4-Hydroxybenzoic acid

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4-Hydroxybenzoic acid
Skeletal formula Ball-and-stick model
Identifiers
CAS number 99-96-7 YesY
PubChem 135
ChemSpider 132 YesY
EC number 202-804-9
DrugBank DB04242
KEGG C00156 YesY
ChEBI CHEBI:30763 YesY
ChEMBL CHEMBL441343 YesY
Jmol-3D images Image 1
Image 2
Properties
Molecular formula C7H6O3
Molar mass 138.121 g/mol
Appearance white crystalline
Odor odorless
Density 1.46 g/cm³
Melting point 214.5 °C (418.1 °F; 487.6 K)
Solubility in water 0.5 g/100 mL
Solubility soluble in alcohol, ether, acetone
slightly soluble in chloroform
negligible in CS2
log P 1.58
Acidity (pKa) 4.54
Hazards
MSDS HMDB
Main hazards Irritant
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
LD50 2200 mg/kg (oral, mouse)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

4-Hydroxybenzoic acid is a monohydroxybenzoic acid, a phenolic derivative of benzoic acid. It is a white crystalline solid that is slightly soluble in water and chloroform but more soluble in polar organic solvents such as alcohols and acetone. 4-Hydroxybenzoic acid is primarily known as the basis for the preparation of its esters, known as parabens, which are used as preservatives in cosmetics and some ophthalmic solutions. It is isomeric with 2-hydroxybenzoic acid, known as salicylic acid, a precursor to aspirin.

Natural occurrences[edit]

It is found in plants of the genus Vitex such as V. agnus-castus or V. negundo, and in Hypericum perforatum (St John's wort). It is also found in Spongiochloris spongiosa, a freshwater green alga.

The compound is also found in Ganoderma lucidum, a medicinal mushroom with the longest record of use.

Cryptanaerobacter phenolicus is a bacterium species that produces benzoate from phenol via 4-hydroxybenzoate.[1]

Occurrences in food[edit]

4-Hydroxybenzoic acid can be found naturally in Cocos nucifera.[2] It is one of the main catechins metabolites found in humans after consumption of green tea infusions.[3] It is also found in wine,[4] in vanilla, in Macrotyloma uniflorum (horse gram) and in Phyllanthus acidus (Otaheite gooseberry).

Açaí oil, obtained from the fruit of the açaí palm (Euterpe oleracea), is rich in p-hydroxybenzoic acid (892 ± 52 mg/kg).[5] It is also found in cloudy olive oil.

It is also found in the edible mushroom Russula virescens (green-cracking russula).

Related compounds[edit]

p-Hydroxybenzoic acid glucoside can be found in mycorrhizal and non-mycorrhizal roots of Norway spruces (Picea abies).[6]

Violdelphin is an anthocyanin, a type of plant pigments, found in blue flowers and incorporating two p-hydroxy benzoic acid residues, one rutinoside and two glucosides associated with a delphinidin.

Agnuside is the ester of aucubin and p-hydroxybenzoic acid.[7]

Metabolism[edit]

Biosynthesis[edit]

Chorismate lyase is an enzyme that transforms chorismate into 4-hydroxybenzoate and pyruvate. This enzyme catalyses the first step in ubiquinone biosynthesis in Escherichia coli and other Gram-negative bacteria.

Benzoate 4-monooxygenase is an enzyme that utilizes benzoate, NADPH, H+ and O2 to produce 4-hydroxybenzoate, NADP+ and H2O. This enzyme can be found in Aspergillus niger.

As an intermediate[edit]

The enzyme 4-methoxybenzoate monooxygenase (O-demethylating) transforms 4-methoxybenzoate, an electron acceptor AH2 and O2 into 4-hydroxybenzoate, formaldehyde, the reduction product A and H2O. This enzyme participates in 2,4-dichlorobenzoate degradation in Pseudomonas putida.

The enzyme 4-hydroxybenzaldehyde dehydrogenase uses 4-hydroxybenzaldehyde, NAD+ and H2O to produce 4-hydroxybenzoate, NADH and H+. This enzyme participates in toluene and xylene degradation in bacteria such as Pseudomonas mendocina. It is also found in carrots (Daucus carota).

