NO146837B - DEVICE FOR STORAGE AND DOSED DELIVERY OF FLUID, EXAMPLE IN CONNECTION WITH PLANT CULTURES - Google Patents

Description

Process for the production of new cyclo-tri- or tetra-siloxanes.

The present invention relates to a

a method for producing cyclic tri- or tetra-diorganosiloxanes containing nitrile groups bound to silicon through carbon.

Until now, a number of cyclic polydiorganosiloxanes and polymers thereof have been

known in the area. These polymers have

have been useful for the production of silicone rubber, which has found extensive use for

many purposes. Although the silicone rubbers known to date are satisfactory to many

purpose, these rubbers have been deficient with regard to one or more properties. Thus, in certain cases the tensile strength has been less than desired, in other cases the resistance to the effect of ionizing radiation has been low,

in other cases, the resistance to

swelling under the influence of hydrocarbon solvents has been unsatisfactory and in other cases again the thermal stability has not been as high as desired.

The present invention is based on

the discovery of a new class of cyclic tri- or tetra-diorganosiloxanes, which can be polymerized into high molecular weight polydiorganosiloxanes which materials exhibit a

combination of greater tensile strength, increased

resistance to irradiation, increased resistance to solvents and

improved thermal stability compared

with the conventional silicone rubbers.

The cyclic tri- or tetra-diorganosiloxanes which are prepared according to the present

invention has the formula

where R is a monovalent, optionally halogenated hydrocarbon radical, R' is a divalent hydrocarbon radical with at least 2 carbon atoms, so that the nitrile group is bound to silicon through at least two carbon atoms, and a and n are either 0 or 1.

Among the radicals denoted by R in formula (1), mention may be made, for example, of alkyl radicals, such as methyl, ethyl, propyl, octyl or octadecyl radicals; cycloalkyl radicals, such as cyclohexyl or cycloheptyl radicals, aryl radicals, such as phenyl, naphthyl, tolyl or xylyl radicals, aralkyl radicals, such as benzyl or phenylethyl radicals, alkenyl radicals, such as vinyl or alkyl radicals as well as halogenated derivatives of the above-mentioned radicals , e.g. chloromethyl or bromophenyl radicals. Among the divalent hydrocarbon radicals denoted by R' in formula (1) are included, e.g. arylene radicals such as p-phenylene, m-phenylene or naphthylene radicals and alkylene radicals such as ethylene or propylene radicals. The preferred class of radicals within the scope of the designation R' are the divalent alkylene radicals which result in a cyanoalkyl radical of the formula:

bonded to silicon, where b is an integer that is at least equal to 2 and is preferably 2 or 3. The nitrile-containing radical is preferably a beta-cyanethyl radical or a gamma-cyanopropyl radical.

Among the cyclopolysiloxanes within the scope of formula (1) can be mentioned, for example, l-methyl-l-beta-cyanethyl-3,3,5,5-tetraphenylcyclotrisiloxane, which is the preferred cyclic material within the scope of the present invention, as well as 1-methyl -1-beta-cyanethyl-3,3,5,5,7,7-hexamethylcyclotetrasiloxane; 1,1-bis-(beta-cyanoethyl)-3,3,5,5-tetraphenylcyclotrisiloxane; and 1-(p-cyanophenyl)-1,3,3,5,5,7,7-heptaphenyl-cyclotetrasiloxane.

The cyclo-tri- or tetra-siloxanes within the framework of formula (1) are prepared by reacting a di- or tri-diphenylsiloxane with a hydroxy-terminated chain with the formula: where n is as previously stated, with a diorganodihalosilane of the formula:

where R, and R' and a are as previously indicated and X is halogen, preferably chlorine. When preparing the preferred cyclo-tri- or tetra-siloxanes according to the present invention, methyl-beta-cyanethyldichlorosilane is reacted with tetraphenyldisiloxanediol-1,3.

It is seen that formula (3) comprises two compounds, namely tetraphenyldisiloxanediol-1,3 and hexaphenyltrisiloxanediol-1,5.

It will also be seen that many diorgano-dihalogenosiloxanes are included within the framework of formula (4). Examples of these many compounds are methyl-beta-cyano-ethyldichlorosilane, bis-(beta-cyanethyl)-dichlorosilane, phenyl-gamma-cyanopropylchlorosilane, bis-(gamma-cyanopropyl)-dichlorosilane, and phenyl-p-cyanophenyldichlorosilane.

The diorganodihalosilanes within the framework of formula (4) as well as the di- or tri-diphenylsiloxanes with hydroxy-terminated chains according to formula (3) are known in the field. For example, many of the diorganodihalosilanes corresponding to formula (4) are described in the U.S. patent 2,971,970 — Bluestein and 2,911,426 — Jex et al.

The reaction which leads to the formation of the cyclic tri- or tetra-diorganosiloxanes with formula (1) involves reacting one mole of materials with a hydroxy-terminated chain according to formula (3) with one mole of the diorganodihalosilane with formula (4) and leads to the formation of two moles of hydrogen halide. To facilitate the reaction, a hydrogen halide acceptor consisting of a tertiary amine such as pyridine or triethylamine is used. Theoretically, one mole of the hydrogen halide acceptor is required for each mole of hydrogen halide formed. Although the theoretical quantity ratio between the reactants is as described above, the quantity ratio between these components can be varied within wide limits. For example, the di- or tri-diphenylsiloxane with a hydroxy-terminated chain of formula (3) can be used in an amount of from 0.5 to 2 mol per moles of the diorganodihalosilane of formula (4). It is preferable to use the hydrogen halide acceptor in excess, as from 3 to 30 mol hydrogen halide acceptor is used per moles of that of the other reactants which are present in the least amount. Although the quantity ratio between the components can be varied as described above, it is preferable to carry out the reaction between equimolar amounts of the di- or tri-diphenylpolysiloxane with a hydroxy-terminated chain of formula (3) and the diorganodihalosilane of formula (4). As the reaction between these two reactants is essentially quantitative, the use of an equimolecular mixture of these two reactants facilitates the isolation of the desired cyclo-tri- or tetra-siloxane of formula (1) from the reaction mixture.

