MXPA97006438A - Process for the preparation of 1,2-benzisotiazolin-3-o - Google Patents

Abstract

The present invention relates to a process for manufacturing BIT of the formula 1, characterized in that it comprises reacting a bisamide of the formula 2, in water or an organic liquid containing water, with a bisulfite or a bisulfite-releasing agent or a mixture thereof, wherein R is cycloalkyl containing up to 8 carbon atoms or C1-20 alkyl optionally substituted by phenyl, X is halogen, nitro, alkoxy or nitrile, and n is 0 to

Description

PROCESS FOR THE PREPARATION OF 1, 2-BENZISOTIAZOLIN-3 -ONAS DESCRIPTION OF THE INVENTION The present invention relates to a process for making 1,2-benzisothiazolin-3-ones and to the use of the compounds made by him as industrial biocides. The 1,2-benzisothiazolin-3-ones (hereinafter "BIT") have been known for a long time, including their use as industrial biocides. There are 3 common methods for manufacturing BIT as described in GB 848,130. The first method involves making a 2-halogenothiobenzoyl halide and reacting this with a primary amine to obtain substituted BIT N. The 2-halogenothiobenzoyl halide is generally made by cleaving the disulfide bond of 2,2'-dithio-bis-benzoic acid with halogen and simultaneously or sequentially converting the carboxylic acid groups to acid halides. A second method involves preparing a 2-halogenothiobenzamide and cyclizing this compound in the presence of acid or alkali. 2-Halogenothiobenzamide is typically made by converting 2,2'-dithio-bis-benzoic acid to bisamide and then splitting the disulfide bond with halogen. Halogen is frequently chlorine as provided by sulfuryl chloride. A third method involves the disproportionation of 2,2'-dithio-bis-benzamides by heating in the presence of sodium hydroxide solution. Due to increasingly increasing environmental pressures, there is a growing need to avoid processes involving the cleavage of the disulfide bond in the bisamide precursors by halogen, when BITs are manufactured, since they can produce pentahalophenols, especially pentachlorophenols. Thus, alternative methods of converting 2, 2'-dithiobisamides (hereinafter "bisamides" to BIT by cyclization without halogen) have been sought, one of which is the disproportionation of bisamide in alkali in the presence of oxygen or an oxygen releasing agent, as described in EP 187, 439. This method gives high yields of BIT by itself and 6-chloro-BIT No examples of N-alkyl-BIT derivatives are recorded The disulfide bond of the bisamides it can also be split up using bisulfite, which results in the formation of Bunte salts, which can then be cycled under alkaline conditions to give the BITs.This general reaction to manufacture Bunte salts and BITs has been described by Tyrrell (Tetrahedron Letters 26 1753 (1985)) using bisamide precursors containing an amino substituent on the amide group, only the only example is given in this description, where a 47% yield of the Bunte salt is obtained at artir of a bisamide having a piperidinyl group in the amido substituent. The preparation of the other two BIT derivatives containing an N-ethyl-piperidinyl and N-ethyl-pyrrolidinyl group have also been described by Baggaley et al in J. Med. Chem 28. 1661-1667, 1985 using Bunte salt as an intermediate, but the total BIT yield of bisamide again is low at 22% and 21% yield, respectively. This preparative method does not appear to have been followed further, possibly due to the sensitivity of the method to the substituents found in the case of diphenyl disulfide as described by Lecher (et al) in J.O.C. 20. 475 (1955). Here it is described that good yields of the Bunte salts were obtained in the case of bis- (3-nitrophenyl) disulfide, bis- (2-aminophenyl) disulfide, bis- (2-benzoylaminophenyl) disulfide and poor yield of diphenyl disulfide. No Bunte salt was identified from bis- (2-nitrophenyl) disulfide, bis- (2-methoxyphenyl) disulfide and 2,2'-dithiobisbenzothiazole. Because the performance of the Bunte salts of diphenyl disulfides is clearly influenced by the nature of the substituent 2 in particular, there is no indication in Lecher whether the presence of the 2-carbonamido groups as in the bisamides will give high yields of the Bunte salts. . Now it has been found that some bisamides can be converted to Bunte salts in high performance, by the reaction with bisulfite and especially a bisulfite release agent and that the bunte salts thus obtained can be easily converted to BIT. The yield of N-alkyl-BIT using this process is greater than that obtained using the method described in EP 187,349. In accordance with the present invention, a process for manufacturing BIT of formula 1 is provided.

