42.1 g (0.219 mol, 85%) |
With hydrogenchloride; sodium hydroxide; calcium chloride; In water; |
EXAMPLE 50 g (0.258 mol) of <strong>[1201-31-6]2,3,4,5-<strong>[1201-31-6]tetrafluorobenzoic acid</strong></strong> and 41.4 g (1.04 mol) of sodium hydroxide are introduced first into 687 g of water, the resulting solution is heated to 100 C. and stirred at this temperature for 12 to 14.5 hours. The end point of the reaction is determined by gas chromatography. 57.2 g of calcium chloride are then added, and the pH is brought to 1 with 30% hydrochloric acid. The solutionis continuously extracted with MTBE (methyl tert.-butyl ether) for 16 hours, and the solvent is then distilled off. The dry residue (44.6 g) is recrystallized at 145 C. from 1,2-dichlorobenzene to give 42.1 g (0.219 mol, 85%) of white to slightly beige-colored 4-hydroxy-2,3,5-trifluorobenzoic acid which gives the expected values in all analytical tests. The 3-hydroxy-2,4,5-trifluorobenzoic acid content ofless than 5 mol % of the crude product also formed in the reaction is completely removed by dissolution and reprecipitation (recrystallization). |
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To 50 ml of water were added 10 g of <strong>[1201-31-6]2,3,4,5-<strong>[1201-31-6]tetrafluorobenzoic acid</strong></strong> and 4.5 g of sodium hydroxide, and the mixture was heated to reflux for 4 hours. The reaction mixture was made acidic by addition of hydrochloric acid, extracted with ethyl acetate, and then washed sequentially with water and an aqueous saturated sodium chloride solution. The organic layer was dried over magnesium sulfate, and then concentrated under reduced pressure, and the residue was obtained. The residue, 14 g of propargyl bromide and 18 g of potassium carbonate were added to 100 ml of DMF, and the mixture was stirred at room temperature for 1 day. The reaction mixture was added to water, made acidic by addition of diluted hydrochloric acid, and then extracted with ethyl acetate. The organic layer was washed sequentially with water and aqueous saturated sodium chloride solution, dried, and then concentrated under reduced pressure. The residue was subjected to silica gel column chromatography, and 6.5 g of 2-propynyl 4-(2-propynyloxy)-2,3,5-trifluorobenzoate was obtained.2-Propynyl 4-(2-propynyloxy)-2,3,5-trifluorobenzoate [Show Image] 1H-NMR (CDCl3) delta: 2.55 (1H, t, J = 2.4 Hz), 2.57 (1H, t, J = 2.4 Hz), 4.94 (2H, d, J = 2.4 Hz), 4.96 (2H, d, J = 2.4 Hz), 7.55 (1H, ddd, J = 11.1, 6.1, 2.3 Hz). |