JPS6116254B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing pinacolone (tertiary butyl methyl ketone). As a method for producing pinacolone, an acid-catalyzed rearrangement reaction of pinacol obtained by dimerization of acetone (pinacol-pinacolone rearrangement reaction) has been known for a long time (for example, Org.Synth., Coll.
Vol., 1, pp. 459-463). This reaction requires at least a stoichiometric amount of metallic magnesium (or metallic aluminum), which requires toxic mercuric chloride during the acetone dimerization step, which is mostly converted to elemental mercury. Moreover, carrying out the reaction on an industrial scale involves various problems, such as the need for a large excess of acetone, which is converted into a salt, and the reduction of the acetone to produce isopropanol as a by-product. Another known method is to hydrolyze 4,4,5-trimethyl-1,3-dioxane obtained by the Prins reaction of 2-methyl-2-butene and formaldehyde in the presence of a strong acid (Germany). Patent No. 714488 and U.S. Patent No.
(See No. 4059634). However, this method also has drawbacks in that the yield of pinacolon is low and a large amount of viscous by-products are produced, not only in terms of the reaction process but also in terms of product purity. As a result of intensive studies to solve the above-mentioned problems, the inventors found the following general formula () [In formula (), W and Y are hydrogen atoms, and X and Z are the same or different, respectively.
OH, Cl, Br or RCOO (where R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), or one of W and Y is a hydrogen atom and the other is a single form a bond,
Pinacolon is produced by heating a compound represented by the following formula (Z represents OH, Cl, Br, HSO ₄ , H ₂ PO ₄ , ClO ₄ or RCOO (where R is the same as above) in an aqueous solution of a strong inorganic acid. The present inventors have discovered that this can be easily obtained, leading to the present invention. Furthermore, it has been found that by allowing a salt of a strong inorganic acid to coexist in the reaction system during this reaction, the yield of pinacolon can be further improved and the concentration and amount of the strong inorganic acid used can be reduced. In the present invention, pinacolon is produced by decomposition rearrangement of the compound represented by the general formula (). For example, in the general formula (), W and Y are both hydrogen atoms, X is a chlorine atom, and Z is
The rearrangement of a compound with a CH ₃ COO group to pinacolone is shown by the following formula. The compound represented by the general formula () used as a raw material in the present invention is 4,4,5-trimethyl-1,3- obtained by the reaction of 2-methylbutene-2 or 3-methylbutene-1 with formaldehyde.
It is readily available with or without dioxane (e.g. Chem.Rev. 51
505 (1952), Zhur. Obshchei Khim. 27 2806
(1957), and Journal of Industrial Chemistry 72 1715 (1969),
(See Special Publication No. 59-14011). Specifically 2,3
-dimethylbutane-1,3-diol, 2,3-
dimethyl-3-chlorobutan-1-ol, 2,
3-dimethyl-3-bromobutan-1-ol,
2,3-dimethylbuten-2-ol-1,2,
These include 3-dimethylbuten-3-ol-1 and their aliphatic carboxylic acid esters having 1 to 4 carbon atoms. The inorganic strong acid aqueous solution preferably used in the present invention is an aqueous solution of hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid or perchloric acid, and two or more of them may be used in combination. Hydrochloric acid is particularly preferred from the viewpoint of price, reaction yield, and other aspects. Although the acid concentration and acid amount in the aqueous phase of the reaction mixture may change as the reaction progresses, in the present invention, the acid concentration in the aqueous phase of the reaction system is preferably 0.5 mol/Kg or more during the entire reaction period. 1.0 mol/Kg or more and the amount of the inorganic strong acid in the aqueous phase is maintained at 0.1 times the mole or more, preferably 0.5 times the mole or more relative to the raw materials in the reaction system, depending on the type of the inorganic strong acid and the raw materials. Pinacolone can be obtained in a satisfactory yield. In the present invention, the salt of the inorganic strong acid that can be used in combination with the inorganic strong acid needs to be at least partially soluble in the reaction system, and preferably has a solubility in water of 35 or more at 100°C. Both neutral and acidic salts can be used, such as lithium, sodium, potassium, rubidium,
Cesium, copper (), magnesium, calcium, strontium, barium, zinc, cadmium, aluminum, scandium, zirconium, titanium (), tin (), manganese (),
Iron, cobalt (), chlorides and bromides of nickel, ammonium, sodium, rubidium,
Sulfates of cesium, magnesium, cadmium, zinc, aluminum, cobalt (), copper (), nickel (), manganese (), calcium,
Examples include perchlorates of silver, strontium, sodium, barium, magnesium, etc., acid salts such as sodium hydrogen sulfate, potassium hydrogen sulfate, sodium dihydrogen phosphate, and complex salts such as potassium magnesium chloride sulfate. can. Among these, salts with high molar solubility and high stability in the aqueous phase under the reaction conditions are preferable. Considering this point, salts of alkali metals and alkaline earth metals in the second to fourth periods are the most suitable. preferable. Although the acid radicals of the inorganic strong acid and the acid radical of the inorganic strong acid salt used in the reaction do not necessarily have to be the same, combinations that would produce poorly soluble salts under the reaction conditions must be avoided. Furthermore, two or more salts of inorganic strong acids may be used in combination within the range that satisfies the above-mentioned solubility, but in this case as well, combinations that would produce poorly soluble salts under the reaction conditions must be avoided. The amount of the inorganic strong acid salt to be used can be arbitrarily selected depending on the concentration of the inorganic strong acid in the aqueous phase under the reaction conditions and within the range of the solubility of the salt. On the other hand, if the acid concentration is low, it can be increased, but the sum of the acid radicals of the inorganic strong acid and the acid radicals of the inorganic strong acid salt should be at least 2.5 mol or more per 1 kg of the aqueous phase of the reaction system. is preferred. In other words, when the method of the present invention is carried out using a strong inorganic acid salt in addition to an aqueous solution of an inorganic strong acid, the concentration of the sum of acid groups derived from both the strong inorganic acid and the strong inorganic acid salt is at least 1 kg per 1 kg of the aqueous phase.
