3-Chloro-3-methyl-1-butyne

• series of benzo[b]pyrano[2,3-i]xanthen-6-ones and benzo[b]pyrano[3,2-h]xanthen-7-ones
• 6-hydroxy-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one
• 5-hydroxy-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one
• 3,3-dimethyl-3Hbenzofuro[3,2-f][1]-benzopyran

115-19-5

1111-97-3

The process is shown in Figure 1. First, the chlorination reactor was turned on and a reflux condensing unit was installed. The reaction vessel was cooled to 10 °C, followed by the sequential addition of concentrated hydrochloric acid, zinc chloride and polyethylene glycol 600. 2-methyl-3-butyn-2-ol was mixed with sulphuric acid and slowly added dropwise to the reaction vessel when the reactor temperature dropped to 0 °C. The reaction temperature was maintained at 0 °C for 2 hours. After the dropwise addition was completed, the reaction temperature was maintained between 0 and 5°C for 2 hours. Upon completion of the reaction, the mixture was transferred to a washing kettle for washing. This was followed by stirring and standing for layering. After separation of the aqueous layer, the organic layer was transferred to the extraction kettle. After filtration and drying, 3-chloro-3-methyl-1-butyne was obtained (95% yield, 99% purity).