Which comprises reacting a bisamide of formula 2 (2) in water or an organic liquid containing water with a bisulfite or a bisulfite releasing agent or a mixture thereof; wherein R is hydrogen, cycloalkyl, alkyl, alkyl substituted by hydrogen, halogen, C1_6 alkoxy, carboxy, carbon, ida, sulfonamide, nitrile or aryl or optionally substituted aryl; X is halogen, nitro, alkoxy or nitrile; and n is from 0 to 4. When R is alkyl it can be linear or branched and is preferably C1_2 Q 'alkyl, more preferably C1_12 alkyl and especially C1_g alkyl. Examples of such groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, tert-butyl, amyl, i-amyl, n-hexyl, i-hexyl, 2-ethylbutyl, n-heptyl, n -octyl, i-octyl, 2-ethylhexyl, n-decyl and n-dodecyl. When R is cycloalkyl, the alicyclic ring preferably contains up to 8 carbon atoms such as cyclopropyl and especially cyclohexyl. When R is aryl, it preferably contains up to 10 carbon atoms and is especially phenyl. When R is substituted aryl, the substituent may be as described for the substituted alkyl.

When R is alkyl substituted by aryl, the aryl group is preferably phenyl and is especially benzyl and more especially 2-phenylethyl. The phenyl ring in these substituted alkyl groups can themselves be further substituted as described for the substituted aryl, but is preferably unsubstituted. Halogen means fluorine, iodine, bromine and especially chlorine. Preferably n is 0. The bisulfite releasing agent can be any agent that produces the bisulfite ion in aqueous media and preferably is sulfur dioxide in aqueous alkaline media and especially metabisulfite. The reaction of the bisamide with a bisulfite or a bisulfite releasing agent can be catalyzed by oxygen or a metal such as copper, iron and cobalt, which may be present as a salt. When R is H in the BIT of formula I, the BIT can be prepared in the form of its salt with an alkali metal or ammonia. Examples of alkali metals are potassium and especially lithium or sodium. It is especially preferred that R is unsubstituted or 2-phenylethyl alkyl.

