6674-22-2

Colorless to yellow liquid

Although all commercially available DBU is produced synthetically, it may also be isolated from the sea sponge Niphates digitalis.The biosynthesis of DBU has been proposed to begin with 1,6-hexanedial and 1,3-diaminopropane. 

Nonflammable

The synthesis of DBU is as follows:As a base, sodium hydroxide was used at a concentration of 25% by weight and 2.3 times molar equivalent. A stirrer was placed in a 100 mL screw tube, and 11.5 g (50 mmol) of DBU hydrochloride, 8.5 g of toluene and 18.5 g (116 mmol) of 25% sodium hydroxide aqueous solution were charged at room temperature. It was placed on a magnetic stirrer and mixed for 1 hour with stirring. The mixture was separated with a 100 mL separatory funnel to obtain 18.8 g of the upper layer containing DBU and 18.4 g of the lower layer of the aqueous layer. The upper layer portion was analyzed by gas chromatography and contained 31.9% by weight of DBU, and the yield was 6.0 g (39.4 mmol) in a yield of 78.8%.

Fractionally distil DBU under vacuum. Also purify it by chromatography on Kieselgel and eluting with CHCl3/EtOH/25% aqueous NH3 (15:5:2) and checking by IR and MS. [Oediger et al. Chem Ber 99 2012 1962, Angew Chem, Int Ed Engl 6 76 1967, Guggisberg et al. Helv Chim Acta 61 1057 1978, Beilstein 23/5 V 271.]

The Initial Threshold Screening Level (ITSL) for 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU) is 25 μg/m3 with an annual averaging time.