JPH07179451A - Method for producing coumarins - Google Patents

Abstract

PURPOSE:To obtain cumarins useful as an intermediate for perfumes, medicines and agrochemicals and dyes at a high reaction rate by subjecting 3,4- dihydrocumarins to dehydrogenation reaction by evaporating a reacted liquid using a specific heating calorie. CONSTITUTION:3,4-Dihydrocumarins of formula I (R1 to R4 each is H, methyl or ethyl and two or more groups thereof are H) are subjected to dehydrogenation reaction using 80-1000kcal/kg.hr heating calorie per unit reacted liquid in the presence of a metal catalyst such as a solid metal catalyst obtained by supporting palladium on an active carbon to provide the objective cumarins of formula II.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method for producing coumarins from 3,4-dihydrocoumarins. Coumarin and its derivatives are especially important compounds in the perfume industry, and are also important compounds as intermediates for agricultural chemicals, drugs or dyes.

[0002]

2. Description of the Related Art As a conventional method for obtaining coumarins,
In the presence of a hydrogenation-dehydrogenation catalyst such as palladium, 3- (2
-Oxocyclohexyl) propionic acid ester by heating for cyclodehydrogenation reaction (US Patent No.
No. 3,442,910), and a method of producing by carrying out cyclization dehydrogenation in the presence of barium sulfate, nickel oxide and the like as a cocatalyst together with a noble metal catalyst such as palladium (JP-A-60-181082).

Further, a method for producing coumarins by using 3,4-dihydrocoumarins as a raw material and performing a dehydrogenation reaction in the presence of a noble metal catalyst such as palladium (Ber., 70B, 735-8).
(1936), JP-A-05-117262), a method for producing coumarins by dehydrogenation using chlorine, bromine, oxygen or sulfur (Monatsh., (34), 1671 to 72 (1913), German Patent First
No. 276667) is known.

[0004]

When a 3- (2-cyclohexanoyl) propionic acid ester is heated in the presence of a palladium catalyst to undergo a cyclization dehydrogenation reaction, it is not always necessary to collect coumarins. The rate is not high and many 3,4-dihydrocoumarins are by-produced. Further, when producing coumarins by dehydrogenation reaction using 3,4-dihydrocoumarins as raw materials, it is difficult to remove chlorine or sulfur by the method of dehydrogenation using chlorine or sulfur, etc. The process becomes complicated.

On the other hand, the method of carrying out the dehydrogenation reaction of 3,4-dihydrocoumarins in the presence of a palladium catalyst is relatively easy in the purification step, but the production of coumarins by the dehydrogenation reaction and the production of hydrogen by-product The hydrogenation reaction occurs at the same time and the coumarins become 3,4-dihydrocoumarins, so that the dehydrogenation reaction does not always proceed sufficiently, and the yield of coumarins is not high. In order to promote the dehydrogenation reaction, for example, a method of performing the dehydrogenation reaction under reduced pressure (Japanese Patent Laid-Open No. 5-1171).
No. 262) has been proposed.

The inventors of the present invention have conducted extensive research on a method for producing coumarins having a high yield when producing coumarins from 3,4-dihydrocoumarins. As a result, the reaction rate of dehydrogenation reaction is The amount of evaporation from the liquid affects the reaction rate, and the reaction rate is remarkably increased by increasing the evaporation amount per unit reaction liquid amount or the heating amount per unit reaction liquid amount for evaporating the reaction liquid to carry out the dehydrogenation reaction. It was found that the above-mentioned improvements were made, and the invention was completed.

[0007]

That is, the present invention is based on the general formula:

[Chemical 3] (In the formula, R _{1 to} R ₄ each represent a hydrogen atom, a methyl group or an ethyl group, and at least two groups of R _{1 to} R ₄ are hydrogen atoms). In the presence of a metal catalyst, the general formula 4

[Chemical 4] When producing coumarins represented by the formula (R _{1 to} R ₄ are the same as the groups described above), the heating amount per unit reaction liquid amount for evaporating the reaction liquid is 80 to 1000 kc.
It is a method for producing coumarins, characterized in that the treatment is carried out at al / kg · hr.

