Butyroin (CAS no ), which is also known as 4-Octanone, 5-hydroxy-, could be produced through the following two production methods.

Method one:

A 500-mL, three-necked, round-bottomed flask is equipped with a mechanical stirrer, a short gas inlet tube, and an efficient reflux condenser fitted with a potassium hydroxide drying tube. The flask is charged with 13.4 g (0.05 mol) of 3-benzyl-5-(2-hydroxyethyl)-4-methyl-1,3-thiazolium chloride, 72.1 g (1.0 mol) of butyraldehyde, 30.3 g (0.3 mol) of triethylamine, and 300 mL of absolute ethanol. A slow stream of nitrogen is begun, and the mixture is stirred and heated in an oil bath at 80°C. After 1.5 hr the reaction mixture is cooled to room temperature and concentrated by rotary evaporation. The residual yellow liquid is poured into 500 mL of water contained in a separatory funnel, and the flask is rinsed with 150 mL of dichloromethane which is then used to extract the aqueous mixture. The aqueous layer is extracted with a second 150-mL portion of dichloromethane. The combined organic phases are washed with 300 mL of saturated sodium bicarbonate and with 300 mL of water. The dichloromethane is removed by rotary evaporation under slightly diminished pressure. Distillation through a 20-cm Vigreux column gives 51–54 g (71–74%) of product as a colorless to light-yellow liquid, n_D²⁰ 1.4309, bp 90–92°C (13–14 mm).

Method two:

In a 3-l. three-necked, round-bottomed flask, fitted with a long reflux condenser and an efficient mechanical stirrer, are placed 92 g. (4 gram atoms) of clean metallic sodium and about 150 cc. of xylene. The sodium is finely powdered by heating the flask until the sodium melts and then cooling with very vigorous stirring. The cooled xylene is decanted, and the powdered sodium is thoroughly washed with four or five portions of dry, alcohol-free ether. About 1.2 l. of absolute ether is added, and the flask is fitted with a reflux condenser, a 250-cc. separatory funnel, and a mechanical stirrer.

The stirrer is started, and 232 g. (2 moles) of purified ethyl n-butyrate is slowly run in from the separatory funnel. It is advisable to add first a portion of about 25 cc.; the heat of reaction soon causes the ether to boil; the rest of the ester is then run in at such a rate that gentle ebullition is maintained. Stirring is continued until there is no further reaction and practically all the sodium has been converted into the voluminous yellow-white solid which begins to appear almost at once.

The reaction flask is now surrounded by an ice bath, and the contents are vigorously stirred while a cooled solution of 210 g. of sulfuric acid (sp. gr. 1.84) in 350 cc. of water is carefully run in from the separatory funnel. The stirrer is now removed and the flask is allowed to stand in the ice bath until the lower layer of hydrated sodium sulfate (Na₂SO₄·10H₂O) has solidified. The ether solution is decanted and the sodium sulfate crystals washed with 100–200 cc. of ether.

The combined solution and washings are shaken with about 100 cc. of 20 per cent sodium carbonate solution and are then dried over anhydrous potassium carbonate. The ether and alcohol are removed rapidly by distillation, and the residue is fractionated under reduced pressure in a 250-cc. modified Claisen flask. The main fraction boils at 80–86° at 12 mm.; a fraction boiling up to about 15° above the main fraction should also be collected. The low-boiling and high-boiling fractions can be refractionated for recovery of a small additional amount of butyroin. The total yield is 94–101 g. (65–70 per cent of the theoretical amount) of product that is colored yellow by traces of the diketone.