JP4910383B2 - Process for producing α-methyl-1,3-benzenedioxol-5-propanal - Google Patents

Description

  The present invention relates to a process for producing α-methyl-1,3-benzenedioxol-5-propanal useful as a fragrance.

  As a method for producing α-methyl-1,3-benzenedioxole-5-propanal, Patent Document 1, Patent Document 2, Patent Document 3 and Non-Patent Document 1 describe a method for producing safrole or isosafrole by hydroformylation. However, there is a safety problem in using carbon monoxide, and the yield is about 30%, which is not sufficient. Another problem was the formation of isomers that were difficult to separate.

  Non-Patent Document 2 describes a production method by Heck reaction using 4-bromo-1,2-methylenedioxybenzene and β-methylallyl alcohol as raw materials. There wasn't.

  Patent Document 4 describes a production method by reduction of piperonylidenepropanal. However, an alcohol compound in which the target α-methyl-1,3-benzenedioxol-5-propanal is further reduced is disclosed. This was difficult to separate during purification. Piperonylidenepropanal used in the production method is produced from isosafrole by condensation of heliotropin and propanol in Non-patent Document 3 and Patent Document 5 and by Vilsmeier reaction in Patent Document 6. However, the former has low selectivity and low yield (yield of about 30 to 50%), and the latter has a problem that a large amount of phosphorus waste is produced as a by-product.

Patent Document 7 discloses a process for producing 1-acetoxy-3- (3,4-methylenedioxyphenyl) propene that can be derived into α-methyl-1,3-benzenedioxol-5-propanal. Although described, there is no description on an industrial production method from methacrolein to α-methyl-1,3-benzenedioxol-5-propanal.
JP-A-53-137963 JP-A-54-9271 German patent invention No. 2235466 Japanese Patent Publication No. 48-1380 U.S. Pat. No. 2,102,965 JP-A-10-120673 International Publication No. 04/054997 Pamphlet C1 Mol. Chem. 1985, p. 213 Journal of Organic Chemistry. 1976, 41, p. 1206 Am. Perfumer. 1930, p. 617

  Provided is an industrially suitable production method for easily and yielding α-methyl-1,3-benzenedioxol-5-propanal useful as a fragrance by an environmentally friendly method with little waste That is.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention are friendly to the environment of α-methyl-1,3-benzenedioxol-5-propanal useful as a fragrance, simple and good in yield. An industrial production method was found and the present invention was completed.
That is, the present invention relates to a method for producing α-methyl-1,3-benzenedioxole-5-propanal comprising the following steps.
(1) Periodic table 11 to 13 methacrolein and carbon in the presence of a catalyst containing at least one compound selected from the group consisting of triflate compounds and halogen compounds and boron halides of group 11-13 elements, tin and lanthanoid elements A first step of synthesizing 3,3-dialkylcarbonyloxy-2-methyl-propene by reacting with a carboxylic acid anhydride of formula 1-10.
(2) Next, the 3,3-dialkylcarbonyloxy-2-methyl-propene obtained in the first step is reacted with 1,2-methylenedioxybenzene in the presence of the same catalyst as in the first step. Second step of synthesizing 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene.
(3) A third step in which the reaction solution in the second step is washed with water to remove the catalyst.
(4) 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene obtained through the third step is reacted with alcohol in the presence of a base to produce α-methyl- Fourth step for producing 1,3-benzenedioxole-5-propanal.

  INDUSTRIAL APPLICABILITY According to the present invention, there is provided not only a simple and good yield of α-methyl-1,3-benzenedioxol-5-propanal useful as a fragrance but also an environmentally friendly industrial production method with little waste. can do.

According to the present invention, waste is reduced by a method for producing α-methyl-1,3-benzenedioxol-5-propanal comprising the following steps (1) to (4), and it is simple and good in yield. α-methyl-1,3-benzenedioxole-5-propanal can be produced.
(1) In the presence of a catalyst containing a compound containing at least one selected from the group consisting of triflate compounds of 11 to 13 elements of element periodic table, tin and lanthanoid elements, halogen compounds, and boron halides; A first step of synthesizing 3,3-dialkylcarbonyloxy-2-methyl-propene by reacting with a carboxylic acid anhydride having 1 to 10 carbon atoms.
(2) Next, the 3,3-dialkylcarbonyloxy-2-methyl-propene obtained in the first step is reacted with 1,2-methylenedioxybenzene in the presence of the same catalyst as in the first step. Second step of synthesizing 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene.
(3) A third step in which the reaction solution in the second step is washed with water to remove the catalyst.
(4) 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene obtained through the third step is reacted with alcohol in the presence of a base to produce α-methyl- Fourth step for producing 1,3-benzenedioxole-5-propanal.

