Benzoic acid

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Benzoic acid
Skeletal formula
Skeletal formula
Ball-and-stick model
Ball-and-stick model
Names
Preferred IUPAC name
Benzoic acid[1]
Systematic IUPAC name
Benzenecarboxylic acid
Other names
  • Carboxybenzene
  • E210
  • Dracylic acid
  • Phenylmethanoic acid
  • Phenylcarboxylic acid
  • Benzoyl alcohol
  • Benzoylic acid
  • Carboxylbenzene
  • Hydrogenphenic acid
  • Phenoic acid
Identifiers
3D model (
JSmol
)
3DMet
636131
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard
 100.000.562 Edit this at Wikidata
EC Number
  • 200-618-2
E number E210 (preservatives)
2946
KEGG
MeSH benzoic+acid
RTECS number
  • DG0875000
UNII
  • InChI=1S/C7H6O2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9) checkY
    Key: WPYMKLBDIGXBTP-UHFFFAOYSA-N checkY
  • InChI=1/C7H6O2/c8-7(9)6-4-2-1-3-5-6/h1-5H,(H,8,9)
    Key: WPYMKLBDIGXBTP-UHFFFAOYAD
  • O=C(O)c1ccccc1
Properties
C7H6O2
Molar mass 122.123 g/mol
Appearance Colorless crystalline solid
Odor Faint, pleasant odor
Density 1.2659 g/cm3 (15 °C)
1.0749 g/cm3 (130 °C)[2]
Melting point 122 °C (252 °F; 395 K)[7]
Boiling point 250 °C (482 °F; 523 K)[7]
1.7 g/L (0 °C)
2.7 g/L (18 °C)
3.44 g/L (25 °C)
5.51 g/L (40 °C)
21.45 g/L (75 °C)
56.31 g/L (100 °C)[2][3]
Solubility Soluble in
phenyls, liquid ammonia, acetates
Solubility in methanol 30 g/100 g (−18 °C)
32.1 g/100 g (−13 °C)
71.5 g/100 g (23 °C)[2]
Solubility in ethanol 25.4 g/100 g (−18 °C)
47.1 g/100 g (15 °C)
52.4 g/100 g (19.2 °C)
55.9 g/100 g (23 °C)[2]
Solubility in acetone 54.2 g/100 g (20 °C)[2]
Solubility in olive oil 4.22 g/100 g (25 °C)[2]
1,4-dioxane
 55.3 g/100 g (25 °C)[2]
log P 1.87
Vapor pressure 0.16 Pa (25 °C)
0.19 kPa (100 °C)
22.6 kPa (200 °C)[4]
Acidity (pKa)
−70.28·10−6 cm3/mol
1.5397 (20 °C)
1.504 (132 °C)[2]
Viscosity 1.26 mPa (130 °C)
Structure
Monoclinic
Planar
1.72 
dioxane
Thermochemistry
146.7 J/mol·K[4]
167.6 J/mol·K[2]
Std enthalpy of
formation
(ΔfH⦵298)
 −385.2 kJ/mol[2]
Std enthalpy of
combustion
(ΔcH⦵298)
 −3228 kJ/mol[4]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Irritant
GHS labelling:
GHS05: CorrosiveGHS08: Health hazard[8]
Danger
H318, H335[8]
P261, P280, P305+P351+P338[8]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
1
0
Flash point 121.5 °C (250.7 °F; 394.6 K)[7]
571 °C (1,060 °F; 844 K)[7]
Lethal dose or concentration (LD, LC):
1700 mg/kg (rat, oral)
Safety data sheet (SDS) JT Baker
Related compounds
Other cations
 Sodium benzoate,
Potassium benzoate
Hydroxybenzoic acids
Aminobenzoic acids,
Nitrobenzoic acids,
Phenylacetic acid
Related compounds
 Benzaldehyde,
Benzyl alcohol,
Benzoyl chloride,
Benzylamine,
Benzamide,
Benzonitrile
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

Benzoic acid

benzyl), 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.

Benzoic acid occurs naturally in many plants

food preservatives. Benzoic acid is an important precursor for the industrial synthesis of many other organic substances. The salts and esters of benzoic acid are known as benzoates /ˈbɛnzoʊ.eɪt/
.

History

Benzoic acid was discovered in the sixteenth century. The

gum benzoin was first described by Nostradamus (1556), and then by Alexius Pedemontanus (1560) and Blaise de Vigenère (1596).[10]

Justus von Liebig and Friedrich Wöhler determined the composition of benzoic acid.[11] These latter also investigated how hippuric acid is related to benzoic acid.

