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 Ball-and-stick model of part of thecrystal structure | |
 Ball-and-stick model of packing in the crystal structure | |
| Names | |
|---|---|
| Preferred IUPAC name Sodium benzoate | |
Other names
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| Identifiers | |
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3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| ECHA InfoCard | 100.007.760 |
| E number | E211(preservatives) |
| RTECS number |
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| UNII | |
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| Properties | |
| C7H5NaO2 | |
| Molar mass | 144.105 g·mol−1 |
| Appearance | white or colourless crystalline powder |
| Odor | odorless |
| Density | 1.497 g/cm3 |
| Melting point | 410 °C (770 °F; 683 K) |
| 62.65 g/100 mL (0 °C) 62.84 g/100 mL (15 °C) 62.87 g/100 mL (30 °C) 74.2 g/100 mL (100 °C)[1] | |
| Solubility | soluble in liquidammonia,pyridine[1] |
| Solubility inmethanol | 8.22 g/100 g (15 °C) 7.55 g/100 g (66.2 °C)[1] |
| Solubility inethanol | 2.3 g/100 g (25 °C) 8.3 g/100 g (78 °C)[1] |
| Solubility in1,4-Dioxane | 0.818 mg/kg (25 °C)[1] |
| Pharmacology | |
| A16AX11 (WHO) | |
| Hazards | |
| GHS labelling: | |
 [2] | |
| Warning | |
| H319[2] | |
| P305+P351+P338[2] | |
| NFPA 704 (fire diamond) | |
| Flash point | 100 °C (212 °F; 373 K) |
| 500 °C (932 °F; 773 K) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 4100 mg/kg (oral, rat) |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Sodium benzoate also known asbenzoate of soda is thesodiumsalt ofbenzoic acid, widely used as afood preservative (with anE number ofE211) and apickling agent. It appears as a white crystalline chemical with theformula C6H5COONa.
Sodium benzoate is commonly produced by the neutralization ofsodium hydroxide (NaOH) withbenzoic acid (C6H5COOH),[3] which is itself produced commercially bypartial oxidation oftoluene withoxygen.
Sodium benzoate can bedecarboxylated with strongbase and heat, yieldingbenzene:[4]
Sodium benzoate is not a naturally occurring substance. However many foods are natural sources of benzoic acid, its salts, and itsesters.[5]Fruits andvegetables can be rich sources, particularly berries such ascranberry andbilberry. Other sources includeseafood, such asprawns, anddairy products.[citation needed]
Sodium benzoate can act as a food preservative. It is most widely used in acidic foods such assalad dressings (for exampleacetic acid invinegar),carbonated drinks (carbonic acid),jams andfruit juices (citric acid),pickles (acetic acid),condiments, andfrozen yogurt toppings. It is also used as a preservative in medicines and cosmetics.[6][7] Under these conditions it is converted intobenzoic acid (E210), which isbacteriostatic andfungistatic. Benzoic acid is generally not used directly due to its poor water solubility.Concentration as a food preservative is limited by the FDA in the U.S. to 0.1% by weight.[8] Sodium benzoate is also allowed as an animal food additive at up to 0.1%, per the Association of American Feed Control Officials.[9]Sodium benzoate has been replaced bypotassium sorbate in the majority of soft drinks in theUnited Kingdom.[10]
In the 19th century, sodium benzoate as a food ingredient was investigated byHarvey W. Wiley with his 'Poison Squad' as part of theUS Department of Agriculture. This led to the 1906Pure Food and Drug Act, a key event in theearly history of food regulation in the United States.
Sodium benzoate is used as a treatment forurea cycle disorders due to its ability to bind amino acids.[11][12] This leads to excretion of these amino acids and a decrease in ammonia levels. Recent research shows that sodium benzoate may be beneficial as an add-on therapy (1 gram/day) inschizophrenia.[13][14][15] TotalPositive and Negative Syndrome Scale scores dropped by 21% compared to placebo.
Sodium benzoate, along withphenylbutyrate, is used to treathyperammonemia.[16][17]
Sodium benzoate, along withcaffeine, is used to treatpostdural puncture headache, respiratory depression associated with overdosage ofnarcotics,[18][19] and withergotamine to treatvascular headache.[20]
Sodium benzoate is also used infireworks as a fuel inwhistle mix, a powder that emits a whistling noise when compressed into a tube and ignited.[21][22]
The mechanism starts with the absorption of benzoic acid into the cell. If theintracellular pH falls to 5 or lower, theanaerobic fermentation ofglucose throughphosphofructokinase decreases sharply,[23] which inhibits the growth and survival of microorganisms that cause food spoilage.
In theUnited States, sodium benzoate is designated asgenerally recognized as safe (GRAS) by theFood and Drug Administration.[24] The International Programme on Chemical Safety found no adverse effects in humans at doses of 647–825 mg/kg of body weight per day.[25][26]
Cats have a significantly lower tolerance against benzoic acid and itssalts than rats and mice.[27]
The human body rapidly clears sodium benzoate by combining it withglycine to formhippuric acid which is then excreted.[26] The metabolic pathway for this begins with the conversion of benzoate bybutyrate-CoA ligase into an intermediate product,benzoyl-CoA,[28] which is then metabolized byglycineN-acyltransferase into hippuric acid.[29]
In combination withascorbic acid (vitamin C, E300), sodium benzoate andpotassium benzoate may formbenzene. In 2006, the Food and Drug Administration tested 100 beverages available in the United States that contained both ascorbic acid and benzoate. Four had benzene levels that were above the 5ppbMaximum Contaminant Level set by theEnvironmental Protection Agency for drinking water.[30] Most of the beverages that tested above the limit have been reformulated and subsequently tested below the safety limit.[30] Heat, light and shelf life can increase the rate at which benzene is formed. Hot peppers naturally contain vitamin C ("nearly as much as in one orange"[31]) so the observation about beverages applies to pepper sauces containing sodium benzoate, likeTexas Pete.
Research published, including in 2007 for the UK'sFood Standards Agency (FSA) suggests that certainartificial colors, when paired with sodium benzoate, may be linked tohyperactive behavior and other ADHD symptoms. The results were inconsistent regarding sodium benzoate, so the FSA recommended further study.[32][33][34] The Food Standards Agency concluded that the observed increases in hyperactive behavior, if real, were more likely to be linked to the artificial colors than to sodium benzoate.[34] The report's author, Jim Stevenson fromSouthampton University, said: "The results suggest that consumption of certain mixtures of artificial food colours and sodium benzoate preservative are associated with increases in hyperactive behaviour in children. . . . Many other influences are at work but this at least is one a child can avoid."[34]
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Although the maximum rate of biotransformation of benzoic acid tohippuric acid varied between 17.2 and 28.8 mg.kg-1.h-1 among the six individuals, the mean value (23.0 mg.kg-1.h-1) was fairly close to that provided by daily maximum dose (0.5 g.kg-1.day-1) recommended in the treatment ofhyperammonaemia in patients with inborn errors ofureagenesis
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