The enzyme that 2,4'-dihydroxyacetophenone dioxygenase transforms 2,4'-dihydroxyacetophenone and O2 into 4-hydroxybenzoate and formate. This enzyme participates in bisphenol A degradation. It can be found in Alcaligenes sp.

The enzyme 4-chlorobenzoate dehalogenase uses 4-chlorobenzoate and H2O to produce 4-hydroxybenzoate and chloride. It can be found in pseudomonas sp.

The enzyme 4-hydroxybenzoyl-CoA thioesterase utilizes 4-hydroxybenzoyl-CoA and H2O to produce 4-hydroxybenzoate and CoA. This enzyme participates in 2,4-dichlorobenzoate degradation. It can be found in Pseudomonas sp.

The enzyme 4-hydroxybenzoate nonaprenyltransferase uses nonaisoprenol diphosphate and 4-hydroxybenzoate to produce diphosphate and nonaprenyl-4-hydroxybenzoate. This enzyme participates in ubiquinone biosynthesis.

The enzyme 4-hydroxybenzoate geranyltransferase utilizes geranyl diphosphate and 4-hydroxybenzoate to produce 3-geranyl-4-hydroxybenzoate and diphosphate. Biosynthetically, alkannin is produced in plants from the intermediates 4-hydroxybenzoic acid and geranyl pyrophosphate. This enzyme is involved in shikonin biosynthesis. It can be found in Lithospermum erythrorhizon.

The enzyme 3-hydroxybenzoate—CoA ligase uses ATP, 3-hydroxybenzoate and CoA to produce AMP, diphosphate and 3-hydroxybenzoyl-CoA. The enzyme works equally well with 4-hydroxybenzoate. It can be found in Thauera aromatica.

Biodegradation[edit]

The enzyme 4-hydroxybenzoate 1-hydroxylase transforms 4-hydroxybenzoate, NAD(P)H, 2 H+ and O2 into hydroquinone, NAD(P)+, H2O and CO2. This enzyme participates in 2,4-dichlorobenzoate degradation. It can be found in Candida parapsilosis.

The enzyme 4-hydroxybenzoate 3-monooxygenase transforms 4-hydroxybenzoate, NADPH, H+ and O2 into protocatechuate, NADP+ and H2O. This enzyme participates in benzoate degradation via hydroxylation and 2,4-dichlorobenzoate degradation. It can be found in Pseudomonas putida and Pseudomonas fluorescens.

The enzyme 4-hydroxybenzoate 3-monooxygenase (NAD(P)H) utilizes 4-hydroxybenzoate, NADH, NADPH, H+ and O2 to produce 3,4-dihydroxybenzoate (protocatechuic acid), NAD+, NADP+ and H2O. This enzyme participates in benzoate degradation via hydroxylation and 2,4-dichlorobenzoate degradation. It can be found in Corynebacterium cyclohexanicum and in Pseudomonas sp.

The enzyme 4-hydroxybenzoate decarboxylase uses 4-hydroxybenzoate to produce phenol and CO2. This enzyme participates in benzoate degradation via coa ligation. It can be found in Klebsiella aerogenes (Aerobacter aerogenes).

The enzyme 4-hydroxybenzoate—CoA ligase transforms ATP, 4-hydroxybenzoate and CoA to produce AMP, diphosphate and 4-hydroxybenzoyl-CoA. This enzyme participates in benzoate degradation via coa ligation. It can be found in Rhodopseudomonas palustris.

Lecythophora hoffmannii is a plant pathogen that commonly inhabits fertile soil. It is known to metabolize aromatic compounds of low molecular weight, such as p-hydroxybenzoic acid.

Glycosylation[edit]

The enzyme 4-hydroxybenzoate 4-O-beta-D-glucosyltransferase transforms UDP-glucose and 4-hydroxybenzoate into UDP and 4-(beta-D-glucosyloxy)benzoate. It can be found in the pollen of Pinus densiflora.

Chemistry[edit]

The Hammett equation describes a linear free-energy relationship relating reaction rates and equilibrium constants for many reactions involving benzoic acid derivatives with meta- and para-substituents.