It is preferably 2.5 mol or more. If the concentration of the acid radicals derived from the strong inorganic acid and the strong inorganic acid salt is less than 2.5 mol per kg of the aqueous phase of the reaction system, it is difficult to obtain a practical yield of pinacolon, which is not preferred. In addition to water, the reaction can also be carried out in the presence of a diluent inert to the reaction, such as saturated hydrocarbons and ketones, such as methylbutane,
hexane, cyclohexane, butyl chloride, 1,
Examples include hydrophobic compounds such as 1,1-trichloroethane, 1,1,1,2-tetrachloroethane, carbon tetrachloride, and pinacolon. However, no particular benefit is provided by the use of diluents. The reaction temperature is preferably in the range of 40 to 200°C, particularly 60 to 150°C, and furthermore, in the latter stage of the reaction, at least
It is necessary to complete the reaction at a temperature of 80°C or higher. The reaction is usually carried out at a pressure of at least atmospheric pressure and not more than 30 kg/cm ² , but this pressure is not critical, and the reaction can be carried out even under pressures exceeding this range if the above temperature conditions can be maintained. When the reaction is carried out at a temperature higher than the boiling point of the reaction mixture, it is appropriate that the reaction pressure is freely adjustable for the reaction mixture at the reaction temperature;
Pressurization with inert gas is not particularly necessary. The reaction method is as follows: (1) A strong inorganic acid aqueous solution or an aqueous solution containing an inorganic strong acid and an inorganic strong acid salt is maintained at a predetermined reaction temperature while stirring, and the general formula ()
A method of reacting while continuously or intermittently adding one or more compounds represented by the formula (2) to an aqueous solution of an inorganic strong acid or an aqueous solution containing a strong inorganic acid and a strong inorganic acid salt represented by the general formula () A method is used in which one or more compounds are mixed, kept at a predetermined temperature with stirring, and allowed to react. Generally, method (1) is preferred because it provides a higher yield of pinacolon. The method of the present invention can be carried out either continuously or batchwise. The reaction time naturally varies depending on the amount of raw materials used, the concentration and amount of the inorganic strong acid aqueous solution or the aqueous solution containing an inorganic strong acid and an inorganic strong acid salt, the reaction temperature, etc., but is usually 1 to 20 hours. Methods for obtaining pinacolon from the reaction mixture after the reaction include (a) separating the organic phase from the aqueous phase and then subjecting the organic phase to distillation as it is or after neutralizing if necessary; (b) reaction. After neutralizing the mixture,
Alternatively, a method may be used in which the organic phase is separated from the aqueous phase and subjected to distillation, or (c) a method in which the reaction mixture is directly subjected to distillation. If method (a) or (c) is used, it is possible to recycle all or part of the aqueous phase to the reaction system and reuse it, but it is difficult to efficiently separate and obtain pinacolon and operationally. From this point of view, method (a) is the most preferable. As the distillation method, steam distillation, normal pressure distillation, or vacuum distillation is used. In the present invention, the combined use of a strong inorganic acid salt not only has the effect of increasing the reaction yield or reducing the concentration and amount of the strong inorganic acid necessary to maintain the reaction yield, but also has the effect of separating the reaction mixture from the organic phase. This is advantageous in reducing the amount of organic matter that partitions into the aqueous phase during separation into the aqueous phase. Pinacolon obtained by the present invention is industrially useful as a solvent and as a synthetic intermediate for agricultural chemicals, rubber chemicals, etc. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, the yield in the examples means the mol% of the produced pinacolon based on the starting material supplied to the reaction system, unless otherwise specified. Example 1 A 300 ml four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a dropping funnel was charged with 109.5 g of 10% by weight hydrochloric acid (0.300 mol of hydrogen chloride) and 22.6 g (0.533 mol) of lithium chloride. Heat with stirring. Purity is determined when the liquid temperature reaches 100℃
40.5 g (0.310 mol) of 90.2% 2,3-dimethylbutane-1,3-diol (the rest being 3-methylpentane-1,3-diol) were introduced via the dropping funnel over a period of 4 hours. The reaction mixture refluxes as the raw materials are introduced, and the reflux temperature at the end of the raw material introduction is
It was 90.0℃. The reaction was worked up by refluxing for an additional 2 hours. The reflux temperature at this time (hereinafter referred to as the temperature at the end of the reaction) was 90.5°C. The reaction mixture was neutralized by gradually adding an equivalent amount of sodium hydroxide while stirring while cooling in an ice-water bath. Next, the organic phase was separated from the reaction mixture and analyzed by gas chromatography to determine the pinacolon yield. The results are shown in Table 1. Examples 2 and 3 Table 1 shows the amount of hydrochloric acid used without coexisting lithium chloride.
