JPH0414085B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to carrying out organic reactions in specific reaction media.

It is generally known to carry out organic reactions in organic solvents. The most important solvents are aliphatic or aromatic hydrocarbons or the corresponding alcohols, some ketones, ethers, esters and short-chain chlorinated hydrocarbons. Decisive for the selection of the solvent as reaction medium is the solubility of the compounds reacting with each other in the solvent as well as the solubility of the reaction products in the solvent. Additionally, the volatility, flammability and evaporation rate of the solvent are important for its selection as a reaction medium. Furthermore, the choice of solvent as reaction medium in almost all cases depends on the extent to which this solvent reacts with the reactants or reaction products.

Furthermore, it is known that a number of organic reactions proceed in the above-mentioned solvents only with insufficient yield or with the formation of impure end products. Therefore, for carrying out organic reactions, it is possible to have good solubility for the reactants or the desired end product and to carry out the desired reactions with few or only minor side reactions. The problem arose of finding a reaction medium which could be carried out in such a way that the purest possible product was obtained. In this case, the process to be carried out should be possible to carry out in the sought-after solvent as simply as possible and without large equipment outlays.

By the way, in achieving this task, a liquid solution is used, which is characterized in that the reactants are dissolved or dispersed or emulsified in silicone oil, the reaction is carried out in silicone oil, and then the reaction product is separated by a method known per se. A method has been found to carry out organic reactions in a reaction medium.

The process according to the invention is suitable, inter alia, in the reaction of amines with alkyl halides, such as when carrying out condensation reactions or substitution reactions in which hydrogen halides, in particular hydrogen chloride, are liberated. The reaction of amines, especially tertiary amines, with alkyl halides forms quaternary ammonium salts. In this case, the reactants are, on the one hand, alkyl halides whose alkyl groups may be substituted by functional groups that do not react with siloxanes, and on the other hand, amines. Generally, the substitution reaction proceeds according to the following formula.

However, R' sometimes represents an alkyl group having 1 to 8 C atoms, R represents hydrogen or an alkyl group of C _{1 to 4} , and R'' represents H or R'. It's okay to be hot.

When preparing compounds according to these formulas, the method of working in siloxanes has the advantage that the products are obtained in high purity and high yields. The methods of working in solvents used so far give lower yields and the reaction products obtained are not in very pure form. Examples of compounds that can be produced by this method are oxirane methanamine-N, N,
N-trimethyl chloride (also known as glycidyltrimethylammonium chloride),
Tetrabutylammonium bromide and benzyltriethylammonium bromide.

Suitable starting compounds for preparing the organic ammonium salts are also aromatic sulfonic acids or sulfonic acid chlorides, which can be reacted according to the invention with amines. In this case, the aromatic nucleus may be substituted by an alkyl group or a halogen. In this case, both sulfonamide acids and tertiary ammonium salts can be produced. The process according to the invention has the advantage here that the desired reaction product is precipitated as a solid in the siloxane and can therefore be easily separated from the other reactants.

Furthermore, the process according to the invention in siloxane as reaction medium makes it possible to carry out phase transformation reactions,
In this case, an aqueous phase is mainly used as the second phase. However, it is also possible to use other organic solvents that are immiscible with siloxane as the second phase.

If one of the reactants is insoluble in the silicone oil, it can be melted, dissolved in a molten state and added to the silicone oil, or dissolved in an organic solvent and added to the silicone oil. Subsequently, the organic solvent used can be distilled off.

The siloxanes that can be used according to the invention are oligomers and polymers based on dimethylsiloxane, which may have a cyclic and chain structure. Branched structures are also possible. It must not react with alkyl halides and preferably be free of functional groups. Furthermore, this can be done at room temperature as well as up to approximately 200°C, especially up to 100°C.
It should be liquid at temperatures up to. The viscosity of usable siloxanes, which can also be called silicone oils, is between 40 and about 20,000 cSt at 25°C, especially between 50 and 20,000 cSt.
It is between 2000cSt. The majority of the compounds listed below satisfy this condition.

The silicone oils that can be used include, in particular, groups as structural elements: [In that case X represents an alkyl group having 1 to 4 C atoms, in particular a methyl group or a phenyl group]
Such compounds containing . Preference is given to using compounds in which at least one of the two groups X is a phenyl group. Examples of compounds that fall into this formula are hexamethyldisiloxane, hexaethyldisiloxane, hexakis(2-ethylbutoxy)
Disiloxane, 1,3-di-methyl-1,3-diphenyldisiloxane, 1,1,3,3-tetraphenyl-1,3-dimethyldisiloxane, 1,
1,5,5-tetraphenyl-1,3,3,5-
Tetramethyltrisiloxane, 1,1,3,5,
These are 5-pentaphenyl-1,3,5-trimethyltrisiloxane, polydimethylsiloxane, polydimethyldiphenylsiloxane, polymethylphenyldiphenyldisiloxane, and polydiphenylsiloxane. The terminal groups of the polymer are in particular trimethylsiloxy groups.

Examples of silicone oils having a ring structure are hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane or hexaphenylcyclotrisiloxane.

Also, alkyltrialkoxysilanes whose ester groups are completely substituted by trialkylsilyl groups (alkyl has 1 to 4 C atoms)
According to the invention, it can be used as a reaction medium. Such compounds and their preparation are described, for example, in German Patent No. 2,642,833. "Schweitzerkreuz"
The compound tetrakis(trialkylsiloxy)silane, commercially known under the name (Schweizerkreuz), can also be used according to the invention. This compound can be understood as an orthosilicate ester in which the alkyl group of the ester group is replaced by a trialkylsilyl group.

