JPS5835193B2 - 3.4- Methylenedioxystyrene - Google Patents

Description

Detailed Description of the Invention The present invention involves methylenating p-ethylcatechol with dihalomethane and a caustic alkali to produce 3,4-methylenedioxyethylbenzene, which is then subjected to a dehydrogenation reaction in the gas phase using a catalyst. The present invention relates to a method for producing 3,4-methylenedioxystyrene.

3,4-methylenedioxystyrene is one of the catechol derivatives that have a vinyl group in the molecule, and it is possible to use this vinyl group or use the reactivity of the methylene group to introduce other functional groups, or to further By deriving other functional groups, it is highly useful as a raw material for medicines, fragrances, special polymers, and other materials, and has extremely high utility value.

From its structure, it is thought that 3,4-methylenedioxystyrene can be synthesized by decarboxylation of 3,4-methylenedioxycinnamic acid, but in this method, the starting material 3,4- Since methylenedioxycinnamic acid is very expensive, it is economically quite disadvantageous in terms of raw material costs when compared to the process of the invention.

The method of the present invention produces 3,4-methylenedioxystyrene in high yield and high selectivity by easy means from p-ethylcatechol, which is easily and inexpensively obtained from 4-vinylcyclohexane-1,2-diol. make things possible.

The method of methylenating catechol, methylcatechol, etc. to produce methylenedioxybenzene and methylenedioxytoluene is known, and the method of producing unsaturated alkylbenzenes such as styrene by dehydrogenating alkylbenzenes such as ethylbenzene using a catalyst is known. is also known.

However, there is no report on producing 3,4-methylenedioxyethylbenzene by methyleneating p-ethylcatechol (3,4-methylenedioxyethylbenzene is considered to be a new compound.

Therefore, it goes without saying that 3,4-methylenedioxystyrene was produced by dehydrogenation of 3,4-methylenedioxyethylbenzene.

In addition, there is no example of dehydrogenating only an alkyl group with high selectivity without substituting or changing a compound having a complex substituent such as a methylenedioxy group.
There is also no teaching suggesting the possibility of producing 3,4-methylenedioxystyrene by dehydrogenation of 4-methylenedioxyethylbenzene.

Furthermore, when 3,4-methylenedioxyethylbenzene is subjected to a dehydrogenation reaction under the conditions normally used for dehydrogenating ethylbenzene, etc., the decomposition of the 3,4-methylenedioxy group is significant, resulting in a high selectivity. In the method of the present invention, which aims to obtain 3,4-methylenedioxystyrene, it is necessary to select reaction conditions different from those conventionally used for producing styrene from ethylbenzene.

Therefore, the present invention economically produces 3,4-methylenedioxystyrene with high selectivity by dehydrogenating 3,4-methylenedioxyethylbenzene obtained by methylenating p-ethylcatechol under specific conditions. The purpose is to manufacture.

The present inventors conducted various studies on the methylenation of p-ethylcatechol and the dehydrogenation reaction of the obtained 3,4-methylenedioxyethylbenzene, and found that 3,4-methylenedioxyethylbenzene is We found that methylenation could be obtained in good yield by methylenation using dihalomethane and a caustic alkali, and we also carried out contact under mild conditions in the gas phase using 3,4-methylenedioxyethylbenzene as a catalyst and a metal oxide. The present invention was completed by discovering that 3.4 methylenedioxystyrene can be obtained with high selectivity by dehydrogenation.

The dihalomethane used in the method of the present invention includes dichloromethane, dibromomethane, silodomethane, and dichloromethane, but industrially it is preferable to use dichloromethane.

Moreover, it is preferable to use caustic soda as the caustic alkali.

The catalyst used in the present invention for the dehydrogenation of 3,4-methylenedioxyethylbenzene is iron, copper, magnesium, zinc,
Oxides of bismuth, molybdenum, potassium, etc., or mixtures of two or more of these oxides are used.