The reaction was carried out in the same manner as in Example 1 except that
The results in Table 1 were obtained by processing analysis. [Table] Example 4 Purity containing 7.7% of 3-methylpentane-1,3-diol as an impurity in the same equipment as Example 1
39.6 g (0.310 moles) of 92.3% 2,3-dimethylbutane-1,3-diol and 167.0 g (0.979 moles of hydrogen chloride) of 21.4 wt% hydrochloric acid were charged and heated under reflux for 4 hours with stirring. The reflux temperature at this time was 87.5-95.0°C. The reaction mixture was prepared in Example 1.
When processed and analyzed in the same manner as above, the yield of pinacolon was
It was 52.5%. Examples 5 and 6 Example 1 except that 2,3-dimethyl-3-hydroxybutyl acetate was used as the starting material and the amount of hydrochloric acid (HCl/raw material molar ratio) was 1.50.
The reaction and processing analysis was carried out in the same manner as in 2 and 2, and the results shown in Table 2 were obtained. [Table] [Table] Values based on the charged aqueous solution Examples 7 to 8 2,3-dimethyl-3 as the starting material
The reaction was carried out in the same manner as in Example 1 except that -chlorobutyl acetate and 2,3-dimethyl-2-butenyl acetate were used in the presence of magnesium chloride, and the results shown in Table 3 were obtained by treatment analysis. [Table] *Means the same as in Table 2 Examples 9 and 10 2,3-dimethylbutane-1,
86.7 mol% 3-diol diacetate and 2,3-
Dimethyl-3-hydroxybutyl acetate 13.3
The reactions were carried out in the same manner as in Examples 1 and 4, except that a mixture consisting of mol % was used, and the results shown in Table 4 were obtained. [Table] Examples 11-12 The reaction was carried out in the same manner as in Example 1 except that sulfuric acid was used as the inorganic strong acid and sodium hydrogen sulfate was used as the inorganic strong salt. The results shown in Table 5 were obtained. Reference Examples 1-2 In Example 11, sodium sulfate was not used together,
As an inorganic strong acid, the concentration is 10.0wt% and
A reaction was performed in the same manner as in Example 11 using a 20.5 wt % sulfuric acid aqueous solution, and the treatment and analysis were conducted. The results are also listed in Table 5. [Table] [Table] Examples 13 to 21 In a 300 ml four-necked flask equipped with a stirrer, reflux condenser, thermometer and dropping funnel, hydrochloric acid and optionally LiCl or LiCl as a salt of a strong inorganic acid were added.
Charged with MgCl ₂ and heated with stirring. The liquid temperature
When the temperature reaches 100℃, the general formula () is used as the starting material.
0.310 mol of the compound shown is added from the dropping funnel to 4
introduced over time. The reaction mixture refluxed as the raw materials were introduced. After the introduction of the starting materials was completed, the reaction was completed by further refluxing for 2 hours (the reflux temperature at this time is referred to as the temperature at the end of the reaction). The resulting reaction mixture was neutralized by gradually adding an equivalent amount of sodium hydroxide while stirring while cooling in an ice-water bath. Next, the organic phase was separated from the reaction mixture and analyzed by gas chromatography to determine the pinacolon yield. The results are shown in Table 6. [Table] [Table]

Claims (1)

[Claims] 1. The following general formula () [In formula (), W and Y are hydrogen atoms, and X and Z are the same or different, respectively.
OH, Cl, Br or RCOO (where R is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms), or one of W and Y is a hydrogen atom and the other is a single form a bond,
A method for producing pinacolon, which comprises heating a compound represented by the following formula: Z represents OH, Cl, Br, or RCOO (wherein R is the same as above) in an aqueous inorganic acid solution. 2. The method for producing pinacolon according to claim 1, wherein at least a partially soluble salt of an inorganic strong acid is present in the reaction system. 3. 1 kg of a reaction mixture in which the amount of inorganic strong acid and the amount of inorganic strong acid present in the reaction system is the sum of their acid groups.
The method for producing pinacolon according to claim 1 or 2, wherein the amount is at least 2.5 moles or more.