JPH08277237A - Production of vinyl ethers - Google Patents

Abstract

PURPOSE: To efficiently and economically obtain vinyl ethers useful as a raw material for medicines, agrochemicals in an industrial scale by feeding acetals into an,organic solvent containing an acidic substance and carrying out dealcoholization reaction of the acetals. CONSTITUTION: Dealcoholization reaction of acetals is carried out by intermittently or continuously feeding acetals (preferably 1,1-dimethoxyethane or 2,2- dimethoxypropane) of formula I [R1 , R2 and R4 are each H, 1-10C alkyl or an aryl; R3 is a 1-10C alkyl] into an organic solvent containing an acidic substance (e.g. acetic acid or benzenesulfonic acid) which is a catalyst to intermittently or continuously distill alcohols of the formula, R3 OH and the objective compound of formula II. The acidic substance is preferably used in an amount of 0.01-10 pts.wt. based on 100 pts.wt. of the organic solvent charged in initial period. The reaction is preferably carried out at 100-200 deg.C by distillation style of liquid phase reaction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for economically producing vinyl ethers useful as raw materials for pharmaceuticals, agricultural chemicals, and polymers on an industrial scale.

[0002]

2. Description of the Related Art Conventionally, as to a method for producing vinyl ethers from acetals, (1) a method of dealcoholation by thermal decomposition in the presence of equimolar amounts of phosphorus pentoxide and quinoline (for example, J. Chem. So.
c. 2052 (1955) (2) A method of obtaining a product by decomposing acetals with an acid catalyst and trapping the produced alcohol with an acid anhydride in the system (for example, J. Org. Ch.
em. , 38 , 2910, 1973, Helv. Chi
m. Acta, 1158 (1967)) (3) Method of decomposing acetals using p-toluenesulfonic acid as a catalyst (Bull. Chem. Soc. J.
pn. 3089 (1976) (4) A method of thermally decomposing acetals in a gas phase using a catalyst obtained by mixing clay, asbestos, and glass and firing the mixture (J.
Chem. Soc. 3388 (1958)) (5) A method of thermally decomposing acetals in a gas phase by using a zeolite carrying sodium as a catalyst (Japanese Patent Laid-Open No. 62-62160).
(-87247 gazette) etc. are known.

By the way, in the above-mentioned conventional methods for producing vinyl ethers, the methods (1), (3) and (4) have a low yield and cannot be industrially produced efficiently. In addition, the method (2) requires an acid anhydride in an equimolar amount with the acetals to be decomposed, so that the cost becomes very high. Furthermore, the method (5) has a risk of ignition and is problematic in industrialization.

[0004]

On the other hand, the present invention provides a method for efficiently obtaining vinyl ethers on an industrial scale without the above-mentioned problems.

[0005]

[Means for Solving the Problems] The above-mentioned object is to provide a compound of formula (2)

[0006]

Embedded image (In the formulas, R ₁ , R ₂ and R ₄ are hydrogen atoms and have 1 to 1 carbon atoms.
0 represents an alkyl group or an aryl group, R ₃ represents an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₄ may be bonded to each other with a methylene group to form a ring). Alcohols represented by the formula (3) R ₃ OH (3) (wherein R ₃ represents an alkyl group having 1 to 10 carbon atoms) by carrying out dealcoholization reaction by intermittently or continuously supplying, And equation (1)

[0007]

[Chemical 4] (In the formulas, R ₁ , R ₂ and R ₄ are hydrogen atoms and have 1 to 1 carbon atoms.
0 represents an alkyl group or an aryl group, R ₃ represents an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₄ may be bonded to each other with a methylene group to form a ring). It can be achieved by distilling intermittently or continuously.

The above equations (1), (2) and (3)
R ₁ , R ₂ , R ₃ and R _{4 in} will be described.

R ₁ , R ₂ and R ₄ are the same or different and each is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an aryl group, and examples of the alkyl group include methyl,
It is a group such as ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl and decyl, and the aryl group is a phenyl group and a toluyl group. R ₃ is an alkyl group having 1 to 10 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl. And so on. Further, R ₂ and R ₄ may be bonded by a methylene group to form a ring such as cyclopentane, cyclohexane, cycloheptane or cyclooctane.

