JP4472033B2 - Method for producing linear organohydrogensiloxane oligomer - Google Patents

Description

【００４３】
表１から明らかなように、原料シロキサン中のＭ／Ｄ^H 比が上昇するにつれて、より低い分子量の直鎖状ポリメチルハイドロジェンシロキサンが多く生成している。Ｍ／Ｄ^H 比が１〜１０の範囲にわたり、ＭＤ^H Ｍ生成量は２２％から３１％まで上昇しているが、この程度の変化であれば、連続法によるＭＤ^H Ｍの製造における平衡化反応の制御は容易である。ＭＤ^H _zＭの生成量もまた、Ｍ／Ｄ^H 比が１〜４の範囲で１３．２〜１９．０％であって、十分に制御しうる。
【００４４】
図２は、それぞれの平衡化した混合物中のＭＭとＭＤ^H Ｍを、原料シロキサン中のＭ／Ｄ^H の関数としてプロットしたものである。また図３は、Ｍ／Ｄ^H 比が増加するにつれてＭＭのＭＤ^H Ｍに対する比が上昇することを示す。Ｍ／Ｄ^H 比の上昇につれて、ＭＭの生成比が大きくなり、蒸留の際に多量のＭＭを留去する必要があることがわかる。
【００４５】
実施例１１、１２
参考例１で用いたのと同様のＭＭとＭＤ^H _xＭを原料として用い、溶媒として後から配合するＭＭを含めて算出したＭ／Ｄ^H比を２．４とし、参考例１と同様な方法によって調製した混合シロキサンに、参考例１で用いたのと同じ塩化ホスホニトリル化合物のＭＭ溶液を配合した。これを温度６５℃（実施例１１）および２５℃（実施例１２）にそれぞれ保持して平衡化反応を行った。３０分間隔で一部の試料を採取して、参考例１と同様のガスクロマトグラフィーにかけて、生成物中のＭＤ^HＭの割合を追跡した。その結果を図４に示す。
【００４６】
図４から明らかなように、反応温度６５℃では、平衡化時間２時間で平衡化がほぼ完了しているのに対し、反応温度２５℃では、７時間後もまだ平衡化が完了しなかった。
【図面の簡単な説明】
【図１】平衡における各ＭＤ^H _zＭの、種々のＭ／Ｄ^H 比における含有量を示すグラフである。
【図２】平衡におけるＭＭとＭＤ^H Ｍとのそれぞれの含有量の、Ｍ／Ｄ^H 比による変化を示すグラフである。
【図３】平衡におけるＭＭとＭＤ^H Ｍに対する比の、Ｍ／Ｄ^H 比による変化を示すグラフである。
【図４】各平衡化温度におけるＭＤ^H Ｍの含有量の、平衡化時間による変化を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a linear organohydrogensiloxane oligomer, and more particularly to a method particularly suitable for producing a linear methylhydrogensiloxane oligomer.
[0002]
In the following description, linear polymethylsiloxane and linear polymethylhydrogensiloxane in which the organic group bonded to the silicon atom is a methyl group will be mainly described, but the present invention is not limited to this. Absent. The following abbreviations are used for the siloxane units of these methyl polysiloxanes.
M: Trimethylsiloxy unit
D: Dimethylsiloxane unit
D^H : Methylhydrogensiloxane unit
[0003]
[Prior art]
Organohydrogensiloxane oligomers represented by linear methylhydrogensiloxane oligomers, especially MD^H 1,1,1,3,5,5,5-heptamethyltrisiloxane represented by M, MD^H ₂1,1,1,3,5,7,7,7-octamethyltetrasiloxane represented by M is a surface treatment of various inorganic substances by utilizing the reactivity of Si—H bonds in the molecule. It is used for chemical modification of organic compounds and intermediates for synthesizing organosilicon compounds.
[0004]
For the production of such a linear organohydrogensiloxane oligomer, for example, an end-stopper such as hexamethyldisiloxane represented as MM, and D^H Cyclic and / or linear polymethylhydrogensiloxane having units such as D^H _FourAnd / or α, ω-bis (trimethylsilyl) poly (methylhydrogensiloxane) are mixed at a blending ratio that provides the desired oligomer with high selectivity and equilibrated with an equilibration catalyst such as activated clay. After that, a method is known in which activated clay is filtered off and the product is distilled.
