JP3282386B2 - Method for producing piperonal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing piperonal (heliotropin) in high yield by oxidizing 3,4-methylenedioxymandelic acid. Piperonal is a blended base material for heliotrope-based fragrances, is widely used as general cosmetic fragrances, and is a very useful compound as a raw material for synthesizing pharmaceuticals and agricultural chemicals and as a brightener for metal plating.

[0002]

2. Description of the Related Art As a method for producing piperonal by oxidizing 3,4-methylenedioxymandelic acid, a method of oxidizing with dilute nitric acid in the presence of a silver benzoate-iodine complex salt (PS Raman Current Science, 1958, 27, 22)
Or oxidation with nitric acid at a reaction temperature up to 100 ° C (Pe
rfumer & Flavorist, 14 , 13 (1989)). However, none of these methods has a high yield of piperonal, and furthermore, because nitric acid is used to oxidize 3,4-methylenedioxymandelic acid, nitrogen oxides by-produced from nitric acid are discarded. Or have to be recovered and regenerated to nitric acid. As a general treatment method of nitrogen oxides, for example, a method of decomposing into nitrogen or the like using a denitration catalyst, a method of adsorbing and disposing by an adsorbent, and a method of absorbing and dissolving in water or alkali are known. However, each of these treatment methods has problems with the service life of the denitration catalyst, the decomposition efficiency of nitrogen oxides, the adsorbing ability of the adsorbent, the post-treatment of the adsorbent, the treatment of wastewater, and the treatment of generated salts. Not always satisfactory. Regeneration of nitrogen oxides into nitric acid is also complicated and not easy.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method for producing piperonal by oxidizing 3,4-methylenedioxymandelic acid, which solves the complicated problem associated with the treatment of by-produced nitrogen oxides. It is an object of the present invention to provide an industrially suitable piperonal production method capable of producing piperonal in a high yield.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to convert 3,4-methylenedioxymandelic acid with nitrate and / or nitrite in the presence of sulfuric acid in the presence of a mixed solvent consisting of water and an organic solvent. This is achieved by a method for producing piperonal, which is characterized by oxidizing.

Hereinafter, the present invention will be described in detail. 3,4-
Methylenedioxymandelic acid is produced, for example, by a known method of reacting 1,2-methylenedioxybenzene derived from catechol with glyoxylic acid.

[0006] Sulfuric acid is used in an amount of usually 0.01 to 10 mol, preferably 0.5 to 3 mol, per 1 mol of 3,4-methylenedioxymandelic acid. If the amount of sulfuric acid used is too large, side reactions (such as the production of piperonyl acid) will proceed, reducing the selectivity for piperonal and reducing the quality of the product. In addition, it is preferable to use sulfuric acid usually diluted with water in order to suppress a side reaction.

In the present invention, nitrates and / or nitrites are used as oxidizing agents to oxidize 3,4-methylenedioxymandelic acid to piperonal. Preferable examples of the nitrate include nitrates of alkali metals such as sodium nitrate and potassium nitrate.
Preference is given to nitrites of alkali metals such as sodium nitrite and potassium nitrite. These nitrates and nitrites may be used alone or as a mixture.
Further, in the present invention, nitrates and nitrites recovered from by-produced nitrogen oxides as described later can be reused as oxidizing agents without discarding them as nitrates and nitrites.

[0008] The nitrates and / or nitrites are usually used in a slight excess of the stoichiometric amount. That is, the nitrate is 3,
Normally, 0.67 to 0.9 mol, preferably 0.67 to 0.9 mol, per mol of 4-methylenedioxymandelic acid is used alone.
0.85 mol is used. Nitrite is usually used alone in an amount of 2 mol per mol of 3,4-methylenedioxymandelic acid.
３3 mol, preferably 2-2.7 mol. When a mixture of nitrate and nitrite is used, the total mole number of 1 / 0.67 times mole of nitrate and 1/2 times mole of nitrite is not less than 3,4-methylenedioxymandelic acid. I just need. If too much nitrate or nitrite is used, side reactions (such as the production of piperonyl acid) will proceed, reducing the selectivity for piperonal and reducing the quality of the product.
On the other hand, if the amount used is small, the reaction is not completed. The nitrate and nitrite may be in any form as long as the required amount can be present in the reaction system, whether a solid or an aqueous solution. Although the concentration of this aqueous solution is not particularly limited, it is preferable to use a saturated solution in order to shorten the time of dropping when the reaction is performed by dropping an aqueous solution of nitrate and / or nitrite, as described later.

