- One-pot synthesis of 4, 5 - dichloro - 2 - isothiazolinone process
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The invention discloses a process for synthesizing 4,5-dichloro-2-methylisothiazolinone by a one-pot method. The process comprises the following steps: mixing methyl acrylate, a methylamine aqueous solution and sulfur to obtain a mixture, introducing hydrogen sulfide gas into the mixture to generate a dimethyl 3,3'-dithiobispropionate crude product; and then, on the basis of the dimethyl 3,3'-dithiobispropionate crude product, introducing methylamine gas to synthesize N, N'-dimethyl-3,3`- dithiodipropionamide, thereby obtaining the product 4,5-dichloro-2-methylisothiazolinone by reacting chlorine gas with the N, N'-dimethyl-3,3- dithiodipropionamide. According to the method provided by the invention, the technical process is simplified, the operation cost is reduced, and wastewater generation amount is greatly reduced; and three steps of carrying out Michael addition reaction, amidation and chlorination can be carried out in the same reaction kettle, so that separating and purifying processes of an intermediate product are reduced, and therefore, the equipment investment is low, and the obtained product is high in purity.
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Paragraph 0036; 0039; 0040
(2017/08/25)
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- PREPARATION METHOD OF N,N'-DIALKYL-3,3'-DITHIODIPROPIONAMIDE
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This disclosure relates to a method for preparing N,N′-dimethyl-3,3′-dithiodipropionamides, which is an intermediate compound used for preparation of substituted 3-isothiazolones, including reacting 3,3′-dithiopropionic acid alkyl ester with an alkylamine at a temperature of from 0 to 50° C. in the presence of a polar solvent.
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Page/Page column 7
(2013/02/28)
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- Method of preparing N,N′-disubstituted-3,3′-dithiodipropionamide and method of preparing substituted 3-isothiazolone by using the same
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A method of preparing N,N-disubstituted-3,3′-dithiodipropionamide of formula (2) is provided. In the method, 3-mercaptopropionamide of formula (4) reacts with an aqueous solution of amine to prepare N-substituted-3-mercaptopropionamide of formula (3) and N-substituted-3-mercaptopropionamide reacts with an aqueous solution of hydrogen peroxide. In addition, a method of preparing substituted 3-isothiazolone is provided. In the method, the produced N,N-disubstituted-3,3′-dithiodipropionamide reacts with a halogenating agent, wherein X and Z are same or different and each selected from the group consisting of hydrogen or a lower alkyl group; Y is selected from the group consisting of hydrogen, an alkyl group of 1 to 18 carbon atoms, a cycloalkyl group of up to 10 carbon atoms, an aralkyl group of up to 10 carbon atoms, an aryl group of up to 10 carbon atoms, a halogen-, lower alkyl- or lower alkoxy-substituted aryl group, a cyano alkyl group, a carboalkoxyalkyl group, a haloalkyl group, an alkoxyalkyl group, an aryloxyalkyl group of up to 12 carbon atoms, an aralkoxyalkyl group of up to 12 carbon atoms, a dialkylaminoalkyl group, an alkylacyl group of up to 8 carbon atoms, a lower alkylsulfonyl group, an arylsulfonyl group of up to 10 carbon atoms, a cyano group and a carbamoyl group.
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- Nitrosamine-free 3-isothiazolone
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Nitrosamine-free 3-isothiazolone biocidal compositions suitable for applications where substantial human or animal contact is anticipated, their method of use and process of preparation are disclosed.
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- SYNTHESES OF β-LACTAMS BY RING CONTRACTION OF ISOTHIAZOLIDINONES
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Several methods have been developed for the preparation of β-lactams from isothiazolidinones.Oxidation of 2-t-butyl-4,4-diphenyl- and 2,4,4-trimethyl-isothiazolidin-3-ones (4a) and (4b) with sulphuryl chloride afforded the 5-chloroisothiazolidinones (5a) and (5b), which were converted into 1-t-butyl-3,3-diphenyl- nd 1,3,3-trimethyl-4-phenylthioazetidin-2-ones (6a) and (6b) by treatment with phenyl-lithium.Alternatively, reaction of the isothiazolidinones (4a) and (4b) with phenyl-lithium gave N-t-butyl-2,2-diphenyl- and N,2,2-trimethyl-3-phenylthiopropionamides(12a) and (12b), which were transformed into the β-lactams (6a) and (6b) by halogenation at C-3, followed by treatment with potassium amide.These are examples of methods used to prepare β-lactams from isothiazolidinones.The verstility of these reactions and their relevance to penicilin biosynthesis is discussed.
- Easton, Christopher J.
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p. 153 - 158
(2007/10/02)
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