Amygdalin

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Amygdalin
Names
IUPAC name
(2R)-[β-D-Glucopyranosyl-(1→6)-β-D-glucopyranosyloxy]phenylacetonitrile
Systematic IUPAC name
(2R)-Phenyl{[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-({[(2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}methyl)oxan-2-yl]oxy}acetonitrile
Other names
Amygdaloside
D-Mandelonitrile-β-gentiobioside
D-Mandelonitrile 6-O-β-D-glucosido-β-D-glucoside
Properties
C20H27NO11
Molar mass 457.429 g/mol
Appearance Colorless rhombic crystals
Odor Odorless (pure)
Almond-like (impure)
Melting point 223–226 °C (433–439 °F; 496–499 K)
Boiling point Decomposes
8.3 g/100 ml (10 °C)[1]
Solubility Reacts with acids, bases
Poorly soluble in cold ethanol, methanol
Insoluble in ethers, halocarbons, hydrocarbons
Solubility in chloroform 0.029 g/100 g (15 °C)[2]
Solubility in ethanol 0.14 g/100 g (10 °C)
11.4 g/100 g (78 °C)
Vapor pressure ~0 mmHg
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
522 mg/kg (rat, oral)
443 mg/kg (mice, oral)
Related compounds
Related compounds
Benzaldehyde
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Amygdalin (from Ancient Greek: ἀμυγδαλή amygdalē 'almond') is a naturally occurring chemical compound found in many plants, most notably in the seeds (kernels) of apricots, bitter almonds, apples[3], peaches, cherries and plums, and in the roots of manioc.

Natural amygdalin has the (R)-configuration at the chiral phenyl center. Under mild basic conditions, this stereogenic center isomerizes; the (S)-epimer is called neoamygdalin.

Properties

Chemical

Amygdalin is classified as a cyanogenic glycoside, because each amygdalin molecule includes a nitrile group, which can be released as the toxic cyanide anion by the action of a beta-glucosidase.

Strong acids will also cleave the molecule, releasing hydrogen cyanide in air. Sulfuric acid decomposes it into d-glucose, benzaldehyde and hydrogen cyanide, while hydrochloric acid gives mandelic acid, d-glucose and ammonia.[4]

Hydrolysis of amygdalin will yield laetrile.

Physical

Amygdalin is a colorless crystalline solid, soluble in water, but mostly insoluble in organic solvents, except for hot ethanol.

Availability

Amygdalin can be found in the seeds (kernels) of apricots[5], bitter almonds[6], apples[7], peaches, cherries and plums[8], and in the roots of manioc.

Amygdalin is usually extracted by finely grinding the seed kernels, then the paste is soaked in water, and the resulting mixture is either stirred or u in an ultrasonic bath. A solvent extraction may be done before water is added, to remove any oils or other non-polar compounds, as amygdalin is almost insoluble in most organic solvents used for extractions, like chloroform, dichloromethane, ethyl acetate, hexane, toluene.

An alternative way, which was how amygdalin was first discovered, is by boiling the kernels in hot ethanol. After the alcohol is removed, diethyl ether is added, which causes amygdalin to precipitate. Further recrystallization can be used to increase the purity.[4][9]

Preparation

Although amygdalin can be produced synthetically, it's quite expensive to do so, and thus it's cheaper to extract it from plants.

Projects

  • Compound collecting
  • Make cyanides
  • Make benzaldehyde

Handling

Safety

Amygdalin is highly toxic, due to its ability to release hydrogen cyanide during its breakdown.

Amygdalin, as well as laetrile (also called "vitamin B17", even though it is not a true vitamin by any definition), its derivative, is sometimes used in alternative (aka quackery) medicine, as a "natural" treatment for cancer, however, all studies one so far show that it is completely ineffective in treating cancer as well as any other medical conditions. As a consequence of its toxicity, consuming this product is a very bad idea.

Storage

Should be kept in closed bottles.

Disposal

Can be safely neutralized with bleach and poured down the drain or in the ground.

References

  1. Chemist's Handbook. - T. 2. - L.-M.: Chemistry, 1964 (Справочник химика. - Т. 2. - Л.-М.: Химия, 1964)
  2. Solubility Handbook. - T.1, Book.2. - M.-L.: IAN USSR, 1962(Справочник по растворимости. - Т.1, Кн.2. - М.-Л.: ИАН СССР, 1962)
  3. https://www.sciencedirect.com/science/article/abs/pii/S0308814614013077
  4. 4.0 4.1 Jaime Wisniak; Pierre-Jean Robiquet; Educación Química, Volume 24, Supplement 1, March 2013, Pages 139-149
  5. Godtfredsen et al.; Acta chemica Scandinavica. Series B: Organic chemistry and biochemistry; vol. 32; (1978); p. 588,590
  6. Bolarinwa, I., Orfila, C., and Morgan, M. (2014). Amygdalin content of seeds, kernels and food products commercially available in the UK. Food Chem 152(1):133-139.
  7. https://www.redalyc.org/journal/1699/169959152001/html/
  8. https://www.frontiersin.org/articles/10.3389/fpls.2015.00276/full
  9. 1911 Encyclopædia Britannica/Amygdalin

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