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Column 技術屋の解説

Column 技術屋の解説

2021.05.15

「No.5」Let us talk about the Odors of Iron

The odors of iron, that people think, is not iron compounds. It is smell of organic substances such as “Oct-1-en-3-one”, “Methylphosphine” and “Dimethylphosphine” etc.

Definition:

“Organic substance” is a substance composed mainly of carbon, hydrogen, and oxygen. Carbon dioxide is generated when burned.

“Inorganic substance” is a substance composed mainly of metal elements. There is almost no carbon dioxide even if burned.

The melting (liquefaction) point of iron is about 1540°C, and the boiling (vaporization) point is about 2860°C. In the past, there have been serious accidents (fatal accidents etc.) to people by the blast furnaces. Iron does not vaporize unless it becomes hotter than the temperature of the blast furnace.

Because the smell is felt when the substance adheres to the nasal olfactory receptor (odor sensor). So, it is dangerous if such a high-temperature substance is entered to the nose. Sometimes people say that rusty iron is gradually decreasing. It seems to be thought that it is “decreasing = vaporizing”, but this is “weathering”. It is not vaporizing, because the substance (metal) is just showing a phenomenon that is broken into pieces by oxidation etc.

Iron and iron compounds are vaporized only at high-temperature like boiling point and are not vaporized at room temperature. So what substances are vaporizing and adhering to the nasal odor sensor? It is the sebum dirt of the person and the dirt (organic substances), which drifts in the air, and adhere to iron surface. Then some chemical reactions occur, and three substances above mentioned are generated. By vaporizing these substances and adhering them to the nasal odor sensor, it is felt as a smell. This is generally said as “the odors of iron”.

Reference:

Museum of Organic Chemistry and its Branch of “The true identity of the Iron Odor”

http://blog.livedoor.jp/route408/archives/50674724.html

Museum of Organic Chemistry and its Branch of “Compound of blood smell”

http://blog.livedoor.jp/route408/archives/52263811.html

“The Two Odors of Iron when Touched or Pickled: (Skin) Carbonyl Compounds and Organophosphines”

Dietmar Glindemann Dr., Andrea Dietrich Prof. Dr. , Hans‐Joachim Staerk Dr. , Peter Kuschk Dr.

Volume45, Issue42, Oct. 27, 2006, Pages 7006-7009

https://onlinelibrary.wiley.com/doi/10.1002/anie.200602100

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