[0005]
When using such a method, especially MD^H M or MD^H ₂When M is the target product, the selectivity of these target oligomers is low, unreacted MM and higher degree of polymerization MD in the product.^H _zThe content of M (z> 1) is extremely large. MM and byproduct MD^H _zBy recovering and recycling M, the overall conversion rate to the target oligomer can be improved, but the process including filtration of activated clay becomes complicated and the selectivity of the target oligomer is low. In addition, the recirculation amount relative to the production amount is large, and it is economically disadvantageous to combine the use amount of activated clay, the amount of filtration work, and the power cost of distillation / recirculation.
[0006]
In addition, other strongly acidic or strongly alkaline catalysts generally used for the equilibration reaction of polyorganosiloxane lead to the cleavage reaction of Si—H bond. Therefore, equilibration using such an organohydrogensiloxane oligomer as a target product is performed. Can not be used.
[0007]
Linear halogenated sulfonitrile compounds are known as catalysts for the equilibration reaction of polyorganosiloxane and the polycondensation reaction of polyorganosiloxane having a hydroxyl group at the terminal. In JP-A-8-109261, in the presence of the linear halogenated phosphonitrile compound, a mixture of MM and a polydiorganosiloxane containing a diorganosiloxane unit such as D unit is equilibrated. A method for producing a specific linear organosiloxane oligomer such as MDM with high yield is disclosed. However, this publication does not describe the production of a polyorganohydrogensiloxane oligomer by an equilibration reaction using the phosphonitrile compound. In addition, such a linear halogenated phosphonitrile compound is used to equilibrate polyorganohydrogensiloxane without side reactions such as cleavage of the Si—H bond, so that a linear polyorganohydrogen is obtained. It is not known that siloxane oligomers can be synthesized with good yield.
[0008]
[Problems to be solved by the invention]
The object of the present invention is to provide linear organohydrogensiloxane oligomers, in particular MD.^H M or MD^H ₂An object of the present invention is to provide a method for producing a linear methylhydrogensiloxane oligomer having a specific degree of polymerization such as M with good selectivity and high yield.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventor used a linear halogenated phosphonitrile compound for the equilibration reaction using a linear organohydrogensiloxane oligomer as a target product. Linear organohydrogensiloxane oligomers, particularly linear methylhydrogensiloxane oligomers having a specific degree of polymerization, without causing side reactions such as Si-H bond cleavage in the equilibration step and catalyst deactivation step Has been found to be able to be produced with good yield, and the present invention has been completed.
[0010]
That is, the method for producing the linear organohydrogensiloxane oligomer of the present invention comprises:
(1) (A) a linear organosiloxane oligomer having a triorganosiloxy unit, and (B) a linear polyorganohydrogensiloxane having a higher degree of polymerization than the cyclic organohydrogensiloxane oligomer and / or the target product. Mixing to obtain a siloxane mixture;
(2) adding a catalytic amount of (C) a linear halogenated phosphonitrile compound to the mixture and causing an equilibration reaction;
(3) deactivating the linear halogenated phosphonitrile compound; and
(4) Step of recovering the obtained linear organohydrogensiloxane oligomer
It is characterized by including.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
(A) used in the present invention is a linear organosiloxane oligomer having a triorganosiloxy unit, which gives a terminal triorganosiloxy group to the target linear organohydrogensiloxane oligomer. Examples of (A) include dimers consisting only of the triorganosiloxy units, trimers containing intermediate diorganosiloxane units, tetramers, pentamers, etc., and mixtures containing them. Dimers are preferred because they can be synthesized in good yields, have an appropriate polymerization rate, and can be easily recovered unreacted. Especially the target is MD^H _zIn the case of an oligomer that does not contain a diorganosiloxy unit, as shown by M (wherein z is a positive integer), (A) is also a dimer that does not contain the unit, in particular MM. .
