1,3,5-Tribromobenzene → 1,3-Dibromo-5-dimesitylborylbenzene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

6.25 ml (0.01 mol) of 1.6 M butyllithium in hexane are added over 5 minutes at -78° C. to a suspension of 3.14 g (0.01 mol) of 1,3,5-tribromobenzene in 50 ml of diethyl ether. The reaction mixture is stirred at -78° C. for 2 hours, during which a yellow-orange suspension is produced. 2.68 g (0.01 mol) of solid dimesitylfluoroborane are added, and the reaction mixture is warmed to room temperature over about one hour. The mixture is then diluted with 50 ml of hexane and cooled to 0° C. The solid produced is filtered, washed several times with cold hexane and then washed with water and, finally, with methanol, until the solid is colourless. Drying gives 3.54 g (0.0073 mol; i.e. 73% of theory) of a white solid (1,3-dibromo-5-dimesitylborylbenzene). Following purification by chromatography (hexane; SiO2) a melting point of 190-191° C. is obtained. Elemental analysis for C24H25BBr2 gives: C calc.: 59.55%; found: 59.52% H calc.: 5.21%; found: 5,12%

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