- Method for preparing 3 - amino -2, 4 -dimethylthiophene (by machine translation)
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The invention relates to the field, and relates to the field of chloroacetamide preparation. The invention discloses a preparation method, namely 3 -) and -2 dimethylamino 4 - and the method comprises the following steps, 1) cyclization decarboxylation 2, 5 -dimethyl -3 -thiobenzoic acid, 2, 4 -dimethyl tetrahydrothiophene -3 - ketone; 2) rearrangement to obtain 2 amino 4 -3 -dimethylthiophene after condensation with hydroxylamine or a salt thereof in the presence of an acid 3 - anhydride -2 and 4 - a base in the presence of an acid anhydride and a base. By the method, the yield is high, and the yield is high. The preparation method of-amino,dimethylthiophene is suitable for large-scale production. 3 -2 4 . (by machine translation)
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Page/Page column 7; 8
(2019/08/12)
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- Method for preparing 2,4-dimethyltetrahydrothiophene-3-one
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The invention relates to a method for preparing 2,4-dimethyltetrahydrothiophene-3-one. The method comprises the following steps: preparing an intermediate 3-mercaptoisobutyric acid from an initial raw material methacrylic acid by adopting thiourea as a mercapto group donor; preparing an intermediate 2,5-dimethyl-3-thiaadipic acid from the intermediate 3-mercaptoisobutyric acid and 2-halogenopropionic acid under the action of an alkali; and preparing 2,4-dimethyltetrahydrothiophene-3-one from the intermediate 2,5-dimethyl-3-thiaadipic acid under the action of a diluent and a metal catalyst. The method for preparing the intermediate 2,5-dimethyl-3-thiaadipic acid from the initial raw material methacrylic acid with low price has the advantages of simple steps, high yield, high product purity, small amount of three wastes in the production process, and industrial production facilitation.
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Paragraph 0034; 0035
(2017/07/21)
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