Phloroglucinol

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Phloroglucinol
Names
IUPAC name
Benzene-1,3,5-triol
Other names
1,3,5-Benzenetriol
1,3,5-Trihydroxybenzene
Cyclohexane-1,3,5-trione
Phloroglucine
Properties
C6H6O3
C6H3(OH)3
Molar mass 126.11 g/mol
Appearance Colorless solid
Odor Aromatic
Density 1.5 g/cm3
Melting point 219 °C (426 °F; 492 K)
Boiling point Sublimes
1.06 g/100 ml (20 °C)
Solubility Miscible with acetone, diethyl ether, ethanol, isopropanol, methanol, pyridine
Hazards
Safety data sheet Sigma-Aldrich
Lethal dose or concentration (LD, LC):
5000 mg/kg (rat, oral)
Related compounds
Related compounds
Phenol
Resorcinol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Phloroglucinol is an organic compound with the formula C6H3(OH)3.

Phloroglucinol is one of three isomeric benzenetriols. The other two isomers are hydroxyquinol (1,2,4-benzenetriol) and pyrogallol (1,2,3-benzenetriol).

Properties

Chemical

Phloroglucinol is a weak triprotic acid. The first two pKa's are 8.5 and 8.9.

As an enol, phloroglucinol in principle exists in equilibrium with keto tautomers. Evidence for this equilibrium is provided by the formation of the oxime:

C6H3(OH)3 + 3 NH2OH → (CH2)3(C=NOH)3 + 3 H2O

But it behaves also like a benzenetriol as the three hydroxyl groups can be methylated to give 1,3,5-trimethoxybenzene.

Physical

Phloroglucinol is a colorless solid, though air oxidation will give it a beige tint, which is soluble in water, alcohols and ether.

From water, phloroglucinol crystallizes as the dihydrate, which has a melting point of 116–117 °C, but the anhydrous form melts at a much higher temperature, at 218–220 °C. It does not boil intact, but it does sublime.

Availability

Phloroglucinol is sold by chemical suppliers.

Preparation

A complex but good purity route involves nitrating benzene to trinitrobenzene, which is reduced to triaminobenzene, then treated with an alkaline hydroxide to yield phlorogluciol. This latter reaction is noteworthy, because ordinary aniline derivatives are usually unreactive toward hydroxide.

Can be obtained from phloretin.

Projects

  • Reagent in the Tollens' test for pentoses
  • Wiesner test for the detection of lignin
  • Gunzberg's test for the qualitative detection of free hydrochloric acid in gastric juice
  • Synthesis of trinitrophloroglucinol
  • Preparation of TATB
  • Synthesis of leptospermone

Handling

Safety

Phloroglucinol is irritant and exposure to large amounts may be harmful.

Phloroglucinol is used as a treatment for gallstones, spasmodic pain and other related gastrointestinal disorders.

Storage

In closed airtight bottles.

Disposal

Can be neutralized with a solution of Fenton's reagent.

References

Relevant Sciencemadness threads