Benzyl alcohol: Difference between revisions

{{Short description|Aromatic alcohol}}

{{Distinguish|benzoic acid|cresol|phenol}}

{{Use dmy dates|date=April 2020}}

{{Chembox

|Verifiedfields = changed

|Watchedfields = changed

|verifiedrevid = 443418046

|Name = Benzyl alcohol

|ImageFile = alkohol_benzylowy.svg

|ImageSize = 150px

|ImageName = Benzyl alcohol

|ImageFile1 = Benzyl-alcohol-3D-vdW.png

|ImageSize1 = 100px

|ImageName1 = Benzyl alcohol

|PIN = Phenylmethanol<br/>(Hydroxymethyl)benzene

|OtherNames = Benzyl alcohol<br/>α-Cresol<br/>α-Toluenol<br/>α-Hydroxytoluene<br/>alpha-Hydroxyphenylmethane<br/>Phenylcarbinol<br/>Benzenemethanol<br/>Benzyl hydroxide<br/>Benzylic acid

|Section1={{Chembox Identifiers

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = LKG8494WBH

|KEGG_Ref = {{keggcite|correct|kegg}}

|KEGG = D00077

|InChI = 1/C7H8O/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2

|InChIKey = WVDDGKGOMKODPV-UHFFFAOYAH

|SMILES1 = c1ccc(cc1)CO

|ChEMBL_Ref = {{ebicite|correct|EBI}}

|ChEMBL = 720

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/C7H8O/c8-6-7-4-2-1-3-5-7/h1-5,8H,6H2

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = WVDDGKGOMKODPV-UHFFFAOYSA-N

|CASNo = 100-51-6

|CASNo_Ref = {{cascite|correct|CAS}}

|EINECS = 202-859-9

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 13860335

|ChEBI_Ref = {{ebicite|correct|EBI}}

|ChEBI = 17987

|SMILES = c1ccc(cc1)CO

|PubChem = 244

|RTECS = DN3150000

}}

|Section2={{Chembox Properties

|Properties_ref = <ref>{{cite web |url=http://sitem.herts.ac.uk/aeru/footprint/en/Reports/953.htm |title=Benzyl alcohol |archive-url=https://web.archive.org/web/20090726101848/http://sitem.herts.ac.uk/aeru/footprint/en/Reports/953.htm |archive-date=2009-07-26 }}</ref>

|C=7 | H=8 | O=1

|Appearance = Colorless liquid

|Odor = Slightly aromatic

|Density = 1.044 g/cm³

|MeltingPtC = -15.2

|BoilingPtC = 205.3

|VaporPressure = 0.18&nbsp;kPa (60&nbsp;°C)

|Solubility = 3.50 g/100 mL (20&nbsp;°C) <br /> 4.29 g/100 mL (25&nbsp;°C)

|SolubleOther = Soluble{{vague|date=February 2016}} in [[benzene]], [[methanol]], [[chloroform]], [[ethanol]], [[diethyl ether|ether]], [[acetone]]

|Solvent = other solvents

|RefractIndex = 1.5396

|LogP = 1.10

|pKa = 15.40

|Viscosity = 5.474 cP

|Dipole = 1.67 D

|MagSus = −71.83·10⁻⁶ cm³/mol

}}

|Section3={{Chembox Thermochemistry

|DeltaHf = −352 kJ/mol

|Entropy = 217.8 J/(K·mol)

}}

|Section4={{Chembox Hazards

|FlashPtC = 93

|AutoignitionPtC = 436

|ExploLimits = 1.3–13%

|ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/b1885.htm External MSDS]

|LD50 = 1250 mg/kg (rat, oral)