[0012]
Examples of the organic group bonded to the silicon atom include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, and dodecyl; cycloalkyl groups such as cyclohexyl; 2-phenylethyl, 2-phenylpropyl Aralkyl groups such as vinyl; allyl, 1-butenyl, alkenyl groups such as 1-hexenyl; monovalent hydrocarbon groups such as aryl groups such as phenyl, tolyl; and chloromethyl, 3-chloropropyl, 3 And monovalent substituted hydrocarbon groups such as 1,3,3-trifluoropropyl, which may be the same or different, but are easy to synthesize and handle, and the target product is also an organohydrogensiloxane oligomer. Whether it is easy to process various substrates such as fibers, water repellency and reactivity , A methyl group is particularly preferred. Such (A) includes MM, MDM, MD₂ M, MD_Three Illustrative are linear methylsiloxane oligomers such as M and mixtures thereof, with MM being particularly preferred for the reasons described above.
[0013]
(B) used in the present invention gives an intermediate organohydrogensiloxane unit to the target linear organohydrogensiloxane oligomer, and even if it is cyclic, it has a higher degree of polymerization than the target. Polyorganohydrogensiloxane may be sufficient, and a mixture of both may be sufficient. Depending on the object, it may be composed only of organohydrogensiloxane units excluding molecular ends, or it may contain organohydrogensiloxane units and diorganosiloxane units. In the case of a linear polyorganohydrogensiloxane, the molecular end may be a triorganosiloxy group or a silanol group.
[0014]
Examples of the organic group bonded to the silicon atom are the same as those described in the above (A), and a methyl group is particularly preferable because of the same reason as in (A), in particular, easy synthesis. Such (B) is D^H _xD_y (Wherein x is a positive integer, y is 0 or a positive integer, and x + y is 3 to 8), specifically D^H _Three, D^H _Four, D^H _ThreeD, D^H ₂D₂ , D^H D_Three , D^H _Five, D^H _FourD, D^H _ThreeD₂ , D^H ₂D_Three , D^H D_Four , D^H ₆, D^H ₇, D^H ₈And cyclic polymethylhydrogensiloxanes exemplified by these and mixtures thereof; and MD having a higher degree of polymerization than the target product and may be a single compound or a mixture^H _xD_y A linear polymethylhydrogensiloxane represented by M (where x is a positive integer, y is 0 or a positive integer), and a corresponding silanol group-containing linear chain in which both ends are silanol groups Polymethylhydrogensiloxane is used and the target is MD^H _zWhen M (wherein z is a positive integer), y = 0 is used.
[0015]
Step (1) is a step of preparing a mixed siloxane by mixing (A) and (B). Mixing may be performed at ordinary temperature by a conventional method, but may be performed under heating or cooling as necessary. The mixing ratio of (A) and (B) can be arbitrarily set within the range of, for example, 1:99 to 99: 1, preferably 5:95 to 95: 5, by weight, depending on the molecular structure of the target product. That is, M / D of raw material^H Molar ratio, for example MD^H When M is the target product, it is preferably set to 1.0 to 10.0, more preferably 1.5 to 5.0, and MD^H ₂When M is the target, it is preferably set to 0.5 to 3.0. This ratio is not only the selectivity of the target oligomer in the equilibration reaction, but also when the distillation in the step (4) described below is carried out by a batch method, the above selection is related to the design of the distillation column in the step. It may be selected from both the ratio and the production ratio of the dimer to the target oligomer.
[0016]
As described above, although a silanol group-containing polyorganohydrogensiloxane can also be used as (B), the silanol content in the siloxane mixture is preferably as low as possible relative to the total amount of (A) and (B). Specifically, it is preferably 700 ppm or less. When the silanol group content is high, the water produced by the silanol group or its condensation reaction may hydrolyze the (C) linear halogenated phosphonitrile compound used as a catalyst in the (2) equilibration step. is there.
[0017]
Step (2) is a step of adding a catalytic amount of (C) to the mixed siloxane obtained in step (1) to cause an equilibration reaction.
[0018]
(C) used in the present invention is a linear halogenated phosphonitrile compound that functions as a catalyst for promoting the equilibration reaction of (A) and (B), and phosphite amide dichloride, phosphate amide dichloride, Examples include polyphosphazene.
