- Preparation method of 4,5-dichloro-2-hydroxypyridine
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The invention discloses a preparation method of 4,5-dichloro-2-hydroxypyridine. The method comprises the following steps that S1, chlorine-containing organic matter and 2,4,5-trihydroxy pyridine are added into a reaction bottle in sequence, heating reflux is conducted for 16-48 hours, concentration and extraction are conducted, organic phases are combined, a drying agent is added to the organic phases, filtering and rotary evaporation are conducted, and a solvent is removed for obtaining a 2,4,5-trichloropyridine crude product; S2, the 2,4,5-trichloropyridine crude product is dissolved in a polar solvent, an aqueous NaOH solution is added at 0-25 DEG C, a reaction is conducted for 1-6 hours at 0-25 DEG C, extraction is conducted, organic phases are combined, a drying agent is added to theorganic phases, filtering and rotary evaporation are conducted, and a solvent is removed for obtaining a 4,5-dichloro-2-hydroxypyridine crude product; S3, the 4,5-dichloro-2-hydroxypyridine crude product is subjected to recrystallization for obtaining a 2,4,5-trichloropyridine pure product. According to the preparation method of the 4,5-dichloro-2-hydroxypyridine, the raw materials are easy to obtain, the preparation process and purification steps are simple, and industrialization is conveniently achieved.
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Paragraph 0022; 0024; 0026
(2019/10/01)
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- 3 -AZABICYCLO [4.1.0] HEPTANES USED AS OREXIN ANTAGONISTS
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This invention relates to 3-azabicyclo[4.1.0] heptane derivatives (I) and their use as orexin receptor antagonists.
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Page/Page column 66-67
(2010/11/05)
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- STRONG CHLORINATION OF 2-PICOLINE
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The strong thermal and photochemical chlorination of 2-picoline hydrochloride at 80-150 deg.C was investigated.It occurs with change in the phase state of the reaction mixture.Among the chlorination products there were 17 compounds, 15 of which were isolated and identified.The main factor affecting the degree of chlorination is temperature, with increase in which the limiting degree of chlorination in the investigated range decreases.The penta-, hexa-, and heptachloro derivatives are formed mainly by initial chlorination of the pyridine ring with subsequent chlorination of the methyl group.
- Kosorotov, V. I.,Stul', B. Ya.,Dzhagatspanyan, R. B.
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p. 1845 - 1851
(2007/10/02)
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