|NFPA-H = 1 | NFPA-F = 1 | NFPA-R = 0

}}

|Section5={{Chembox Pharmacology

|ATCCode_prefix = P03

|ATCCode_suffix = AX06

'''Benzyl alcohol''' (also known as '''α-[[cresol]]''') is an [[aromatic]] [[alcohols|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 as a solvent for its polarity, low toxicity, and low [[vapor pressure]]. Benzyl alcohol has moderate [[solubility]] in water (4&nbsp;g/100&nbsp;mL) and is [[miscibility|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 oil]]s including [[jasmine]], [[hyacinth (plant)|hyacinth]] and [[ylang-ylang]].<ref>{{Merck11th|1138}}</ref> It is also found in [[castoreum]] from the [[castor sac]]s of beavers.<ref>{{Cite book | title = The Beaver: Its Life and Impact | author = Dietland Muller-Schwarze | year = 2003 | page = 43 | isbn = 978-0-8014-5010-5 | url = https://books.google.com/books?id=HZ5WjXB5Pr8C&q=Castoreum%20beekeeping&pg=PA43}}</ref> Benzyl esters also occur naturally.<ref>{{cite journal |doi=10.1104/pp.006460|title=Characterization of an Acyltransferase Capable of Synthesizing Benzylbenzoate and Other Volatile Esters in Flowers and Damaged Leaves of Clarkia breweri|year=2002|last1=d'Auria|first1=John C.|last2=Chen|first2=Feng|last3=Pichersky|first3=Eran|journal=Plant Physiology|volume=130|issue=1|pages=466–476|pmid=12226525|pmc=166578}}</ref>

== Preparation ==

Benzyl alcohol is produced industrially from [[toluene]] via [[benzyl chloride]], which is hydrolyzed:

: C₆H₅CH₂Cl + H₂O → C₆H₅CH₂OH + HCl

Another route entails hydrogenation of [[benzaldehyde]], a by-product of the oxidation of toluene to [[benzoic acid]].<ref name="ull">{{Ullmann|author=Friedrich Brühne|author2=Elaine Wright|title=Benzyl Alcohol|year=2007|doi=10.1002/14356007.a04_001}}</ref>

For laboratory use, [[Grignard reaction]] of [[phenylmagnesium bromide]] (C₆H₅MgBr) with [[formaldehyde]] and the [[Cannizzaro reaction]] of benzaldehyde also give benzyl alcohol. The latter also gives benzoic acid, an example of an organic [[disproportionation]] reaction.

== Reactions ==

Like most alcohols, it reacts with [[carboxylic acid]]s to form [[ester]]s. In organic synthesis, benzyl esters are popular [[protecting group]]s because they can be removed by mild [[hydrogenolysis]].<ref>{{OrgSynth | last1 = Furuta | first1 = Kyoji | last2 = Gao | first2 = Qing-Zhi | last3 = Yamamoto | first3 = Hisashi | title = Chiral (Acyloxy)borane Complex-Catalyzed Asymmetric Diels-Alder Reaction: (1''R'')-1,3,4-Trimethyl-3-Cyclohexene-1-Carboxaldehyde | prep = cv9p0722 | volume = 72 | page = 86 | year = 1995 | collvol = 9 | collvolpages = 722}}</ref>

Benzyl alcohol reacts with [[acrylonitrile]] to give [[N-Benzylacrylamide|''N''-benzylacrylamide]]. This is an example of a [[Ritter reaction]]:<ref>{{OrgSynth | last = Parris | first = Chester L. | title = ''N''-benzylacrylamide | prep = cv5p0073 | volume = 42 | page = 16 | year = 1962 | collvol = 5 | collvolpages = 73}}</ref>

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

== Applications ==

Benzyl alcohol is used as a general [[solvent]] for inks, waxes, shellacs, paints, [[lacquer]]s, 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.<ref>{{citation | url = http://www.chemicalland21.com/industrialchem/solalc/BENZYL%20ALCOHOL.htm | title = Benzyl alcohol | publisher = chemicalland21.com | access-date = 2006-05-14 | archive-url = https://web.archive.org/web/20090421060841/http://chemicalland21.com/industrialchem/solalc/BENZYL%20ALCOHOL.htm | archive-date = 2009-04-21 }}</ref>

It is a precursor to a variety of [[ester]]s and [[diethyl ether|ethers]], used in the soap, perfume, and [[flavor industry|flavor industries]]. E.g. [[benzyl benzoate]], [[benzyl salicylate]], [[benzyl cinnamate]], [[dibenzyl ether]], [[benzyl butyl phthalate]].

