JPS6248659B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing α-branched carboxylic acid esters directly from olefins, ethers or alcohols. Conventionally, as a one-step production method for alkyl esters of α-branched carboxylic acids, olefins such as ethylene and propylene are reacted with generalized carbon in the presence of a BF ₃ /alcohol catalyst to form a carboxylic acid group with one more carbon atom than the olefin. Carbonylation method for producing carboxylic acid esters having
147235 and Japanese Patent Application Laid-Open No. 108541)
Ethers like MTBE as BF ₃ ―H ₃ PO ₄ ―
A method of reacting with carbon monoxide in the presence of a CH ₃ OH catalyst (British Patent No. 1232317) is known. However, in these reactions, it is difficult to obtain α-branched carboxylic acid esters in good yield, and BF ₃
Considering the highly corrosive nature of the catalyst system, various problems have arisen industrially due to the material and structure of the reaction vessel. The present inventors continued intensive research to improve these drawbacks, and found that by using a boron trifluoride/alcohol complex catalyst containing a copper () compound and a silver compound, olefin, ether, or alcohol can be monoxidized. The present invention was completed by discovering a method for directly producing α-branched carboxylic acid ester from carbon at low temperature and low pressure. That is, the present invention is directed to the formula BF ₃ .ROH [wherein R is an alkyl group having 1 to 4 carbon atoms]. ] A complex and an aliphatic or alicyclic olefin having 3 to 8 carbon atoms in the presence of a copper() compound and/or a silver compound, formula R ¹ OR ² [However, R ¹ is an alkyl having 3 to 6 carbon atoms] The group R ² is an alkyl group having 1 to 4 carbon atoms. The gist of this invention is a method for producing an α-branched carboxylic acid ester, which is characterized by reacting an ether or an alkyl alcohol having 3 to 6 carbon atoms with carbon monoxide. The catalyst used in the present invention is a boron trifluoride/alcohol complex represented by the molecular formula of BF ₃ .ROH, and can be synthesized by blowing boron trifluoride gas into an alcohol solution. R as alcohol
is an alkyl alcohol which is a lower alkyl group such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, or t-butyl. Copper () compound and/or used in this catalyst
Alternatively, any silver compound may be used as long as it produces copper () carbonyl and/or silver carbonyl in the reaction system, but it is preferable to use it in the form of a monovalent oxide, borofluoride, or fluoride. . As the copper() compound, copper oxide is preferably used, and as the silver compound, silver oxide, silver borofluoride, and silver fluoride are preferably used. It is also possible to use a mixture of equal amounts of metallic copper and a copper() compound, such as copper powder and cupric oxide, instead of the copper() compound. Although the molar ratio of copper () carbonyl and/or silver carbonyl to BF ₃ .ROH complex is not particularly strict, it is preferably used within the range of 0.01 to 0.1 per mole of BF ₃ .ROH complex. Next, the olefin used as a raw material in the present invention may be any olefin used in the well-known Kotsuho reaction, but aliphatic olefins and alicyclic olefins having 3 to 8 carbon atoms are used. For example, propylene, n-butylene, i-butylene,
These include pentene, hexene, octene, cyclopentene, and cyclohexene. Further, the ether used as a raw material in the present invention is an ether represented by the molecular formula of R ¹ OR ² , and R ¹
is an alkyl group having 3 to 6 carbon atoms, and R ² is methyl, ethyl, n-propyl, i-propyl,
N-butyl, i-butyl, and t-butyl are lower alkyl groups having 1 to 4 carbon atoms. R ¹ and R ² may be different or the same. Further, the alcohol used as a raw material is an alkyl alcohol having 3 to 6 carbon atoms. The reaction of the present invention is carried out at a temperature range of -10°C to +100°C. In this temperature range, the copper() compound and silver compound used as cocatalysts are Cu in the reaction system.
(CO) ⁺ _o (n=1~4), Ag(CO) ⁺ _n (m=1~
2) exists in the form of Of these, especially copper
= 3 and 4, and for silver, m = 2 has a large promoter effect. On the high temperature side of this temperature range, n and m have values close to 1, respectively, and on the low temperature side they have values close to 4 and 2, respectively. Therefore, at high temperatures, the concentration of metal carbonyl having a catalytic effect decreases, but the reaction rate increases, and at low temperatures, the values of n and m increase, so that the reaction can proceed advantageously. The reaction pressure is not particularly limited, but in view of the balance between reaction rate and manufacturing cost, it is generally desirable to carry out the reaction at 0.1 to 200 atmospheres, preferably 1 to 20 atmospheres. The reaction may be carried out in batch mode, semi-batch mode or continuous mode. Next, among these methods, a batch reaction method will be explained. According to the present invention, copper() carbonyl and/or silver carbonyl/