The raw material used in the reaction has the formula (2) (wherein R ₁ , R ₂ and R ₄ are hydrogen atoms or 1 to 10 carbon atoms).
Represents an alkyl group or an aryl group, and R ₃ has 1 to 1 carbon atoms.
10 represents an alkyl group, and R ₂ and R ₄ may combine with each other with a methylene group to form a ring), and the acetals can also be obtained by reacting aldehydes or ketones with alcohols. Alternatively, it can also be synthesized by acetalization using an orthoester (for example, Synthesis, 1970, 41).
9).

Acetals which can be particularly preferably used in the present invention include 1,1-dimethoxyethane and 1,1-dimethoxyethane.
1-diethoxyethane, 1,1-dimethoxypropane,
1,1-Diamyloxyethane, 1,1-diisoamyloxyethane, 1,1-dimethoxy-3-phenylpropane, 2,2-dimethoxypropane, 2,2-dimethoxybutane, 2,2-dimethoxy-2 -Phenylethane,
1,1-dimethoxycyclohexane, 1,1-diisopropylcyclohexane and the like.

The acidic substance used in the present invention includes, for example, aliphatic monocarboxylic acids such as acetic acid, propionic acid and butanoic acid; aliphatic dicarboxylic acids such as succinic acid and adipic acid; aromatic carboxylic acids such as benzoic acid and terephthalic acid. acid;
Aromatic sulfonic acids or salts thereof such as benzenesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonic acid pyridinium salt, p-toluenesulfonic acid quinolinium salt; sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, nickel sulfate, Examples thereof include sulfates such as copper sulfate and zirconium sulfate; hydrogen sulfates such as sodium hydrogen sulfate and potassium hydrogen sulfate. As these acidic substances, commercially available products may be used as powders or crystals, and commercially available products may be melted and solidified and pulverized to an appropriate size.

The amount of the acidic substance as the reaction catalyst is 0.001 to 1 with respect to 100 parts by weight of the organic solvent initially charged.
It is about 00 parts by weight, and when considering the productivity due to the conversion rate of the raw material, the operability in the implementation, and the cost of the catalyst,
0.01 to 10 parts by weight is suitable.

The organic solvent used in the present invention may be any one as long as it is stable under acidic conditions. For example, aromatic hydrocarbons such as toluene, xylene and mesitylene; aliphatic hydrocarbons such as decane, dodecane, tetradecane, hexadecane and paraffin; aliphatic or aromatic ethers such as dioctyl ether, anisole and diphenyl ether; methyl octanoate, Ethyl octanoate, methyl nonanoate, ethyl nonanoate, dimethyl phthalate, diethyl phthalate,
Aliphatic or aromatic esters such as dipropyl phthalate, dibutyl phthalate, dioctyl phthalate and bis (2-ethylhexyl) phthalate are used. The boiling point of the solvent is preferably one that can be used under normal pressure as an operation during the reaction because the reaction temperature is high and the reaction system is a reaction distillation type, and it is not included in the distillation. It is preferable that there is a difference in boiling point from the target product to some extent in terms of distillation recovery after the reaction.

The amount of the organic solvent used in the reaction is determined by the amount of the above catalyst to be dissolved or dispersed. Normal,
It is from 1 to 100,000 parts by weight, preferably from 10 to 10,000 parts by weight, based on the catalyst.

The operating temperature in the present invention is 50 ° C. to 30 ° C.
The temperature is 0 ° C., and in consideration of the heat source, the life of the catalyst, etc., it is preferably performed at 100 ° C. to 200 ° C. The reaction is
The reaction can be carried out under atmospheric pressure, but the reaction may be carried out under reduced pressure or under pressure in consideration of the boiling point of the product, safety, and the boiling point of the raw material.

The reaction is carried out in a liquid phase reactive distillation format.
More specifically, a solvent and a catalyst are initially charged in the reactor and the temperature is raised to a predetermined temperature. After the temperature is raised, the raw material acetal is added dropwise. At the same time as the dropping, the dealcoholization reaction proceeds, and vinyl ethers and alcohols as products start to distill. When the raw materials are fed into the reaction system, the catalyst concentration in the system is not changed and the distillate amount is adjusted.