It can be used as a local anesthetic, especially with epinephrine.<ref>{{Cite journal |last=Wilson |first=L. |last2=Martin |first2=S. |date=May 1999 |title=Benzyl alcohol as an alternative local anesthetic |journal=Annals of Emergency Medicine |volume=33 |issue=5 |pages=495–499 |doi=10.1016/s0196-0644(99)70335-5 |pmid=10216324}}</ref>

As a dye solvent, it enhances the process of dying wool, nylon, and leather.<ref name="AshAsh2004">{{cite book |author1=Michael Ash |author2=Irene Ash |title=Handbook of Preservatives |url=https://books.google.com/books?id=XZ2QB7bu5LwC&pg=PA487 |year=2004 |publisher=Synapse Info Resources |isbn=978-1-890595-66-1 |page=292}}</ref>

=== Use in health care ===

Benzyl alcohol is used as a [[bacteriostat]]ic preservative at low concentration in intravenous medications, cosmetics, and topical drugs.<ref name="analsci.27.865">{{cite journal |author=H. A. Mashayekhi |author2=M. Rezaee |author3=Sh. S. Garmaroudi |author4=N. Montazeri |author5=S. J. Ahmadi |title=Rapid and sensitive determination of benzaldehyde arising from benzyl alcohol used as preservative in an injectable formulation solution using dispersive liquid–liquid microextraction followed by gas chromatography |journal=Anal. Sci.

|volume=27 |issue=8 |pages=865–868 |year=2011 |doi=10.2116/analsci.27.865|pmid=21828928 |doi-access=free }}</ref> Some caution is necessary if a high percent of benzyl alcohol is used as benzaldehyde arises from benzyl alcohol when used as preservative in an injectable formulation solution.<ref name="analsci.27.865"/><ref>{{cite journal |author=N. N. Sudareva |author2=E. V. Chubarova |title=Time-dependent conversion of benzyl alcohol to benzaldehyde and benzoic acid in aqueous solutions |journal=J. Pharm. Biomed. Anal. |volume=41 |issue=4 |pages=1380–1385 |year=2006 |doi=10.1016/j.jpba.2006.02.028|pmid=16564153 }}</ref>

Benzyl alcohol, sold under the brand name '''Ulesfia''', was approved by the U.S. [[Food and Drug Administration]] (FDA) in 2009, as a 5% solution for the treatment of [[Head-louse infestation|head lice]] in people 6&nbsp;months of age and older.<ref name="Ulesfia FDA label">{{cite web | title=Ulesfia- benzyl alcohol lotion | website=DailyMed | date=8 April 2019 | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5754f979-32b7-4406-a3a9-ed36aac6a37a | access-date=27 April 2020}}</ref> It affects the louse's [[Spiracle (arthropods)|spiracles]], preventing them from closing.<ref name="Ulesfia FDA label" /> These then become clogged with water or mineral oil or other matter and cause the insect to die from [[asphyxiation]].<ref name="Ulesfia FDA label"/>

Benzyl alcohol is used effectively for treating lice infestations as the active ingredient in lotion shampoo with 5% benzyl alcohol.<ref name="Ulesfia FDA label" />

Benzyl alcohol is an ingredient used in the manufacture of soaps, topical creams, skin lotions, shampoos, and facial cleansers and is popular due to its anti-bacterial and anti-fungal properties. It is a common ingredient in a variety of household products.

== Safety ==

Sensitization to benzyl alcohol occurs very rarely, mainly in patients with [[stasis dermatitis]].<ref>{{Cite web |title=Registration Dossier - ECHA |url=https://echa.europa.eu/registration-dossier/-/registered-dossier/14748/7/5/1 |access-date=2023-04-20 |website=echa.europa.eu |language=en-GB}}</ref>

Benzyl alcohol is not considered to be a carcinogen, and no data are available regarding teratogenic or reproductive effects.<ref name="ull" />

Benzyl alcohol has low acute toxicity with an {{LD50}} of 1.2 g/kg in rats.<ref name="ull" /> 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 [[infant|neonates]] and is associated with the [[gasping syndrome]].<ref name="pth">{{citation | editor=Jerrold B. Leikin | editor2=Frank P. Paloucek | author=Carl R. Baum | contribution=Examples of mass exposures involving the pediatric population | title=Poisoning and Toxicology Handbook | edition=4th | publisher=Informa | year=2008 | page=726}}.</ref><ref>{{citation | author=Juan Gershanik | title=The gasping syndrome and benzyl alcohol poisoning | journal=[[N Engl J Med]] | year=1982 | volume=307 | issue=22 | pages=1384–8 | doi=10.1056/nejm198211253072206|display-authors=etal | pmid=7133084}}.</ref>

== References ==

== External links ==

{{Alcohols }}

{{Portal bar | Medicine}}

{{Authority control}}

[[Category:Primary alcohols]]

[[Category:Perfume ingredients]]

[[Category:Aromatic solvents]]

[[Category:Benzyl compounds]]

[[Category:E-number additives]]

[[Category:Antimicrobials]]