2.jpg) | |
| Names | |
|---|---|
| Other names Neutral zinc cyanide (1:2) | |
| Identifiers | |
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3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.008.331 |
| EC Number |
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| RTECS number |
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| UNII | |
| UN number | 1713 |
| |
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| Properties | |
| Zn(CN)2 | |
| Molar mass | 117.444 g/mol |
| Appearance | white solid |
| Density | 1.852 g/cm3, solid |
| Melting point | 800 °C (1,470 °F; 1,070 K) (decomposes) |
| 0.0005 g/100 mL (20 °C) | |
| Solubility | attacked byalkalies,KCN,ammonia |
| −46.0·10−6 cm3/mol | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | Toxic, releases cyanide-ion in body[1] |
| GHS labelling:[2] | |
  | |
| Danger | |
| H300,H301,H310,H330,H410 | |
| P260,P262,P264,P270,P271,P273,P280,P284,P301+P310,P302+P350,P304+P340,P310,P320,P322,P330,P361,P363,P391,P403+P233,P405,P501 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 100 mg/kg, rat (intraperitoneal) |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Zinc cyanide is theinorganic compound with the formulaZn(CN)2. It is a white solid that is used mainly for electroplating zinc but also has more specialized applications for thesynthesis of organic compounds.
In Zn(CN)2, zinc adopts the tetrahedral coordination environment, all linked bybridgingcyanideligands. The structure consists of two "interpenetrating" structures (blue and red in the picture above). Such motifs are sometimes called "expandeddiamondoid" structures. Some forms of SiO2 adopt a similar structure, wherein the tetrahedral Si centres are linked by oxides. The cyanide group shows head to tail disorder with any zinc atom having between one and four carbon neighbours, and the remaining being nitrogen atoms.[4] It shows one of the largestnegative coefficients of thermal expansion (exceeding the previous record holder,zirconium tungstate).
Typical for an inorganic polymer, Zn(CN)2 is insoluble in most solvents. The solid dissolves in, or more precisely, is degraded by, aqueous solutions of basic ligands such ashydroxide,ammonia, and additional cyanide to give anionic complexes.
Zn(CN)2 is easy to make by combining aqueous solutions of cyanide and zinc ions, for example via thedouble replacement reaction betweenKCN andZnSO4:[5]
For commercial applications, some effort is made to avoidhalide impurities by usingacetate salts of zinc:[5][6]
Zinc cyanide is also produced as a byproduct of certaingold extraction methods. Procedures to isolate gold from aqueous gold cyanide sometimes call for the addition of zinc:
The main application of Zn(CN)2 is for electroplating of zinc from aqueous solutions containing additional cyanide.[6]
Zn(CN)2 is used to introduce theformyl group in toaromatic compounds in theGatterman reaction where it serves a convenient, safer, and non-gaseous alternative toHCN.[7] Because the reaction usesHCl, Zn(CN)2 also supplies the reactionin situ withZnCl2, aLewis acid catalyst. Examples of Zn(CN)2 being used in this way include the synthesis of 2-hydroxy-1-naphthaldehyde and mesitaldehyde.[8]
Zn(CN)2 is also employed as a catalyst for the cyanosilylation of aldehydes and ketones.[9]
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