반응 #2076050
ord-42ee087ae19441098e187eaa6f4e16ba
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후처리
- 1workup.ADDITIONare introduced into a 500 ml reaction flask
실험 절차
In a nitrogen atmosphere, 30.1 g (84 mmol t.q.) of 2-bromo-1-(4-bromomethyl-phenyl)-2-methyl-propan-1-one, 150 g of dioxane and 0.5 g of tetrabutylammonium bromide, dissolved in 15 g of water, are introduced into a 500 ml reaction flask. Then, at about 80° C., an initial amount of 34.7 g of 15% sodium hydroxide solution is added dropwise over about two hours. The reaction solution is alkaline, about pH 9-10. The reaction is checked using a 1H NMR spectrum. The intermediate formed in part, 1-(4-bromomethyl-phenyl)-2-hydroxy-2-methyl-propan-1-one, accumulates and, despite the addition of sodium hydroxide solution, the reaction stops before completion. The addition of sodium hydroxide solution is then interrupted and the salt-containing aqueous phase is separated off. Further 15% sodium hydroxide solution is slowly added dropwise at about 80° C. to the organic phase, totalling 44.8 g (0.164 mol) of 15% sodium hydroxide solution. The bromide, 1-(4-bromomethyl-phenyl)-2-hydroxy-2-methyl-propan-1-one, slowly disappears and the pH of the reaction solution remains at about 10. The salt-containing aqueous phase is again separated off and the organic phase is concentrated, resulting in 13.4 g of yellow oil which, in the 1H NMR spectrum, is a product mixture. The oil is separated on a silica gel column. A mixture of ethyl acetate: mixed hexanes 1:1 is used as eluant. Three liquid products are obtained and confirmed using a 1H NMR spectrum: 2-hydroxy-1-(4-hydroxymethyl-phenyl)-2-methyl-propan-1-one (Example 3a) as main product, the dimer 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyloxymethyl]-phenyl}-2-methyl-propan-1-one (Example 3b) as subsidiary product and, as components of a further small fraction which is separated by HPLC, 2-hydroxy-2-methyl-1-p-tolyl-propan-1-one and 1-(4-dibromomethyl-phenyl)-2-hydroxy-2-methyl-propan-1-one.