Atropine

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Atropine
Names
IUPAC name
(RS)-(8-Methyl-8-azabicyclo[3.2.1]oct-3-yl) 3-hydroxy-2-phenylpropanoate
Other names
3-Hydroxy-2-phenyl-propionic acid tropan-3-yl ester
DL-Hyoscyamine
Tropine tropate
Properties
C17H23NO3
Molar mass 289.375 g/mol
Appearance Colorless crystalline solid
Odor Odorless
Density 1.205 g/cm3[1]
Melting point 118.5 °C (245.3 °F; 391.6 K)
Boiling point 83–88 °C (181–190 °F; 356–361 K) (sublimation at 0.02 mmHg)[2]
0.22 mg/100 ml (at 25 °C)
Solubility Reacts with strong acids and strong bases
Very soluble in acetone, DMSO, ethanol
Slightly soluble in benzene, carbon tetrachloride, chloroform, dichloromethane
Practically insoluble in diethyl ether, diisopropyl ether, pyridine
Solubility in benzene 0.9214 g/ 100 ml (15 °C)[3]
Solubility in benzonitrile 3.91 g/100 ml (25 °C)[4]
Solubility in chloroform 6.756 g/100 ml (25 °C)[5]
Solubility in dichloromethane 6.523 g/100 ml (25 °C)[5]
Solubility in diethyl ether 0.563 g/100 ml (25 °C)[5]
Vapor pressure ~0 mmHg
Acidity (pKa) 9.84
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
750 mg/kg (rat, oral)
Related compounds
Related compounds
 Scopolamine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Atropine is a tropane alkaloid, used in medicine as anticholinergic medication and in ophthalmology to dilate pupils for medical exams, as well as treatment of uveitis and early amblyopia. Atropine is commonly encountered as an enantiomeric mixture of d-hyoscyamine and l-hyoscyamine, the latter being responsible for most of its physiological effects.

Properties

Chemical

Atropine reacts with acids to form water soluble salts. Atropine sulfate is commonly encountered.

Strong acids will hydrolyze atropine to tropane and tropic acid.

Physical

Atropine is a colorless crystalline solid, insoluble in water but soluble in organic solvents, like ethanol (50 g/100 ml). Its melting point is given as either 118.5 °C[8] (the most recent value) or between 114-116 °C[9] (older literature), with one source indicating an even lower value of 105.85 °C.[10]

Availability

Atropine is found in many members of the family Solanaceae. The most commonly found source is the deadly nightshade (Atropa belladonna), which is often an unwanted weed can grow free on fields, gardens or in some places even on the sidewalks. Other sources of atropine are the Datura family plant, like Datura innoxia[11], D. wrightii, D. metel[12], and D. stramonium[13], as well as other plants like Hyoscyamus niger[14], H. desertorum[15], Solandra grandiflora[16], etc. Seeds of such plants can be bought from plant stores, online or sometimes found growing near fences, as the plant is known to be invasive if left to grow unchecked. All these plants contain a mixture of the tropane alkaloids, namely atropine, scopolamine, and hyoscyamine, and thus purification is required to separate atropine.[17] A video showing and (attempted) extraction of Datura alkaloids can be found here.

Atropine can be extracted from old atropine medicine, though this may not be easy to acquire, as atropine is only available as prescription medicine. Also, such solutions are often very diluted (usually around 0.5 %), so a large amount if atropine medicine is required to obtain any practical amounts of the stuff.

Lastly, pure atropine can be bought from chemical suppliers, though its availability to private individuals varies from country. Make sure to check your local laws before working with this compound.

Preparation

Atropine can be synthesized by the reaction of tropine with tropic acid in the presence of hydrochloric acid.[18][19][20][21]

A similar route involves the reaction of tropine sulfate with tropic acid, in isopropanol.[22]

As tropine is hard to come by, total synthesis of atropine is expensive compared to its extraction and purification from natural sources.

Projects

  • Anticholinergic medication for heart
  • Antidote to cholinesterase inhibitors
  • Compound collecting
  • Make tropine

Handling

Safety

Atropine is toxic if ingested, injected or inhaled. Common side effects include dry mouth, abnormally large pupils, urinary retention, constipation, and a fast heart rate.

