g of crude hexanediol- (3,4) -dione- ( 2.5) between 45 and 6O ⁰ C is kept. The solution will be obtained. This product can be used directly for is filtered, concentrated in vacuo and the reverse cyclization. _{Taken from a mixture of CHCl 3} and CCl ₄ by recrystallization in 500 ml of warm ethyl acetate. The organic solution is filtered and ao (40:60) or methylene chloride is obtained, concentrated in vacuo, with 336 g of the crude product of the purified compound having the following spectral data: crystallize. Umkris: ulization from vinegar- IR, v _r0 = 1710cm- »(CHCl ₃ ), NMR, = 2.25ppm, ethyl acid ester or by sublimation becomes pure 6H, s; 4.25 ppm, 2H, s; 4.37 ppm, 2H, see melting-hexanediol- (3,4) -dione- (2,5) from m.p. 89 to 90 ° C, point: 58 to 60 ° C.

keep. 35.

(b) A mixture of 625g of a 40% aqueous Example Ä

A solution of pyruvaldehyde, 815 ml of water and To a solution of 10 g of hexanediol- (3,4) -dione-185 g of pure acetic acid, (2.5) in 100 ml of a molar aqueous solution of and heated to 40 to 50 ° C under nitrogen. 20 ml of trisodium phosphate are then added in portions to 220 g of powdered zinc, a solution of disodium monohydrogen phosphate, the temperature being between 40 and 50 ° C., whereupon the pH of this solution is increased by adding. The addition takes about 3 hours, if a molar solution of orthophosphorus is added, and the mixture is stirred for a further 2 hours with room acid (about 70 to 80 ml) set to 8 to 8.2 temperature. Then it is filtered off and then metallic zinc which has reacted for 24 hours is removed and the filtrate is heated in the 35 to 75 ° C. The mixture is then vacuumed for 24 hours at 35 to 40 ° C, the zinc acetate is continuously separated with a 1: 1 (v / v) mixture by filtration and the filtrate is diluted with 2 liters of ether and petroleum ether (boiling range 30 to 50 ° C) water. The whole is then extracted with a mixture, and the organic extracts (250 ml) of ether-petroleum ether (boiling range 30 to 50 ° C.) are then dried over sodium sulphate. Then 2: 1 (v / v) one week and then with a corresponding 40 the extract is concentrated, and 8.70 g of the corresponding 9: 1 (Wv) mixture is obtained for another week of 2,5-dimethyl-4, 5-dihydrofuranol- (3) -one- (4), which continuously extracts. After removal the measure by NMR analysis is practically pure. The evacuated solvents will be 198.5 g (80%) of the raw booty is 55 to 60% of theory.
Hexanediol- (3,4) -dione- (2,5) obtained, which crystallizes in the cold The hexanediol- (3,4) -dione- (2,5) used above. 45 is made as follows:

A solution of 22 g of hydrated sodium example 2 acetate, 0.67 g of sulfuric acid, 200 ml of water and

72.6 g acetol is heated to 90 ⁰ C. Through this

A solution of 5.4 g of hexanediol- (3,4) -dione- (2,5) solution becomes an air in the course of 70 hours 100 ml of a 5 ° stream saturated with sodium bicarbonate are blown, then the solution is in vacuo Solution is continuously concentrated to dryness with n-pentane for one week, then dissolved in 200 ml of water. and then also taken with it for a week and continuously at 10% for 50 hours 10 to 15% pentane (v / v) ether containing (v / v) petroleum ether (boiling range 30 to 50 ° C). After separating the organic phase, the ether is extracted. After separating the the combined extracts (150 ml of n-pentane 55 organic phase are the combined extracts and 200 ml of ether-n-penthan) dried over sodium sulfate (200 ml) and then dried over sodium sulfate dried and then evaporated to dryness. It evaporated completely giving 13.9 g of crude hexane 2.42 g (51% of theory) of crude 2,5-dimethyl-diol- (3,4) -dione- (2,5) are obtained, which without white-4,5-dihydrofuranoI- (3) -one- (4) obtained, which was used for the cyclization by tere purification, sublimation is cleaned according to Example 1. That can do 60 den.

Claims (1)

