- Preparation method of 2 -mercapto -1 - methylimidazole
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The invention discloses a preparation method of electronic grade 2-sulfydryl-1-methylimidazole. The method comprises the following steps: (1) a water solution of chloroacetaldehyde dimethyl acetal andmethylamine performs tank closing reaction for 16h at 80 to 85 DEG C; cooling and pressure release are performed; a solvent is used for extraction; the solvent is concentrated; rectification under vacuum is performed to obtain an intermediate of methylaminoacetaldehyde dimethyl acetal; (2) the methylaminoacetaldehyde dimethyl acetal and t-butyl thionitrile react under the boron trifluoride catalysis; condensation reaction is performed at 50 to 70 DEG C to obtain 2-tert-butyl sulfenyl-1-methylimidazole; (3) a solvent is added into the 2-tert-butyl sulfenyl-1-methylimidazole; a catalyst and anorganic solvent are added; reaction is performed at constant temperature; after filtering, filter liquid is concentrated; then, electronic grade water crystallization is performed to obtain the product of 2-sulfydryl-1-methylimidazole. The preparation method has the advantages that the raw material price is low; the environment-friendly effect is achieved; the operation of the synthesis method issimple and convenient; the product quality conforms to application standards of electronic chemicals.
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Paragraph 0020; 0030-0031; 0034-0035; 0038-0039
(2020/07/13)
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- Methimazole preparation method
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The invention discloses a methimazole preparation method, which comprises: 1) carrying out an ammonolysis reaction on dimethylchloroacetal and a methylamine methanol solution at a temperature of 125-135 DEG C, adding the alkoxide of an alkali metal after completing the reaction, carrying out a neutralization reaction, filtering, distilling to remove the methanol, and carrying out pressure reducing distillation to obtain an intermediate methylamino dimethoxyethane; and 2) adding sodium thiocyanate and the methylamino dimethoxyethane obtained in the step 1) into purified water, adding hydrochloric acid at a room temperature in a dropwise manner, carrying out a reaction for 12-15 h at a temperature of 50-60 DEG C, carrying out pressure reducing distillation to remove the water after completing the reaction, adding ethyl acetate and a drying agent, carrying out heating reflux for 30 min, carrying out hot filtering, distilling the filtrate until the remaining volume of the ethyl acetate is 1/3, and carrying out cooling crystallization to obtain the methimazole. According to the present invention, the preparation method has advantages of low cost, short route, convenient operation and environmental protection, and the high-quality methimazole can be obtained through the method.
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Paragraph 0032; 0036; 0037; 0041; 0042
(2017/12/09)
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- Amidation of unactivated ester derivatives mediated by trifluoroethanol
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A catalytic amidation protocol mediated by 2,2,2-trifluoroethanol has been developed, facilitating the condensation of unactivated esters and amines, furnishing both secondary and tertiary amides. The complete scope and limitations of the method are described, along with modified conditions for challenging substrates such as acyclic secondary amines and chiral esters with retention of chiral integrity.
- McPherson, Christopher G.,Caldwell, Nicola,Jamieson, Craig,Simpson, Iain,Watson, Allan J. B.
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supporting information
p. 3507 - 3518
(2017/04/26)
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