Good results have been maintained when R is methyl, n-butyl, n-hexyl, i-hexyl, n-octyl, 2-phenylethyl, 2-ethylbutyl and 2-ethylhexyl. The bisulfite or etabisulfite is preferably present in the form of a water soluble salt such as an alkali metal salt or ammonium salt. The preferred alkali metals are lithium, potassium and especially sodium. Metabisulfite is preferred since in many cases, it gives higher yields of Bunte salt and therefore BIT. The amount of bisulfite or bisulfite release agent is preferably at least one mole and more preferably at least two moles per mole of bisamide. Generally, there is no advantage in using a large excess of bisulfite or bisulfite release agent. In this way, the amount of metabisulfite is preferably less than 8 moles and especially less than 5 moles of metabisulfite per mole of bisamide. Higher yields of N-alkyl-BIT have been obtained with 2.5 to 3 moles, for example 2.75 moles of metabisulfite for each mole of bisamide. In the case of bisulfite, the amount of bisulfite is preferably less than 10 mol and especially less than 8 mol of bisulfite per mol of bisamide. As mentioned in the above, water may be the medium in which bisamide is reacted with bisulfite or the bisulfite releasing agent and this has been found to be an effective reaction medium for BIT itself (formula 1, R is H) and N-alkyl of C1_-BIT. However, for the N-substituted BITs, the reaction medium is preferably an organic liquid. The organic liquid can be hydrophilic or hydrophobic but is preferably hydrophilic. When the organic liquid is hydrophobic, is preferably a solvent for the bisamide and can be an aliphatic hydrocarbon, a chlorinated aliphatic hydrocarbon, an ether, ester or an aromatic hydrocarbon. Examples of the hydrophobic organic liquids are methylene chloride, chloroform, carbon tetrachloride, trichlorethylene, perchlorethylene, trichloroethane, n-heptane, petroleum ether, diethyl ether, ethyl acetate and toluene. Where the organic liquid is hydrophobic, the bisulfite or the bisulfite releasing agent can be dissolved in water and the bisamide converted to the Bunte salt by mixing the two phases. The Bunte salt is soluble in water and is retained in the aqueous phase so it can be easily separated by the single-phase decoupling. When the organic liquid is hydrophilic, it is preferably a glycol, ketone, carbitol, amide, sulfoxide and especially alcohol. Examples of such solvents are ethylene glycol, diethylene glycol, propylene glycol, acetone, ethylethyl ketone, methyl and ethylcarbitol, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, propanol, isopropanol, butanol, isobutanol and tert-butanol, including mixtures thereof. Methanol, ethanol and ethylene glycol are especially preferred, especially methanol. It is also preferred that the hydrophilic liquid contains sufficient water to dissolve the bisulfite or the agent that releases the bisulfite. In the case of bisulfite, the amount of water is preferably greater than 5%, more preferably greater than 10% and especially greater than 20% in relation to the amount of the organic liquid. It is also preferred that the amount of water is less than 100%, more preferably less than 70% and especially less than 50% relative to the weight of the organic liquid. In the case of the metabisulfite, the amount of water is preferably at least 1% more, preferably at least 2% and especially at least 4% relative to the weight of the organic liquid. The amount of water of preference is less than 20%, more preferably less than 15% and especially less than 12% relative to the weight of the organic liquid. Good results have been obtained, when the amount of water in relation to the organic liquid is from 6 to 10% and especially around 8%. The bisulfite or metabisulfite can be added to the organic liquid as an aqueous solution or a suspension, but is preferably added in solid form to the bisamide in the organic liquid. This is particularly advantageous in the case of metabisulfite. The formation of the Bunte salt is very easy and can be carried out by heating the bisamide, the bisulfite and / or bisulfite release agent in the organic liquid at a temperature below 100 ° C. For convenience, it is preferred to carry out the reaction under reflux in water, the organic liquid or a mixture of organic liquid / water. Bunte salt can be isolated by any method known in the art, such as water filtration or evaporation, organic liquid or organic liquid / water mixtures. In a preferred method a hydrophobic liquid, which is a non-solvent for the Bunte salt is added to remove the hydrophilic liquid or the hydrophilic liquid / water mixture as an azeotrope. Another preferred method, where the organic liquid is hydrophilic, is to add more water to effect the separation / sedimentation of the Bunte salt. This latter method has been found to be particularly effective for N-alkyl-BIT containing more than 3 carbon atoms in the alkyl chain. Examples of preferred hydrophobic liquids which form azeotropic mixtures with water and / or hydrophilic liquid are xylene, toluene, hexane, cyclohexane and methylcyclohexane. The preferred hydrophobic liquid which forms an azeotrope is toluene. The Bunte salt thus obtained can be converted into high yield, which in most cases is quantitative, treating the Bunte salt with alkali, especially aqueous alkali liquor. Preferably the alkali is a hydroxide, alkali metal or ammonium carbonate or bicarbonate. Hydroxides are preferred. The preferred alkali metals are lithium, potassium and especially sodium. The amount of alkali is relatively unimportant, but it is generally in a large excess relative to the amount of Bunte salt. It is preferred that the amount of alkali in the alkaline liquor accord be sufficient to give a pH above 9, more preferably above 11 and especially above 13. The cyclization of the Bunte salt to form a BIT occurs rapidly in presence of alkali and generally this reaction can be carried out at 20-30 ° C. Normally no higher temperatures are required. When the Bunte salt has been isolated it can be treated directly with aqueous alkaline solution when the N-substituted BIT is separated either as an oil or a solid.

When the Bunte salt is present in a hydrophobic liquid as a dispersion, this dispersion can be treated with aqueous alkali so that the BIT dissolves in the hydrophobic liquid during its formation. The BIT can then be isolated by removal of the hydrophobic liquid or by any convenient method, such as evaporation or steam washing of the liquid. Depending on the actual BIT and its subsequent commercial use, it is sometimes convenient to choose hydrophobic liquid in which the BIT is subsequently formulated, as this eliminates the need to isolate the BIT first. As mentioned in the above, bisamide is obtained from 2,2 '-dithiobis-benzoic acid (hereinafter DTBA) which is frequently contaminated by polysulfides of the formula 3 where X and n are as defined in the above; and p is 1 or 2.