Specific examples of the 3,4-dihydrocoumarins used in the present invention include, for example, 3,4-dihydrocoumarin, 5-methyl-3,4-dihydrocoumarin and 6-.
Methyl-3,4-dihydrocoumarin, 7-methyl-3,
4-dihydrocoumarin, 8-methyl-3,4-dihydrocoumarin, 5-ethyl-3,4-dihydrocoumarin, 6
-Ethyl-3,4-dihydrocoumarin, 7-ethyl-
3,4-dihydrocoumarin, 8-ethyl-3,4-dihydrocoumarin, 5,6-dimethyl-3,4-dihydrocoumarin, 5,7-dimethyl-3,4-dihydrocoumarin, 5,8-dimethyl- 3,4-dihydrocoumarin,
6,7-Dimethyl-3,4-dihydrocoumarin, 6,8
-Dimethyl-3,4-dihydrocoumarin, 7,8-dimethyl-3,4-dihydrocoumarin, 5-methyl-6-ethyl-3,4-dihydrocoumarin, 5-methyl-7-ethyl-3,4- Dihydrocoumarin, 5-methyl-8-ethyl-3,4-dihydrocoumarin, 6-methyl-7-ethyl-3,4-dihydrocoumarin, 6-methyl-8-ethyl-3,4-dihydrocoumarin, 7- Methyl-8-ethyl-3,4-dihydrocoumarin, 5-ethyl-6-methyl-3,4-dihydrocoumarin, 5-ethyl-7-methyl-3,4-dihydrocoumarin, 5-ethyl-8-methyl -3,4-dihydrocoumarin, 6-ethyl-7-methyl-3,4-dihydrocoumarin, 6-ethyl-8-methyl-3,4-dihydrocoumarin, 7-ethyl-8-methyl-3,4- The Dorokumarin the like, but not limited to.

The metal catalyst used in the present invention comprises a metal such as palladium, platinum, rhodium or ruthenium, which is a group IIA, IIIA, IVA or VIA element or compound of the periodic table, such as carbon, alumina, A solid metal catalyst or the like supported on a carrier such as silica gel or barium sulfate, which is impregnated with a metal by a known method, for example, an impregnation supporting method ("catalyst experiment manual" edited by the Catalysis Society, published by Maki Shoten),
Although it can be obtained by a method of reducing it with hydrogen at a high temperature, a commercially available product may be used as it is.

As the metal catalyst, a solid metal catalyst supporting palladium is preferable, and a solid metal catalyst supporting palladium on activated carbon is particularly preferable. Further, a chromium compound or the like may be supported together with a metal such as palladium on the metal such as palladium in an amount of about 1 to 20% by weight.

The supporting rate of metal such as palladium on the carrier is preferably about 0.5 to 10% by weight. Although the amount of the catalyst used depends on the loading rate, if the amount is small, the reaction activity is extremely low.
Since the cost of the catalyst is high, the metal content is about 0.001 to 1% by weight, preferably about 0.01 to 0.1% by weight, based on 3,4-dihydrocoumarins.

The catalyst can be used repeatedly in this reaction. Further, in the dehydrogenation reaction, metallic chromium, metallic tungsten, barium sulfate, magnesium trisilicate, zirconia or the like may be added as a co-catalyst together with a solid metal catalyst such as palladium. Co-catalyst is 3,4
-Generally about 0.01 to 3 for dihydrocoumarins
Weight percent is used.

In the present invention, 3,4-dihydrocoumarins are 3,4-dihydrocoumarins produced by subjecting 3- (2-oxocyclohexyl) propionic acid esters to cyclization dehydrogenation in the presence of a palladium catalyst or the like. Coumarins and coumarins separated from each other by distillation, crystallization and the like are used, but other ones may be used without any particular limitation.

In the present invention, a solvent is not necessary,
It can also be carried out using a solvent. Examples of the solvent include phenyl ether, benzyl ether, methyl-α-naphthyl ether, ethylnaphthalene, dimethylbiphenyl, dodecane, tetradecane, tetralin, acetophenone,
Examples thereof include phenyl propyl ketone, methyl benzoate, dimethyl glutamate and the like.

In the present invention, the reaction pressure is about 200 To.
rr-1.5 atm, preferably about 300-700 To
rr. The reaction temperature is about 200 to 300 ° C, preferably about 230 to 290 ° C.

In the present invention, the reaction temperature is determined by the composition of the reaction solution, the pressure and the like. The dehydrogenation reaction is performed so that the heating amount per unit reaction liquid amount for evaporating the reaction liquid becomes a predetermined value or the reaction liquid evaporation amount per unit reaction liquid amount becomes a predetermined value. It is carried out by heating the liquid for several hours to several tens of hours.