In preparing the catalyst, iron, copper, magnesium, zinc,
In addition to these metal oxides, raw materials for bismuth, molybdenum, and potassium oxides include compounds that can be converted into oxides by heating or firing in the presence or absence of air, such as organic metals of these metals. , organic salts, halides, hydroxides, carbonates, nitrates and other various inorganic salts can be used.

The catalyst can be prepared by any known method such as mixing method, immersion method, coprecipitation method, etc. When using the catalyst, any method such as fixed bed method, moving bed method, fluidized bed method, etc. can be used. can.

In addition, if the activity of the catalyst decreases due to the adhesion of carbonaceous matter on the catalyst surface, the activity can be easily regenerated by heating in the presence of oxygen or air to burn off the carbonaceous matter. .

In the methylenation of p-ethylcatechol, organic polar solvents that have the effect of promoting the reaction are used as reaction solvents, such as sulfoxide-based solvents such as dimethyl sulfoxide, formamide-based solvents such as dimethylformamide, and sulfolane. It is a suitable solvent for use.

In order to prevent air oxidation of the reactants during methylenation, the reaction is carried out for 4 to 5 hours at a temperature at which the reactants reflux, while preventing air from entering the reaction system.

In addition, when the raw materials p-ethylcatechol and caustic alkali are supplied to the reaction system during the reaction, it is preferable to divide them into small amounts and add them alternately at intervals of 5 to 10 minutes in order to increase the yield.

Also, when 3,4-methylenedioxyethylbenzene is catalytically dehydrogenated in the gas phase using the catalyst detailed above, the reaction is carried out at a temperature ranging from 400°C to 550°C, preferably from 450°C to 550°C. It is carried out at a temperature in the range of 550°C.

In addition, the liquid hourly space velocity (LH8V) when supplying 3,4-methylenedioxyethylbenzene to the reaction zone is 0.1 hr.
It is preferably about 10 to 10 hours.

Furthermore, this dehydrogenation reaction can be carried out in the presence or absence of a diluent, and under normal pressure, reduced pressure, or increased pressure; however, when using a diluent, 3,4-methylenedioxyethylbenzene is Partial pressure 1/2 to l/20
It is preferable to maintain the atmospheric pressure and total pressure at around 1 atm.

As diluents, substances which are inert with respect to the reaction and gaseous under the reaction conditions may be used, such as water, low-boiling petroleum fractions, hydrocarbons such as benzene, carbon dioxide, nitrogen, etc. Several inorganic gases are used, and water is especially economical and suitable for use.

Note that the unreacted 3,4-methylenedioxyethylbenzene used in this dehydrogenation reaction and p-ethylcatechol, which is the main component of the by-product produced during the reaction, can be recycled by returning them to an appropriate location in the process. Usable.

The use of high temperatures in the dehydrogenation reaction is undesirable because it significantly increases the by-product of ethylphenol, which cannot be recycled and reused in this method.

For example, when the temperature used in the dehydrogenation reaction is 500°C, about 80% of the byproduct is recyclable p-ethylcatechol, but when the temperature is 560°C, about 70% is converted to ethylphenol, which cannot be reused. do.

The method of the present invention will be specifically illustrated below using Examples and Comparative Examples, but these are merely illustrative and do not limit the scope of the invention.

Example 1 450 rr Ll of dimethyl sulfoxide and 100 rr Ll of dichloromethane were placed in a fourth flask (No. 11) equipped with a stirrer and a reflux condenser, and after purging the system with nitrogen, heating was carried out while shutting off outside air to prevent air from entering. Reflux and add a solution of p-ethylcatechol 1381 in 50 TL of dimethyl sulfoxide and 83' of caustic soda. Each was divided into 20 equal parts and added at 10 minute intervals.

After adding p-ethylcatechol and caustic soda,
Further, 201111 dichloromethane was added and the reaction was continued for 1 hour, and then the reaction product was steam distilled.

