EP1863786A1

EP1863786A1 - Method for the representation of 3,3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide

Info

Publication number: EP1863786A1
Application number: EP06723124A
Authority: EP
Inventors: Alexander Straub; Hans-Joachim Ressel
Original assignee: Bayer CropScience AG
Current assignee: Bayer CropScience AG
Priority date: 2005-03-11
Filing date: 2006-02-27
Publication date: 2007-12-12
Also published as: CN101137640A; DE102005011229A1; IL185858A0; JP2008532960A; WO2006094667A1

Abstract

The invention relates to a method for producing 3,3,4,4-tetrachlorotetrahydrothiophene dioxide, in which phosphoryl chloride that has no harmful effect at all on the global ozone layer is advantageously used as a solvent in the chlorination reaction.

Description

Process for the preparation of 3,3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide

The present invention relates to a novel process for the preparation of the already known 3,3,4,4-tetrachlorotetrahydrothiophene dioxide. This compound is required as an intermediate for the synthesis of 3,4-dichlorothiophene dioxide, which has fungicidal properties or can itself be used as a precursor for fungicides. The presentation is described in J. Org. Chem. 1960, 20, 346. First, a chlorine addition to sulfolene to 3,4-Dichlorsulfolan. For the following raduclear substitution with chlorine more energetic conditions are necessary. In the literature, the synthesis with radical initiators such as azoisobutyronitrile (AEBN) or dibenzoyl peroxide (DBPO) in carbon tetrachloride as a solvent has been described (see JP-A 2-243685, US 3,963,751, JP-A 60-132979, ES-A 549317, JP-A). A 63-156785).

The use of radical starters often results in a slow reaction. Therefore, a number of photochemical processes are described in carbon tetrachloride (USSR Khim Seraorg, Sdedin, Soderzh, Neftya Wa Nefteprod, 1972, 9, 218, JP-A 5-339259, JP-A 5-339258, ES-A 2008765; US 2,957,887, JP-A 7-48365).

The methods known from the literature can be summarized in the following scheme

In both steps, the use of the ozone-damaging carbon tetrachloride for the chlorination reactions is common to these methods (ozone-depleting potential ODP = 1.1). Since this solvent may no longer be used because of the Montreal Convention in the future, should a new Oz ^{'on-uήgefährliches} and inexpensive solvents are found that can act as a substitute in industrial scale. For this purpose, trifluoromethylbenzene (yield: 71.2%, JP-A 7-48365) and hexachloroacetone (yield 66.5%; JP-A 10-101668) have hitherto been proposed. However, both solvents are relatively expensive and are not inert in the presence of radical initiators or under photolytic reaction conditions. The reactions require more chlorine, are slower, less selective and less complete than in carbon tetrachloride. The product only occurs in impure form. We found that trifluoromethylbenzene was converted under the reaction conditions into partly foul-smelling chlorinated derivatives. Hexachloroacetone in turn can be recovered only with difficulty because of its high boiling point (203 ⁰ C).

The use of phosphorus oxychloride as a solvent for polymerizations using, for example, benzoyl peroxide, AIBN or tert-butyl hydroperoxide is also described (Die Macromolecular Chemistry 1966, 99, 76-84). However, chlorination reactions or photochemical reactions were not considered here. FR-A 773679 mentions the use of POCl ₃ as a solvent for gaseous hydrocarbons and as a reaction medium for their reaction with chlorine gas.

JP-A 5-339258 claims the photochlorination of 3,4-dichlorotetrahydrothiophene, l-dioxide in an inert solvent. Mentioned here are carbon tetrachloride, chloroform, chlorobenzene and carbon disulfide. The latter is unsuitable for this reaction because of its low boiling point and its very low ignition temperature. In the course of photochlorination in, chloroform or chlorobenzene we found, on the other hand, that these solvents are also chlorinated in many different ways, with ozone-detrimental products being formed in large quantities.

The present invention therefore provides a process for preparing 3,3,4,4-tetrachlorotetrahydrothiophene, 1,1-dioxide of the formula (I)

characterized in that in a first step 2,5-dihydrothiophene-1, l-dioxide (sulfolene) of the formula (H)

in the presence of an inert solvent and in the presence of a chlorinating agent and the resulting cis / trans-3,4-dichlorotetrahydrothiophene-l, l-dioxide (3,4-dichlorosulfolane) of the formula m

in a second step in the presence of phosphoryl chloride, in the presence of a radical source and in the presence of a chlorinating agent.

In the first step of the addition of chlorine to sulfolene in POCl ₃ , it was surprisingly found that the cis form of 3,4-dichlorotetrahydrothiophene, 1,1-dioxide crystallized in the cold in pure form from the phosphoryl chloride solution of the approach. The cis-shape has the advantage that in the subsequent photochlorination to 3,3,4,4-Tetrachlortetrahydrothiophen-l, l dioxide more readily reacted than the trans compound.

