JP2821630B2 - Method for producing Z- (alkoxycarbonyl) ethyl phosphinate - Google Patents

Description

The present invention relates to a method for producing 2- (alkoxycarbonyl) ethylphosphinic acid ester.

The phosphinic acid ester according to the present invention is a novel compound and is effective, for example, as an intermediate for pesticides.

[Conventional technology]

It is known that methyl 2- (methoxycarbonyl) ethylphosphinate similar to the compound according to the present invention is synthesized by a reaction between methyl hypophosphite and methyl acrylate (CA. vol83.147545). ).

Further, although the compound according to the present invention has a basic structure different from that of the compound according to the present invention, compounds in which R 'and R "in the phosphinic acid ester represented by the following general formula are an alkyl group or a phenyl group shown in the following table are also described, for example, in the literature shown in the following table. It is described in.

[Problems to be Solved by the Invention] However, the method of synthesizing 2- (alkoxycarbonyl) ethylphosphinic acid ester by the reaction between methyl hypophosphite and methyl acrylate as described above is disclosed by the present inventors. Experiments have shown that alkyl hypophosphite is an unstable compound that easily causes disproportionation to generate phosphine (PH ₃ ), and has been pointed out in the literature (Vest
n.Mosk.Univer.Khim., 13 (3), 361 (1972). Therefore,
Since this reaction requires not only special safety measures in operation but also a low yield, there is a problem in industrially carrying out the reaction.

Further, the other phosphinic esters described above are synthesized by a method different from the esterification reaction by so-called dehydration treatment, and the basic structure is different from the compound according to the present invention.

Generally, the esterification reaction is carried out by removing by-produced water, that is, a so-called dehydration treatment. However, there is no literature in the literature on the successful synthesis of an ester by the dehydration reaction between phosphinic acid and an alcohol.

The present inventors have attempted synthesis of phosphinic esters by various conventionally known production methods, but have not obtained anything that can be expected.

However, surprisingly, they have found that 2-carbonylethylphosphonic acid and alcohol are easily esterified by reflux dehydration reaction in the presence of an inert solvent, and completed the present invention.

[Means for solving the problem]

That is, the method for producing a phosphinic acid ester represented by the above formula [1] provided by the present invention comprises the following general formula: Wherein R ³ represents hydrogen or a C _{2 to} C ₂₀ alkyl group or a phenyl group, and 2-carbonylethylphosphinic acid represented by the general formula: R ¹ OH wherein R ¹ is a C _{2 to} C ₂₀ It represents an alkyl group or a phenyl group. ] In the presence of an inert solvent in a reflux dehydration reaction.

The phosphinic acid ester according to the present invention is a novel compound unknown in the literature, and this compound is industrially useful as an intermediate material for various phosphinic acid derivatives, particularly as an intermediate for agricultural chemicals.

Such a phosphinic ester is produced by subjecting a phosphinic acid and an alcohol to a reflux dehydration reaction of the following formula, as described above.

This reaction is based on the starting material phosphinic acid represented by the formula (II).
An excess of alcohol is used, and in most cases 1.1 to 3.0 times mol is appropriate. However, when the compound of the formula [III] is 2-carbonylethylphosphinic acid (R ³ ＨH), a double amount of the above ratio is appropriate.

The inert solvent used in this reaction means an organic solvent that does not react with any of the raw materials involved in the reaction and does not inhibit the dehydration reaction, for example, benzene, toluene, xylene,
Chloroform and the like can be mentioned.

Note that in the raw material, but R ¹ in the alcohol (R ¹ OH) is R ³ and same or different alkyl group of the starting phosphinic acid (II) as described above, when the heterologous as R ¹ in the reaction It should be noted that transesterification with R ³ may partially occur.

The reaction temperature of the present invention is naturally determined by the azeotropic point of the solvent used and water, and is generally in the range of 40 to 130 ° C.

Although this reaction proceeds without a catalyst, a small amount of a known Lewis acid such as aluminum chloride, paratoluenesulfonic acid, and sulfuric acid may be added as a catalyst. In general, the reaction rate tends to be faster when a catalyst is added. The progress of the reaction is monitored by the amount of water produced as a by-product, and the reaction is terminated when no more water is distilled off.

Therefore, the degree varies depending on the type of raw materials and the presence of a catalyst, but when no catalyst is used, the reaction time is in the range of 8 to 20 hours, and the presence of a Lewis acid substantially reduces the reaction time. It is industrially preferable to carry out the reaction in the presence of a Lewis acid since it can be reduced to half. However, in this case, it is necessary to wash and dry after completion of the reaction. That is, after completion of the reaction, necessary unit operations such as separation, washing with water, drying and the like are performed by a conventional method to collect the product and finish it as a product.

The structure of the product is confirmed by a conventional instrumental analysis such as ¹ H NMR, IR, MS, GC, and LC.

〔Example〕

The present invention will be specifically described with reference to examples.

Example 1 <Synthesis of 2-ethylhexyl 2- (2-ethylhexyloxycarbonyl) ethylphosphinate> 2- (2-ethylhexyloxycarbonyl) ethylphosphinic acid was placed in a four-necked flask equipped with a reflux tube, a stirrer, and a thermometer. After charging 31.2 g (0.125 M), 20.8 g (0.16 M) of 2-ethylhexyl alcohol and 60 ml of benzene, the mixture was heated. When the bath temperature exceeded 135 ° C, the dehydration reaction started.

The progress of the reaction was monitored while checking it by NMR, IR, MS and the like, and the reaction was terminated after 18 hours while maintaining the inside of the reaction system at 94 ° C.

