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The mysterious origins of hydrocyanic acid: How was this toxic compound first discovered?
Hydrogen cyanide, historically known as Prussian acid, is a toxic and mysterious compound that has been shrouded in mystery for centuries since it was first discovered. As a chemical component, its molecular formula is HCN, and it is a frequent subject in various chemical discussions due to its extremely high toxicity. Since the 18th century, the discovery, naming and manufacturing process of this compound has carried the wisdom of scientists, as well as people's exploration and application of this dangerous substance.
Hydrogen cyanide is a highly toxic and flammable liquid with a boiling point slightly higher than room temperature, only 25.6°C.
History of Discovery and Naming
Hydrocyanic acid was first isolated in 1752 by French chemist Pierre Macquer, who converted Prussian blue into iron oxide and added a volatile component to obtain Hydrocyanic acid. With further research by Swedish chemist Carl Wilhelm Scheele in 1782, this compound gradually became known to everyone and was given the German name Blausäure, which means "blue" in Chinese, because of its acidity. acid". In English-speaking countries, it is widely known as Prussian acid.
In 1787, French chemist Claude Louis Berthollet demonstrated that Prussian acid contained no oxygen, an important contribution to acid theory at the time.
Chemical properties
The chemical properties of hydrocyanic acid are equally impressive; it is a weak acid with a pKa value of 9.2. In water, HCN partially ionizes to form cyanide ions (CN−), and the reaction exhibits the acidic behavior of hydrocyanic acid. Hydrogen cyanide is not just a chemical substance; it has a wide range of uses, from synthetic plastics to the pharmaceutical industry.
Hydrocyanic acid has a faint odor, similar to the aroma of bitter almonds, which may not be detectable to some people as it is a recessive genetic trait.
Production and Synthesis
Industrially, hydrocyanic acid is produced mainly by the Andrussow oxidation process, which involves the chemical reaction of methane and ammonia with oxygen at 1200°C. In 2006, U.S. production of hydrocyanic acid ranged from 50 to 100 million pounds, demonstrating its importance in the industry.
Applications of Hydrocyanic Acid
Hydrogen cyanide is an important precursor for the manufacture of sodium cyanide and potassium cyanide, which are widely used in gold and silver mining and metal electroplating. In addition, many useful organic compounds, such as the amino acid isoleucine, can be prepared using intermediates of hydrocyanic acid.
Through the cyanidation process, hydrocyanic acid is added to butadiene to synthesize adiponitrile, a precursor to nylon-6,6.
Existence of Hydrocyanic Acid in Nature
Hydrogen cyanide is not only used in industry, but can also be extracted from the cores of certain fruits. Nuts such as bitter almonds contain compounds that gradually release hydrocyanic acid. It is estimated that every 100 grams of apple seeds can produce about 70 mg of hydrocyanic acid. Additionally, some animals secrete hydrocyanic acid as a defense mechanism.
Biological effects of hydrocyanic acid
In vivo, the production of hydrocyanic acid is related to the activity of the nervous system. Studies have shown that certain neurons release hydrocyanic acid when activated and may play a role as a regulator in neurotransmission. Such characteristics have prompted the scientific community to conduct in-depth research on the biological functions of hydrocyanic acid.
ConclusionHydrocyanic acid is a fascinating chemical due to its history, chemical properties, natural sources, and its role in industry and in living organisms. Its mysterious origin and complexity make us wonder what other secrets hydrogen cyanide might reveal in future scientific explorations.