In the present invention, the heating amount per unit reaction liquid amount for evaporating the reaction liquid is about 80 to 1000 kc.
al / kg · hr, preferably about 80 to 400 kcal
/ Kg · hr. This heating amount is about 80 kcal
If it is smaller than / kg · hr, the reaction rate becomes small.
Further, even if the heating amount is larger than about 1000 kcal / kg · hr, there is no problem in the reaction, but the cost of the apparatus and energy for heating increases.

Heating amount Q ₄ [k] for evaporating the reaction liquid
cal / hr] is the amount of heat Q ₁ [kcal /
heat] Q ₂ [kcal / hr]
(The amount of heat of vapor and condensate between the reactor and the condenser is not included), and the amount of heat generated by the reaction Q ₃ [kca
1 / hr] is added. Q ₄ = Q ₁ −Q ₂ + Q ₃ (I) The heating amount Q [kcal / kg · hr] per unit amount of reaction liquid for evaporating the reaction liquid is the heating amount Q ₄ [kcal for evaporating the reaction liquid. / Hr] is the reaction liquid volume W [kg]
It is calculated by dividing by. Q = Q ₄ / W (II)

The relationship of the equation (III) is given between the reaction rate constant k [m ³ / mol · hr] and the heating amount Q [kcal / kg · hr] per unit reaction liquid volume for evaporating the reaction solution. There is. K is a constant determined by the amount of catalyst and the like. logk = 0.5 × logQ + K (III) Therefore, in order to obtain the target reaction rate, Q is obtained from the formula (III), and the heat quantity Q ₁ [kcal / kcal / added to the reactor is obtained from the formulas (II) and (I). hr].

Although the reaction liquid to be evaporated is accompanied by vapor pressure of coumarins, since the latent heats of vaporization of coumarins and 3,4-dihydrocoumarins are close to each other, they can be regarded as almost 3,4-dihydrocoumarins. Therefore, this heating amount is 3,
It can be divided by the latent heat of vaporization of the 4-dihydrocoumarins to obtain almost the amount of vaporization.

When the amount of heat released in the reactor is smaller than the amount of heat required to evaporate the reaction liquid, the amount of evaporation can be almost regarded as the amount of condensation that is completely condensed in the condenser. Therefore, the amount of heating can be adjusted with this amount of condensation as a guide.

The reaction system used in the present invention may be a batch system or a continuous system. The reactor may be a stirred tank type, an external circulation type tank type, a tube type, a circulation tube type, or the like, but is not particularly limited. The heating method is external jacket type, internal heat exchange coil type, raw material steam blowing type, external heat exchanger type, open flame type,
An external electric heating type, an internal electric heating type, an induction electromagnetic type, and a method combining them are used.

It is preferable that the vaporized vapor is totally or partially condensed by a condenser or the like and then returned to the reactor in whole or partially.

[0024]

INDUSTRIAL APPLICABILITY The method of the present invention has a significantly improved reaction rate as compared with the conventional methods, and its industrial value is great.

[0025]

EXAMPLES Examples will be given below to specifically explain the present invention, but the present invention is not limited to these examples. In addition, the heating amount and the reaction rate constant per unit reaction liquid amount for evaporating the reaction liquid in the examples are values calculated by the following method.

[Amount of heating per unit amount of reaction liquid for evaporating reaction liquid] Q ₁ = (heat medium flow rate) × (specific gravity of heat medium) × (specific heat of heat medium)
× (temperature difference between inlet and outlet) Q ₃ = (reaction rate) × (reaction liquid amount) × (reaction heat) Q ₄ = Q ₁ − Q ₂ + Q ₃ Q = Q ₄ / W where Q ₁ : heating amount [Kcal / hr] Q ₂ : Heat dissipation amount [kcal / hr] Q ₃ : Heat generation amount [kcal / hr] Q ₄ : Heating amount for evaporating reaction liquid [kcal / h]
r] W: Reaction liquid amount [kg] Q: Heating amount per unit reaction liquid amount for evaporating the reaction liquid [kcal / kg · hr]

[Reaction rate constant] r = kC ^{2 When} approximated by reaction rate constant k, where: r: reaction rate [mol / m ³ · hr] (rate of disappearance of 3,4-dihydrocoumarin) k: reaction rate constant [M ³ / mol · hr] C: 3,4-dihydrocoumarin concentration [mol / m ³ ]

