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Tin is not commonly used in pharmacy and is usually rarely found in medicines. It is used primarily in alternative medicine in various dosage forms, for example in homeopathy and anthroposophic medicine. This usually under the name Stannum or Stannum metallicum (metallic tin). Also known is the tin ointment (Stannum metallicum unguentum). Tin should not be confused with zinc.
Structure and properties
Tin (Sn) is a chemical element with atomic number 50. It exists as a soft, silvery heavy metal with a comparatively low melting point of about 232 °C. It is easy to machine, form and cast. When tin is bent, a peculiar crunching sound is heard, the so-called tin cry. Tin is contained in bronze together with copper. It is obtained mainly from the mineral cassiterite, which contains tin dioxide (SnO2). Tin reacts with acids and bases, in which it is soluble. The reaction with hydrochloric acid is shown below:
- Sn (tin) + 2 HCl (hydrochloric acid) SnCl2 (tin chloride) + H2 (hydrogen)
The oxidation number is usually +2 or +4. Tin(II) chloride dihydrate (Stannosi chloridum dihydricum, SnCl2 – 2 H2O) is monographed in the pharmacopoeia. It exists as a white crystalline powder and is readily soluble in water. When exposed to air, it weathers. A thinly rolled tin foil is called tinfoil. Today, aluminum is usually used for this purpose. Tinsel is made of tin foil.
Fields of application
- In alternative medicine, for example, tin is used for inflammatory and degenerative diseases, liver disease, lung disease, depressive moods, fatigue and exhaustion.
- In dentistry.
- As a preservative for selected foods (stannous chloride for asparagus, E 512).
