557-21-1 zinc cyanide

Zinc cyanide. Solutions of the reactants are prepared by dis solving 100 g. of technical sodium cyanide (97-98 per cent. NaCN) in 125 ml. of water and 150 g. of anhydrous zinc chloride in the minimum volume of 50 per cent, alcohol (1). The sodium cyanide solution is added rapidly, with agitation, to the zinc chloride solution. The precipitated zinc cyanide is filtered off at the pump, drained well, washed with alcohol and then with ether. It is dried in a desiccator or in an air bath at 50°, and preserved in a tightly stoppered bottle. The yield is almost quantitative and the zinc cyanide has a purity of 95-98 per cent. (2). It has been stated that highly purified zinc cyanide does not react in the Adams modification of the Gattermann reaction (compare Section IV,12l). The product, prepared by the above method is, however, highly satisfactory. Commercial zinc cyanide may also be used. 

The only important precaution in this preparation is to ensure an excess of zinc chloride over sodium cyanide. If the latter is in excess, the zinc cyanide generally precipitates as a sticky mass, which is difficult to filter and unsatisfactory for the preparation of hydroxy-aldehydes. 

Commercial zinc cyanide is quite satisfactory. It may be prepared as described in Section 11,50,iS. If the zinc cyanide is too highly purified, it does not react well. 

Technical grade zinc cyanide was used as supplied by Matheson, Coleman and Bell. Other Lewis acids, notably aluminum chloride, zinc bromide, and zinc iodide may be used as catalysts for the reaction. 

Zinc cyanide [557-21-1] M 117.4, m 800"(dec), d 1.852. It is a POISONOUS white powder which becomes black on standing if Mg(OH)2 and carbonate are not removed in the preparation. Thus wash well with H2O, then well with EtOH, Et20 and dry in air at 50°. Analyse by titrating the cyanide with standard AgN03. Other likely impurities are ZnCl2, MgCl2 and traces of basic zinc cyanide the first two salts can be washed out. It is soluble in aq KCN solns. However, if purified in this way Zn(CN)2 is not reactive in the Gattermann synthesis. For this the salt should contain at least 0.33 mols of KCl or NaCl which will allow the reaction to proceed faster. [J Am Chem Soc 45 2375 1923, 60 1699 1938-, Org Synth Coll Vol III 549 1955.]... 

Cyanide Copper cyanide Nickel cyanide Potassium cyanide Silver cyanide Sodium cyanide Zinc cyanide... 

The electrophile 4 adds to the aromatic ring to give a cationic intermediate 5. Loss of a proton from 5 and concomitant rearomatization completes the substitution step. Subsequent hydrolysis of the iminium species 2 yields the formylated aromatic product 3. Instead of the highly toxic hydrogen cyanide, zinc cyanide can be used. The hydrogen cyanide is then generated in situ upon reaction with the hydrogen chloride. The zinc chloride, which is thereby formed, then acts as Lewis acid catalyst. 

Synthesis of the remaining half of the molecule starts with the formation of the monomethyl ether (9) from orcinol (8). The carbon atom that is to serve as the bridge is introduced as an aldehyde by formylation with zinc cyanide and hydrochloric acid (10). The phenol is then protected as the acetate. Successive oxidation and treatment with thionyl chloride affords the protected acid chloride (11). Acylation of the free phenol group in 7 by means of 11 affords the ester, 12. The ester is then rearranged by an ortho-Fries reaction (catalyzed by either titanium... 

Tin-zinc alloys of a wide range of composition can be electrodeposited from sodium stannate/zinc cyanide baths only the coatings with 20-25% zinc have commercial importance . 

Cyanide solutions are used almost exclusively. One typical solution contains copper cyanide 26 g/1, zinc cyanide 11 g/1, sodium cyanide (total) 45 g/1 and sodium cyanide ( free ) 7 g/l This bath is operated at pH 10.3-11.0, 110 A/m and 27-35 C, with 75 Cu-25 Zn alloy anodes. Many other solutions are used including a special rubber-bonding bath and a high-speed bath which is capable of being used at up to 16 A/dm . ... 

Write the complete Lewis structure for each of the following compounds (a) zinc cyanide (b) potassium tetrafluoroborate (c) barium peroxide (the peroxide ion is 022-). 

Formylation with Zinc Cyanide and HCI The Gatterman Reaction... 

When zinc cyanide is heated with zinc, it reacts violently causing incandescence. 

Thus, co-deposition of silver and copper can take place only when the silver concentration in the electrolyte falls to a very low level. This clearly indicates that the electrolytic process can, instead, be used for separating copper from silver. When both silver and copper ions are present, the initial deposition will mainly be of silver and the deposition of copper will take place only when the concentration of silver becomes very low. Another example worth considering here is the co-deposition of copper and zinc. Under normal conditions, the co-deposition of copper and zinc from an electrolyte containing copper and zinc sulfates is not feasible because of the large difference in the electrode potentials. If, however, an excess of alkali cyanides is added to the solution, both the metals form complex cyanides the cuprocyanide complex is much more stable than the zinc cyanide complex and thus the concentration of the free copper ions available for deposition is considerably reduced. As a result of this, the deposition potentials for copper and zinc become very close and their co-deposition can take place to form alloys. 

---