Hydrochloric Acid → Trichlorogermane propionic acid

Participants

Reaction Steps

To a 2 L round bottom flask purged with argon was added successively: germanium tetrachloride (200 g [0.9346 mol]), tetramethyl disiloxane (125 g[0.93 mol]), and acrylic acid (70.0 g[0.97 mol]). The reaction flask was purged with argon then sealed by placement of a ground glass stopper with a teflon sleeve and secured via teflon tape. The slightly cloudy mixture changed to a clear, colorless homogeneous solution within about 2 hours, and this was stirred for seven days at ambient temperature. The volatile components were removed via vacuum (0.5 to 5 mmHg) while the product mixture was heated to an internal temperature of 70° C.-80° C., where it was a homogeneous, clear and colorless viscous solution (melt). Evacuation was continued until no more distillate was observed (ca. 2 hours). This was cooled to an ambient temperature to yield a white amorphous solid. To this was added 950 mL of concentrated HCl. The resulting heterogeneous mixture was warmed to an internal temperature of 60° C.-70° C., and stirred for four hours. The cooled mixture was extracted 3 times with 500 mL of dichloromethane. The combined extracts were evaporated under reduced pressure via rotary evaporator to give a while amorphous solid. This was dissolved in ca. 1 L boiling hexane (until a clear colorless homogeneous hot solution was obtained), and let cool gently to ambient temperature. The product, trichlorogermane propionic acid, was isolated via suction filtration, washed once with hexane to give fine prisms, mp 75° C.-79° C. This was immediately taken up (vigorous reaction), with careful addition of 850 mL of ammonium hydroxide (29% ammonia). The resulting turbid mixture was stirred for 4 days at ambient temperature (the mixture changes to a clear, colorless homogeneous solution within 3 hours). To this homogeneous solution was added dropwise over two hours through a reflux condenser 400 mL of concentrated sulfuric acid. NOTE: This is a very vigorous reaction and should be handled with extreme care. A white precipitate formed after addition of ca. 375 mL of acid. The pot was stirred for 48 hours, and then the white solid was isolated via suction filtration, washed successively with 2×150 mL water, 1×150 mL acetone, and 1×200 mL of diethyl ether, then this brilliant white solid was air dried overnight, and then taken up with 150 mL hot water, then cooled and filtered to yield 78.84 g (50%) of analytically pure carboxyethyl germanium sesquioxide.

Provenance & Evidence