1 2 organic nitrogen bases are for example those Claim: from formic acid, acetic acid, propionic acid, malon acid, maleic acid, tartaric acid and citric acid Process for the production of 2,5-dimethyl- and piperidine, dimethylpiperidm, piperazine, picoline, 4,5-dihydrofuranol- (3) -one- (4), characterized by 5 morpholine or pyrrolidine, where piperidine acetate denotes that one hexanediol- (3,4) - is preferred. Suitable neutral or acidic alkali salts of a dione (2.5) in the presence of a salt of an organic mineral acid are those of sodium or potassium niche carboxylic acid with an organic nitrogen or lithium with sulfuric acid, carbonic acid, phosphorous base or a neutral or acidic alkali metal phosphoric acid or boric acid, e.g. B. sodium sulfate, nasal salts a mineral acid as a catalyst among io trium bisulfate, sodium carbonate, sodium bicarbonate, Use of water at a pH of sodium orthophosphate, sodium monohydrogenphos-6 up to 9 and a temperature of 20 to 150 ° C phat, sodium dihydrogen phosphate or sodium borate, cyclized. Mixtures of such salts can also be used as cycli- use conversion catalysts. Preferred Kata-15 lysers of this type are sodium carbonate or bicarbonate and mixtures of sodium orthophosphate, sodium monohydrogen phosphate and sodium dihydrogen phosphate. The invention relates to a process for the preparation of the pH value to be maintained depends essentially development of 2,5-dimethyl-4,5-dihydrofuranol- (3) -one- (4). ao from the catalyst used, but this compound has valuable organoplic general optimal results when in properties and is therefore used as a flavoring medium with a pH of about 7 to 8 for foods and beverages. will. The cyclization is carried out at a temperature. A known process for the preparation of 2.5- between 20 and 150 ° C, preferably dimethyl-4,5-dihydrofuranol- (3) -one- (4), but at the reflux temperature of the reaction in, ithamnose in the presence of piperidine acetate mixture under nitrogen or CO ₂ .
to be heated (see Proceedings American Society The hexane to be used as starting material Brewing Chemists [1963], p. 84). However, since rhamdiol- (3,4) -dione- (2,5) can be obtained by reducing nose is a relatively expensive natural product that can only be found in pyruvaldehyde, for example with stannous chloride, Small insufficient quantities are available, it is sodium formaldehyde sulfoxylate or a metal in 30 not a suitable starting material for the industrial form of chips or in powder form, for example Production of the mentioned dihydrofuran derivative. Tin, zinc, cadmium or iron, in the presence of Another known method for the production of hydrochloric acid, sulfuric acid or acetic acid, wherein gevon 2,5-dimethyl-4,5-dihydrofuranol- (3) -one- (4) powdered zinc together with acetic acid is preferably acetylformion to hydrogenolyze, in 35 is obtained. The reduction can be done in hydrodem the latter with hydrogen in the presence of philic solvents such as methanol, ethanol, isoeines palladium-carbon catalyst and propanol or preferably water, at temperatures of the crude product by chromatography on SiO ₂ from 20 to 100 ° C, preferably at about 40 cleans (see. Helvetica Chimica Acta, Vol. 49, p. 53 to 50 ° C, can be made.
[1966]). The yield of pure product is only 40. The hexanediol- (3,4) dione- (2,5) can also be obtained by about 10% of theory. catalytic oxidation of 2,5-dimethyl-2,5-dimeth- Another known method for the preparation of oxy-3,4-dihydrofuran according to Bulletin Societe Chimivon 2,5-dimethyl-4,5-dihydrofuranoI- (3) -one- (4) beque de France, p. 997 (1957) produce,
is in it, 2,5-dihydroxymethyl-3,4-dibenzoxyfuran. Furthermore, the hexanedioI- (3,4) -dione- (2,5) can also to be catalytically hydrogenated (cf. Journal of Organic 45 by oxidation of acetol by means of a stream of air Chemistry, Vol. 31, p. 2391 [1966]). The essential r in a <* jepufferten aqueous solution at a tem-drawback to this method is that the synchronous werthese obtained temperature between 40 and about 150 ⁰ C of the intermediate, the 2,5-dihydroxy the. At higher temperatures in this range, methyl-3,4-dibenzoxyfurans, four chemical processes, must carry out the oxidation under pressure; In addition, the total working temperature is preferably at about 90 ° C and with the desired product only about 6.5% with a pH value between 5 and 6,
the theory. All these methods described above are un- Example 1 economical laboratory methods necessary for the preparation of a solution of piperidine acetate which thereby Preparation of the dihydrofuran derivative mentioned in 55 has been prepared by adding 1.49 g of acetic acid and are useless on an industrial scale. then 1.2 ml of piperidine to 17 ml of water dropwise It has now been found that the 2,5-di- is added, the temperature being kept below or at methyl-4,5-dihydrofuranol- (3) -one- (4) at economic 20 ° C 2.85 g lightly under nitrogen and in significantly better yields of hexanediol- (3,4) -dione- (2,5), which, as indicated below, is obtained by adding hexanediol- (3,4) -dione- ( 2.5) 60 has been prepared according to (a) or (b), added, in the presence of a salt of an organic carbon- Then the mixture is heated under reflux for one week acid with an organic nitrogen base or in a nitrogen atmosphere and then neutral or acidic alkali metal salt of a mineral acid between 0 and 10 ° C by means of a 4 ⁿ / o strength aqueous catalyst using water and NaOH solution. Then the whole thing is extracted continuously with ether with a pI-Herl of ( to 9 and a temperature of 65 overnight. The 20 to 150 "C. Combined ethereal extracts (250 ecm) are cyclized Those to be used as cyclization catalysts - dried over sodium sulfate and then to dryness Evaporated salts of an organic carboxylic acid with a, 1.85 g of crude 2,5-dimethyl-4,5-