  As the methacrolein used in the first step, a commercially available product can be used. For example, paraformaldehyde and propionaldehyde are reacted in the presence of an aqueous solution of a secondary amine mineral salt adjusted to pH 2-5. Can also be manufactured.

  Here, secondary amine mineral salts include dimethylamine, diethylamine, di-n-butylamine, methylethylamine, methyl-n-butylamine, diphenylamine, diethanolamine, methylethanolamine, morpholine, piperidine, piperazine, pyrazolidine, pyrrolidine, Examples of salts of secondary acids such as pyrazole and indole, such as hydrochloric acid, sulfuric acid, and phosphoric acid include mineral acids such as morpholine, such as hydrochloric acid, sulfuric acid, and phosphoric acid.

  The degree of polymerization of paraformaldehyde is not particularly limited, and trioxane can be used. Moreover, these can use a commercially available thing.

As a method for synthesizing the methacrolein, for example, a synthesis method including the following steps can be used.
(A) Step A in which an aqueous solution of a mineral salt of a secondary amine adjusted to a pH value of 2 to 5 with a mineral acid and a secondary amine is mixed with paraformaldehyde, and then heated to be completely dissolved.
(B) Step B, in which 1 to 100 times mol of propionaldehyde is added to the secondary amine mineral acid salt and refluxed to the mixed liquid obtained in Step A to generate methacrolein,
(C) Step C for isolating and purifying methacrolein produced in Step B by azeotropic distillation with water in the reaction solution,
(D) After the azeotropic distillation in step C, step D in which the residual distillation solution is subjected again to step A as an aqueous solution of a secondary amine mineral acid salt.

  The heating in Step A is 70 to 100 ° C., and the stirring time is preferably 5 minutes to 10 hours, and more preferably 10 minutes to 5 hours.

  The addition of propionaldehyde in Step B can be added all at once, but it is preferable to add it in portions or continuously add dropwise to the reaction solution. Here, dripping is 20 to 40 ml / min. The reflux time is 1 to 10 hours.

  The azeotropic distillation in step C can be carried out at an azeotropic temperature of 55 to 120 ° C, preferably 69 to 100 ° C.

  The methacrolein can be obtained by separating the mixed liquid of methacrolein and water obtained by the azeotropic distillation by an ordinary method such as liquid separation.

  In Step D, when the pH value of the distillation residual liquid after azeotropic distillation in Step C deviates from 2 to 5, the pH value is adjusted to 2 to 5 with the mineral acid or base used in the reaction, It is preferable to use again for A process as the aqueous solution of the secondary amine mineral acid salt.

As the catalyst used in the first step, a catalyst containing at least one compound selected from the group consisting of elemental periodic table group 11-13 elements, tin and lanthanoid element triflate compounds and halogen compounds, and boron halides is used. It is done.
Here, the name of the element group is the group 18 element periodic table, IUPAC inorganic compound nomenclature, 1990.
Based on the year.

Examples of the triflate compounds and halogen compounds of Group 11 elements of the periodic table include copper, silver and gold triflate compounds and halogen compounds. Copper, silver and gold triflate compounds are preferred, and copper triflate compounds are more preferred.
Here, “triflate” means trifluoromethanesulfonate.

As the triflate compounds and halogen compounds of Group 12 elements of the periodic table, zinc halides (zinc fluoride, zinc chloride, zinc bromide, zinc iodide), cadmium halides (cadmium fluoride, cadmium chloride, cadmium bromide) , Cadmium iodide), mercury halides (
Mercury fluoride, mercury chloride, mercury bromide, mercury iodide) and the like. Of these, zinc halides are preferred, and zinc chloride is more preferred.