[0019]
Among such (C) linear halogenated phosphonitrile compounds, since the siloxane equilibration reaction rate is high, the general formula:
[X_Three P (NPX₂)_m X]⁺ [AX_{v-t + 1} R_t ]^-       ...... (I)
Wherein X represents a halogen atom which may be the same or different, A represents an atom having a Pauling electronegativity of 1.5 to 2.2, and R represents a carbon atom having 2 to 12 carbon atoms. Represents an alkyl group, m is an integer of 1 to 8, v is the valence or oxidation state of A, and t is a number of 0 <t <v). Examples of X include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom is preferable because synthesis is easy and catalytic ability is high. Examples of A include elements such as phosphorus, antimony, and iron in which halides can form a Lewis acid. Phosphorus is preferable because it is easy to synthesize and does not attack Si-H bonds.
[0020]
Such a linear halogenated phosphonitrile compound has a general formula:
Cl_Three P (NPCl₂)_m NPCl_Three ・ PCl₆           ...... (Ia)
Is preferably a linear phosphonitrile chloride compound represented by the formula:
Cl_Three P (NPCl₂) NPCl_Three ・ PCl₆             ...... (Ib)
The compound shown by is especially preferable.
[0021]
Other types of (C) used in the present invention include a general formula:
OX₂ P (NPCl₂)_n NPX_3-p(Y)_p                ...... (II)
Or
OX₂ P (NPCl₂)_n N (H) P (O) X_2-q(Y)_q    ...... (III)
(Wherein X is as described above; Y is OH, OR¹ Or OC (O) R² Represents R¹ And R² Each represents an alkyl group or an aryl group; n represents an integer of 0 to 8; p is 0, 1 or 2; q is 0 or 1) at least a part of the terminal phosphorus atom Oxidized one is preferred. R¹ And R² Examples thereof include linear or branched alkyl groups such as methyl, ethyl, propyl and butyl; and aryl groups such as phenyl and tolyl. Among the above, it is more preferable that n is an integer of 1 to 8, p is 0 or 1, q is 0, X is a chlorine atom, and Y is a hydroxyl group; It is particularly preferable that p is 1.
[0022]
Among the P═O bond-containing halogenated phosphonitriles represented by the above general formula (II) or (III), compounds in a more preferable range include, for example, the general formula:
OCl₂ P (NPCl₂)_n NPCl₂(OH) ...... (IIa)
OCl₂ P (NPCl₂)_n NPCl_Three                   ...... (IIb)
OCl₂ P (NPCl₂)_n N (H) P (O) Cl₂       ...... (IIIa)
(Wherein n is an integer of 0 to 8).
[0023]
For the equilibration reaction in step (2), a compound containing the above-mentioned linear phosphonitrile compound and active hydrogen having a pKa value of 18 or less, such as carboxylic acids, halogenated alkane carboxylic acids, alcohols or phenols The reaction product with is also effective. In addition, (PNCl₂)_s Cyclic halogenated phosphonitrile compounds such as (wherein s is 3 or 4) are also effective. However, these have a very low reaction rate compared with the (C) linear halogenated phosphonitrile compound used in the present invention.
[0024]
The amount of (C) used is an amount effective to easily disproportionate them (A) and (B). The amount of (C) is not particularly limited, but is preferably in the range of 5 to 500 ppm, more preferably 10 to 100 ppm, based on the total weight of the starting materials (A) and (B).
[0025]
In order to promote the dispersion of (C) in the system so that the reaction proceeds smoothly, (C) is preferably added after being dispersed or dissolved in an inert medium. The concentration of (C) in such a dispersion or solution is preferably 0.1 to 10% by weight, more preferably 0.5 to 5% by weight. Inert media include aromatic hydrocarbons such as benzene, toluene and xylene; chlorinated hydrocarbons such as methylene chloride, trichloroethane and 1,3,5-trichlorobenzene; such as ethyl acetate and butyl acetate. Esters; and organosiloxanes such as hexamethyldisiloxane and polydimethylsiloxane are preferred, and organosiloxanes are preferred, since the organosiloxanes participate in the equilibration reaction as in (A) and (B). , M / D by adding^H When the ratio is affected, it is necessary to reduce the amount used as a solvent when setting the blending ratio of (A) and (B) in step (1).
