Mercury(II) Thiocyanate


[592-85-8]  · C2HgN2S2  · Mercury(II) Thiocyanate  · (MW 316.77)

(catalyst for addition of HSCN to alkynes1,2)

Alternate Name: mercuric thiocyanate.

Physical Data: mp ca. 165 °C (dec).

Solubility: slightly sol H2O, alcohols; sol NH3 and NH4 salts.

Form Supplied in: white, odorless needles or powder.

Handling, Storage, and Precautions: acute poison; exposure to all mercury compounds is to be strictly avoided. Releases toxic Hg fumes when heated to decomposition. Protect from light.

Mercury(II) salts, e.g. Hg(SCN)2, catalyze addition of thiocyanic acid (HSCN) across the triple bond of a variety of alkynes (eq 1);1,2 HSCN is formed in situ from Bu4N+SCN- and a strong acid (H2SO4, HCl, or HBF4).2 Hg(SCN)2 appears to be the catalyst of choice as it suppresses the formation of the corresponding methyl ketones.2 In the presence of Bromine, Hg(SCN)2 has been reported to effect a formal addition of Br-SCN across a C=C bond (due to the replacement of HgX in the primary adduct by halogen).3

1. (a) Larock, R. C. AG(E) 1978, 17, 27. (b) Larock, R. C. T 1982, 38, 1713. (c) Larock, R. C. Organomercury Compounds in Organic Synthesis; Springer: Berlin, 1985. (d) Larock, R. C. Solvomercuration/Demercuration Reactions in Organic Synthesis; Springer: Berlin, 1986.
2. Giffard, M.; Cousseau, J. CC 1979, 1026.
3. Barluenga, J.; Martinez-Gallo, J. M.; Nájera, C.; Yus, M. JCR(S) 1986, 274.

Pavel Ko&cbreve;ovský

University of Leicester, UK

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