DE1668957C - Process for the production of maltol - Google Patents

Description

Although it is from the in Chemical Abstracts, Vol. 42 According to Example 1, 10.0 g of 6-methylkomen-

(1948), 3 to col. 1 Sp. 566, Abs., 567 Abs, beschriebe- acid and 40 cc Diäthylenglykoldibutyläther 45 mines work known Komen acid using 60 utes to 230 to 245 ^'1 C heated, and the mixture is of copper powder in a stream of carbon dioxide by long - then as described in Example 1, res heating to decarboxylate, but it is then the resulting distillate is then cooled to 25 ° C, surprisingly, that the inventive maltol is filtered off, this Dissolved in a 30 cm process without a catalyst and in much hot water, the solution filtered while hot and carried out successfully for a shorter period of time. 65 cooled to 10 ^{0 C.}

In the process according to the invention, the maltol which then crystallizes out is separated off

moderately the 6-methylcomic acid in about 2 to and in the air dried. The connection is melting about 5 parts by weight of dimethyl phthalate, diethylene at 160 to 161.5 ° C. By further narrowing the

Filtrate to a third of its volume and filtering off the crystalline precipitate , a further amount of maltol with a melting point of 158 to 160 ^° C. is obtained. The overall yield of maltol is 45%.
Be above 25 cc * -Methylnaph Thalin used instead of the 40 cc Diäthylenglykoldibutyläther, NEN yields the maltol after recrystallization, mp 160 to 161.5 "C ¹ in a yield of 32%. Some maltol was during the distillation by Burn lost.

Claims (1)

glycol dibutyl ether, "-Methylnaphthalin as decar- Piitentansnriirh · boxylating solvent suspended and then the ^{p The} suspension is heated to 250 ° C. with stirring. At a Temperature of about 150 ⁰ C, the acid almost Komen Process for the production of maltol, there is completely dissolved, and at about 220 ⁰ C a violent occurs, characterized by the fact that 6-Me carbon dioxide is generated. If the temperature of thylkomic acid in dimethyl phthalate, diethylene- 'is gradually increased to glycol dibutyl ether or α-methylnaphthalene than 250 ° C. in the course of about 20 to 25 minutes, then practically no solvent develops and the mixture then develops more carbon dioxide. heated to a temperature of about 250 ° C. io The 6-methylcomic acid to be used as the starting material can, for example, by reacting comenic acid with formaldehyde in an alkaline medium with formation of 6-hydroxymethylcomic acid, Halo- generation of these to 6-halomethylkomenic acid and 15 reduction "of the latter can be obtained. The 6-methylcomic acid can also be made from kojic acid by reacting with formaldehyde in the presence of alkali Formation of 6-hydroxymethylkojic acid, reduction So far, maltol has been used in limited quantities to produce 6-methylkojic acid and to oxidize the latter difficult and costly extraction processes can be obtained from 20 to 6-methylcomic acid, or the Made of natural products. The industrial maltol-kojic acid can be produced with formaldehyde and a secondary production depends e.g. B. from the dry distillation of ren amine to a Ν, Ν-disubstituted 6-aminome-Holzab, it is known that these pyrolysis reactions are converted into thylkojic acid, this to 6-methylkojic acid generally give only low yields of maltol. reduced and the latter to 6-methylcomic acid oxy-Ferner such isolation processes are efficient. moderately from the total amount of easily accessible that produced by the process according to the invention Raw material dependent. Finally, the maltol provided by the product is particularly suitable for use with such a dry distillation obtained maltol as a taste and aroma improver,
agreed impurities, eliminating its use
as a flavor enhancer is impaired. 30 B is ρ ie I 1 It is also known to make maltol from chlormaltol Reduction with zinc / glacial acetic acid (Journal of the American In a 25 cm c three-necked round bottom flask with mechanical Chemical Society, Vol. 73 [1951], pp. 5912 and 5913) or a stirrer, thermometer and short distillation from Pyromeconic acid by condensation with a formal head, which with a round-bottom flask as a collecting vessel, desehyd / piperidine and subsequent hydrogenation of which is bound, 3.0 g (0.012 mol) of 6-methylkomenhaitenen are obtained Mannich base in the presence of palladium acid (mp 237.5 to 238 "C) in 12 ecm dimethyl phthalate (Journal of the American Chemical Society, vol. 69 suspended, and the suspension is stirred and charged [1947], P. 2908). heats. As soon as a temperature of 150 "C has been reached These procedures result in only little to moderate exertion, most of the 6-methylcomic acid is in booty on maltol. 40 solution gone. At a temperature of about The invention now enables the synthetic production of 215 ⁰ C, a strong evolution of carbon dioxide sets in, position of maltol from 6-methylcomic acid, which lasts about 15 minutes. Then allowing the turn, ie increase of kojic acid of a substance, the external temperature to 250 ⁰ C, cooled then easily in large amounts from technical fermentation process, the mixture to about 100 ° C, and distilled this and other starting compounds obtainable, 45 under a Pressure of about 20 mm at an outside can be made. The present invention manufactured temperature of 180 to 250 ⁰ C, wherein the distillation is presented maltol, until only very little usually remains free of impurities, as is continued in the gewon- by dry distillation in the piston material. Most of the distilled maltol are present. It provides much more prominent at a temperature of 140 to 150 ⁰ C. The better yields than the previously known methods. 50 distillate is then ^{cooled to 150 0} C, the It has now been found that maltol is sucked off in a simple manner, crystalline product precipitated in this way, in better yields and in a purer form, and washed with 5 ecm of ethyl acetate and then obtained that 6 -Methylkomenic acid in dehydration. The maltol obtained has a melting point of 157 to 160 "C methyl phthalate, diethylene glycol dibutyl ether or a yield of 51% of theory.
<\ - methylnaphthalene suspended as a solvent and 55 then the mixture up to a temperature of about Example 2 250 "C heated.