[0026]
The equilibration reaction can usually proceed at a temperature of 35 to 110 ° C., preferably 60 to 90 ° C., and reaches equilibrium in 1.5 to 3.0 hours, for example, 65 ° C. and 2.0 hours. The reaction proceeds even near room temperature, that is, at a temperature of 15 ° C. or higher and lower than 35 ° C., but it takes a long time of 7 hours or longer to reach equilibrium. When the reaction is carried out at a high temperature exceeding 110 ° C., the cleavage of Si—H bonds occurs, which may cause gelation of the siloxane mixture with generation of hydrogen gas. The reaction may be performed by a batch method or a continuous method.
[0027]
Step (3) is a step of deactivating (C) used as the equilibration catalyst prior to separation and recovery of the reaction product. If an attempt is made to recover the reaction product by distillation without passing through such a deactivation step, first, an excess of a dimer such as MM distills and M / D in the system is recovered.^H Since the ratio changes, a re-equilibration reaction occurs, and as a result, the target specific linear organohydrogensiloxane oligomer cannot be obtained in high yield.
[0028]
The deactivation of (C) is performed by neutralizing with a weak alkaline substance. Examples of weak alkaline substances used include ammonia; hexamethyldisilazane; aliphatic primary, secondary, or tertiary organic amines such as ethylamine, diethylamine, triethylamine, propylamine; and magnesium oxide can do. Hexamethyldisilazane is particularly preferred because it can be uniformly dissolved in the system. Strong alkaline substances such as potassium hydroxide and sodium hydroxide are not suitable because they cause cleavage of the Si—H bond in the product. The amount of neutralizing agent used must be sufficient to neutralize (C) and stop further equilibration reactions of the reaction mixture, resulting in a stable product. This amount is determined based on the total content of acidic substances in the system including (C), and is generally up to 10 to 100 ppm based on the total weight of (A) and (B). In the present invention, by adding such an amount of weakly alkaline substance, it was found that (C) can be deactivated while suppressing the cleavage of the Si—H bond in the product. A special effect was obtained that the chain polyorganohydrogensiloxane can be obtained in good yield. When the catalyst is excessively neutralized with an alkaline substance, it is necessary to add an excessive amount of (C) when the catalyst is reacted again in the subsequent recovery batch.
[0029]
Neutralization can be performed by adding and stirring the above weak alkaline substance at room temperature.
[0030]
Step (4) is a step of recovering the obtained linear organohydrogensiloxane oligomer. Recovery is usually performed by distillation. Distillation is performed at normal pressure, but the target is MD^H _zWhen it has a high boiling point such as M (wherein z ≧ 4), it may be carried out under reduced pressure. Further, a batch method or a continuous method may be used, or a combination of both may be used.
[0031]
When the object is synthesized with high selectivity by the step (2) of the present invention, the object is particularly MD.^H In the case of a low molecular weight oligomer such as M, the amount of MM in the production system is larger than the target product. For example, the target is MD^H For M, MM is MD^H It reaches 1.5 to 4.5 times M. Therefore, a simple batch distillation requires significant time and energy costs to remove MM.
[0032]
Therefore, in the step (4), a continuous method or a semi-continuous method using two or three distillation columns is preferable. For example, MD^H When M is an object, it is more preferable to take the following operation method:
First column: MM from the top of the column, and about 90% MD from the middle of the column, depending on the boiling point of each component^H M, MD^H ₂M and MD^H _ThreeA crude distillation column from which a heavy component is removed from the bottom of the column; and
Second Tower: MD from the middle fraction^H M, MD^H ₂M and MD^H _ThreeA rectifying tower that performs M rectification.
Then, the first column forms part of the continuous system, the purification in the second column is performed by a batch method, and if necessary, the surplus time in the second column or the MM from the top fraction in the third column. Perform rectification.
[0033]
In this way, a linear organosiloxane oligomer can be produced with good yield, and in particular, a linear polyorganosiloxane having a specific molecular structure can be produced with good selectivity. The method for producing a linear organosiloxane oligomer of the present invention can be applied to various types of linear organosiloxane oligomers. For the synthesis of linear methylhydrogensiloxane oligomers having a polymerization degree, that is, 3 to 8 silicon atoms. MD which can be preferably applied, and in particular the intermediate unit is a methylhydrogensiloxane unit^H _zIt is suitable for synthesizing M (z is 1 to 6, particularly 1 or 2) with high selectivity.