Examples of triflate compounds and halogen compounds of Group 13 elements of the periodic table include boron triflate compounds and halogen compounds, with boron halogen compounds being preferred.
Boron halogen compounds include boron fluoride, boron trifluoride diethyl ether complex, boron trifluoride tetrahydrofuran complex, boron trifluoride acetic acid complex salt, boron trifluoride dihydrate, boron trifluoride n-butyl ether complex Among them, boron trifluoride diethyl ether complex and boron trifluoride acetic acid complex salt are preferable. These compounds can use commercially available products.

Examples of triflate compounds and halogen compounds of tin and lanthanoid elements include tin triflate, tin halides (tin fluoride, tin chloride, tin bromide, tin iodide), cerium halides (cerium fluoride, cerium chloride, odor Cerium iodide, cerium iodide), cerium triflate, dysprosium halide (dysprosium fluoride, dysprosium chloride, dysprosium bromide, dysprosium iodide), dysprosium triflate, holmium halides (holmium fluoride, holmium chloride, holmium bromide) , Holmium iodide), holmium triflate, erbium halide (erbium fluoride, erbium chloride, erbium bromide, erbium iodide), erbium triflate, thulium halide (thulium fluoride, Thulium bromide, thulium bromide, thulium iodide), thulium triflate, ytterbium halide (ytterbium fluoride, ytterbium chloride, ytterbium bromide, ytterbium iodide), ytterbium triflate, lutetium halide (lutetium fluoride, lutetium chloride) , Lutetium bromide, lutetium iodide), lutetium triflate and the like. Alternatively, these compounds include hydrates thereof.
Among these compounds, tin chloride, tin triflate, cerium triflate, erbium triflate, or ytterbium triflate is preferable.

  The usage-amount of the said catalyst is 1 mol or less with respect to 1 mol of methacrolein, Preferably it is 0.005-0.5 mol. If the amount used is less than this range, the reaction is not completed in 24 hours. If the amount is too large, complicated operations such as decomposition and disposal of an excessive amount of catalyst are required, and this is not suitable for an industrial scale.

  Examples of the carboxylic acid anhydride having 1 to 10 carbon atoms include acetic anhydride, propionic anhydride, and anhydride acid, and acetic anhydride is preferable.

  The usage-amount of a C1-C10 carboxylic acid anhydride is 1-10 mol with respect to 1 mol of methacrolein, Preferably it is 1-5 mol.

  The synthesis reaction of 3,3-dialkylcarbonyloxy-2-methyl-propene in this step is performed without solvent.

The reaction temperature varies depending on the type of raw material and the like, but is −10 to 80 ° C., preferably 0 to 50 ° C.
Although reaction time changes with the usage-amounts of said catalyst, a carboxylic acid anhydride, etc., and temperature, it is 0.5 to 24 hours.

  This step is usually performed in an inert gas atmosphere such as argon or nitrogen, or in a gas stream of these gases. The reaction pressure used is usually atmospheric pressure.

  The 3,3-dialkylcarbonyloxy-2-methyl-propene synthesized in the first step can be isolated and purified by a method such as distillation and used in the next step. It can also be used.

  A commercially available product can be used as 1,2-methylenedioxybenzene in the second step.

  The amount of methylenedioxybenzene used is 1 to 50 mol, preferably 1 to 20 mol, per 1 mol of 3,3-dialkylcarbonyloxy-2-methyl-propene.

  As the catalyst, the same catalyst as that used in the first step can be used.

  The usage-amount of a catalyst is 1 mol or less with respect to 1 mol of 3, 3- dialkyl carbonyloxy-2-methyl- propene, Preferably it is 0.01-0.5 mol. If the amount used is less than this, the reaction will not be completed in 24 hours. If the amount used is too large, complicated operations such as decomposition and disposal of an excessive amount of catalyst such as boron halide are required, which is not suitable on an industrial scale.

  The synthesis reaction of 1-alkylcarbonyloxy-3- (3,4-methylenedioxyphenyl) propene in the second step is carried out without solvent.

  The reaction temperature varies depending on the type of raw material, but is −10 to 80 ° C., preferably 0 to 50 ° C.

  The reaction time varies depending on the catalyst and the amount of 1,2-methylenedioxybenzene used, and the temperature, but is 0.5 to 24 hours.

  This step is usually performed in an inert gas atmosphere such as argon or nitrogen, or in a gas stream of these gases. The reaction pressure used is usually atmospheric pressure.

