Bromocyclopentane → 4-Cyclopentyloxy-3-hydroxybenzaldehyde

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

In a 10 L 4 necked RB flask fitted with a mechanical stirrer, reflux condenser, was added DMF (3.5 L), 3,4-Dihydroxybenzaldehyde (1.15 Kg, 8.3M), cyclopentyl bromide (3.1 kg, 20.3 M) and powdered anhydrous potassium carbonate (1.15 kg, 20.3 M) at temperature in the range of 25-35° C. under stirring. The reaction mixture was heated to temperature of 75-80° C. under stirring and maintained under stirring for 1 hr. To the reaction mixture, powdered potassium carbonate (140 g, 1M) was added at temperature of 75-80° C. under stirring. After addition, the reaction mixture was maintained at 75-80° C. for 1 hr. The progress of the reaction was monitored by TLC and HPLC. After ascertaining the completion of the reaction, the reaction mixture was brought to 25-35° C. and filtered. The inorganic salt cake was washed with DMF (300 ml×2) and combine the washings with filtrate. The organic layer was concentrated at temperature below 75° C. under high vaccum. Add toluene (2 L) to the residue of distil of the residual DMF. Add toluene (2 L) to the resulting mass and distill off the traces of DMF. To the resulting mass, add toluene (5.7 L), celite (300 g), activated charcoal (100 g), 5% sodium hydroxide solution (1.2 L) and cool to 10-15° C. under stirring. Separate the organic and aqueous layer. The organic layer was repeatedly extracted with 5% sodium hydroxide solution (1.2 L×5) and combine the aqueous sodium hydroxide layers. The aqueous layer was washed with toluene (2 L×2) and separate the aqueous layer. The pH of the aqueous layer was adjusted to acidic 2-3 with conc. HCl (1.1 L) at 10-15° C. under stirring. The precipitated solid was filtered, washed with water(2 L×3) filtered and dried in the hot air oven below 60° C. temp. The product appear as cream color solid, weighing about 920-950 g, yield 54%-56% purity 98-99%, m.p 87-89° C. The IR (KBr) spectrum shows 3300 (OH str), 3150 (CH str), 1670 (CHO str), 1620 (C═C str). The 1H-NMR (DMSO-d6) shows δ 9.8 (s, 1H), 9.2 (s, 1H), 7.1 (d, 1H), 7.2-7.4 (m, 2H), 4.9 (m, 1H), 1.4-2.0 (m, 8H). The CI mass shows m/z 206 (M+). The elemental analysis shows calculated % C, 69.88; % H, 6.84; % O, 23.27; observed % C, 69.70; % H, 6.65; % O, 23.15.

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