Benzyl alcohol

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Benzyl alcohol
Benzyl alcohol
Benzyl alcohol
Names
IUPAC name
Phenylmethanol
Other names
Phenylcarbinol
Identifiers
100-51-6 YesY
ChEBI CHEBI:17987 YesY
ChEMBL ChEMBL720 YesY
ChemSpider 13860335 YesY
EC Number 202-859-9
Jmol 3D model Interactive image
Interactive image
KEGG D00077 YesY
PubChem 244
RTECS number DN3150000
UNII LKG8494WBH YesY
  • InChI=1S/C7H8O/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2 YesY
    Key: WVDDGKGOMKODPV-UHFFFAOYSA-N YesY
  • InChI=1/C7H8O/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2
    Key: WVDDGKGOMKODPV-UHFFFAOYAH
  • c1ccc(cc1)CO
  • c1ccc(cc1)CO
Properties[1]
C7H8O
Molar mass 108.14 g·mol−1
Appearance colorless liquid
Odor slightly aromatic
Density 1.044 g cm−3
Melting point −15.2 °C (4.6 °F; 257.9 K)
Boiling point 205.3 °C (401.5 °F; 478.4 K)
3.50 g/100 mL (20 °C)
4.29 g/100 mL (25 °C)
Solubility soluble in benzene, methanol, chloroform, ethanol, ether, acetone
log P 1.10
Vapor pressure 0.18 kPa (60 °C)
Acidity (pKa) 15.40
1.5396
Viscosity 5.474 cP
1.67 D
Thermochemistry
217.8 J/K mol
-352 kJ/mol
Pharmacology
ATC code P03AX06
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Benzyl alcohol is an aromatic alcohol with the formula C6H5CH2OH. The benzyl group is often abbreviated "Bn" (not to be confused with "Bz" which is used for benzoyl), thus benzyl alcohol is denoted as BnOH. Benzyl alcohol is a colorless liquid with a mild pleasant aromatic odor. It is a useful solvent due to its polarity, low toxicity, and low vapor pressure. Benzyl alcohol is partially soluble in water (4 g/100 mL) and completely miscible in alcohols and diethyl ether.

Natural occurrences

Benzyl alcohol is produced naturally by many plants and is commonly found in fruits and teas. It is also found in a variety of essential oils including jasmine, hyacinth, and ylang-ylang.[2]

It is also one of the chemical compounds found in castoreum from the castor sacs of Beavers.[3]

Preparation

Benzyl alcohol is prepared by the hydrolysis of benzyl chloride using sodium hydroxide:

C6H5CH2Cl + NaOH → C6H5CH2OH + NaCl

It can also be prepared via a Grignard reaction by reacting phenylmagnesium bromide (C6H5MgBr) with formaldehyde, followed by acidification.

Reactions

Like most alcohols, it reacts with carboxylic acids to form esters. In organic synthesis, benzyl esters are popular protecting groups because they can be removed by mild hydrogenolysis.[4] it will show SN2 mechanism. Benzyl alcohol reacts with acrylonitrile to give N-benzylacrylamide. This is an example of a Ritter reaction:[5]

C6H5CH2OH + NCCHCH2 → C6H5CH2N(H)C(O)CHCH2

Applications

Benzyl alcohol is used as a general solvent for inks, paints, lacquers, and epoxy resin coatings. Thus it can be used in paint strippers especially when combined with compatible viscosity enhancers to encourage the mixture to cling to painted surfaces.[6] It is also a precursor to a variety of esters, used in the soap, perfume, and flavor industries. It is also used as a photographic developer.

Nanotechnological uses

Benzyl alcohol has been used as a dielectric solvent for the dielectrophoretic reconfiguration of nanowires.[7][8]

Use in health care

Benzyl alcohol is used as a bacteriostatic preservative at low concentration in intravenous medications, cosmetics and topical drugs.

The use of benzyl alcohol as a 5% solution has been approved by the U.S. FDA in the treatment of head lice in children older than 6 months and in adults.[9]

Other uses

Benzyl alcohol has nearly the same refraction index of quartz and wool fibre. If a clear quartz object is immersed in benzyl alcohol, it becomes almost invisible. This test has been used to determine non-destructively whether an object is truly made of quartz (see crystal skull). Similarly, white wool immersed in benzyl alcohol also becomes almost invisible clearly revealing contaminants such as dark and medullated fibres and vegetable matter.

Safety

Benzyl alcohol is only a mild acute toxin with an LD50 of 1.2 g/kg in rats.[10] It oxidizes rapidly in healthy individuals to benzoic acid, conjugated with glycine in the liver, and excreted as hippuric acid. Very high concentrations can result in toxic effects including respiratory failure, vasodilation, hypotension, convulsions, and paralysis.

Benzyl alcohol is toxic to neonates, it is associated with the gasping syndrome.[11][12]

Benzyl alcohol has been reported to cause skin allergy.[13]

Benzyl alcohol is severely toxic and highly irritating to the eye.[10] Pure benzyl alcohol produces corneal necrosis.[14]

Benzyl alcohol is not considered to be a carcinogen and no data are available regarding teratogenic or reproductive effects.[10]

References

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  3. The Beaver: Its Life and Impact. Dietland Muller-Schwarze, 2003, page 43 (book at google books)
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  7. A. D. Wissner-Gross, "Dielectrophoretic reconfiguration of nanowire interconnects", Nanotechnology 17, 4986–4990 (2006).
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External links