Sodium cyanide

Sodium cyanide is an inorganic compound represented by the chemical formula NaCN. Sodium cyanide is described as a white water soluble inorganic compound with a high affinity for metals. This makes it highly toxic and consequently is only used sparingly, usually in gold mining. When used in gold mining, it's high reactivity with metals is exploited. When it is used as an acid, it forms the toxic gas hydrogen cyanide. Sodium cyanide was declared a Priority Existing Chemical by NICNAS in May 2002 in response to environmental concerns included reports of mass bird poisoning as a result of consumption of cyanide-contaminated water at Tailing's dam in Australia. As a result of this action, NaCN is now highly regulated and sparingly used in industrial enterprises.

Properties
Sodium cyanide is produced by treating hydrogen cyanide with sodium hydroxide

HCN + NaOH → NaCN + H2O Worldwide production was estimated at 500,000 tons in the year 2006. In former times, it was prepared by the Castner-Kellner process involving the reaction of sodium amide with carbon at elevated temperatures.

NaNH2 + C → NaCN + H2 The structure of solid NaCN is related to that of sodium chloride] The anions and cations are each six-coordinate. Potassium cyanide (KCN) adopts a similar structure. Each Na+ forms pi-bonds to two CN− groups as well as two "bent" Na---CN and two "bent" Na

Because the salt is derived from a weak acid, NaCN readily reverts to HCN by hydrolysis: the moist solid emits small amounts of hydrogen cyanide, which smells like bitter almonds (not everyone can smell it—the ability thereof is due to a genetic trait. Sodium cyanide reacts rapidly with strong acids to release hydrogen cyanide. This dangerous process represents a significant risk associated with cyanide salts. It is detoxified most efficiently with hydrogen peroxide (H2O2) to produce sodium cyanate (NaOCN) and water

NaCN + H2O2 → NaOCN + H2O

Synthesis
Sodium Cyanide is produced by treating hydrogen cyanide with sodium hydroxide. The estimated global production of this compound was around 500,000 tons in 2006. In the past, it was prepared by the Castner-Kellner process invoking the reaction of sodium amide with carbon at elevated temperatures. Due to its toxicity it is not readily available to the general public and is regulated by the CDC.

Uses
NaCN is used extensively in gold mining, particularly in Australia. In this process, the high affinity of gold for cyanide is exploited which induces gold metal to oxidize and dissolve in the presence of air and water. The following equation describes the process:

4Au + 8NaCN + O2 +2H2O -> 4Na[Au(CN02)] + 4NaOH

Potassium cyanide (KCN) a similar compound to sodium cyanide is also used in a similar method potassium gold cyanide

KAu(CN)2) few other methods exist for this extraction process.

NaCN is also widely used in chemical production. Surprisingly, several nutrients can be derived from sodium cyanide including cyanuric chloride, cyanogen chloride, and many different types of nitriles. in organic synthesis, cyanide, which is a strong nucleophile is used to prepare nitriles which occur in many specialty drugs including several pharmaceuticals. It is also occasionally used illegally in cyanide fishing and occasionally used by entomologists for collecting jars.

Toxicity
Sodium cyanide is classified as a cyanide salt which are among the most rapidly moving poisons known. Cyanide can quickly and potently inhibit respiration attacking mitochondrial cytochrome oxidase and as a result, blocking electron transport. This results in decreased metabolism, and less oxygen utilization. Lactic acidosis then occurs due to the anaerobic metabolism. NaCN is strictly regulated because of its potentially deadly properties and should not be handled by amateurs.