When the DTBA containing these polysulfides is converted to the bisamide, the bisamide also contains these polysulfide contaminants. A conversion of such bisamide to BIT using halogen to split the disulfide bond, the presence of these polysulfides adversely affects the performance of BIT. The presence of polysulfides and other contaminants in bisamide can also result in unacceptable discoloration of BIT. Now it has been found that these polysulfides can also react with bisulfite or a bisulfite releasing agent to give Bunte salts in high yield and that a BIT obtained from these polysulfides or polysulfides containing bisamide, has a more acceptable color than that obtained when the disulfide bond is split by halogen. According to another aspect of the invention, there is provided a process for manufacturing BIT, which comprises reacting a polysulfide of formula IV or bisamide of formula II, which contains a polysulfide of formula 4 in water, or a liquid organic containing water with bisulfite and / or metabisulfite or a mixture thereof; («) Where R, X, n and p are as defined in the above. When the polysulfide of the formula 4 is present as a contaminant in the bisamide, it is preferably less than 50%, more preferably less than 20% and especially less than 10% by weight in relation to the weight of the bisamide. As mentioned in the above, one of the methods for manufacturing a BIT is by the reaction of a halide 2-halogenothiobenzoyl with a primary amine or ammonia. The 2-halogenothiobenzoyl halide is made by cleaving the disulfide bond of DTBA with halogen either simultaneously or sequentially to the acid halide. If the DTBA contains polysulfides, then the products of the reaction with a primary amine or ammonia are a mixed BIT and bisamides of formulas 2 and 4. The yields of the BIT are therefore reduced. It has now been found that these mixtures of mixed BIT and bisamides can be converted to high quality BIT by treating the mixtures with bisulfite or a bisulfite releasing agent to convert the BIT and mixed bisamides to their Bunte salts and subsequently treat the salt Bunte with alkali to form the BIT- According to yet another aspect of the invention, a process for manufacturing a BIT of the formula 1 is provided. which comprises treating a mixture of the BIT of the formula 1 and the bisamide of the formula 5. wherein X, R and n are defined in the foregoing; and q is 0, 1 or 2; in water or an organic liquid containing water with bisulfite or a bisulfite releasing agent or a mixture thereof. BITs are known industrial biocides and according to another aspect of the invention, the use of BITs made by the processes of this invention as industrial biocides, especially as fungicides and in particular as fungicides of paint film and fungicides for materials, is provided. of plastic. The invention is further described in greater detail in the following examples, in which all references are to parts by weight unless otherwise indicated.

Example 1 Preparation of N-n-butyl-BIT using metabisulfite A mixture of unpurified dithio-2, 2'-bis (Nn-butylbenzamide) (60% by dry weight of bisamide and polysulfides, 13% by weight of Nn-butyl benzisothiazolin-3 -one, the remainder unidentified) (12.8 parts), sodium metabisulfite (11.4 parts), methanol (59 parts) and water (5 parts) is heated and stirred at reflux for 4 hours. The reaction mixture is then cooled, stirred at 20-25 ° C with decolorization charcoal (0.5 parts) for 30 minutes and then filtered. Toluene (65 parts) is added to the filtrate and most of the methanol / water is removed by azeotropic distillation, whereby the Bunte salt is obtained as a suspension in toluene. Water (100 parts) is added to the suspension in toluene and the pH of the aqueous phase is increased above 13.25 by the addition of 47% sodium hydroxide solution. After stirring for 30 minutes at 20-25 ° C, the Bunte salt had been completely cyclized to N-n-butyl-BIT, which is dissolved in the toluene phase. The toluene phase is separated, washed with water (2 x 25 parts) and the toluene is removed by evaporation. The N-n-butyl-BIT is obtained as a yellow oil (10.8 parts). The yield based on the unpurified bisamide is 95% of the theory.

Example 2 Preparation of N-n-butyl-BIT- using bisulfite A mixture of dithio-2,2 '-bis- (N-n-butylbenzamide) (86.5% by dry weight, the remainder unidentified) (4.0 parts), methanol (15.6 parts) and sodium bisulfite solution (58.5% of SO2, 4.93 parts of sodium bisulfite, 13.2 parts of water) is heated and stirred at reflux for 2 hours. The reagents are then cooled, shaken with decolorization charcoal (0.1 parts) at 20-25 ° C for 10 minutes and filtered. The solid is washed with methanol / water (2: 1) (10 parts) and the washing is combined with the filtrate. The 47% sodium hydroxide liquor is added to the filtrate to raise the pH above 13.5 and the stirring is continued for 30 minutes at 20-25 ° C to convert the Bunte salt to BIT. The BIT is then extracted in toluene (50 parts) and the toluene phase is separated and washed with water (2 x 25 parts). Finally, the toluene is removed by distillation so that the N-n-butyl-BIT is recovered as a pale yellow oil (2.42 parts). The yield based on bisamide is 70% of the theory.

