2-Ethylchromone (CAS NO.: ), which is known as Chromone, 2-ethyl-, could be produced through the following synthetic routes.

In a 1-l. three-necked flask fitted with a reflux condenser, a dropping funnel, and a stirrer are placed 24 g. (1.05 gram atoms) of oxide-free sodium and 200 ml. of xylene. The condenser is protected by a drying tube containing soda-lime. The flask is surrounded by an oil bath which is heated until the sodium is melted. The stirrer is started, and, after the sodium is powdered, the oil bath is removed. When the contents of the flask have cooled to room temperature, the stirrer is stopped, the xylene decanted, and the sodium washed with 100 ml. of dry ether to remove traces of xylene.

The flask is replaced and completely surrounded by an ice bath. A current of nitrogen is passed through the flask for 5 minutes by means of a rubber tube attached to the dropping funnel. The nitrogen inlet tube is removed, and a mixture of 60 g. (0.44 mole) of o-hydroxyacetophenone and 125 g. (140 ml., 1.2 moles) of ethyl propionate is placed in the dropping funnel and protected by a soda-lime tube. The ester-ketone mixture is dropped very slowly onto the powdered sodium. After a small amount (2–5 ml.) of the mixture has been added, the ice bath is removed and the flask warmed with the hand to make sure that the reaction has started. When the reaction has started, the funnel is adjusted so that one-half of the ester-ketone mixture is added over a period of 1.5–2 hours. After half of the mixture has been added, the rate of addition is again regulated so that the remainder is added in 30 minutes.

After all the ester-ketone mixture has been added and the reaction has subsided, the ice bath is removed and replaced by a steam bath. The crust on the mixture is broken up and the mixture heated on a steam bath until all the sodium has reacted (30–60 minutes). The reaction mixture is allowed to cool and is poured with stirring onto 300 g. of crushed ice. Ninety-five milliliters of glacial acetic acid in 350 ml. of water is added, and the mixture is stirred for 30 minutes. The organic layer which separates is removed by means of a separatory funnel, and the water layer is extracted three times with 200-ml. portions of ether. The extracts are combined with the original organic material, and the ether is distilled from a steam bath. To the residue are added 150 ml. of glacial acetic acid and 10 ml. of concentrated hydrochloric acid, and the solution is refluxed for 30 minutes, after which it is allowed to cool to room temperature.

The entire reaction mixture is then subjected to fractional distillation through a Widmer column. The material boiling up to 120° is removed at atmospheric pressure and discarded. The contents of the flask are cooled and the pressure reduced to 7 mm. The fraction up to 80°/7 mm. is removed and discarded. The material boiling at 80–90°/7 mm. is collected, and, after the contents of the flask have been cooled, the pressure is reduced to 2 mm. and all the material boiling up to 110°/2 mm. is collected and combined with the 80–90°/7 mm. fraction. The next fraction, boiling at 110–138°/2 mm., is collected separately. On refractionation of the lower fraction (b.p. 80°/7 mm.–110°/2 mm.) there is obtained 13–15 g. of o-hydroxyacetophenone (b.p. 87–88°/7 mm.). To the residue after recovery of the o-hydroxyacetophenone is added the fraction boiling at 110–138°/2 mm. The pressure is again reduced to 2 mm. and the fraction boiling at 124–126°/2 mm. collected. This fraction is pure 2-ethylchromone and weighs 42–45 g. (70–75% based on the ketone not recovered).