  When synthesizing 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene, 1,2-dialkylcarbonyloxy-2-methyl-propene is 1,2- When methylenedioxybenzene is used in excess, unreacted 1,2-methylenedioxybenzene can be recovered by distillation and used again as 1,2-methylenedioxybenzene in the second step.

The water washing in the third step is preferably 0.1 to 50 L of water with respect to 1 mol of the total amount of catalyst used in the first step and the second step, which is present in the reaction solution obtained in the second step. Is preferably 2 to 20 L. The number of washings and the washing time are appropriately selected.
After washing with water, the reaction solution containing 1-alkylcarbonyloxy-3- (3,4-methylenedioxyphenyl) propene does not require chromatographic purification means that are industrially low in productivity, and may be distilled or recycled. Although 1-alkylcarbonyloxy-3- (3,4-methylenedioxyphenyl) propene can be appropriately purified by means of crystallization, it can also be used in the next step without isolation and purification.

  This step is usually performed in an inert gas atmosphere such as argon or nitrogen, or in a gas stream of these gases. The reaction pressure used is usually atmospheric pressure.

  Examples of the alcohol used in the fourth step include a linear lower aliphatic alcohol having 1 to 8 carbon atoms (methanol, ethanol, propanol, butanol, etc.), and a linear divalent lower aliphatic having 2 to 8 carbon atoms. Alcohol (ethylene glycol, propylene glycol, etc.) is used. Methanol, ethanol, propanol, ethylene glycol and propylene glycol are preferred, and methanol, ethanol and ethylene glycol are more preferred. These alcohols can also be used as a mixture.

The usage-amount of alcohol is 1 mol-30 mol with respect to 1 mol of 1-alkylcarbonyloxy-3- (3,4-methylenedioxyphenyl) propene, Preferably it is 3-14 mol.
If the amount of the solvent used is lower than this range, the reaction is difficult to proceed and the yield is lowered. Further, if it is higher than this, the productivity is lowered.

  Bases include alkali metal carbonates or alkaline earth metal carbonates (lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, calcium carbonate, etc.), alkali metal bicarbonates (sodium bicarbonate, potassium bicarbonate, Cesium bicarbonate, etc.), alkali metal hydrides (lithium hydride, sodium hydride, potassium hydride, etc.), alkali metal alkoxides (sodium methoxide, sodium ethoxide, potassium ethoxide, potassium t-butoxide, etc.) , Alkali metal hydroxides or alkaline earth metal hydroxides (lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, etc.), preferably alkali metal carbonates, alkali metal Hydroxides or alkali metal alkoxides, more preferred Alkali metal carbonates and alkali metal alkoxides are used. Of the alkali metal carbonates, potassium carbonate is most preferred, and among the alkali metal alkoxides, sodium methoxide is most preferred. In addition, you may use these bases individually or in mixture of 2 or more types.

  The amount of the base used is preferably 0.001 to 1 mol, and more preferably 0.001 to 0. 1 mol per 1 mol of 1-alkylcarbonyloxy-3- (3,4-methylenedioxyphenyl) propene. 2 moles.

  When an alkali metal or alkaline earth metal hydroxide or carbonate is used as the base, it can also be used as an aqueous solution thereof. Moreover, when using an alkali metal alkoxide, it can also be used as an alcohol solution. The concentration of these solutions is preferably 2 to 50 weight percent.

  This step is performed without a solvent.

  The reaction temperature is 0 to 65 ° C, preferably 15 to 40 ° C.

  Although reaction time changes with the usage-amount of alcohol and a base, and reaction temperature, it is 0.5 to 24 hours. When the reaction time becomes longer, decomposition of the product α-methyl-1,3-benzenedioxol-5-propanal proceeds and the yield decreases. When the reaction time is short, the reaction is not completed.

  This step may be performed in the air, but is usually performed in an inert gas atmosphere such as argon gas or nitrogen gas, or in a gas stream thereof. The reaction pressure used is usually atmospheric pressure.

  The alcohol used in the fourth step can be recovered by distillation and used again as the alcohol in the fourth step.

  The synthesized α-methyl-1,3-benzenedioxol-5-propanal does not require industrially low-purity chromatographic purification means, and is neutralized, extracted and concentrated after completion of the reaction. It can be purified appropriately by distillation or recrystallization as necessary after usual post-treatment such as.

  Examples of the present invention will be described below.

