Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1997-07-17
1999-08-10
Stockton, Laura L.
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D27504
Patent
active
059360941
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for making 1,2-benzisothiazolin-3-ones and to the use of compounds made thereby as industrial biocides.
1,2-Benzisothiazolin-3-ones (hereinafter "BIT") have long been known including their use as industrial biocides.
There exist three common methods for making BIT as disclosed in GB 848,130.
The first method involves making a 2-halogenothiobenzoyl halide and reacting this with a primary amine to obtain a N-substituted BIT. The 2-halogenothiobenzoyl halide is generally made by cleaving the disulphide 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 making a 2-halogenothiobenzamide and cyclising this compound in the present of acid or alkali. The 2-halogenothiobenzamide is typically made by converting 2,2'-dithio-bis-benzoic acid to bisamide and thereafter cleaving the disulphide bond with halogen. The halogen is often chlorine as provided by sulphuryl chloride.
A third method involves the disproportionation of 2,2'-dithio-bis-benzamides by heating in the presence of sodium hydroxide solution.
Owing to increasing environmental pressures there is a growing need to avoid processes involving the cleavage of the disulphide bond in bisamide precursors by halogen when making BIT's since these can given rise to pentahalophenols, especially pentachlorophenols. Thus, alternative methods of converting 2,2'-dithiobisamides (hereinafter "Bisamide") to BIT by non-halogen cyclisation have been sought.
One such method is the disproportionation of bisamide in alkali in the presence of oxygen or an oxygen release agent as disclosed in EP 187,349. This method gives high yields of BIT itself and 6-chloro-BIT. No examples of N-alkyl-BIT derivatives are recorded.
The disulphide bond of bisamides may also be cleaved using bisulphite which results in the formation of Bunte salts which may then be cyclised under alkaline conditions to give BIT's. Such a general reaction for making Bunte salts and BIT's has been disclosed by Tyrrell (Tetrahedron Letters 26 1753 (1985)) using bisamide precursors containing an amino substituent in the amide group. Only the one example is given in this disclosure where a 47% yield of the Bunte salt was obtained from a bisamide having a piperidinyl group in the amido substituent. The preparation of two further BIT derivatives containing a N-ethyl-piperidinyl and N-ethyl-pyrrolidinyl group have also been disclosed by Baggaley et al in J.Med.Chem 28 1661-1667, 1985 using the Bunte salt as intermediate but the overall yield of BIT from bisamide is again low at 22% and 21% yield, respectively. This preparative method does not appear to have been pursued further due possibly to the sensitivity of the method to the substituents found in the case of di-phenyl disulphide as disclosed by Lecher (et al) in J.O.C. 20 475 (1955). Here it is disclosed that good yields of Bunte salts were obtained in the case of bis-(3nitrophenyl) disulphide, bis-(2-aminophenyl) disulphide, bis-(2-benzoylaminophenyl) disulphide and a poor yield from di-phenyl disulphide. No Bunte salt was identified from bis-(2-nitrophenyl) disulphide, bis-(2-methoxyphenyl) disulphide and 2,2'-dithiobisbenzothiazole. Because the yield of Bunte salts from di-phenyl disulphides is clearly influenced by the nature of the 2-substituent in particular there is no indication in Lecher whether the presence of 2-carbonamido groups as in bisamides will give high yields of Bunte salts.
We have now found that some bisamides can be converted to Bunte salts in high yield by reaction with bisulphite and especially a bisulphite-release agent and that the Bunte salts so obtained may be readily converted to BIT. The yield of N-alkyl-BIT using this process is higher than that obtained using the method disclosed in EP 187,349.
According to the present invention there is provided a process for making BIT of formula 1 ##STR2## which comprises reacting a bisamide of formula 2 ##STR3##
in water or an organic liquid co
REFERENCES:
patent: 4736040 (1988-04-01), Tonne et al.
patent: 5315009 (1994-05-01), Austin et al.
Tyrrell: "Synthesis of Bunte Salts from 1,2-Benzisothiazol-3-ones and Vice Versa" Tetrahedron Letters, vol. 26, No. 14, pp. 1753-1756, 1985. XP002004537. See especially p. 1755.
Baggaley et al: "Inhibitors of Blood Platelet Aggregation. Effoects of Some 1,2-Benzisothiazol-3-ones on Platelet Responsiveness to Adenosine Diphosphate and Collagen", J. Med. Chem 1985, vol. 28, No. 11, pp. 1661-1667, XP002004538. see especially Table 1, enteries 19 and 26, and method d, p. 1666.
Lecher et al: "Some New Methods and preparing Bunte Salts", Journal of Organic Chemistry, vol. 20, 1955, pp. 475-487, XP002004539.
Okachi et al., J. Med. Chem. 28, 1772-1779 (1985).
Szabo et al., Tetrahedron 44(10), 2985-92, (1988).
Stockton Laura L.
Zeneca Limited
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