Example 1 (Reference Example) 94.9 g (=1.026 mol) of epichlorohydrin is dissolved in 450 ml of hexamethyldisiloxane. 5.9 g (=1 mol) of trimethylamine is introduced into the solution using a gas introduction tube within 2.5 hours. Already after 1 hour the desired oxirane methylamine
N,N,N-trimethyl chloride precipitated as a solid; no temperature increase occurred and the reaction temperature was between 20 and 25 DEG C. during the entire reaction.

After 24 hours, the solid was filtered off through a closed filter, washed with hexamethyldisiloxane and then with methyl ethyl ketone and subsequently dried in vacuo.

The epoxy content of the dried product was 93-94%.

1 mol of epichlorohydrin was added to the mother liquor, and 59 g of trimethylamine was again introduced into this solution. After 24 hours, the precipitated final product was isolated and worked up as described above. The solid obtained also had a purity of 93-94%.

Example 2 (Reference Example) 138.7 g of epichlorohydrin was dissolved or suspended in 378 g of polydimethylsiloxane having a viscosity of 50 cSt at 25°C. Subsequently, 59 g of trimethylamine were introduced. Epichlorohydrin completely dissolves in polydimethylsiloxane during introduction, and after 20 minutes oxirane methylamine-N,N,N
- The first crystals of trimethyl chloride formed.
After 24 hours had elapsed, the solid obtained was filtered off and worked up as described above, first washing with polydimethylsiloxane.

The mother liquor was treated in the same way. Again, the first crystals formed after 20 minutes. After 24 hours, the precipitate was also filtered off and worked up as described above.
It had a purity of 92-93%. The yield was 55% based on the trimethylamine used.

The remaining mother liquor was further worked up in the same manner as the mother liquor of the first batch. This gave the final product with the same purity; however, the yield was 72% based on trimethylamine.

Example 3 (Reference Example) Working in the same way as Examples 1 and 2, but using polymethylphenylsiloxane as silicone oil. Post-treatment of the first reaction with precipitate, 93-95
% purity, a yield of 37.4% based on trimethylamine was obtained. Work-up of the mother liquor of this first reaction gave a yield of 92% based on the trimethylamine used.

Example 4 Preparation of Tetrabutylammonium Bromide The preparation of this compound is described, for example, in U.S. Pat.
It is described in the specification of No. 3965178. In this case, working in acrylonitrile as solvent, yields of more than 50% are obtained. However, working with acrylonitrile requires significant safety precautions that make the process uneconomical. In order to avoid this drawback, it has already been proposed to carry out the reaction in higher alcohols, esters or ketones. However, in this case a yield of only about 50% was obtained, with reaction times of about 48 hours being necessary in some cases.

According to the invention, 186 g of tributylamine is added to 1000 g of polydimethylsiloxane having a viscosity of 50 cSt.
(=1 mol) was dissolved. To this solution was added 1 mol (=137 g) of lightly colored butyl bromide.
At the beginning of the reaction, bring the mixture to 150-155 ml under light reflux.
The reaction was carried out at ℃ for 20 hours. Thereafter, the volatile components still remaining were separated off under reduced pressure.

The resulting reaction mixture was cooled and the resulting crystalline slurry was taken up in water. The lower solution of tetrabutylammonium bromide was separated and the color removed by washing with toluene. From the remaining aqueous solution,
234.5 g of white pure final product by evaporation
can be obtained, which is 99.5 to 100% with respect to Br.
It had a purity of The yield was 72.6%.

Example 5 (Reference Example) Preparation of benzyltriethylammonium chloride 101 g (1 mol) of triethylamine were dissolved in 200 g of polydimethylsiloxane according to Example 4.
137 g (1 mole) of benzyl chloride was stirred into this solution. After a reaction time of 5 hours at 80° C., a large amount of solid had already formed, which was filtered off and washed with methyl ethyl ketone.

After drying, 174 g of benzyltriethylammonium chloride with a purity of 99.4-99.5% was obtained. The yield was 76.3%.

Example 6 (Reference example) Under nitrogen, silicone oil PD-5 (manufacturer's
600 g of methyl-phenyl-polysiloxane obtained under the name Bayer AG, Leverkusen) were added to 216.4 g of ethoxymethylene malonic acid diethyl ester.
(=1 mol) and 108 g (=1 mol) of 6-methyl-2-aminopyridine. The aminopyridine was then present in a molten state and in this state was soluble in the silicone oil. The mixture was kept at a reaction temperature between 90 and 100 DEG C. and the alcohol produced in the reaction that took place was distilled off under slight vacuum. After no more alcohol distills, the reaction medium is
Cooled to 60°C.

In the cooled silicone oil, the desired methylpyridylaminomethylene malonic acid diethyl ester precipitated in crystalline form, which was filtered off, washed at 20° C. and dried. The yield of the product thus obtained, with a purity of 99%, was 316 g = 96.9%.

Claims (1)

[Claims] 1. A method characterized in that an amine and an alkyl halide are dissolved, suspended or emulsified in silicone oil, reacted in the silicone oil, and then the reaction product is separated by a method known per se. A method of carrying out an organic reaction in a liquid reaction medium. 2 Formula as silicone oil: 2. The process according to claim 1, wherein an oligomeric or polymeric alkylsiloxane or arylsiloxane having a structural element of the formula: X represents an alkyl group or a phenyl group. 3. The method according to claim 1, wherein a silyl group-substituted silicic acid ester is used as the silicone oil. 4. The method according to any one of claims 1 to 3, wherein the reaction product is separated using a solvent insoluble in silicone oil.