The reaction liquid obtained by the reaction consists of acetals as raw materials, vinyl ethers as target products, and desorbed alcohols. These can be easily separated by distillation. Further, the unreacted raw material can be converted to the desired vinyl ethers by separating by distillation and subjecting to the reaction again.

[0019]

EXAMPLES The specific constitution of the method for producing vinyl ether according to the present invention will be described below based on examples, but the present invention is not limited thereto.

Example 1 50 g of dimethyl phthalate and 2.50 g of adipic acid were charged into a 100 ml three-necked flask, and the temperature was raised to 120 ° C. 2,2-dimethoxypropane 1 per hour
0.15 g was fed, and the amount of 2,2-dimethoxypropane fed thereafter was adjusted with the distillation of the product after the start of the reaction. When the reaction was carried out for 8 hours, 2,2-
The conversion of dimethoxypropane was 70% and the selectivity to 2-methoxypropene was 96%. 79.8 g of 2,2-dimethoxypropane was fed to obtain 73.7 g of distillate. This was distilled to obtain 36.5 g of 2-methoxypropene having a purity of 95% (yield: 62.8%).

Example 2 50 g of anisole and 0.
25 g of potassium hydrogen sulfate was added and the temperature was raised to 120 ° C. 2,2-dimethoxypropane 1 per hour
0.15 g was fed, and the amount of 2,2-dimethoxypropane fed thereafter was adjusted with the distillation of the product after the start of the reaction. After reacting for 10 hours, 2,2
The conversion of dimethoxypropane was 71% and the selectivity to 2-methoxypropene was 93%. 111.1 g of 2,2-dimethoxypropane was fed to obtain 106.4 g of distillate. This product was distilled to give 95% pure 2-
49.2 g (yield 60.7%) of methoxypropene was obtained.

Example 3 In a 100 ml three-necked flask, 50 g of anisole and 0.
25 g of p-toluenesulfonic acid pyridinium salt was added and the temperature was raised to 120 ° C. 2,5-Dimethoxypropane was fed at 10.15 g per hour, and the amount of 2,2-dimethoxypropane fed thereafter was adjusted along with the distillation of the product after the start of the reaction. When the reaction was carried out for 10 hours, the conversion of 2,2-dimethoxypropane was 7
The selectivity to 2% and 2-methoxypropene was 91%. 105.2 g of 2,2-dimethoxypropyne was fed to obtain 99.4 g of distillate. This was distilled to obtain 45.7 g (yield 59.6%) of 2-methoxypropene with 95% purity.

[0023]

INDUSTRIAL APPLICABILITY According to the present invention, vinyl ethers useful as raw materials for pharmaceuticals, agricultural chemicals and polymers can be produced on an industrial scale and economically.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C07C 41/28 C07C 41/28 43/166 43/166 // C07B 61/00 300 C07B 61/00 300 C07C 27/00 9155-4H C07C 27/00 C08F 16/16 MKY C08F 16/16 MKY (72) Inventor Takashi Onishi 36 Towada, Kamisu-cho, Kashima-gun, Ibaraki Prefecture Kuraray Co., Ltd.

Claims (1)

[Claims] 1. In an organic solvent containing an acidic substance, a compound of the formula (2) (In the formulas, R ₁ , R ₂ and R ₄ are hydrogen atoms and have 1 to 1 carbon atoms.
0 represents an alkyl group or an aryl group, R ₃ represents an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₄ may be bonded with a methylene group to form a ring). Alcohols represented by the formula (3) R ₃ OH (3) (wherein R ₃ represents an alkyl group having 1 to 10 carbon atoms) by carrying out dealcoholization reaction by intermittently or continuously supplying, And the formula (1) (In the formulas, R ₁ , R ₂ and R ₄ are hydrogen atoms and have 1 to 1 carbon atoms.
0 represents an alkyl group or an aryl group, R ₃ represents an alkyl group having 1 to 10 carbon atoms, and R ₂ and R ₄ may be bonded to each other with a methylene group to form a ring). A process for producing vinyl ethers, which comprises distilling intermittently or continuously.