In the second step of the radical substitution of hydrogen by chlorine, it was surprisingly found that unlike many other solvents, POCl _{3 has} excellent properties under the drastic reaction conditions investigated as the reaction medium. It may, for example, in conjunction with the chlorine introduced during the reaction itself chlorinating or catalyzing act on the chlorination. The reaction is favored by the better solubility of chlorine in phosphoryl chloride and the binding capacity of phosphoryl chloride for the liberated hydrogen chloride. After completion of the reaction, the phosphoryl chloride can be recovered by simple distillation and recycled. It also allows the performance of photochemical chlorination in highly concentrated solution, because it has very good dissolution properties compared to sulfolene. It has been found that phosphoryl chloride has very good dissolution properties with respect to the educt and the product. This prevents precipitation during the reaction, which in turn would reduce light transmittance and thus slow down the chlorination in photocatalysis.

The boiling point of POCl ₃ is sufficient. high in order to be able to perform photochlorinations even in the required heat.

On completion of the reaction, on the other hand, after cooling the solution, crystallization of the target product in high purity allows the impurities to remain in the solution.

The sulfolene of the formula (U) used as starting material in carrying out the process according to the invention is a known synthetic chemical.

The occurring in carrying out the process according to the invention as an intermediate ^, 4 Dichlorsulfolan of formula (JS) is also known. 3,4-dichlorosulfolane of formula (JE) may be in cis form or in trans form or in mixtures of both. Unless otherwise indicated, both forms are included.

Suitable solvents for carrying out the first step of the process according to the invention are all conventional inert organic solvents. Alkanes such as cyclohexane, methylcyclohexane, heptane, octane, petroleum ether or POCl ₃ are preferably usable. POCl ₃ is hydrolyzed in the air by moisture immediately, so it has no persistence and no

Ozone-threatening potential. POCl ₃ is a low-cost industrial chemical and can easily be recovered by distillation.

Suitable chlorinating agents for the first step of the process according to the invention are chlorine and, for the second step, all customary agents for such reactions, preference being given to using chlorine gas. ^■

When carrying out the second step of the process according to the invention, all customary radical sources can be used. Preferably usable are light or free radical generators such as DBPO, AIBN ₅ tert-butyl hydroperoxide or succinic acid peroxide.

As light sources visible light, UV light or near UV light come into question, however, UV light or near UV light is preferred. There is no particular limitation on the type of light sources and known UV lamps such as low pressure mercury vapor lamps or high pressure mercury vapor lamps can be used.

The reaction temperatures can be varied within a substantial range when carrying out the first step of the process according to the invention. In general is carried out at tempera- tures of from -10 ⁰ C to +150 ⁰ C, preferably in the range from 0 ⁰ C to 80 ⁰ C.

The reaction temperatures can be varied within a relatively wide range when carrying out the second step of the process according to the invention. In general, one works at temperatures of -10 ⁰ C to +150 ⁰ C, preferably in the range of 50 ⁰ C to 85 ° C. ^{■ ■}

When carrying out the first step of the process according to the invention, in general between 0.8 and 5 mol, preferably between 1 and 3, mol of chlorinating agent are employed per mole of sulfolene of the formula (H).

When carrying out the second step of the process according to the invention, in general between 0.8 and 15 mol, preferably between 3 and 10 mol of chlorinating agent are added per mole of the 3,4-dichlorosulfolane of the formula (HT) and up to the entire reaction time 1 mole of free radical initiator.

If chlorine gas is used as the chlorinating agent, the first and the second step can also be carried out under pressure; generally between 0.8 and 10 bar. The reaction time is dependent on the temperature, the intensity of the light irradiation, the rate of chlorine introduction, the pressure and the amount of the starting materials used. The termination of the reaction takes place when, for example, by NMR study of a sample no reactant and no trichlorosilane, which is passed through as an intermediate, more is found. The reaction can be interrupted and then continued again.

First and second steps can also be carried out as a one-pot reaction, ie without intervening workup of the 3,4-dichlorotetrahydrothiophene-1, l-dioxide. In this case, for example, the product-containing phosphoryl chloride solution of the first step is subjected directly to further photochlorination.

Preparation Examples

example 1

200 g (1.69 mol) of sulfolene are dissolved in 900 ml of phosphoryl chloride. 156 g (2.2 mol) of chlorine are passed in within 4 h, the temperature being kept below 25.degree. Argon is passed through the solution for 12 hours and the 5 ° C. cold suspension is filtered off with suction. It is washed with 60 ml of cold POCl ₃ and the residue is stirred on the suction filter first with 200 ml and then twice with 75 ml of cold cyclohexane.

125 g (39% of theory) of cis-3,4-dichlorotetrahydrothiophene dioxide having a melting point of 126-128 ° C. are obtained as filter residue.

The POCl ₃ -containing solution is evaporated in vacuo and then stirred with 500 ml of isopropanol. The crystals are filtered off with suction and washed twice with 50 ml of isopropanol each time.