Example 1 A stainless steel 100-liter stirring tank equipped with an anchor-type stirring blade, an outer jacket, and a condenser was equipped with 45 kg of 3,4-dihydrocoumarin and a 50% water-containing catalyst in which activated carbon was loaded with 5% by weight of palladium. 0.45 kg was charged. Specific gravity 0.861kg / l, specific heat 0.5 in the outer jacket
While flowing 64 kcal / kg of heat medium at 3.6 m ³ / hr, nitrogen blowing rate was 30 liters / hr, stirring number was 13
It was heated at 0 rpm and a pressure of 600 Torr. When the temperature of the reaction mixture reached 259 ° C., it was set as 0 hour, and then the temperature of the heating medium was adjusted to make the temperature difference between the reaction mixture and the heating medium 39 °
It was set to ℃.

The reaction mixture was sampled at 0 hours, 5 hours and 10 hours and analyzed by gas chromatography. As a result, the concentrations of 3,4-dihydrocoumarin and coumarin were 84.5% by weight, 12.8% by weight for 5 hours, 68.2% by weight, 28.8% by weight and 10% for 5 hours, respectively.
The time was 61.5% by weight, 34.5% by weight, and the reaction rate constant was 6.21 × 10 ⁻⁶ m ³ / mol · hr.

After 5 hours, the temperature of the heat medium at the inlet of the outer jacket was 305.0 ° C., and the temperature of the heat medium at the outlet was 29.
It was 9.6 ° C, and the temperature difference of the heating medium was 5.4 ° C.
The generated heat amount was -199 kcal / hr, and the heat release amount from the reactor through the reaction was 1500 kcal / hr. Therefore, the heating amount per unit reaction liquid amount for evaporating the reaction liquid is 172 kcal / kg · hr. The latent heat of vaporization of 3,4-dihydrocoumarin is 81.
It is 6 kcal / kg, and the evaporation amount of the reaction liquid per unit reaction liquid amount is about 2.1 kg / kg · hr.

Examples 2 to 5 and Comparative Example 1 The same operation as in Example 1 was carried out except for the conditions shown in Table 1. The results are shown in Table 1. In addition, DHCM in the table is 3,4-dihydrocoumarin, and Pd / C is palladium on activated carbon.
With respect to the 50% water-containing catalyst supported by weight%, the evaporation heating amount represents the heating amount per unit reaction liquid amount for evaporating the reaction liquid, and the evaporation amount represents the evaporation amount of the reaction liquid per unit reaction liquid amount.

[0032]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junya Sonobe 3-1,98 Kasugade, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Chemical Co., Ltd. (72) Inventor Hiroshi Ueda Kasuga, Konohana-ku, Osaka City, Osaka Prefecture Naka 3-chome 1-98 Sumitomo Chemical Co., Ltd.

Claims (5)

[Claims] 1. The general formula: (In the formula, R _{1 to} R ₄ each represent a hydrogen atom, a methyl group or an ethyl group, and at least two groups of R _{1 to} R ₄ are hydrogen atoms). By the dehydrogenation reaction in the presence of a metal catalyst, a compound represented by the general formula: When producing coumarins represented by the formula (R _{1 to} R ₄ are the same as the groups described above), the heating amount per unit reaction liquid amount for evaporating the reaction liquid is 80 to 1000 kc.
A method for producing coumarins, characterized in that the method is performed at al / kg · hr. 2. The method for producing coumarins according to claim 1, wherein the heating amount per unit reaction liquid amount for evaporating the reaction liquid is 80 to 400 kcal / kg · hr. 3. The 3,4-dihydrocoumarins are 3,4-
The process for producing coumarins according to claim 1, wherein the coumarin is dihydrocoumarin, and the evaporation amount of the reaction liquid per unit reaction liquid amount is 1 to 12 kg / kg · hr. 4. The 3,4-dihydrocoumarins are 3,4-
The method for producing coumarins according to claim 1, wherein the coumarin is dihydrocoumarin, and the evaporation amount of the reaction liquid per unit amount of the reaction liquid is 1 to 5 kg / kg · hr. 5. The method for producing coumarins according to claim 1, wherein the metal catalyst is a solid metal catalyst in which palladium is supported on activated carbon.