JPH0242837B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a phosphoric acid monoester by phosphorylating an organic hydroxy compound, and more specifically, a novel and efficient method for producing a phosphoric acid monoester selectively and efficiently. The present invention relates to an improved method. [Prior Art] Acidic phosphate esters of organic hydroxy compounds are widely used as fiber treatment agents, emulsifiers, dyeing aids, rust preventives, and the like. Currently, the main method for producing this is to directly react phosphoric anhydride with a hydroxy compound. However, the products produced by this method are phosphoric acid monoester (hereinafter abbreviated as "monoester") and phosphoric acid diester (hereinafter referred to as "diester").
It is a nearly equimolar mixture of (abbreviated as). However, the physical properties of monoesters and diesters have considerable differences. For example, monoester has characteristics such as excellent water solubility, foaming power, detergent power, antistatic ability, and low skin irritation. On the other hand, diesters, which are used as metal extractants from aqueous solutions, have poor solubility and foaming properties in water, and when used as a mixture, they often inhibit their function as monoesters. Applications are often restricted. Therefore, various methods for selectively producing monoesters have been proposed as described below. (1) Method for selectively producing monoesters using condensed phosphoric acid (Japanese Patent Publication No. 43-26492, B.Clake,
et al., J.Am.Chem.Soc., 88 , 4401 (1966)). (2)
A method of synthesizing monoalkyl phosphorodichloridate with phosphoryl chloride and then converting it into phosphoric acid monoester by hydrolysis (Japanese Patent Application Laid-Open No. 50-64226
issue). (3) A method in which phosphoric acid or water is used in combination when phosphorylating with phosphoric anhydride (Japanese Patent Publication No. 14416/1973, Japanese Patent Publication No. 6730/1973). [Problems to be Solved by the Invention] However, all of the above-mentioned prior art methods have the following drawbacks and are hardly used industrially. In other words, in method (1), inorganic orthophosphoric acid is produced as the reaction progresses, and the amount of the produced amount almost matches the reciprocal of the average degree of condensation of condensed phosphoric acid, so in order to reduce the amount of orthophosphoric acid produced, , condensed phosphoric acid with a very high degree of condensation must be used. However, such condensed phosphoric acid with a high degree of condensation has an extremely high viscosity at room temperature and must be heated to facilitate the work, but heating causes problems such as corrosion of the container. Furthermore, it is extremely difficult to industrially produce condensed phosphoric acid with such a high degree of condensation due to restrictions such as the material of the production kettle. Method (2) involves problems such as the raw material sulfolyl chloride is highly toxic and irritating, making it difficult to handle, and there is also a large amount of hydrogen chloride as a by-product, which causes severe corrosion of processing equipment and equipment. . In method (3), if the amount of water or phosphoric acid added increases, the ratio of monoester increases from the perspective of the ratio of monoester to diester, but
At the same time, the amount of inorganic orthophosphoric acid produced increases significantly, the phosphorus reaction rate decreases, and a large amount of inorganic orthophosphoric acid mixed into the product significantly reduces the product value of the product. SUMMARY OF THE INVENTION Therefore, the present invention has been made with the object of eliminating the above-mentioned drawbacks of the prior art methods and providing a method that can selectively and efficiently produce monoesters. [Means for solving the problem] The present inventors modified the conventional method of reacting phosphoric anhydride directly with an organic hydroxy compound, and suppressed the reactivity by reacting phosphoric anhydride with hexaalkyldisiloxane. The inventors discovered that phosphoric acid monoesters of organic hydroxy compounds can be selectively and efficiently produced by forming a condensed phosphoric ester with a specific structure and then reacting this with an organic hydroxy compound, thereby completing the