In 1875 Salkowski discovered the

disputed – discuss
]

Production

Industrial preparations

Benzoic acid is produced commercially by

naphthenates. The process uses abundant materials, and proceeds in high yield.[13]

toluene oxidation
toluene oxidation

The first industrial process involved the reaction of

catalyst. The resulting calcium benzoate is converted to benzoic acid with hydrochloric acid. The product contains significant amounts of chlorinated benzoic acid derivatives. For this reason, benzoic acid for human consumption was obtained by dry distillation of gum benzoin
. Food-grade benzoic acid is now produced synthetically.

Laboratory synthesis

Benzoic acid is cheap and readily available, so the laboratory synthesis of benzoic acid is mainly practiced for its pedagogical value. It is a common undergraduate preparation.

Benzoic acid can be purified by recrystallization from water because of its high solubility in hot water and poor solubility in cold water. The avoidance of organic solvents for the recrystallization makes this experiment particularly safe. This process usually gives a yield of around 65%.[14]

By hydrolysis

Like other nitriles and amides, benzonitrile and benzamide can be hydrolyzed to benzoic acid or its conjugate base in acid or basic conditions.

From Grignard reagent

Bromobenzene can be converted to benzoic acid by "carboxylation" of the intermediate phenylmagnesium bromide.[15] This synthesis offers a convenient exercise for students to carry out a Grignard reaction, an important class of carbon–carbon bond forming reaction in organic chemistry.[16][17][18][19][20]

Oxidation of benzyl compounds

Benzyl alcohol[21] and benzyl chloride and virtually all benzyl derivatives are readily oxidized to benzoic acid.

Uses

Benzoic acid is mainly consumed in the production of phenol by oxidative decarboxylation at 300−400 °C:[22]

The temperature required can be lowered to 200 °C by the addition of catalytic amounts of copper(II) salts. The phenol can be converted to cyclohexanol, which is a starting material for nylon synthesis.

Precursor to plasticizers

Benzoate

phthalates.[22]

Precursor to sodium benzoate and related preservatives

Benzoic acid and its salts are used as

anaerobic fermentation of glucose through phosphofructokinase is decreased by 95%. The efficacy of benzoic acid and benzoate is thus dependent on the pH of the food.[24]
Benzoic acid, benzoates and their derivatives are used as
soft drinks (phosphoric acid), pickles (vinegar
) and other acidified foods.

Typical concentrations of benzoic acid as a preservative in food are between 0.05 and 0.1%. Foods in which benzoic acid may be used and maximum levels for its application are controlled by local food laws.[25][26]

Concern has been expressed that benzoic acid and its salts may react with

ascorbic acid (vitamin C) in some soft drinks, forming small quantities of carcinogenic benzene.[27]

See also: Benzene in soft drinks

Medicinal

Benzoic acid is a constituent of

ringworm and athlete's foot.[28][29] As the principal component of gum benzoin, benzoic acid is also a major ingredient in both tincture of benzoin and Friar's balsam. Such products have a long history of use as topical antiseptics and inhalant decongestants
.

Benzoic acid was used as an

expectorant, analgesic, and antiseptic in the early 20th century.[30]

Niche and laboratory uses

In teaching laboratories, benzoic acid is a common standard for calibrating a

bomb calorimeter.[31]

Biology and health effects

Benzoic acid occurs naturally as do its esters in many plant and animal species. Appreciable amounts are found in most berries (around 0.05%). Ripe fruits of several

Elephas maximus).[32] Gum benzoin contains up to 20% of benzoic acid and 40% benzoic acid esters.[33]

In terms of its biosynthesis, benzoate is produced in plants from cinnamic acid.

4-hydroxybenzoate.[35]

Reactions

Reactions of benzoic acid can occur at either the

carboxyl group
.

Aromatic ring

benzoic acid aromatic ring reactions
benzoic acid aromatic ring reactions

carboxylic group; i.e. benzoic acid is meta directing.[36]

Carboxyl group

Reactions typical for carboxylic acids apply also to benzoic acid.[22]

benzoic acid group reactions
benzoic acid group reactions


Safety and mammalian metabolism

It is excreted as

butyrate-CoA ligase into an intermediate product, benzoyl-CoA,[38] which is then metabolized by glycine N-acyltransferase into hippuric acid.[39] Humans metabolize toluene which is also excreted as hippuric acid.[40]

For humans, the World Health Organization's International Programme on Chemical Safety (IPCS) suggests a provisional tolerable intake would be 5 mg/kg body weight per day.[32] Cats have a significantly lower tolerance against benzoic acid and its salts than rats and mice. Lethal dose for cats can be as low as 300 mg/kg body weight.[41] The oral LD50 for rats is 3040 mg/kg, for mice it is 1940–2263 mg/kg.[32]