In the present invention, the reaction is carried out in a water-organic solvent two-phase system. By performing the reaction in a two-phase system of water-organic solvent, side reactions can be suppressed and the yield of piperonal can be improved, and piperonal can be transferred into an organic solvent, and after the reaction, a liquid separation operation can be performed as it is. Or an extraction operation is performed by adding the same organic solvent as the reaction solvent to facilitate separation and purification of the product.

Examples of the organic solvent include organic solvents which are stable against oxidation and nitration and are hardly mixed with water. Specifically, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, chlorobenzene, n-hexane, n-heptane, n-octane, aliphatic hydrocarbons such as n-decane, cyclohexane, cycloheptane, Alicyclic hydrocarbons such as cyclooctane, ethers such as diisopropyl ether and dibutyl ether, ethyl acetate,
Examples thereof include esters such as butyl acetate, and aliphatic halogenated hydrocarbons such as chloroform and carbon tetrachloride. Among them, toluene, xylene and ethylbenzene are most preferred.

These organic solvents are usually used in an amount of 0.1 to water.
Used in a volume ratio of 10 to 10, preferably 0.2 to 5, and the reaction solvent comprising water and an organic solvent is usually 0.1 to 1 with respect to 1 g of 3,4-methylenedioxymandelic acid.
0 ml, preferably 1-5 ml, is used.

The reaction of the present invention is usually carried out at normal pressure, from 0 to 10
At a temperature of 0 ° C., preferably 30-60 ° C., for example 3,
This is carried out by slowly adding dropwise an aqueous solution of nitrate and / or nitrite to a suspension of 4-methylenedioxymandelic acid, sulfuric acid, water and an organic solvent with stirring. The reaction temperature and the reaction rate can be adjusted by adjusting the dropping rate of the aqueous solution, but the dropping rate is not particularly limited as long as the reaction temperature can be maintained in the above range, and the dropping is usually completed in 1 to 2 hours. Can be done. The reaction atmosphere is not particularly limited, but usually an atmosphere of an inert gas such as nitrogen or argon is preferable.

In the present invention, nitrates and nitrites recovered by absorbing nitrogen oxides by-produced in the reaction into alkalis can be reused as an oxidizing agent for the oxidation of 3,4-methylenedioxymandelic acid. . As a result, the above-mentioned complicated problems associated with the treatment of nitrogen oxides (such as the life of the denitration catalyst and the decomposition efficiency of nitrogen oxides, the adsorbing ability of the adsorbent and the post-treatment of the adsorbent, the treatment of wastewater and the Treatment) can be avoided and the need to regenerate nitric acid from nitrogen oxides is eliminated. Further, since nitrogen oxides can be recovered without being discarded, the unit consumption of nitrogen can be improved.

In the recovery of nitrate and nitrite, the produced nitrogen oxide is brought into contact with air to oxidize nitrogen monoxide contained therein to nitrogen dioxide, and then a mixed gas of nitrogen dioxide and air is passed through an aqueous alkaline solution. This is accomplished by producing nitrate or nitrite. At this time, air is usually used in an amount of 2 to 20 times the volume of nitrogen oxides. In this range, when the proportion of air is high, a large amount of nitrate is generated, and when it is low, a large amount of nitrite is generated. As described above, it is preferable that the air is in excess with respect to the nitrogen oxides. If the air is insufficient, the oxidation of nitric oxide becomes insufficient, and the recovery of nitrate and nitrite decreases.

Examples of the alkali include hydroxides, carbonates and hydrogen carbonates of alkali metals such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate.
The alkali is usually used as an aqueous solution in an amount of 1 to 10 moles, preferably 1 to 2 moles, per 1 mole of nitrogen oxide. When using an aqueous solution of sodium hydroxide, the concentration of sodium hydroxide is usually 5 to 40% by weight, preferably 10 to 40% by weight.
３０30% by weight.

If the temperature at which the nitrogen oxides are absorbed by the alkali is too high, the absorption will be insufficient, and if it is too low, the aqueous solution will solidify and cause problems such as blockage of the conduit. Preferably it is -10 to 10C.
The nitrate or nitrite thus recovered can be reused in the form of an aqueous solution without any separation for the oxidation of 3,4-methylenedioxymandelic acid. At this time, the alkali remains in the aqueous solution. Can also be used without any problem as long as the alkali concentration allows sulfuric acid to exist in a predetermined amount.