present invention. It is something. That is, the method for producing phosphoric acid monoester according to the present invention is to produce polyphosphoric acid obtained by reacting phosphoric anhydride (P ₄ O ₁₀ ) with hexaalkyldisiloxane in a certain proportion, as shown in the following reaction formula (). This method is characterized by phosphorylating an organic hydroxy compound using a trialkylsilyl ester as a phosphorylating agent. (In the formula, R represents an alkyl group, and R' represents an organic hydroxy compound residue.) The present invention will be described in further detail below with respect to the case where hexamethyldisiloxane is used as the hexaalkyldisiloxane. In recent years, the reaction product of phosphoric anhydride and hexamethyldisiloxane, namely polyphosphoric acid trimethylsilyl ester, has been used as a reagent for condensation, dehydration, and rearrangement reactions of various organic compounds (T. Ima-moto, et al. ，
J.Org.Chem., 49 , 1105 (1984)). In the synthesis of polyphosphoric acid trimethylsilyl ester in this case, the molar ratio of hexamethyldisiloxane to phosphoric anhydride (P ₄ O ₁₀ ) is approximately 2. On the other hand, in the present invention, the molar ratio of addition is set to 2.5 or more and less than 6, preferably 3 to 5.
If the addition molar ratio is less than 2.5, the diester by-product rate will increase during phosphorylation;
If the molar ratio of addition is 6 or more, diester by-product production can be suppressed, but the yield of monoester will decrease, which is not practical. The reason for this is thought to be as follows. In other words, when the ratio of hexamethyldisiloxane to be reacted to phosphoric anhydride is small, the degree of condensation is large and the degree of substitution of trimethylsilyl groups is low, resulting in highly reactive polyphosphoric acid trimethylsilyl ester, and when this reacts with an organic hydroxy compound, Not only monoesters but also diesters are produced as by-products. Conversely, when the ratio of hexamethyldisiloxane to phosphoric anhydride is increased, the degree of condensation is small and the degree of substitution of trimethylsilyl groups is high, resulting in a polyphosphoric acid trimethylsilyl ester with low reactivity. It is assumed that monoesters are selectively produced. This polyphosphoric acid trimethylsilyl ester obtained by the reaction of phosphoric anhydride and hexamethyldisiloxane does not have a single structure;
As shown in formula (), it is a mixture of several types of condensates, and it is thought that the proportion of each type and the degree of condensation of each type change depending on the reaction ratio of both types. Polyphosphoric acid trimethylsilyl ester prepared with a specific reaction ratio as used in the present invention was analyzed by ^31P NMR and found to contain a branched phosphoric acid group surrounded by three phosphoric acid groups that cause diester formation. What you have (type: B)
It has become clear that the content of phosphoric acid is small, and the resulting condensed phosphoric acid is mainly composed of linear or cyclic tetramers (type: A or C). Furthermore, unlike phosphoric anhydride and other condensed phosphoric acids, this reaction product can be dissolved in an organic solvent in any proportion and the reaction can be carried out in a homogeneous phase. Therefore, the reaction proceeds quickly under mild conditions, and monoesters can be obtained in good yields. Furthermore, it is possible to phosphorylate organic hydroxy compounds that could not be phosphorylated due to dehydration, decomposition, etc., in the conventional method of directly reacting phosphoric anhydride. As the alkyl group in the hexaalkyldisiloxane used in the present invention, a lower alkyl group having 4 or less carbon atoms is used. In addition, organic hydroxy compounds include linear and/or branched saturated or unsaturated aliphatic alcohols (e.g., amyl alcohol, 2-ethylhexanol, octanol, decanol, dodecanol, hexadecanol, oleyl alcohol, etc.), fatty alcohols, etc. Cyclic alcohols (e.g. cyclohexanol, cyclopentanol, etc.), aromatic alcohols (e.g. benzyl alcohol), phenols (phenol,
alkylphenols, etc.) and their polyalkylene glycol ethers (so-called nonionic surfactants), polyalkylene glycols (polyethylene glycol, polypropylene glycol, etc.), polyols (ethylene glycol, glycerin, etc.), terpene alcohols (borneol, menthol, etc.) ), cholesterol,