Example 1
Under a nitrogen stream, 2039.2 g (20.0 mol) of acetic anhydride was added to a 20 L separable flask, and 3.0 g (0.02 mol) of boron trifluoride diethyl ether complex was added. 1000.0 g (14.3 mol) of methacrolein was dropped over 40 minutes at an internal temperature of 4 to 5 ° C., and the mixture was stirred at an internal temperature of 4 to 5 ° C. for 2 hours. When quantified by gas chromatography, the yield of 3,3-diacetoxy-2-methyl-propene was 2264.0 g (the yield was 92.1% based on methacrolein). Subsequently, 1,8711.7 g (71.3 mol) of 1,2-methylenedioxybenzene was added to the reaction solution, and 60.7 g (0.4 mol) of boron trifluoride diethyl ether complex was added at an internal temperature of 38 ° C. After stirring at 40 ° C. for 3 hours, the reaction mixture was quantified by high performance liquid chromatography. The yield of 1-acetoxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene was 2797.6 g (the yield was 83.7% based on methacrolein). The reaction solution was washed twice with 2200 mL of water, and 7,160 g of 1,2-methylenedioxybenzene was recovered from the organic layer under reduced pressure. Methanol 5485.5 g (171.2 mol) was added to the kettle residue, potassium carbonate 78.9 g (0.6 mol) was added at 25 ° C., and the mixture was stirred for 1 hour. Next, 85.7 g (1.4 mol) of acetic acid was added and stirred for 15 minutes, and then methanol was distilled off. The organic layer was washed with 2200 mL of water and distilled under reduced pressure to obtain 2191.6 g of α-methyl-1,3-benzenedioxol-5-propanal. The yield of α-methyl-1,3-benzenedioxole-5-propanal was 80.0% based on methacrolein.

Example 2
Under a nitrogen stream, 2039.2 g (20.0 mol) of acetic anhydride was added to a 20 L separable flask, and 29.2 g (0.2 mol) of zinc chloride was added. 1095.3 g (14.3 mol) of methacrolein was added dropwise at an internal temperature of 4 ° C. over 1 hour, followed by stirring at an internal temperature of 4 ° C. for 2 hours and 30 minutes. When quantified by gas chromatography, the yield of 3,3-diacetoxy-2-methyl-propene was 2385.0 g (the yield was 97.1% based on methacrolein). Subsequently, 1,871 g (71.3 mol) of 1,2-methylenedioxybenzene was added to the reaction solution, and 194.5 g (1.4 mol) of zinc chloride was added at an internal temperature of 18 ° C. The reaction solution was heated over 30 minutes and stirred at an internal temperature of 40 ° C. for 2 hours and 30 minutes. When the reaction solution was quantified by high performance liquid chromatography, the yield of 1-acetoxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene was 2731.0 g (yield was 81.6% based on methacrolein). Met. The reaction solution was washed three times with 2200 mL of water, and 5505.0 g (45.1 mol) of 1,2-methylenedioxybenzene was distilled off from the organic layer under reduced pressure. Methanol (5485.5 g, 171.21 mol) was added to the kettle residue, and the internal temperature was cooled to 0 ° C. 39.4 g (0.28 mol) of potassium carbonate was added and stirred at an internal temperature of 0 ° C. for 1 hour, and 19.7 g (0.14 mol) of potassium carbonate was further added and stirred at an internal temperature of 0 ° C. for 1 hour. Next, 77.1 g (1.28 mol) of acetic acid was added and stirred for 15 minutes, and then methanol was distilled off. The organic layer was washed with 2200 mL of water twice and distilled under reduced pressure to obtain α-methyl-1,3-benzenedioxol-5-propanal 2208.0 g and 1,2-methylenedioxybenzene 1406.0 g. Obtained. The yield of α-methyl-1,3-benzenedioxole-5-propanal was 80.5% based on methacrolein.