Chemical production[edit]

4-Hydroxybenzoic acid is produced commercially from potassium phenoxide and carbon dioxide in the Kolbe-Schmitt reaction.[8] It can also be produced in the laboratory by heating potassium salicylate with potassium carbonate to 240 °C, followed by treating with acid.[9]

Chemical reactions[edit]

4-Hydroxybenzoic acid has about one tenth the acidity of benzoic acid, having an acid dissociation constant Ka = 3.3 x 10−5 M at 19 °C.[citation needed] Its acid dissociation follows this equation:

HOC6H4CO2H \overrightarrow{\leftarrow} HOC6H4CO2 + H+

Chemical use[edit]

Vectran is a manufactured fiber, spun from a liquid crystal polymer. Chemically it is an aromatic polyester produced by the polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid.

4,4'-Dihydroxybenzophenone is generally prepared by the rearrangement of p-hydroxyphenylbenzoate. Alternatively, p-hydroxybenzoic acid can be converted to p-acetoxybenzoyl chloride. This acid chloride reacts with phenol to give, after deacetylation, 4,4'-dihydroxybenzophenone.

Safety[edit]

4-Hydroxybenzoic acid is a popular antioxidant in part because of its low toxicity. The LD50 is 2200 mg/kg in mice (oral).[10]

See also[edit]

References[edit]

  1. ^ Cryptanaerobacter phenolicus gen. nov., sp. nov., an anaerobe that transforms phenol into benzoate via 4-hydroxybenzoate. Pierre Juteau, Valérie Côté, Marie-France Duckett, Réjean Beaudet, François Lépine, Richard Villemur and Jean-Guy Bisaillon, IJSEM, January 2005, vol. 55, no. 1, pages 245-250, doi:10.1099/ijs.0.02914-0
  2. ^ Profiling C6–C3 and C6–C1 phenolic metabolites in Cocos nucifera. Gargi Dey, Moumita Chakraborty and Adinpunya Mitra, Journal of Plant Physiology, Volume 162, Issue 4, 22 April 2005, Pages 375-381 doi:10.1016/j.jplph.2004.08.006
  3. ^ Catechin metabolites after intake of green tea infusions. P. G. Pietta, P. Simonetti, C. Gardana, A. Brusamolino, P. Morazzoni and E. Bombardelli, BioFactors, 1998, Volume 8, Issue 1-2, pp. 111–118, doi:10.1002/biof.5520080119
  4. ^ Comparison of Phenolic Acids and Flavan-3-ols During Wine Fermentation of Grapes with Different Harvest Times. Rong-Rong Tian, Qiu-Hong Pan, Ji-Cheng Zhan, Jing-Ming Li, Si-Bao Wan, Qing-Hua Zhang and Wei-Dong Huang, Molecules, 2009, 14, pages 827-838, doi:10.3390/molecules14020827
  5. ^ Pacheco-Palencia LA, Mertens-Talcott S, Talcott ST (Jun 2008). "Chemical composition, antioxidant properties, and thermal stability of a phytochemical enriched oil from Acai (Euterpe oleracea Mart.)". J Agric Food Chem 56 (12): 4631–6. doi:10.1021/jf800161u. PMID 18522407. 
  6. ^ Phenolics of mycorrhizas and non-mycorrhizal roots of Norway spruce. Babette Münzenberger, Jürgen Heilemann, Dieter Strack, Ingrid Kottke and Franz Oberwinkler, Planta, Volume 182, Number 1, pages 142-148, doi:10.1007/BF00239996
  7. ^ Eva Hoberg, Beat Meier and Otto Sticher (September–October 2000). "An analytical high performance liquid chromatographic method for the determination of agnuside and p-hydroxybenzoic acid contents in Agni-casti fructose". Phytochemical Analysis 11 (5): 327–329. doi:10.1002/1099-1565(200009/10)11:5<327::AID-PCA523>3.0.CO;2-0. 
  8. ^ Edwin Ritzer and Rudolf Sundermann “Hydroxycarboxylic Acids, Aromatic” in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi: 10.1002/14356007.a13_519
  9. ^ C. A. Buehler and W. E. Cate (1943), "p-Hydroxybenzoic acid", Org. Synth. ; Coll. Vol. 2: 341 
  10. ^ Lewis, R.J. Sax (1996). Dangerous Properties of Industrial Materials 1–3 (9th ed.). New York, NY: Van Nostrand Reinhold. p. 2897. 

External links[edit]

4-Hydroxybenzoic acid at Phenol-Explorer.eu