Because the di- or tri-diphenylsiloxanes with a hydroxy-terminated chain corresponding to formula (2) and the cyclic tri- or tetra-diorganosiloxanes of formula (1) are solids at room temperature, it is preferable to carry out the reaction in the presence of a solvent which is inert to the reactants under the reaction conditions, and which is a solvent for all reactants and reaction products with the exception of the product formed by the hydrogen halide and the hydrogen halide acceptor. Suitable solvents include diethyl ether, tetrahydrofuran, tetrahydropyran, n-hexane, xylene and toluene. In general, the solvent is used in an amount of from 1 to 50 parts by weight calculated on the total weight of the other components of the reaction mixture.

As the reaction leading to the formation of the cyclic tri- or tetra-diorganosiloxane of formula (1) proceeds at a satisfactory rate at room temperature, it is preferable to carry out the reaction at such a temperature, i.e. a temperature of approximately 15 to 25° C. Application of higher temperatures, e.g. however, temperatures of around 25 to 120° C are not excluded. Depending on the quantity ratio between the reactants, the reaction temperature and the solvent used, the time required to carry out the reaction can vary from approx. 1 hour to 24 hours or more.

When the reaction is complete, the reaction mixture consists of a solution of the desired cyclic tri- or tetra-diorganosiloxane of formula (1) together with any unreacted starting materials and a precipitate of a substance such as pyridine hydrochloride. This precipitate is filtered from the reaction mixture, and the solvent and volatile starting materials are distilled from the resulting filtrate, whereby a solid product is obtained. This crude product is recrystallized from a suitable solvent such as benzene, n-hexane, n-butanol, a mixture of these materials, or a mixture of ethanol and cyclohexane to form the purified cyclic tri- or tetra-diorganosiloxane corresponding to formula (1 ).

The following examples illustrate the invention. All parts are parts by weight.

Example 1.

To a solution of 8.4 parts of methyl-beta-cyanoethyldichlorosilane and 15 parts of pyridine in 210 parts of diethyl ether was added a solution of 20.7 parts of tetraphenyldisiloxanediol-1,3 in 70 parts of diethyl ether. The resulting reaction mixture was stirred for two hours and allowed to stand for 16 hours at room temperature, during which pyridine hydrochloride precipitated from the reaction mixture. This pyridine hydrochloride was removed by filtration and the solvent was removed by evaporation. This resulted in a solid which was dissolved in hot toluene. The solution was filtered to remove a small amount of pyridine hydrochloride that remained. The toluene was then removed by evaporation, and the resulting solids were recrystallized from a mixture of 4 parts by volume of cyclohexane and 1 part by volume of ethanol. The purified material obtained was 1-methyl-1-beta-cyanethyl-3,3,5,5-tetraphenylcyclotrisiloxane

with the formula

This white crystalline material had a melting point of 100.5 to 101.5° C. Infrared analysis showed a doublet at 8.9 µm, and a maximum at 13.9 µm corresponding to the diphenylsiloxy unit; a maximum at 7.9 u corresponding to the methyl group; and maxima at 4.45, 8.4, 11 and 11.3 a corresponding to the beta-cyan-ethylsilyl group.

Chemical analysis showed the presence of 2.83 percent nitrogen, while the theoretical value is 2.75 percent N.

Example 2.

By the method in example 1, gamma-cyanopropylheptaphenyl-cyclotetrasiloxane is produced with the formula:

by reacting one mole of phenyl-gamma-cyanopropyldichlorosilane with one mole of hexaphenylcyclotrisiloxanediol-1.5 in the presence of 5 moles of pyridine and 5 parts by weight of diethyl ether per part of the other components in the reaction mixture.

Example 3.

By the method in example 2, 1-methyl-1-m-cyanophenylhexa-phenylcyclotetrasiloxane is produced with the formula:

by reacting methyl-m-cyanophenyldichlorosilane with hexaphenyltrisiloxanediol-1,5.

Example 4.

By the method in example 3, 1,1-bis-(beta-cyanethyl)-3,3,5,5-tetraphenylcyclotrisiloxane is prepared with the formula By reacting bis-(beta-cyanethyl)-dichlorosilane with tetraphenylsiloxanediol-1,3.

Claims (1)

Process for the production of new cyclo-tri- or tetra-siloxanes, which can be polymerized into high-molecular polydiorganosiloxanes, with the formula: characterized in that a compound with the formula: in the presence of a hydrogen halide acceptor is reacted with a compound of the formula: where R is an optionally halogenated monovalent hydrocarbon radical, R' is a divalent hydrocarbon radical with at least 2 carbon atoms such that the nitrile group is bound to silicon through at least 2 carbon atoms, X is halogen and a and n are either 0 or 1, and cyclo-tri - or the tetrasiloxane is then separated from the reaction mixture.