Cyanide salts, caution

Caution This reaction involves highly toxic cyanide salts. It may be carried out safely, however, if prudent laboratory procedures are practiced. In particular, cyanide residues should be collected and disposed of separately (Note 1), and the entire sequence should be perform,ed in an efficient hood. 

Caution. This synthesis should be carried out in a well-ventilated hood because of the use of highly poisonous hydrogen sulfide. Usual safety measures recommended for handling cyanide salts should be carefully observed during the synthesis and the disposal of the residues. Exposure of any of those products to acids could result in liberation of highly poisonous hydrogen cyanide. 

Caution. Although no problems were encountered in the syntheses that follow, transition metal perchlorates are potentially explosive and should be prepared in small quantities. Due care must be taken when handling perchlorate and cyanide salts. All materials are commercial samples of reagent grade unless indicated otherwise. 

Caution. The cyanide anion is a strong respiratory inhibitor. Ai such, it is a strong base, thus producing the weak, highly toxic, hydrocyanic acid on protonation. Hence, alkali metal cyanide salts must be handled with great care. Toxic CO is evolved in Section 37.A. All operations should be conducted in an efficient fume hood. 

CAUTION Cyanide salts can be absorbed through the skin and are extremely toxic. Appropriate safety precautions and first aid procedures should be adopted when handling cyanide salts... 

The resultant solid mercury salt is contacted with a mixture of 23 g potassium cyanide (n Caution. Cyanide compounds are extremely poisonous.) and 48 g potassium carbonate in 350 mL of water and 200 mL of heptane. After stirring for several hours, the phases were separated. The heptane phase is stirred vigorously with 12.5 g KCN and 24 g K2C03 in 175 mL water. After separating the phases, the organic phase is washed successively with 250 mL portions of 0.5 M K2C03, HzO, 0.5 M HN03, 0.5 M NaOH, and H20. The solvent is concentrated at reduced pressure to provide 52 g of the title compound. 

Caution Cyanide salts are formed in this procedure. All procedures should be... 

CAUTION It is of prime importance to recognize and become familiar with the extreme toxicity of cyanide salts and HCN gas. 

Potassium cyanide. (CAUTION ) Dissolve 25 g of the salt in 35 mL of de-ionised water to which has been added 5 mL of concentrated ammonia solution. Make up to 50 mL with de-ionised water and filter if necessary. 

Caution. Because of the toxic nature of cyanide, special care should be exercised in these preparations. We make amylnitrite available in the laboratory as an antidote to acute cyanide poisoning. Organic soluble salts of cyanide (and potentially cyanometallates) are especially hazardous contact poisons because they are transported intraveneously through the skin. 

CAUTION Foaming This operation, as well as the rest of the experiment, MUST be carried out in a well-ventilated hood because vapors of hydrogen cyanide (from the excess of the potassium salt used) are liberated by the add.]... 

The most satisfactory method of preparation of a copper(i) cyanide solution is to dissolve the copper(i) cyanide (90 g, 1 mol) in a solution of sodium cyanide (125 g, 2.5 mol) (CAUTION) in 600 ml of water. If it is desired to avoid the preparation of solid copper(i) cyanide, the following procedure may be adopted. Copper(i) chloride, prepared from 35 g of copper(n) sulphate pentahydrate as described under 22 above, is suspended in 60 ml of water contained in a 500-ml round-bottomed flask, which is fitted with a mechanical stirrer. A solution of 18.5 g of sodium cyanide (96-98%) in 30 ml of water is added and the mixture is stirred. The copper(i) chloride passes into solution with considerable evolution of heat. As the copper(i) cyanide is usually employed in reactions with solutions of aryl diazonium salts it is usual to cool the resulting copper(i) cyanide solution in ice. 

WARNING Synthetic work involving cyanides requires great caution because of the extreme toxicity of gaseous HCN. This is readily released from any alkali-metal cyanide or labile metal-cyano complex by even very weak acids, including salts that are acidic due to hydrolysis. 

C. Decontamination (see p 46). Caution-. Avoid contact with cyanide-containing salts or solutions, and avoid inhaling vapors from vomitus (which may give off hydrogen cyanide gas). 

A similar procedure can be used to destroy hydrogen cyanide, but precautions must be taken to avoid exposure to this very toxic gas. Hydrogen cyanide is dissolved in several volumes of ice water. Approximately 1 molar equivalent of aqueous sodium hydroxide is added at 4 to 10 °C to convert the hydrogen cyanide into its sodium salt, and then the procedure described above for sodium cyanide is followed. (CAUTION Sodium hydroxide or other bases, including sodium cyanide, must not be allowed to come into contact with Uquid hydrogen cyanide because they may initiate a violent polymerization of the hydrogen cyanide.)... 

The most common salt of trade and utility is K CN. A convenient and safe method of preparation on a scale of 1-10 mmol is reduction of barium [ CJcarbonate with potassium azide at elevated temperatures the procedure is highly reproducible and gives radiochemical yields in the range of 90-98% . In this procedure an intimate mixture of barium [ C]-carbonate, potassium azide and carefully dried sea sand is heated at temperatures slowly increasing from 450 to 700 °C. The resulting crude product is acidified with 85% phosphoric acid, and H CN released is expelled with helium into a methanolic solution of potassium methoxide, from which the K CN is isolated in solid form by evaporation of the solvent. (Caution HCN is volatile and extremely toxic.) Sodium [ C]cyanide can be prepared the same way, except using methanolic sodium methoxide. Potassium [ " C]-cyanide is indefinitely stable as a dry solid at ambient temperature the sodium salt is somewhat less so. 

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