DE3309564A1 - Process for the preparation of 5-acetoxymethyl furfural - Google Patents

Abstract

5-Hydroxymethyl furfural can be isolated from solutions containing dimethyl sulphoxide in the form of 5-acetoxymethyl furfural, which has greater volatility and can be distilled without decomposition, when the acetylation step is carried out using acetic anhydride in the presence of 4-dialkylaminopyridine. Due to its reactive groups, the acetoxy compound as well as the hydroxy compound on which it is based can be used as an intermediate for a variety of purposes which is accessible from hexoses and thus from renewable raw materials.

Description

HOECHST AKTIENGESELLSCHAFT HOE 83 / F 040 Dr.KL / mü

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Process for the production of 5-acetoxymethyl-furfural

Due to its reactive groups, 5-acetoxymethyl-furfural is, like the underlying 5-hydroxymethyl-furfural, a versatile intermediate product (Informations Chemie 214 (Special June 1981 > 203-209). These compounds have recently gained interest because 5 -Hydroxymethyl-furfural can be obtained by dehydrating Hcxosen and thus from renewable raw materials.

Preferred starting materials for this dehydration reaction are technical ones containing fructose and fructose Products like the so-called fructose syrups made by enzymatic Isomerization of corn starch are available. Dehydration works particularly well in polar solvents, in particular dimethyl sulfoxide, at temperatures from 50 to 180 C in the presence of acidic catalysts, especially high molecular weight acidic compounds (JP-OSS 79/154 757 and 81/139 473).

The isolation of the 5-hydroxymethylfurfural thus obtained from the solutions obtained in this way, however, is difficult and requires a multi-stage extraction (J. Chem. Tech. Biotechnol. 31 (1981) 135; DE-OS 30 33 527). Since the compound tends to self-condense during distillation (Rev. Pure Appl. Chem. 14 (1964) 161), the distillation is very expensive and requires special equipment measures (Die Starke 29 (1977) 99; U.S. Patent 2,994,645), if appropriate with the addition of a diluent (US Pat. No. 3,201,331).

A separation from the reaction solutions in the form of the more volatile, undecomposed distillable acetoxy derivative fails because 5-hydroxymethylfurfural with acetic anhydride in dimethyl sulfoxide at 8O ⁰ C 76 % furan-2,5-dialdehyde and 9 % 5- (methylthiomethoxy) -methyl-furfural forms (Noguchi Kenkyusho Jiho 22 (1979) 20; CA. 92: 198 18iaO-

BATH ORIGINAL '

It has now been found that 5-acetoxymethyl-furfural from Solutions of 5-hydroxymethylfurfural containing dimethyl sulfoxide can be produced if you use the acetylation Acetic anhydride in the presence of a ^ —Dialkylaminopyridine performs.

Particularly suitable 4-dialkylaminopyridines are those which carry two - preferably identical - lower alkyl groups which can also be linked to form a 5- to 7-membered ring, optionally including a hetero atom such as oxygen or nitrogen. Such compounds are described in DE-OS 2,517 77 ² J. IJ-Dimethyl ami no-pyridi η is particularly preferred.

The acylation reaction is slightly exothermic and may range from -20 to 8O ⁰ C, preferably from 0 up to 60 ° C, especially at 15 to 30 ⁰ C. The amount of 4-dialkylaminopyridine added is 0.001 to 1, preferably 0.01 to 0.5, in particular 0.01 to 0.1 mol %.

The use of 4-dialkylamino-pyridines as acylation catalysts is known per se (Ang. Chera. 90 (1978) 602) and is particularly sensitive to acylation Groups recommended. However, it was not to be expected that in the present case the known oxidation of the primary Alcohol group to the aldehyde group by the dimethyl sulfoxide (J. Amer. Chem. Soc. 85 (1963) 3027) is practically completely suppressed could be. The same applies to the well-known side reaction of dimethyl sulfoxide with the alcohol group ("dimethyl sulfoxide", Dieter Martin, Hermann G. Hanthal; Akademie- • verlag Berlin, 1981, p. 281).

For work-up, the reaction solution is removed from the solid catalyst separated off, for example by filtration or decanting, the dimethyl sulfoxide, advantageously under reduced Print and thin layer, for example in one Rotary evaporator, distilled off and the residue in Vacuum fractionated. 5-Acetoxyrriothyl-furfural also boils

BAD ORlGJI ^ ^f

a pressure of 0.13 to 0.4 mbar in the range from 91 to 95 ⁰ C. \

It can be recrystallized from water for purification. <

The separated acidic catalyst and the recovered ί

Dimethyl sulfoxide can be used again for a new batch: '

can be used. In the following example, the acidic [

Catalyst the commercial product NAFION 501-N from DuPont *

de Nemours, Wilmington / DE, USA. Other suitable L

Products are in the German Offenlegungsschrift 3 033 527,;:

the above Japanese laid-open publications, the - ';}

published European application 56 698 and in ||

Ind. Eng. Chem., Prod. Res. Dev. 14 (1975) 40 mentioned. «

On the basis of this information it follows for the expert,; what other acidic resins are also suitable. . ;

Example j- Preparation of the starting solution:

150 ml of dimethyl sulfoxide are heated with stirring to 80 C ER- i and 100 g fructose added. The heating continues

13O ⁰ C, gives 2 g to the acid catalyst and stirred for 2 STUN ■

den-at 130 ^° C. The reaction solution is then left i. cool to 2O ⁰ C.

Acylation :

0.5 g of 4-dimethylaminopyridine is added to the reaction solution thus obtained, and the mixture is stirred for a further hour. After filtering off the catalyst, the dimethyl sulfoxide is
Rotary evaporator withdrawn and Äcr residue at 0.13 to
0.4 mbar fractionated. The 5-acetoxymethyl-furfura3 goes with
91 to 95 C above. After recrystallizing from water
65 g of pure product of melting point 55 ⁰ C. (70% of
Theory, based on fructose)

Instead of 4-dimethylaminopyridine, another
the 4-dialkyl aminopyridines mentioned in DE-OS 2,517,774
can be used.

Claims (1)

~ ^ 33 09 5 6 A HOE 83 / F 040 Patent claims : 1./Process for the production of 5-acetoxymethyl-furfural j s from solutions of 5-hydroxy j containing dimethyl sulfoxide methyl-furfural, characterized in that the j Acetylation with acetic anhydride in the presence of a ^ J-Di- I alkylamino-pyridines. ■ j 2. The method according to claim 1, characterized in that | the ^ -Di alkyl ami no-pyridi η ^ -Dimethylamino-pyridine is. j 3 · The method of claim 1 or 2, characterized in that the reaction j in the range of -20 to 80 ^0C carried I leads is. j H. Process according to Claims 1 to 3, characterized in that the reaction is carried out at 0 to 60 ° C. 5. The method according to claim 1 to 4, characterized in that; that the reaction at 15 to 3O ⁰ C takes place. ; 6. The method according to claim 1 to 5, characterized in that 0.001 to 1 mol % of the ² l-dialkylamino-pyridines are added per mole of 5-hydroxymethyl-furfural. 7. The method according to claim 1 to 6, characterized in that 0.01 to 0.5 mol % of 4-dialkylamino-pyridiη are added per mole of 5-hydroxymethyl-furfural. 8. The method according to claim 1 to 7, characterized in that 0.01 to 0.1 mol % of Jj-dialkylamino-pyridi η are added per mol of 5-hydroxymethyl-furfural.