Put a BF ₃ ROH solution (prepared separately in advance or in the reactor) into a reactor, and add a small amount of olefin, ether, or alcohol to the reactor while stirring thoroughly at the specified temperature. Add one by one. The reaction proceeds rapidly, and carbon monoxide absorption into the reaction solution eventually stops. After completion of the reaction, the product can be recovered by adding alcohol in an amount equal to the amount of absorbed carbon monoxide to the reaction solution and extracting with a non-polar solvent such as a saturated hydrocarbon such as hexane. At this time, even if a salt such as an alkali metal BF ₄ ^-salt is added, the catalytic action is not inhibited and the extraction effect of the reaction product can be increased.
Further, during the extraction process, the copper and silver compounds remain in the acid catalyst layer, making it possible to carry out the reaction continuously without losing the effect of the co-catalyst. It is also possible to partially recover BF ₃ under reduced pressure after stopping carbon monoxide absorption, then treat the residue with alcohol, and then distill the ester from it. According to the present invention, the effect of copper carbonyl and silver carbonyl as co-catalysts allows the reaction to be carried out under mild conditions at low temperature and low pressure, improving the yield of α-branched carboxylic acid ester, and reducing the loss of raw materials due to the polymerization of olefins. This has the advantage of reducing manufacturing costs, reducing corrosion of equipment, etc. at the same time. The α-branched carboxylic acid ester obtained by the present invention has many uses such as pharmaceuticals, agricultural chemicals, lubricants, monomer raw materials for polymers, comonomers for polymers, and plasticizers. The raw material is propylene boron trifluoride as an olefin, and BF ₃ as an alcohol complex.
Using CH ₃ OH gives methyl isobutyrate,
This produces methyl methacrylate upon dehydrogenation. The present invention will be explained in detail below with reference to Examples. Example 1 0.305 g (2.13 mmol) of cuprous oxide was placed in a 200 ml 4-necked flask equipped with a stirrer, and after replacing the inside of the flask with carbon monoxide, BF ₃ CH ₃ OH complex 30
ml was introduced with a syringe. As soon as stirring was started, carbon monoxide was absorbed, and the production of copper carbonyl was completed within 5 minutes. While vigorously stirring this solution, 3.63 g of diisobutylene was added over 1.7 hours using a microfeeder. After the absorption of carbon monoxide stopped, methanol was added to the reaction solution, ice water was further added, and the mixture was extracted with hexane to obtain a product. The results shown in Table 1 were obtained by gas chromatography analysis of the product. The temperature in this reaction was 35°C and the carbon monoxide pressure was 1 atm. Example 2 In a 200ml 4-necked flask equipped with a stirrer
Take 1.75 g (9.00 mmol) of AgBF ₄ and replace the inside of the flask with nitrogen, then add 26 ml of BF ₃ CH ₃ OH complex.
was introduced with a syringe. After purging the nitrogen in the flask with carbon monoxide, the mixture was stirred for about 1 hour under 1 atm of carbon monoxide to dissolve AgBF ₄ and convert it into a carbonyl complex. While vigorously stirring this solution, 2.90 g of diisobutylene was added over 30 minutes using a microfeeder. Stirring was continued for an additional 10 minutes until absorption of carbon monoxide stopped. The results of the analysis of the reaction product are shown in Table 1. Comparative Example 1 A reaction similar to Example 1 was carried out without adding cuprous oxide. The results are shown in Table-1. Example 3 0.36 g of cuprous oxide was prepared in the same manner as in Example 1.
_{Copper carbonyl} /
A BF ₃ .CH ₃ OH solution was prepared. 2.01 g (22.8 mmol) of methyl-t-butyl ether (MTBE) was added to a vigorously stirred copper carbonyl/BF ₃ CH ₃ OH solution at 21°C under 1 atmosphere of carbon monoxide.
It was dropped for 30 minutes. Thereafter, the reaction was continued for 7 minutes until absorption of carbon monoxide stopped. The analysis results of the product are shown in Table 1. Example 4 The reaction was carried out in the same manner as in Example 3 except that 0.59 g (2.55 mmol) of silver oxide was used instead of cuprous oxide to prepare a silver carbonyl/BF ₃ .CH ₃ OH solution. I went there. The analysis results of the product are shown in Table 1. Example 5 Copper carbonyl/BF ₃ was prepared in the same manner as in Example 3.
A CH ₃ OH solution was prepared, and 2.1 g of t-butanol was added dropwise to the solution under 1 atmosphere of carbon monoxide pressure over 30 minutes. After dropping t-butanol, stirring was continued for 8 minutes until absorption of carbon monoxide stopped. The results of the analysis of the reaction product are shown in Table 1.

