Mercuration Products of Some Aliphatic Ketones and Keto-Acids. 1 H and 13 C NMR Evidence on the Site and Degree of Mercuration. The Crystal and Molecular Structure of 1-(Acetoxymercurio) Butanone

Abstract

Trimercurated acetone, CH₃COC(HgX)₃, X = CH₃OCO⁻, NO₃⁻, is formed by direct mercuration of acetone. The reaction of propyne with aqueous mercuric chloride leads to a mixture of trimercurated acetone, CH₃COC (HgCl)₃, dimercurated acetone, CH₃COCH(HgCl)₂ and trace amounts of monomercurated acetone, CH₃COCH₂HgCl. Direct mercuration of butanone with mercuric acetate leads to the mixture of trimercurated butanone, C₂H₅COC(HgOCOCH₃)₃, dimercurated butanone, C₂H₅COCH(HgOCOCH₃)₂, and monomercurated butanone, C₂H₅COCH₂HgOCOCH₃. 1-(Acetoxymercurio)butanone, C₂H₅COCH₂,HgOCOCH₃, was characterized by X-ray diffraction. It crystallizes in the orthorhombic system, space group Pbca, a = 25.147(6), b = 11.861(3), c = 5.267 (1) Å, Z = 8, D_c = 2.797gcm⁻³, 888 unique reflections with I > 3σ(I), R = 0.065. The reaction of butyne with aqueous mercuric chloride leads to only tri- and dimercurated butanones. The one- and two-dimensional ¹H and ¹³C NMR spectra of soluble chloromercurio derivatives of acetone and butanone revealed the presence of trimercurated and dimercurated ketones and, in the case of acetone, traces of monomercurated ketone as well. Long-range ¹⁹⁹Hg-¹H and ¹⁹⁹Hg-¹³C spin-spin couplings up to four bonds apart were detected in dimercurated and trimercurated derivatives. Trimercurated pyruvic acid is obtained by direct mercuration of pyruvic acid, with mercuric acetate, while the monomercurated acid is obtained when mercuric nitrate or oxide is used as the mercuration agent. Direct mercuration of ethyl acetoacetate and levulinic acid with mercuric acetate or nitrate leads to dimercurated products. It was found that even mercuric chloride easily mercurates ethyl acetoacetate due to its very reactive methylene group.