[0034]
Furthermore, in the present invention, as a step (5), a step of recycling the unreacted (A) recovered in the step (4) and a linear polyorganosiloxane other than the target product is added, and the raw material siloxane is added. The utilization rate of (A) and (B) can be increased. That is, MD^H Taking M as the target, for example, MM distilled from the top of the column in step (4) and MD by rectification^H The higher boiling point MD of the remaining M recovered^H _zM mixture (z is an integer greater than or equal to 2) and / or the bottom fraction of the first column, and the desired M / D^H In order to obtain the ratio, (A) and / or (B) can be newly added and used as the raw material siloxane mixture in step (2).
[0035]
In the case of performing such recycling, if the raw material (A) or (B) contains a polyorganosiloxane containing a trifunctional unit such as a methylsilsesquioxane unit as an impurity, The polyorganosiloxane containing the unit is accumulated in the liquid, which affects the equilibration reaction in the step (2) or lowers the purity of the target product obtained in the step (4). Therefore, when using a raw material containing such a trifunctional unit, it is necessary to limit the number of recirculations or to provide a separate refining process for the circulating flow.
[0036]
In the production method of the present invention, each step may be carried out separately, and each step can be carried out continuously in a single reboiler / column reactor including recirculation.
[0037]
【The invention's effect】
According to the present invention, a linear organohydrogensiloxane oligomer, particularly a specific linear methylhydrogensiloxane oligomer, can be efficiently produced without the need for complicated operations such as filtration of active clay. it can. The linear halogenated phosphonitrile compound used as a siloxane equilibration catalyst in the present invention not only provides an excellent equilibration rate with a relatively low heating temperature, but is not expected from other existing siloxane equilibration catalysts. In addition, the Si—H bond is stably present under the conditions of equilibration and deactivation without cleavage. Furthermore, by using such a compound as an equilibration catalyst, a series of steps including equilibration reaction, deactivation, purification, and by-product recycling can be performed continuously and in high yield. Therefore, the economic effect is great.
[0038]
Linear organohydrogensiloxane oligomers produced by the present invention, especially MD^H M or MD^H ₂A low molecular weight methylhydrogensiloxane oligomer such as M is used for surface treatment of various inorganic substances, chemical modification of organic compounds, and the like, and is useful as an intermediate for various organosilicon compounds.
[0039]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples. In the examples, parts are parts by weight, M / D.^H Indicates a unit molar ratio, and the viscosity is a value at 25 ° C. The present invention is not limited by these examples.
[0040]
  Examples 3-8, Reference Examples 1-4
  MM and general formula MD^H _xA linear polymethylhydrogensiloxane mixture represented by M (x is a positive number) and having a viscosity of 18 cSt, as shown in Table 1, has various M / D values between 0.5 and 20.0.^HBlended at room temperature to give a ratio, 100 parts each of a uniform liquid mixed siloxane was prepared. However, since MM was also used as a solvent for the catalyst as described later, the amount of MM blended in this step was the above M / D.^HThe amount of MM added together with the catalyst as a solvent is subtracted from the amount calculated from the ratio. Then the formula prepared in advance:
    Cl_ThreePNPCl₂NPCl_Three・ PCl₆
0.25 part of a 2% MM solution of a phosphonitrile chloride compound represented by the formula (1) was added to each of the above mixed siloxane solutions. This corresponds to an amount of 50 ppm of the phosphonitrile chloride compound catalyst in the total siloxane. The flask was sealed and stirring was continued in a heating medium at 65 ° C. for 2 hours, and then cooled to room temperature. Neutralized. After several minutes, the solution became cloudy. The solid produced by neutralization was separated by filtration, and the target product was obtained as a filtrate.
[0041]
All samples were analyzed by a gas chromatography apparatus (GC14A model, manufactured by Shimadzu Corporation) equipped with a packed column 3 m and a thermal conductivity detector. The area% of each peak (excluding the minute peak) in the obtained gas chromatogram was as shown in Table 1 and FIG. Also, from the results in Table 1, MM / MD^H The production ratio of M was determined and is shown in Table 1.