In Taipei, Taiwan, a city health survey in 2010 found that 30% of dried and pickled food products had benzoic acid.[42]

See also

  • Niacin – Organic compound and a form of vitamin B3

References

  1. ISBN 978-0-85404-182-4
    .
  2. ^ a b c d e f g h i j "benzoic acid". chemister.ru. Retrieved 24 October 2018.
  3. ^ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand.
  4. ^ a b c Benzoic acid in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-05-23)
  5. ISBN 9781429254366
    .
  6. doi:10.1021/jo01304a033
    .
  7. ^ a b c d Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  8. ^ a b c Sigma-Aldrich Co., Benzoic acid. Retrieved on 2014-05-23.
  9. ^ "Scientists uncover last steps for benzoic acid creation in plants". Purdue Agriculture News.
  10. OCLC 50969944
    .
  11. hdl:2027/hvd.hxdg3f
    .
  12. ^ Salkowski E (1875). Berl Klin Wochenschr. 12: 297–298. {{cite journal}}: Missing or empty |title= (help)
  13. ISBN 978-1-292-02165-2
    .
  14. ISBN 978-0-08-034715-8
    .
  15. ISBN 978-0-534-40833-6
    .
  16. Org. React.
    8: 28–58.
  17. ISBN 978-0-08-052349-1
    .
  18. ^ "The Grignard Reaction. Preparation of Benzoic Acid" (PDF). Portland Community College. Archived from the original (PDF) on 26 February 2015. Retrieved 12 March 2015.>
  19. ^ "Experiment 9: Synthesis of Benzoic Acid via Carbonylation of a Grignard Reagent" (PDF). University of Wisconsin-Madison. Archived from the original (PDF) on 23 September 2015. Retrieved 12 March 2015.
  20. ^ "Experiment 3: Preparation of Benzoic Acid" (PDF). Towson University. Archived from the original (PDF) on 13 April 2015. Retrieved 12 March 2015.>
  21. ISSN 1083-6160
    .
  22. ^
    ISBN 978-3527306732
    ..
  23. PMID 1785916
    .
  24. doi:10.1002/(SICI)1099-1565(199703)8:2<63::AID-PCA337>3.0.CO;2-Y
    .
  25. ^ GSFA Online Food Additive Group Details: Benzoates (2006) Archived 26 September 2007 at the Wayback Machine
  26. ^ EUROPEAN PARLIAMENT AND COUNCIL DIRECTIVE No 95/2/EC of 20 February 1995 on food additives other than colours and sweeteners (Consleg-versions do not contain the latest changes in a law) Archived 19 April 2003 at the Wayback Machine
  27. ^ "Indications of the possible formation of benzene from benzoic acid in foods, BfR Expert Opinion No. 013/2006" (PDF). German Federal Institute for Risk Assessment. 1 December 2005. Archived (PDF) from the original on 26 April 2006. Retrieved 30 March 2022.
  28. ^ "Whitfield Ointment". Archived from the original on 9 October 2007. Retrieved 15 October 2007.
  29. ISBN 978-0-7817-3481-3
    .
  30. ^ Lillard, Benjamin (1919). "Troches of Benzoic Acid". Practical Druggist and Pharmaceutical Review of Reviews.
  31. ^ Experiment 2: Using Bomb Calorimetry to Determine the Resonance Energy of Benzene Archived 9 March 2012 at the Wayback Machine
  32. ^ a b c "Concise International Chemical Assessment Document 26: BENZOIC ACID AND SODIUM BENZOATE".
  33. PMID 5012256
    .
  34. PMID 20035037
    .
  35. PMID 15653882
    .
  36. ^ Brewster, R. Q.; Williams, B.; Phillips, R. (1955). "3,5-Dinitrobenzoic Acid". Organic Syntheses; Collected Volumes, vol. 3, p. 337.
  37. S2CID 13639993
    .
  38. ^ "butyrate-CoA ligase". BRENDA. Technische Universität Braunschweig. Retrieved 7 May 2014. Substrate/Product
  39. ^ "glycine N-acyltransferase". BRENDA. Technische Universität Braunschweig. Retrieved 7 May 2014. Substrate/Product
  40. PMID 6226283
    .
  41. S2CID 2553612
    .
  42. ^ Chen, Jian; Y.L. Kao (18 January 2010). "Nearly 30% dried, pickled foods fail safety inspections". The China Post.

External links

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