Example 3
Under a nitrogen stream, 1527.6 g (15.0 mol) of acetic anhydride was added to a 20 L separable flask, and 2.7 g (0.02 mol) of boron trifluoride diethyl ether complex was added. 919.0 g (12.5 mol) of methacrolein was added dropwise over 40 minutes at an internal temperature of 4 to 5 ° C., and the mixture was stirred at an internal temperature of 4 to 5 ° C. for 2 hours. When quantified by gas chromatography, the yield of 3,3-diacetoxy-2-methyl-propene was 2020.1 g (yield was 94.1% based on methacrolein). Subsequently, 761,3.7 g (62.4 mol) of 1,2-methylenedioxybenzene containing 1,2-methylenedioxybenzene recovered and obtained in Example 1 was added to the reaction solution, and boron trifluoride was added at an internal temperature of 38 ° C. Diethyl ether complex, 53.1 g (0.4 mol) was added. After stirring at 40 ° C. for 3 hours, the reaction mixture was quantified by high performance liquid chromatography. The yield of 1-acetoxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene was 2517.9 g (the yield was 86.2% based on methacrolein). The reaction solution was washed twice with 1900 mL of water, and 6040 g of 1,2-methylenedioxybenzene was recovered from the organic layer under reduced pressure. Methanol 4794.2 g (149.6 mol) containing the methanol recovered and obtained in Example 1 was added to the resulting residue, and 25.9 g (0.2 mol) of potassium carbonate was added at 25 ° C., followed by stirring for 1 hour 30 minutes. did. Subsequently, 28.1 g (0.5 mol) of acetic acid was added and stirred for 15 minutes, and then methanol was distilled off. The organic layer was washed with 1900 mL of water and distilled under reduced pressure to obtain α-methyl-1,3-benzenedioxol-5-propanal 1953.6 g. The yield of α-methyl-1,3-benzenedioxol-5-propanal was 81.5% based on methacrolein.

Reference example 1
49.08 g of water was placed in a 200 mL four-necked flask, and 15.0 g of 98.5 wt% sulfuric acid was added dropwise at an internal temperature of 15 ° C. under water cooling. Next, 26.40 g of 99.0 wt% morpholine was added dropwise. Further, 0.58 g of 98.5% by weight sulfuric acid was added to adjust the pH value to 2.6.
To this was added 32.64 g of 92.0% by weight paraformaldehyde, the temperature was raised to 80 ° C., and the mixture was heated and stirred for 90 minutes to make the reaction solution uniform. The internal temperature was lowered to 50 ° C., and 59.27 g of 98.0 wt% propionaldehyde was added dropwise. The temperature of the heating bath was raised to 80 ° C. and stirred for 2 hours, and then 63.2 mg of hydroquinone was added to the receiver in advance and distilled under normal pressure. The two-layer liquid in the obtained receiver was separated to obtain 68.37 g of an organic layer and 24.34 g of an aqueous layer. As a result of quantifying the organic layer by gas chromatography, methacrolein yield was 96.2% and propionaldehyde conversion was 98.8%.

Claims (4)

A method for producing α-methyl-1,3-benzenedioxol-5-propanal comprising the following steps.
(1) Periodic table of elements Methocrolein and carbon in the presence of a catalyst containing at least one compound selected from the group consisting of triflate compounds of 11 to 13 elements, tin and lanthanoid elements, halogen compounds, and boron halides A first step of synthesizing 3,3-dialkylcarbonyloxy-2-methyl-propene by reacting the carboxylic acid anhydride of Formula 1 to 10 without solvent .
(2) Next, without purifying the 3,3-dialkylcarbonyloxy-2-methyl-propene obtained in the first step, 1,2-methylenedioxybenzene and the same catalyst as in the first step without solvent are used. Second step of synthesizing 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene by reacting in the presence.
(3) A third step in which the reaction solution in the second step is washed with water to remove the catalyst.
(4) The 1-alkylcarbonyloxy-2-methyl-3- (3,4-methylenedioxyphenyl) propene obtained through the third step is reacted with alcohol in the presence of a base without solvent without purification. And a fourth step of producing α-methyl-1,3-benzenedioxole-5-propanal. The process for producing α-methyl-1,3-benzenedioxole-5-propanal according to claim 1, wherein the catalyst in the first step and the second step are the same. In the second step, unreacted 1,2-methylenedioxybenzene used in excess with respect to 3,3-dialkylcarbonyloxy-2-methyl-propene was recovered, and again 1,2-methylene in the second step. The method for producing α-methyl-1,3-benzenedioxole-5-propanal according to claim 1 or 2, which is used as dioxybenzene. The α-methyl-1,3-benzenedioxole- according to any one of claims 1 to 3, wherein the alcohol used in the fourth step is recovered and used again as the alcohol in the fourth step. 5-Propanal production method.