Pyrogallol

Last updated
Pyrogallol
Pyrogallol.svg
Pyrogallol-3D-balls.png
Pyrogallol powder.jpg
Names
Preferred IUPAC name
Benzene-1,2,3-triol
Other names
1,2,3-Trihydroxybenzene
Pyrogallic acid
1,2,3-Benzenetriol [1]
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.603 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 201-762-9
KEGG
PubChem CID
RTECS number
  • UX2800000
UNII
UN number 2811
  • InChI=1S/C6H6O3/c7-4-2-1-3-5(8)6(4)9/h1-3,7-9H Yes check.svgY
    Key: WQGWDDDVZFFDIG-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C6H6O3/c7-4-2-1-3-5(8)6(4)9/h1-3,7-9H
    Key: WQGWDDDVZFFDIG-UHFFFAOYAT
  • Oc1cccc(O)c1O
Properties
C6H6O3
Molar mass 126.11 g/mol
Density 1.453 g/cm3 (4 °C) [1]
Melting point 125.5 °C (257.9 °F; 398.6 K) [1]
Boiling point 307 °C (585 °F; 580 K) [1]
1.561 (134 °C) [1]
Structure [2]
Monoclinic
P21/n
a = 12.1144(11) Å, b = 3.7765(3) Å, c = 13.1365(12) Å
α = 90°, β = 115.484(1)°, γ = 90°
4
Hazards
GHS labelling:
GHS-pictogram-exclam.svg GHS-pictogram-silhouette.svg
Warning
H302, H312, H332, H341, H412
P201, P202, P261, P264, P270, P271, P273, P280, P281, P301+P312, P302+P352, P304+P312, P304+P340, P308+P313, P312, P322, P330, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Pyrogallol is an organic compound with the formula C6H3(OH)3. It is a water-soluble, white solid although samples are typically brownish because of its sensitivity toward oxygen. [3] It is one of three isomers of benzenetriols.

Contents

Production and reactions

It is produced in the manner first reported by Scheele in 1786: heating gallic acid to induce decarboxylation. [3]

Decarboxylation Gallic acid.svg

Gallic acid is also obtained from tannin. Many alternative routes have been devised. One preparation involves treating para-chlorophenoldisulfonic acid with potassium hydroxide, [4] a variant on the time-honored route to phenols from sulfonic acids. [5]

Polyhydroxybenzenes are relatively electron-rich. One manifestation is the easy C-acetylation of pyrogallol. [6]

Uses

It was once used in hair dyeing, dyeing of suturing materials. It also has antiseptic properties.

In alkaline solution, pyrogallol undergoes deprotonation. Such solutions absorb oxygen from the air, turning brown. This conversion can be used to determine the amount of oxygen in a gas sample, notably by the use of the Orsat apparatus. Alkaline solutions of pyrogallol have been used for oxygen absorption in gas analysis.

Use in photography

Pyrogallol was also used as a developing agent in the 19th and early 20th centuries in black-and-white developers. Hydroquinone is more commonly used today. Its use is largely historical except for special purpose applications. It was still used by a few notable photographers including Edward Weston. In those days it had a reputation for erratic and unreliable behavior, due possibly to its propensity for oxidation. It experienced a revival starting in the 1980s due largely to the efforts of experimenters Gordon Hutchings and John Wimberley. Hutchings spent over a decade working on pyrogallol formulas, eventually producing one he named PMK for its main ingredients: pyrogallol, Metol, and Kodalk (the trade name of Kodak for sodium metaborate). This formulation resolved the consistency issues, and Hutchings found that an interaction between the greenish stain given to film by pyro developers and the color sensitivity of modern variable-contrast photographic papers gave the effect of an extreme compensating developer. From 1969 to 1977, Wimberley experimented with the Pyrogallol developing agent. He published his formula for WD2D in 1977 in Petersen's Photographic. PMK and other modern pyro formulations are now used by many black-and-white photographers. The Film Developing Cookbook has examples. [7]

Another developer mainly based on pyrogallol was formulated by Jay DeFehr. The 510-pyro, [8] is a concentrate that uses triethanolamine as alkali, and pyrogallol, ascorbic acid, and phenidone as combined developers in a single concentrated stock solution with long shelf life . This developer has both staining and tanning properties and negatives developed with it are immune to the callier effect. It can be used for small and large negative formats.

The Darkroom Cookbook (Alternative Process Photography) has examples. [9]

Safety

Pyrogallol use, e.g. in hair dye formulations, is declining because of concerns about its toxicity. [10] Its LD50 (oral, rat) is 300 mg/kg. [3]

Pure pyrogallol was found to be extremely genotoxic when inserted into cultured cells, but α amylase proteins protect against its toxicity during everyday exposure. [11] [12]

See also

Related Research Articles

<span class="mw-page-title-main">Benzoic acid</span> Organic compound (C6H5COOH)

Benzoic acid is a white solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring with a carboxyl substituent. The benzoyl group is often abbreviated "Bz", thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.