[0042]
[Table 1]

[0043]
As is clear from Table 1, M / D in the raw siloxane^H As the ratio increases, more of the lower molecular weight linear polymethylhydrogensiloxane is produced. M / D^H MD ranges over the range 1-10^H The amount of M produced has increased from 22% to 31%.^H The control of the equilibration reaction in the production of M is easy. MD^H _zThe amount of M produced is also M / D^H The ratio is 13.2 to 19.0% in the range of 1 to 4, and can be sufficiently controlled.
[0044]
Figure 2 shows the MM and MD in each equilibrated mixture^H M is M / D in raw material siloxane^H Is plotted as a function of. FIG. 3 shows the M / D^H MM MD as the ratio increases^H It shows that the ratio to M increases. M / D^H It can be seen that as the ratio increases, the production ratio of MM increases and a large amount of MM needs to be distilled off during distillation.
[0045]
  Examples 11 and 12
  Reference exampleMM and MD similar to those used in 1^H _xM / D calculated using M as a raw material and including MM to be blended later as a solvent^HThe ratio is 2.4,Reference exampleTo the mixed siloxane prepared by the same method as 1,Reference exampleThe same MM solution of phosphonitrile chloride compound as used in 1 was added. This was held at a temperature of 65 ° C. (Example 11) and 25 ° C. (Example 12), respectively, to carry out an equilibration reaction. Take some samples at 30 minute intervals,Reference exampleSubject to gas chromatography similar to 1 and MD in the product^HThe percentage of M was followed. The result is shown in FIG.
[0046]
As is clear from FIG. 4, at the reaction temperature of 65 ° C., the equilibration was almost completed after the equilibration time of 2 hours, whereas at the reaction temperature of 25 ° C., the equilibration was not yet completed after 7 hours. .
[Brief description of the drawings]
FIG. 1 Each MD in equilibrium^H _zM's various M / D^H It is a graph which shows content in ratio.
Fig. 2 MM and MD in equilibrium^H M / D of each content with M^H It is a graph which shows the change by ratio.
Fig. 3 MM and MD in equilibrium^H M / D of ratio to M^H It is a graph which shows the change by ratio.
FIG. 4 MD at each equilibration temperature^H It is a graph which shows the change of content of M by equilibration time.

Claims (7)

(1) (A) and hexamethyldisiloxane, (B) a cyclic methyl siloxane oligomer and a high degree of polymerization than / or the desired product linear polymethyl hydrogen siloxane, M / D ^H ratio, Mixing to obtain 1.5 to 5.0 to obtain a siloxane mixture (where M is a trimethylsiloxy unit and ^DH is a methylhydrogensiloxane unit) ;
(2) adding a catalytic amount of (C) a linear halogenated phosphonitrile compound to the mixture and causing an equilibration reaction;
(3) a linear phosphonitrile halide compound, the process is deactivated by neutralization with a weak alkaline substance; and (4) obtained 1,1,1,3,5,5,5 hepta A method for producing 1,1,1,3,5,5,5-heptamethyltrisiloxane , comprising a step of recovering methyltrisiloxane . A linear halogenated phosphonitrile compound has the general formula:
[X ₃ P (NPX ₂ ) _m X] ⁺ [AX _{v−t + 1} R _t ] ⁻
Wherein X represents a halogen atom which may be the same or different, A represents an atom having a Pauling electronegativity of 1.5 to 2.2, and R represents a carbon atom having 2 to 12 carbon atoms. The production according to claim 1, which represents an alkyl group, m is an integer of 1 to 8, v is the valence or oxidation state of A, and t is a number 0 <t <v. Method. The production method according to claim 2 , wherein A is phosphorus.   The production method according to claim 1, wherein the catalyst is deactivated by neutralization using a weak alkaline substance selected from the group consisting of ammonia, hexamethyldisilazane, an aliphatic organic amine, and magnesium oxide. The production method according to claim 1, wherein 1,1,1,3,5,5,5-heptamethyltrisiloxane is recovered by distillation.   Furthermore, the manufacturing method of Claim 1 which collect | recovers unreacted (A) by distillation. Furthermore, (5) was recovered as (A), comprising the step of recirculating a linear polymethyl hydrogen siloxane other than the desired product, the production method according to claim 1, wherein.

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