857. ------. [GRESHAM, W. F.] (E. I. du Pont de Nemours & Co.). Recovery of Hydrogen Fluoride-Boron Triflouride Catalysts. United States Patent 2,462,739. Feb. 22, 1949. Chem. Abs., vol. 43. 1949. p. 3949.

Patent Abstracts

Mixtures (I) of MeC₆H₄CHO (II), HF, and BF₃ are formed in the catalytic preparation of (II) from tolune and CO. (I) is treated with 1 mol. NaF at -40º, warmed to 25º, and the precipitate washed with toluene to give 92% recovery of (II). Similarly LiF gives 95% (II): CaF₂ also is effective. The complex (Lif)₂-HF-BF₃ heated 115 min. at 336º-374º gives quantitative recovery of HF and BF₃, and at 302º-317º gives 98.7 and 81.5% respectively. The complex CaF₂-HF-BF₃ in 15 hr. at 300º gives a high recovery of BF₃but very little HF. In 90 min. at 458º-514ºa 20% recovery of HF and BF₃ is obtained from the NaF-HF-BF₃ complex. Treatment of (I) at -40º with 1 mol. NaF and 3 CaF₂ gives 100% removal of HF and BF₃: the heating of the precipitate for 150 min. at 387º-395º allows 45% recovery of HF and BF₃.