<span class="mw-page-title-main">Phenol</span> Organic compound (C6H5OH)

Phenol is an aromatic organic compound with the molecular formula C6H5OH. It is a white crystalline solid that is volatile. The molecule consists of a phenyl group bonded to a hydroxy group. Mildly acidic, it requires careful handling because it can cause chemical burns.

<span class="mw-page-title-main">Picric acid</span> Explosive chemical compound

Picric acid is an organic compound with the formula (O2N)3C6H2OH. Its IUPAC name is 2,4,6-trinitrophenol (TNP). The name "picric" comes from Greek: πικρός (pikros), meaning "bitter", due to its bitter taste. It is one of the most acidic phenols. Like other strongly nitrated organic compounds, picric acid is an explosive, which is its primary use. It has also been used as medicine (antiseptic, burn treatments) and as a dye.

Demethylation is the chemical process resulting in the removal of a methyl group (CH3) from a molecule. A common way of demethylation is the replacement of a methyl group by a hydrogen atom, resulting in a net loss of one carbon and two hydrogen atoms.

Photographic processing or photographic development is the chemical means by which photographic film or paper is treated after photographic exposure to produce a negative or positive image. Photographic processing transforms the latent image into a visible image, makes this permanent and renders it insensitive to light.

<span class="mw-page-title-main">Gallic acid</span> 3,4,5-Trihydroxybenzoic acid

Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6H2(OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It is a white solid, although samples are typically brown owing to partial oxidation. Salts and esters of gallic acid are termed "gallates".

<span class="mw-page-title-main">Aniline</span> Organic compound (C₆H₅NH₂); simplest aromatic amine

Aniline is an organic compound with the formula C6H5NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starting material for fine chemical synthesis. Its main use is in the manufacture of precursors to polyurethane, dyes, and other industrial chemicals. Like most volatile amines, it has the odor of rotten fish. It ignites readily, burning with a smoky flame characteristic of aromatic compounds. It is toxic to humans.

<span class="mw-page-title-main">Polyphenol</span> Class of chemical compounds

Polyphenols are a large family of naturally occurring phenols. They are abundant in plants and structurally diverse. Polyphenols include phenolic acids, flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.

<span class="mw-page-title-main">Stop bath</span>

Stop bath is an acidic solution used for processing black-and-white photographic films, plates, and paper. It is used to neutralize the alkaline developer, thus halting development.

<span class="mw-page-title-main">Iron gall ink</span> Ink made from iron salts and tannic acids from vegetable sources

Iron gall ink is a purple-black or brown-black ink made from iron salts and tannic acids from vegetable sources. It was the standard ink formulation used in Europe for the 1400-year period between the 5th and 19th centuries, remained in widespread use well into the 20th century, and is still sold today.

The first isolation of deoxyribonucleic acid (DNA) was done in 1869 by Friedrich Miescher. DNA extraction is the process of isolating DNA from the cells of an organism isolated from a sample, typically a biological sample such as blood, saliva, or tissue. It involves breaking open the cells, removing proteins and other contaminants, and purifying the DNA so that it is free of other cellular components. The purified DNA can then be used for downstream applications such as PCR, sequencing, or cloning. Currently, it is a routine procedure in molecular biology or forensic analyses.

<span class="mw-page-title-main">Sulfonic acid</span> Organic compounds with the structure R−S(=O)2−OH

In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

<span class="mw-page-title-main">Catechol</span> Organic compound (C6H4(OH)2); benzene with two adjacent –OH groups

Catechol, also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula C6H4(OH)2. It is the ortho isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It was first discovered by destructive distillation of the plant extract catechin. About 20,000 tonnes of catechol are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances. Small amounts of catechol occur in fruits and vegetables.

<span class="mw-page-title-main">Phloroglucinol</span> Chemical compound

Phloroglucinol is an organic compound with the formula C6H3(OH)3. It is a colorless solid. It is used in the synthesis of pharmaceuticals and explosives. Phloroglucinol is one of three isomeric benzenetriols. The other two isomers are hydroxyquinol (1,2,4-benzenetriol) and pyrogallol (1,2,3-benzenetriol). Phloroglucinol, and its benzenetriol isomers, are still defined as "phenols" according to the IUPAC official nomenclature rules of chemical compounds. Many such monophenolics are often termed polyphenols.

<span class="mw-page-title-main">Dakin oxidation</span> Organic redox reaction that converts hydroxyphenyl aldehydes or ketones into benzenediols

The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H2O2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H2O2 is reduced.