Comparative Example A Preparation of N-n-butyl-BIT using oxygen A mixture of dithio-2,2 '-bis (Nn-butylbenzamide) (58.8% by dry weight of bisamide, 9.2% of Nn-butyl-BIT, the remainder unidentified) (20.5 parts), water (200 parts), methanol (20 parts) and aqueous sodium hydroxide liquor (47% sodium hydroxide; 12.8 parts) is stirred at 55 ° C for 24 hours, while oxygen gas is bubbled through the reaction mixture at a rate of 3 times. My gas per second. The reagents are then cooled and the N-n-butyl-BIT is extracted into dichloromethane (20 parts). The organic phase is separated, washed with water (2 x 110 parts) and dried over anhydrous sodium sulfate. The dichloromethane is evaporated leaving the N-n-butyl-BIT as a dark oil (9.4 parts). The yield is 49.5%. This is a much lower yield than that obtained using the method of example 2 and especially that of example 1.

Example 3 Preparation of N-n-hexyl-BIT using metabisulfi or Dithio-2, 2'-bis (N-n-hexylbenzamide) without purification (30 parts at a force of 99%, 0.063 M) is dissolved in methanol (155 parts). Water (13.1 parts) and sodium metabisulfite (31.1 parts) are added and the reagents are stirred at reflux for 6 hours. Then the reactants are cooled, toluene (169 parts) is added and most of the methanol and water are removed as an azeotrope by heating, whereby the Bunte salt is obtained as a suspension in toluene. Water (155 parts) is added followed by sodium hydroxide liquor (43.3 parts, 47% strength (w / w)) and the reagents are stirred for 1 hour at 40-45 ° C when the Bunte salt is cyclized to form Nn-hexyl-BIT which dissolves in the toluene phase. Then add activated carbon (1.13 parts) in water (16 parts) and the reactants are stirred for another 40 minutes at 40-45 ° C. After sieving, the toluene layer is removed, washed with water and finally the toluene is removed by distillation. The product is obtained as a pale yellow oil (24.72 parts at a force of 96.8%, 80.3% of theory).

Example 4 Preparation of N-2-ethylexyl-BIT using metabisulfite This was prepared by a process similar to that described in Example 3 above except that dithio-2,2'-bis (N-2-ethylhexylbenzamide) (29.78 parts, 0.063 M) was used in place of the butyl analogue. The product is obtained as a pale oil (23.93 parts, 70.3% of theory).

Example 5 Preparation of N-2-ethylbutyl-BIT using metabisulfite This was also prepared by a process similar to that described in Example 3 except that dithio-2,2'-bis (N-2-ethylbutylbenzamide) (20.3 parts, 0.043 M) and sodium metabisulfite are used (16.35). parts) in place of the butyl analogue and the amount of the metabisulfite in this example. The product is obtained as a dark yellow oil, which solidified by rest (12.0 parts, 50% of the theory). The performance of the BIT in this example was reduced due to the filtration of the toluene phase after the cyclization of the benzamide precursor to form the BIT which eliminated the product.

Claims (10)

1. A process to manufacture BIT of formula 1 characterized in that it comprises reacting a bisamide of the formula 2 in water or an organic liquid containing water, with a bisulfite or a bisulfite releasing agent or a mixture thereof, wherein R is cycloalkyl containing up to 8 carbon atoms or C? -20 alkyl optionally substituted by phenyl; X is halogen, nitro, alkoxy or nitrile; and n is 0 to 4.

2. The process according to claim 1, characterized in that n is zero.

3. The process according to any of claim 1 or claim 2, characterized in that R is C1-12 alkyl optionally substituted by phenyl.

4. The process according to claim 3, characterized in that R is methyl, n-butyl, n-hexyl, n-octyl, 2-ethylbutyl, 2-ethyl-hexyl, i-hexyl or 2-phenylethyl.

5. The process according to any of claims 1 to 4, characterized in that the agent that liberates the bisulfite is metabisulfite.

6. The process according to any of claims 1 to 5, characterized in that the bisulfite or bisulfite releasing agent is a solid.

7. The process according to any of claims 1 to 6, characterized in that the organic liquid is hydrophilic.

8. The process in accordance with the claim 7, characterized in that the organic liquid is methanol.

9. The process to manufacture the BIT of formula 1 characterized in that it comprises reacting a polysulfide of the formula; or a bisamide of the formula 2 containing a polysulfide of the formula 4 in water or an organic liquid containing water, with bisulfite or a bisulfite releasing agent or a mixture thereof; wherein R, x and n are as defined in claim 1; and p is 1 or 2.

10. A process to manufacture BIT of formula 1 characterized in that it comprises treating a mixture of BIT of the formula 1 and the bisamide of the formula 5. wherein X, R and n are as defined in claim 1; and q is .0, 1 or 2, in water or an organic liquid containing water with bisulfite or a bisulfite releasing agent or a mixture thereof.