This gives 98 g (31% of theory) of a 46:54 cis / trans mixture of 3,4-Dichlortetrahydrothio- phendioxid with the melting point 87-91 ⁰ C.

Example 2

Dissolve 250 g of 3,4-Dxchlortetrahydrothiophendioxid (cis / trans mixture 64:36) in 215o ml of phosphoryl chloride and passed in at 65-70 ⁰ C internal temperature with simultaneous shine on with a mercury immersion lamp (Hanau TQ 150 mercury lamps) within 16.5 Hours a total of 702 g of chlorine gas.

The solvent is then distilled off under reduced pressure and the residue is treated at 6O ⁰ C with 800 ml of cyclohexane and then stirred at room temperature. It is suctioned off at 5 ° C., washed twice with 100 ml of cold cyclohexane each time, and 273.25 g (72% of theory, purity (NMR): 90%) of 3 ₅ 3,4,4-tetrachlorotetrahydrothiophene-1 are obtained , l-dioxide as white crystals. These can still be stirred with cyclohexa / isopropanol 10: 1, to give 244 g (68% of

Theory, purity (NMR): 95%) of 3,3,4,4-tetrachlorotetrahydrothiophene-l, l-dioxide as white crystals of melting point 171-174 ° C.

¹ H-NMR (400 MHz, O ₆ -DMSO): δ = 4.7 (s)

Example 3

160 g (purity 92.8%, 0.785 mol) of 3,4-dichlorotetrahydrothiophene dioxide (cis / trans mixture 68:32) are dissolved in 160 ml (263.2 g, 1.72 mol) of phosphoryl chloride and passed through at 71 -72 ° C internal temperature with simultaneous announcement with a mercury immersion lamp (Hanau Hg spotlight TQ 150) and a 300 W Osram UV lamp within 14 hours a total of 429 g of chlorine gas.

The solution is bubbled with argon at room temperature and cooled to 6 ° C. The resulting white suspension is filtered off with suction and the residue is washed twice with 150 ml of cold cyclohexane each time. It is then washed with 50 ml of cyclohexane. This gives 128.2 g (purity 99.4%) of the tetrachloro compound in 63% yield. From the mother liquors are still 12 g (5% yield) of target product in 92% purity.

Example 4

pot reaction

1st step: chlorine addition

110 g (0.912 mol; 98% purity) are sulfolene (g 300; 1.8 mol; 27% solution; 1.9 equivalents) in 202 ml phosphoryl chloride was suspended while the temperature falls to 13 ⁰ C. Man conducts within 150 min. 80 g (1.13 mol, 1.23 equivalents) of chlorine, the temperature with a

Ice bath is kept at 18-21 ⁰ C. After approximately one quarter of the amount of chlorine has been introduced, the suspension dissolves. From about 50% chlorine amount again creates a thick, but easy to stir

Suspension. According to NMR, the solution contains 90% (cis / trans ratio: 71:29) dichlorosulfolane and 9.4%

Chlorsulfölen. 2nd step: photoinduced chlorine substitution

Then heating the neck and switches at 60 ⁰ C inner temperature, a TQ150 a Hg lamp (300 watts). At 71-73 ° C for a total of 375.7 g (5.8 equivalents) of chlorine are introduced over 13 h. From the reaction escapes a mixture of HCl and chlorine gas. The reaction can be stopped overnight by stopping the gas supply and switching off the heater and the lamp and restarted the next day.

After completion of the hot solution, an argon stream is passed for 1 h and the POCl _{3 is then} distilled off at 200 to 30 mbar via a distillation bridge. The pulpy residue is still easy to stir.

It is mixed at 60 ⁰ C with 330 ml of cyclohexane and stirred for 18 h at room temperature. The crystal slurry is filtered off and washed with 170 and 100 ml of cyclohexane. After drying in the air to obtain 167.4 g Tetrachlorsulfolan having a melting point of 168-171 ⁰ C.

The total yield over two stages is 67%.

Claims

claims

1. Process for preparing 3 ₅ 3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide of the formula (T)

characterized in that in a first step 2,5-dihydrothiophene-1, l-dioxide (sulfolene) of the formula (II)

V (II)

Q is reacted in the presence of an inert solvent and in the presence of a chlorinating agent and the resulting cis / trans-3,4-dichlorotetrahydrothiophene-l, l-dioxide (3,4-dichlorosulphane) of the formula (HI)

in a second step in the presence of phosphoryl chloride, in the presence of a radical initiator and in the presence of a chlorinating agent.

2. The method according to claim 1, characterized in that one uses in the first step, phosphoryl chloride as a solvent.

Verfahren: Process: according to claim 1 or 2, characterized in that as a radical source

Light used.

4. The method according to claim 1 or 2, characterized in that one uses as radical source radical generator from the series DBPO, AIBN, tert-Bμrylhydroperoxid or succinic acid peroxide.

5. Use of phosphoryl chloride as a solvent for photochlorination with chlorine gas.