<span class="mw-page-title-main">Bromocresol purple</span> Chemical compound

Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a dye of the triphenylmethane family and a pH indicator. It is colored yellow below pH 5.2, and violet above pH 6.8. In its cyclic sulfonate ester form, it has a pKa value of 6.3, and is usually prepared as a 0.04% aqueous solution.

<span class="mw-page-title-main">Thermal paper</span> Adding machine, cash register and credit card terminal paper

Thermal paper is a special fine paper that is coated with a material formulated to change color locally when exposed to heat. It is used in thermal printers, particularly in inexpensive devices such as adding machines, cash registers, and credit card terminals and small, lightweight portable printers.

The enzyme gallate decarboxylase (EC 4.1.1.59) catalyzes the chemical reaction

<span class="mw-page-title-main">1,2,3,5-Tetrahydroxybenzene</span> Chemical compound

1,2,3,5-Tetrahydroxybenzene is a benzenetetrol.

Bill Troop is the principal author of "The Film Developing Cookbook", in print continuously since 1998, and widely considered to be the standard contemporary work on black and white film processing and chemistry. An expanded 2nd edition was published in November 2019 and a French translation was published in 2021.

References

  1. 1 2 3 4 5 Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. p. 3.38. ISBN   9781498754293.
  2. ↑ Thakuria, Ranjit; Cherukuvada, Suryanarayan; Nangia, Ashwini (2012). "Crystal Structures of Pyrogallol, Its Hydrate, and Stable Multiple Z ′ Cocrystals with N-Heterocycles Containing Metastable Conformers of Pyrogallol". Crystal Growth & Design. 12 (8): 3944–3953. doi:10.1021/cg3003367.
  3. 1 2 3 Fiege, Helmut; Heinz-Werner, Voges; Hamamoto, Toshikazu; Umemura, Sumio; Iwata, Tadao; Miki, Hisaya; Fujita, Yasuhiro; Buysch, Hans-Josef; Garbe, Dorothea; Paulus, Wilfried (2014). "Phenol Derivatives". Ullmann's Encyclopedia of Industrial Chemistry (7th ed.). Weinheim: Wiley-VCH. p. 1072. doi:10.1002/14356007.a19_313. ISBN   978-3527306732.
  4. ↑ Buzbee, Lloyd R. (1966-10-01). "Rearranged Products from the Reaction of Benzenesulfonic Acids with Caustic". The Journal of Organic Chemistry. 31 (10): 3289–3292. doi:10.1021/jo01348a042. ISSN   0022-3263.
  5. ↑ Magro, Angel A. Núñez; Eastham, Graham R.; Cole-Hamilton, David J. (2009-06-10). "Preparation of Phenolic Compounds by Decarboxylation of Hydroxybenzoic Acids or Desulfonation of Hydroxybenzenesulfonic Acid, Catalysed by Electron Rich Palladium Complexes". Dalton Transactions (24): 4683–8. doi:10.1039/B900398C. ISSN   1477-9234. PMID   19513476.
  6. ↑ Badhwar, I. C.; Venkataraman, K. (1934). "Gallacetophenone". Organic Syntheses. 14: 40. doi:10.15227/orgsyn.014.0040.
  7. ↑ Anchell, Stephen G.; Troop, Bill (1998). The Film Developing Cookbook. ISBN   978-0240802770.
  8. ↑ "510-PYRO". 510-PYRO.
  9. ↑ Anchell, Stephen G. (2016). The darkroom cookbook (Fourth ed.). New York: Routledge. ISBN   9781138959187. OCLC   938707611.
  10. ↑ "Safety data for 1,2,3-trihydroxybenzene". Archived from the original on 2009-02-28. Retrieved 2009-03-05.
  11. ↑ "Cancer Biologists Find DNA-Damaging Toxins in Common Plant-Based Foods". Johns Hopkins Medicine (Press release). Retrieved 11 February 2024.
  12. ↑ Hossain, M. Zulfiquer; Patel, Kalpesh; Kern, Scott E. (Aug 2014). "Salivary α-amylase, serum albumin, and myoglobin protect against DNA-damaging activities of ingested dietary agents in vitro". Food and Chemical Toxicology. 70: 114–119. doi:10.1016/j.fct.2014.05.002. PMC   4095877 . PMID   24842839, summarized in Wasta, Vanessa (30 May 2014). "Compounds in Saliva and Common Body Proteins May Fend Off DNA-Damaging Chemicals in Tea, Coffee and Liquid Smoke" (Press release). Johns Hopkins Medicine. Archived from the original on 27 Feb 2024. Retrieved 11 February 2024.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.