Then, after separating the solvent and excess alcohol,
About 42 g of residual product was obtained. This was subjected to structural analysis by 60 MHz ¹ H-NMR, IR and MS to confirm that it was 2-ethylhexyl 2- (2-ethylhexyloxycarbonyl) ethylphosphinate. The crude yield of this compound was 93%, and the purity was 99% or more as measured by GC.

Example 2 <Synthesis of 2-ethylhexyl 2- (2-ethylhexyloxycarbonyl) ethyl phosphinate> The reaction was performed for 10 hours under the same operating conditions as in Example 1 except that 0.17 g of aluminum chloride was added, and the remaining mixture was mixed. 40 g of the liquid was obtained.

Next, the mixture was washed with 40 ml of water and dried over magnesium sulfate. After the mixture was passed, the solvent and excess alcohol were separated to obtain a residual product. This compound was subjected to a similar structural analysis to confirm that it was the same compound as in Example 1. The crude yield of this compound was 88%.

Example 3 <Synthesis of ethyl 2- (2-ethylhexyloxycarbonyl) ethyl phosphinate> 31.2 g (0.125 g) of 2- (2-ethylhexyloxycarbonyl) ethyl phosphinic acid was placed in the same reaction vessel as in Example 1.
M), 7.4 g (0.16 M) of ethyl alcohol and 60 ml of benzene
, And heated to reach a bath temperature of 85 ° C. and a reaction system temperature of 82 ° C. to start a dehydration reaction.

Further, after the dehydration reaction was continued at this temperature for 18 hours, the reaction was terminated. Hereinafter, post-processing is performed by the same operation, and 25 g of the product is obtained.
I got

This was analyzed by GC-MS. As a result, ethyl 2- (2-ethylhexyloxycarbonyl) ethylphosphinate and 2-ethylhexyl 2- (2-ethylhexyloxycarbonyl) ethylphosphinate were obtained in almost the same amount. Was.

The residual product was placed in a two-necked flask equipped with a reflux tube, a stirrer, and a thermometer, charged with 50 ml of benzene and 50 ml of ethyl alcohol, and then heated to reflux. Mixed solution
Track while checking with GC etc., keep at 80 ° C in the reaction system
After 36 hours, the ratio of ethyl to 2-ethylhexyl is 4 to 1.
Became.

Example 4 <Synthesis of n-butyl 2- (2-ethylhexyloxycarbonyl) ethyl phosphinate> 31.2 g (0.125 g) of 2- (2-ethylhexyloxycarbonyl) ethyl phosphinic acid was placed in the same reaction vessel as in Example 1.
M), 11.8 g (0.16 M) of n-butyl alcohol and 60 ml of benzene were charged, and the mixture was heated. When the bath temperature exceeded 100 ° C., the dehydration reaction started. The reaction system was maintained at 88 ° C. and terminated after 8 hours. After separating off the solvent and excess alcohol, about 30 g of residual product were obtained.

When this was subjected to the same structural analysis as in Example 1, it was confirmed that the main product was n-butyl 2- (2-ethylhexyloxycarbonyl) ethylphosphinate.

Example 5 <Synthesis of phenyl 2- (2-ethylhexyloxycarbonyl) ethyl phosphinate> 31.2 g (0.125 g) of 2- (2-ethylhexyloxycarbonyl) ethyl phosphinic acid was placed in the same reaction vessel as in Example 1.
M), 15.0 g (0.16 M) of phenol and 60 ml of benzene were charged and heated. The dehydration reaction started when the bath temperature reached 130 ° C and the temperature in the reaction system reached 87 ° C. Further, after the dehydration reaction was continued at this temperature for 20 hours, the reaction was terminated. Thereafter, post-treatment was performed in the same manner as above to obtain 37 g of a product.

This was structurally analyzed by the same operation.
It was confirmed to be-(2-ethylhexyloxycarbonyl) ethyl phenyl phosphinate.

Example 6 <Synthesis of butyl 2- (butyloxycarbonyl) ethyl phosphinate> 17.3 g (0.125 M) of 2-oxycarbonylethyl phosphinic acid and 24.0 g (0.325 M) of n-butyl alcohol were placed in the same reaction vessel as in Example 1. Then, 60 ml of benzene was charged and heated to reach a bath temperature of 100 ° C. and a temperature of 85 ° C. in the reaction system to start a dehydration reaction. After 2 hours, about 2.5 ml of water was distilled off, which corresponds to about 1 equivalent of the esterification of the carbonyl group, which is considered to have proceeded preferentially.

Further, after the dehydration reaction was continued for 14 hours and terminated, the same post-treatment was carried out as follows to obtain 35 g of a product.

When this was subjected to structural analysis by the same operation, it was confirmed that it was butyl 2- (butyloxycarbonyl) ethylphosphinate. The crude yield of this compound was 96%.

Physical properties of the compounds obtained in the above Examples were confirmed. Table 1 shows the data.

[Effect of the Invention] The 2- (alkoxycarbonyl) ethylphosphinic acid ester according to the present invention is a novel compound and is industrially useful, for example, to an intermediate for an agricultural chemical.

Such a phosphinic acid ester compound can be industrially advantageously produced by performing an esterification reaction by the method according to the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07F 9/32 CA (STN)

Claims (1)

(57) [Claims] 1. The following general formula: [Wherein R ³ represents a hydrogen atom or a C ₂ -C ₂₀ alkyl group or a phenyl group] and a general formula: R ¹ OH (where R ¹ is C ₂ -C ₂ A 2- (alkoxycarbonyl) ethylphosphinic acid ester, which is subjected to a reflux dehydration reaction with an alcohol represented by the formula ( ₂₀ ) representing an alkyl group or a phenyl group) in the presence of an inert solvent.