Method for preparing alpha-monobrominated ketone and alpha, alpha-dibrominated ketone compounds by selectively brominating ketone compounds

Abstract

The invention discloses a method for preparing alpha-monobrominated ketone and alpha, alpha-dibrominated ketone compounds by selectively brominating ketone compounds. The method comprises the steps of by taking ketone compounds as reactants, taking bromated and metal bromides in the presence of bromic acid or inorganic acid as brominating reagents and taking alcohol as a solvent, selectively brominating the ketone compounds into corresponding alpha-monobrominated ketone. The reaction has effects of high brominating selectivity, gentle reaction condition, high reaction velocity and high yield; the selected brominating reagents are cheap, easily available and low in toxicity; moreover, the method is high in bromine rate which is close to requirements of green chemistry, and therefore, the method is easy for industrial production and has good application prospect.

Description

technical field [0001] The invention belongs to the technical field of organic compound preparation, and specifically relates to a selective preparation method of ɑ-monobromoketone and ɑ, ɑ-dibromoketone compounds. Background technique [0002] Various ɑ-monobromoketones and ɑ,ɑ-dibromoketones are important intermediates of fine chemicals such as medicines and pesticides, so their preparation methods have attracted extensive attention from researchers. The preparation method of ɑ-monobromoketone and ɑ, ɑ-dibromoketone compound is usually carried out by bromination of ketone compound directly with liquid bromine or bromine water in different systems, such as: (T.L.Stuk, B.K. Assink, R.C. Bates, D.T. Erdman, V. Fedij, S.M. Jennings, J.A. Lassing, R.J. Smith, T.L. Smith, Org. process Res. Dev., 2003, 7, 851; C. C. Silveira, C. R. Bernardi, A. L. Braga, T. S. Kaufman, Tetrahedron Lett ., 2001, 42(51), 8947). However, the elemental bromine used in this bromination method has th...

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Problems solved by technology

However, the elemental bromine used in this bromination method has the characteristics of high toxicity, high volatility, and unsafe operation. It will pollute the environment and corrode equipment in industrial production, and the selectivity is poor. The prepared product is often α-monobromo A mixture of ketones and ɑ, ɑ-dibromoketones, in which the highest utilization rate of bromine atoms is only 50%; copper bromide (CuBr 2 ) can also be used as a bromination agent (S.Caron, R.W.Dugger, S.G.Ruggeri, J.A.Ragan, D.H.B.Ripin, Chem.Rev.2006,106,2943) is superior to elemental bromine in selectivity and safety, but reactivity Relatively low; Potassium persulfate and sodium bromide can also be used as brominated reagents (E.H.Kim, B.S.Koo, C.E.Song, K.J.Lee, Synth.Commun., 2001, 31(23), 3627), however persulfate Potassium has extremely strong corrosivity, is unfavorable for industrial production; N-brominated reagent is as N-bromosuccinimide (M.V.Adihikar, S.D.Samant, Ultrasonics Sonochem., 2002,9,107; I.Pravst, M.Zupan ,S.Stavber,Tetrahedron Lett.,2006,47,4707), dibromohydantoin (Gao Guorui, Guan Xixia, Zou Xinzhuo, Organic Chemistry, 2007, 27(1), 109; CN 1733677A) and tribromoisocyanuric acid (L.S.de Almeida, P.M.Esteves, M.C.S.de Mattos, Synlett, 2006, 1515) can carry out bromination reaction under mild conditions, and can selectively prepare ɑ-monobromoketone and ɑ, ɑ-dibromoketone Such compounds, but the price of such brominated reagents is relatively high, and by-products such as succinimide, dimethylhydantoin or isocyanuria are generated after the bromine atom is removed

Hydrogen peroxide and hydrobromic acid complexes are recognized as the greenest brominated reagents, and they have received attention in recent years, but their activity is not high, and catalysts such as lithium chloride are often required, and the reaction time is as long as 24 hours or more to achieve Medium or so yield (A.Podgorsek, S.Stavber, M.Zupan, J.Iskra, Greem Chem., 2007,9,1212; A.Moghimi, S.Ramani, R.Zare, M.Sadeghzadeh, S. Faraji, Iran. J. Org. Chem., 2011, 3(3), 707)

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