Sugars (glucose, sorbitol, etc.) and other organic hydroxy compounds having carbonyl, aldehyde, acrylic, amino, aryl groups, etc. can be used. Known methods can be used for the synthesis of trialkylsilyl polyphosphate in the present invention. Specifically, phosphoric anhydride is dispersed in an inert solvent such as benzene or methylene chloride, hexaalkyldisiloxane is added, and 40%
Stir or reflux to react at ~150°C until phosphoric anhydride disappears. Alternatively, the reaction may be carried out by adding phosphoric anhydride to hexaalkyldisiloxane. This reaction is obtained in approximately 100% yield.
Next, phosphoric anhydride (P ₄ O ₁₀ ) was added to the reaction mixture.
4 times the mole or less of the organic hydroxy compound is added, and the mixture is stirred or refluxed for 0.5 to 5 hours at 20 to 150°C to effect phosphorylation (reaction formula). As a result,
A trialkylsiloxymonophosphoryl group R ₃ Si OP(O)O- is introduced into the organic hydroxy compound. Since the trialkylsilyl group bonded to the phosphoryl group is very susceptible to hydrolysis, when an appropriate amount of water is added to the above reaction product, only the trialkylsilyl group is selectively hydrolyzed to obtain a monoester (reaction formula). Further, the hydrolyzed trialkylsilyl group passes through trialkylsilanol and immediately becomes hexaalkyldisiloxane (reaction formula), which can be recovered together with the solvent by vacuum distillation and reused. 2R ₃ SiOH→R ₃ SiOSiR ₃ + H ₂ O () [Example] Next, embodiments of the present invention will be explained based on Examples and Comparative Examples, but the present invention is not limited to these Examples. It is not something that will be done. In addition, parts and % in each example below indicate parts by weight and % by weight, respectively. Example 1 Phosphoric anhydride 71 in a flask filled with nitrogen gas
160 parts of benzene and 162 parts of hexamethyldisiloxane (molar ratio to phosphoric anhydride)
4.0) and reflux until phosphoric anhydride disappears. The mixture was returned to room temperature, 158 parts of dodecanol was added dropwise, and the mixture was refluxed for 2 hours. After cooling, add 40 parts of water,
After stirring thoroughly, the solvent and the hexamethyldisiloxane produced were recovered by vacuum distillation.
Part of the product is obtained. If necessary, purify further as follows. That is, dissolve this in 500 parts of ether, add 50 parts of water, mix well, separate the aqueous layer, and remove phosphoric acid. Thereafter, the acidic phosphate ester is extracted with a 1N aqueous sodium hydroxide solution. Further, this alkaline solution is acidified with a 1N aqueous hydrochloric acid solution, extracted with ether, dehydrated with sodium sulfate, and the ether is distilled off to obtain 180 parts of purified product (yield: 76%). Product purity was determined by potentiometric titration and elemental analysis. Example 2 A reaction was carried out in the same manner as in Example 1, except that the molar ratio of hexamethyldisiloxane to 71 parts of phosphoric anhydride was changed. The results are shown in Table 1.

[Table] Example 3 The reaction was carried out in the same manner as in Example 1, except that various organic hydroxy compounds shown in Table 2 were used in place of dodecanol in Example 1. The results are shown in Table 2. As a result of elemental analysis, the purity of both samples was approximately 100%.

〔Effect of the invention〕

As can be seen from the above explanation, according to the method of the present invention, a monoester with high purity can be selectively produced efficiently. In particular, the polyphosphoric acid trialkylsilyl ester used as the phosphorylating agent in the present invention has extremely good solubility in organic solvents, so that the reaction can be carried out in a homogeneous phase. Therefore, the reaction proceeds quickly under mild conditions, and the monoester can be obtained in good yield. Furthermore, since the hexaalkyldisiloxane used in the present invention is ultimately recoverable, it also has the advantage of being able to be recycled and reused.

Claims (1)

[Claims] 1. Phosphorylating an organic hydroxy compound using a reaction product obtained by reacting the two at a molar ratio of 2.5 or more and less than 6 of hexaalkyldisiloxane to phosphoric anhydride (P ₄ O ₁₀ ) as a phosphorylating agent. A method for producing a phosphoric acid monoester.