The distillate of this steam distillation was separated into two layers by standing, and after separating the crude 3,4-methylenedioxyethylbenzene in the lower layer, it was purified by vacuum distillation, resulting in 112 grams of pure 3,4-methylene. Dioxyethylbenzene (yield 75 mol%) was obtained.

Example 2 Industrial ferric sulfate (Fe2 (5o4) 3 ” 9
H20) 7t and copper sulfate (CuS04・5H20) 1.6
Magnesium oxide (MgO) 9.5 f? was added and stirred for 3 hours, and the precipitate was filtered, washed with water, dried, and then heated at 650℃ for 3 hours.
Calcinate in air for 20 hours and crush the tablets.
A sieve catalyst was prepared in ~35 meshes.

15 grams of this catalyst was packed into a quartz reaction tube with an inner diameter of 201rt1rL, and a solution of 22.5P of 3,4-methylenedioxyethylbenzene dissolved in 13.8P of toluene was added to the reaction tube at a flow rate of 12.5 rul/hr. At the same time, water was introduced at a rate of 12.3 rrLl/hr to cause a reaction.

When the reaction was carried out at 530 DEG C., 3.4 methylenedioxystyrene was obtained with a pass conversion of 18% by weight and a selectivity of 70% by weight.

It is observed that the new catalyst used in this example has excellent selectivity.

Example 3 A reaction was carried out in the same manner as in Example 2 except for the catalyst, using a commercially available N211 (copper-zinc oxide) catalyst manufactured by JGC Chemical Co., Ltd., which was crushed and reduced to 20 to 35 meshes. When the reaction temperature was 515° C., 3,4-methylenedioxystyrene was obtained with a pass conversion of 5% by weight and a selectivity of 60% by weight.

Example 4 Commercially available standard 1707 catalyst (72.4% MgO-
18,4%Fe2o3-4.6%CuO-4,6%2
A reaction was carried out in the same manner as in Example 2 except for the catalyst, using crushed 0) and sieved into 20 to 35 meshes. When the reaction temperature was 500°C, the -pass conversion rate was 2.
3.4-methylenedioxystyrene was obtained with a selectivity of 3% by weight and a selectivity of 63% by weight.

Example 5 Molybdenum oxide (MoO2) 54.4? , bismuth nitrate (B 1(NOs) 3.5 H2O) 116.4
? After mixing and suspending 8 ml of concentrated nitric acid, 57 nl of water, and 225 g of a 20% aqueous colloidal silica sol solution, the water was evaporated and dried while stirring in a hot water bath.

Next, the catalyst was calcined in air at 540° C. for 16 hours, crushed and sieved into 20 to 35 meshes to prepare a catalyst.

The reaction was carried out in the same manner as in Example 2 except that this catalyst was used. When the reaction temperature was 500°C, the -pass conversion was 5.5% by weight and the selectivity was 3.4% by weight at 65% by weight. -Methylenedioxystyrene was obtained.

Comparative Example 1 A reaction was carried out in the same manner as in Example 2 using the same catalyst as in Example 2. When the reaction temperature was 590°C, the -pass conversion was 35% by weight. In comparison, the selectivity decreased to 41%.

Comparative Example 2 A reaction was carried out in the same manner as in Comparative Example 1 except that the same catalyst as in Example 3 was used. When the reaction temperature was 570°C,
- The pass conversion was 9% by weight and the selectivity was 49.1% by weight.

Comparative Example 3 A reaction was carried out in the same manner as in Comparative Example 1 except that the same catalyst as in Example 4 was used. When the reaction temperature was 570°C,
- the pass conversion is 54% by weight and the selectivity is 48% by weight
Met.

Claims (1)

[Claims] 1 p-Ethylcatechol is methylenated using dihalomethane and a caustic alkali to give 3,4-methylenedioxyethylbenzene, and this 3,4-methylenedioxyethylbenzene is further converted to 400-550% in the gas phase using a metal oxide catalyst. A method for producing 3.4 methylenedioxystyrene, which comprises carrying out a dehydrogenation reaction at a temperature of °C.