In the eye, atropine induces mydriasis (pupil dilation) by blocking contraction of the circular pupillary sphincter muscle, which is normally stimulated by acetylcholine release, thereby allowing the radial iris dilator muscle to contract and dilate the pupil.

Physostigmine, usually as physostigmine salicylate, can be used as antidote in case of atropine poisoning, and it's given via injection.

Storage

Should be kept in glass ampoules, away from light.

Disposal

Can be hydrolyzed to tropine and tropic acid, which are less toxic and safer to discard.

References

  1. ↑ Vafai; Drake; Smith Jr.; Journal of Chemical and Engineering Data; vol. 38; nb. 1; (1993); p. 125 - 127
  2. ↑ Janot; Chaigneau; Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences; vol. 225; (1947); p. 1371
  3. ↑ Goris; Costy; Bulletin des Sciences Pharmacologiques; vol. 29; p. 118; Chem. Zentralbl.; vol. 93; nb. III; (1922); p. 268
  4. ↑ Namor, Angela F. Danil de; Pardo, Maria T. Garrido; Tanaka, David A. Pacheco; Velarde, Felix J. Sueros; Garcia, Jaime D. Cardenas; et al.; Journal of the Chemical Society, Faraday Transactions; vol. 89; nb. 15; (1993); p. 2727 - 2736
  5. ↑ 5.0 5.1 5.2 5.3 Jacobs; Jenkins; Journal of the American Pharmaceutical Association (1912-1977); vol. 26; (1937); p. 599,607
  6. ↑ Patent; XERIS PHARMACEUTICALS, INC.; PRESTRELSKI, Steven, J.; SCOTT, Nancy; WO2014/4895; (2014); (A1) English
  7. ↑ Patent; XERIS PHARMACEUTICALS, INC.; PRESTRELSKI, Steven, J.; SCOTT, Nancy; WO2014/4895; (2014); (A1) English
  8. ↑ Lide, DR (ed.). CRC Handbook of Chemistry and Physics. 81st Edition. CRC Press LLC, Boca Raton: FL 2000, p. 3-27
  9. ↑ Guillory; Hwang; Lach; Journal of pharmaceutical sciences; vol. 58; nb. 3; (1969); p. 301 - 308
  10. ↑ Fukuoka; Makita; Yamamura; Chemical and Pharmaceutical Bulletin; vol. 37; nb. 4; (1989); p. 1047 - 1050
  11. ↑ Kibler; Neumann; Planta Medica; vol. 35; (1979); p. 354,355
  12. ↑ Paris; Cosson; Comptes Rendus Hebdomadaires des Seances de l'Academie des Sciences; vol. 260; (1965); p. 3148
  13. ↑ Moza et al.; Indian Journal of Chemistry; vol. 7; (1969); p. 414
  14. ↑ Sharova et al.; Chemistry of Natural Compounds; vol. 13; (1977); p. 117,118; Khimiya Prirodnykh Soedinenii; vol. 13; (1977); p. 126
  15. ↑ Sabri et al.; Planta Medica; vol. 23; (1973); p. 4-9
  16. ↑ Evans et al.; Phytochemistry (Elsevier); vol. 11; (1972); p. 470
  17. ↑ Chemnitius, J. Prakt. Chem. 116, 276 (1927)
  18. ↑ Ladenburg; Justus Liebigs Annalen der Chemie; vol. 217; (1883); p. 77; Chemische Berichte; vol. 12; (1879); p. 948
  19. ↑ Ladenburg; Chemische Berichte; vol. 12; (1879); p. 944; Justus Liebigs Annalen der Chemie; vol. 217; nb. 117; (1883); p. 118
  20. ↑ Liebermann; Limpach; Chemische Berichte; vol. 25; (1892); p. 929
  21. ↑ Amenomiya; Archiv der Pharmazie (Weinheim, Germany); vol. 240; (1902); p. 501
  22. ↑ Burtner; Cusic; Journal of the American Chemical Society; vol. 65; (1943); p. 262 - 263

Relevant Sciencemadness threads

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