【table】

_[ Table] Example 6 In the method _of Example ₃ , _{copper carbonyl} /
BF ₃ .C ₂ H ₅ OH was prepared and the reaction was carried out in the same manner as in Example 3, except that 5.61 g (50.0 mmol) of diisobutylene was used instead of MTBE. The analysis results of the product are shown in Table 2. Comparative Example 2 The reaction in Example 6 was carried out without using cuprous oxide. The results are shown in Table-2.

[Table] Example 7 In a Teflon-coated electromagnetic stirring autoclave with an internal volume of 250 ml, 40 ml of BF ₃ CH ₃ OH and 0.36 cuprous oxide were added.
g (2.51 mmol) and purged twice with carbon monoxide at 10 atm at room temperature. Five atmospheres of carbon monoxide was added, and 5.3 g of liquefied propylene was injected under vigorous stirring. Furthermore, carbon monoxide was added until the autoclave reached 20 atm, and the internal pressure was maintained at 20 atm by adding carbon monoxide, and the reaction was carried out for 1 hour. The analysis results of the products obtained by methanol and water treatment and subsequent extraction are shown in Table 3. Comparative Example 3 The reaction was carried out in the same manner as in Example 7 except that cuprous oxide was not used and the amount of propylene was changed to 9.8 g. The results are shown in Table 3.

【table】

[Table] Example 8 A copper carbonyl (2.4 mmol)/BF ₃ CH ₃ OH complex solution was prepared in the same manner as in Example 1, and 4.0 g (48.7 mmol) of cyclohexene was added to monoxide at 1 atm. It was added dropwise under carbon over a period of one hour. Thereafter, stirring was continued for 15 minutes until the absorption of carbon monoxide stopped. Gas chromatography analysis revealed that only methyl 1-methylcyclopentanecarboxylate was produced at a yield of 82%.

Claims (1)

[Claims] 1 Formula BF ₃ ·ROH [However, R is an alkyl group having 1 to 4 carbon atoms. ] Aliphatic or cycloaliphatic olefin having 3 to 8 carbon atoms, formula R ¹ OR ² in the presence of the complex and a copper() compound and/or a silver compound
[However, R ¹ is an alkyl group having 3 to 6 carbon atoms, and R ² is an alkyl group having 1 to 4 carbon atoms. A method for producing an α-branched carboxylic acid ester, which comprises reacting the ether or alkyl alcohol having 3 to 6 carbon atoms with carbon monoxide.