What Chemical Derivatives Can Sodium Cyanide Be Used to Prepare?

Sodium cyanide (NaCN) is a highly toxic but important chemical raw material. It plays a crucial role in the synthesis of various Chemical derivatives due to the reactivity of the cyanide group (-CN). Here are some of the key chemical derivatives that can be prepared using Sodium cyanide:

Inorganic Cyanide Derivatives

1.Ferrocyanides: Sodium cyanide reacts with iron salts to produce ferroCyanides. For example, the reaction of Sodium Cyanide with ferrous sulfate can yield sodium ferrocyanide (Na₄[Fe(CN)₆]). This compound is widely used in the production of blue pigments such as Prussian blue, and also has applications in the food industry as an anticaking agent in salt. The chemical reaction can be represented as:

6NaCN + FeSO₄ → Na₄[Fe(CN)₆] + Na₂SO₄

2.Cyanide Complexes of Metals: Sodium cyanide can form complexes with many metal ions. In the extraction of gold and silver, for instance, in the presence of oxygen, gold and silver react with sodium cyanide to form soluble metal cyanide complexes. For gold, the reaction is as follows:

4Au + 8NaCN + O₂ + 2H₂O → 4Na[Au(CN)₂] + 4NaOH

These metal - cyanide complexes are then further processed to obtain the pure metals. In addition to gold and silver, sodium cyanide can also form complexes with metals like copper, zinc, and nickel, which have applications in electroplating and other industries. For example, in electroplating, metal - cyanide complexes are used as electrolytes to ensure a smooth and uniform deposition of the metal on the substrate.

Organic Cyanide Derivatives

1.Malonic Acid Derivatives: Sodium cyanide is used in the synthesis of malonic acid derivatives. One common process is to react sodium cyanide with chloroacetic acid to form cyanoacetic acid first. The reaction is:

ClCH₂COOH + NaCN → NCCH₂COOH + NaCl

Cyanoacetic acid can then be further esterified to produce malonic acid esters, such as diethyl malonate. Malonic acid derivatives are important building blocks in organic synthesis, especially in the synthesis of pharmaceuticals, dyes, and flavors. They are often used in the Knoevenagel condensation and other reactions to construct more complex organic molecules.

2.Nitrile Compounds: Sodium cyanide can be used to convert haloalkanes or aryl halides into nitriles through nucleophilic substitution reactions. For example, when bromoethane reacts with sodium cyanide, propionitrile is formed:

CH₃CH₂Br + NaCN → CH₃CH₂CN + NaBr

Nitriles are versatile compounds. They can be hydrolyzed to form carboxylic acids, reduced to amines, or used in the synthesis of heterocyclic compounds. In the pharmaceutical industry, many drugs contain nitrile functional groups, and the use of sodium cyanide in the synthesis of nitriles provides an important route for the preparation of these drugs.

3.Cyanohydrins: Aldehydes and ketones can react with sodium cyanide in the presence of an acid catalyst to form cyanohydrins. For example, the reaction of acetone with sodium cyanide:

(CH₃)₂CO + NaCN + H⁺ → (CH₃)₂C(OH)CN + Na⁺

Cyanohydrins are useful intermediates in organic synthesis. They can be further transformed into various functional groups, such as carboxylic acids, amines, and alcohols, by appropriate chemical reactions. In the synthesis of some natural products and pharmaceuticals, cyanohydrins play a key role in constructing the carbon - skeleton and introducing functional groups.

4.Triazine Derivatives: In the production of compounds like melamine, sodium cyanide can be involved in the reaction network. Although the direct reaction may be complex and usually involves multiple steps, the cyanide group from sodium cyanide contributes to the formation of the triazine ring structure. Melamine is widely used in the production of plastics, adhesives, and coatings. Another example is the synthesis of cyanuric chloride (trichlorotriazine), which is an important intermediate in the production of herbicides, pesticides, and reactive dyes. The synthesis of cyanuric chloride from sodium cyanide typically involves a series of reactions including chlorination of cyanide - related precursors.

5.Amino Acids and Their Derivatives: In some synthetic routes for amino acids, sodium cyanide can be used. For example, in the Strecker synthesis of amino acids, an aldehyde or a ketone reacts with ammonia and sodium cyanide to form an aminonitrile intermediate, which is then hydrolyzed to the corresponding amino acid. Starting with an aldehyde RCHO, the reactions are as follows:

RCHO + NH₃ + NaCN → RCH(NH₂)CN + NaOH

RCH(NH₂)CN + 2H₂O + H⁺ → RCH(NH₃⁺)COOH + Cl⁻

Amino acids are the building blocks of proteins and have wide applications in the food, pharmaceutical, and cosmetic industries.

It should be emphasized that due to the high toxicity of sodium cyanide, strict safety measures and handling procedures must be followed during its use in the preparation of these chemical derivatives to ensure the safety of personnel and the environment.