As described above, piperonal can be produced in the organic solvent. The target piperonal is, for example, separated from the organic layer and the aqueous layer, and if necessary, the piperonal in the aqueous layer is also extracted with the organic solvent used for the reaction, followed by distillation and / or recrystallization with methanol or the like. Purified by the known method of

[0018]

Next, the present invention will be described specifically with reference to examples. Example 1 In a reactor (500 ml glass four-necked flask), 122 g of water and 55% by weight of 97% by weight sulfuric acid were added at 0 ° C. in an argon stream.
g (0.54 mol), 45.6 g (0.23 mol) of 3,4-methyleneoxymandelic acid and 75 ml of toluene were added and mixed. After heating this mixed solution to 50 ° C., 15.3 g of sodium nitrate was used as an oxidizing agent while stirring.
(0.18 mol) in 16 ml of water was added dropwise over 2 hours. After the dropping of the aqueous solution of sodium nitrate was completed and gas generation was no longer observed, the reaction solution was further stirred for 30 minutes. Nitrogen oxides generated during the reaction were introduced into an oxidation tank (500 ml glass four-necked flask) and mixed with 400 ml / min of air, and then an absorption tank containing 86.4 g of a 10% by weight aqueous sodium hydroxide solution. (500m
l-glass four-necked flask).

After the completion of the reaction, the reaction solution was cooled to room temperature, and piperonal produced by adding 75 ml of toluene (extraction solvent) was completely transferred to the toluene layer. Next, the toluene layer and the aqueous layer were separated, and the toluene layer was analyzed by gas chromatography using n-pentadecane as an internal standard. The aqueous sodium hydroxide solution having absorbed the nitrogen oxides was analyzed by ion chromatography. As a result, the toluene layer contained 33.84 g of piperonal (3,3).
Yield based on 4-methylenedioxymandelic acid: 96
%) And the conversion of 3,4-methylenedioxymandelic acid was 100%. The aqueous sodium hydroxide solution contains 7.7 g (0.09 mol) of sodium nitrate and 6.2 g (0.09 mol) of sodium nitrite.
The recovery of the oxidant was 100%. In addition, the yield, the conversion, and the recovery were each calculated on a molar basis.

Example 2 In Example 1, the oxidizing agent was sodium nitrite.
The reaction was carried out in the same manner as in Example 1, except that 7 g (0.58 mol) was changed to a solution of 69 ml of water. Table 1 shows the results.

Example 3 In Example 1, the oxidizing agent was changed to 7.7 g of sodium nitrate.
(0.09 mol) and 19.9 g of sodium nitrite (0.
29 mol) in 43 ml of water.
The reaction was carried out in the same manner as in Example 1. Table 1 shows the results.

Example 4 In Example 1, the oxidizing agent was sodium hydroxide containing 7.7 g (0.09 mol) of sodium nitrate recovered in Example 1 and 6.2 g (0.09 mol) of sodium nitrite. After concentrating the aqueous solution to 35 g, sodium nitrate was further added to 3.4 g.
The reaction was carried out in the same manner as in Example 1 except that g (0.04 mol) was dissolved. Table 1 shows the results.

[0023]

[Table 1]

[0024]

Industrial Applicability According to the present invention, piperonal can be produced in high yield while efficiently recovering by-product nitrogen oxides as nitrates and nitrites and reusing them in oxidation reactions. As a result, there is no need to regenerate the nitrogen oxides into nitric acid without the need for complicated problems associated with the disposal of nitrogen oxides as described above, and since the basic unit of nitrogen can be improved, It is possible to provide an economical and excellent method for producing piperonal.

────────────────────────────────────────────────── (56) References US Patent 5,095,128 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07D 317/00-317/68 CA (STN) REGISTRY ( STN)

Claims (2)

(57) [Claims] 1. A process for producing piperonal, comprising oxidizing 3,4-methylenedioxymandelic acid with nitrate and / or nitrite in the presence of sulfuric acid in the presence of a mixed solvent comprising water and an organic solvent. Method. 2. A method in which nitrogen oxide by-produced is brought into contact with air to produce
After oxidizing nitric oxide to nitrogen dioxide, this nitrogen dioxide
Nitrate and gas mixture with air
Generates nitrite and converts the nitrate and nitrite to an oxidizing agent
The pipe according to claim 1, wherein the pipe is reused.
A method for producing peronal.