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Benzyl alcohol

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Benzyl alcohol
Benzyl alcohol
Benzyl alcohol
Names
IUPAC name
Phenylmethanol
Other names
Phenylcarbinol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.002.600 Edit this at Wikidata
EC Number
  • 202-859-9
E number E1519 (additional chemicals)
KEGG
RTECS number
  • DN3150000
UNII
  • InChI=1S/C7H8O/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2 checkY
    Key: WVDDGKGOMKODPV-UHFFFAOYSA-N checkY
  • 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 108.140 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 in other solvents Soluble[vague] 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
P03AX06 (WHO)
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 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
1
1
0
Flash point 93 °C (199 °F; 366 K)
436 °C (817 °F; 709 K)
Explosive limits 1.3–13%
Lethal dose or concentration (LD, LC):
1250 mg/kg (rat, oral)
Safety data sheet (SDS) External MSDS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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. The anion produced by deprotonation of the alcohol group is known as benzylate or benzyloxide.

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]

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 for the treatment of head lice in children older than 6 months and in adults.[9] It affects the louse's spiracles, preventing them from closing. These then become clogged with water or mineral oil or other matter and cause the insect to die from asphyxiation.

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 fibers and vegetable matter.

Safety

Benzyl alcohol has low acute toxicity 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

  1. ^ "Benzyl alcohol".
  2. ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.), Merck, 1989, ISBN 091191028X, 1138
  3. ^ Dietland Muller-Schwarze (2003). The Beaver: Its Life and Impact. p. 43.
  4. ^ Furuta, Kyoji; Gao, Qing-Zhi; Yamamoto, Hisashi (1995). "Chiral (Acyloxy)borane Complex-Catalyzed Asymmetric Diels-Alder Reaction: (1R)-1,3,4-Trimethyl-3-Cyclohexene-1-Carboxaldehyde". Organic Syntheses. 72: 86; Collected Volumes, vol. 9, p. 722.
  5. ^ Parris, Chester L. (1962). "N-benzylacrylamide". Organic Syntheses. 42: 16; Collected Volumes, vol. 5, p. 73.
  6. ^ Benzyl alcohol, chemicalland21.com
  7. ^ Alex Wissner-Gross (2006). "Dielectrophoretic reconfiguration of nanowire interconnects" (PDF). Nanotechnology. 17: 4986–4990.
  8. ^ Nanowires get reconfigured, Nanotechweb.org, 19 October 2006
  9. ^ Prescribing Information for Ulesfia Lotion (PDF), Sciele Pharmaceuticals, Inc., April 2009, retrieved 2009-08-29.[dead link]
  10. ^ a b c Friedrich Brühne; Elaine Wright (2007), "Benzyl Alcohol", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, pp. 7–8
  11. ^ Carl R. Baum (2008), "Examples of mass exposures involving the pediatric population", in Jerrold B. Leikin; Frank P. Paloucek (eds.), Poisoning and Toxicology Handbook (4th ed.), Informa, p. 726
  12. ^ Juan Gershanik; et al. (1982), "The gasping syndrome and benzyl alcohol poisoning.", N Engl J Med, 307: 1384–8, doi:10.1056/nejm198211253072206
  13. ^ EJ Curry; EM Warshaw (2005), "Benzyl alcohol allergy: importance of patch testing with personal products.", Dermatitis (16): 203–8
  14. ^ Swarupa G Kulkarni; Harihara M Mehendale (2005), "Benzyl Alcohol", Encyclopedia of Toxicology, vol. 1 (2nd ed.), Elsevier, pp. 262–264
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