Benzyl alcohol (also known as α-cresol) 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.
CAS: 100-51-6 MF: C7H8O MW: 108.14 EINECS: 202-859-9
Synonyms Benzylalkohol;benzylalcohol,benzylalcohol,benzenemethanol;PHENYLMETHANOL/BENZYLALCOHOL;BENZYL ALCOHOL (TECH);BENZYL ALCOHOL NF FCC KOSHER;BENZYL ALCOHOL PERFUME GRADE 99.5% FCC NF;BENZYLALCOHOL,NF;BENZYLALCOHOL,REAGENT,ACS(BULK;benzyl alcohol;phenylmethanol;benzenemethanol;100-51-6;phenylcarbinol;benzylalcohol;Benzoyl alcohol;Benzenecarbinol;alpha-Toluenol;Phenylmethyl alcohol;Hydroxytoluene;(Hydroxymethyl)benzene;Phenolcarbinol;Benzal alcohol;Methanol, phenyl-;alpha-hydroxytoluene;benzylic alcohol;Alcool benzylique;Benzylicum;Phenylcarbinolum;Euxyl K 100;hydroxymethylbenzene;Bentalol;Ulesfia;66072-40-0;Phenyl Methanol;Phenyl-Methanol;BENZYL-ALCOHOL;Caswell No. 081F;alcoholum benzylicum;Benzyl alcohol (natural);FEMA No. 2137;Benzylalkohol;NCI-C06111;Alcool benzilico;Aromatic alcohol;Alcohol, Benzyl;Alcohol bencilico;.alpha.-Toluenol;Alcool benzilico [DCIT];Itch-X;NSC 8044;HSDB 46;benzenmethanol;.alpha.-Hydroxytoluene;Benzalalcohol;Benzalcohol;CCRIS 2081;Aromatic primary alcohol;Alcoolbenzylique;Alcohol,benzyl;Alcool benzylique [INN-French];Benzyl alkohol;Alcohol bencilico [INN-Spanish];Methanol benzene;Alcoholum benzylicum [INN-Latin];UNII-LKG8494WBH;Alcohol benzylicus;NSC-8044;EINECS 202-859-9;BnOH;LKG8494WB;MFCD00004599;EPA Pesticide Chemical Code 009502;BRN 0878307;Sunmorl BK 20;DTXSID5020152;CHEBI:17987;INS NO.1519;AI3-01680;INS-1519;Hydroxymethyl resin (100-200 mesh);TOLUENE,ALPHA-HYDROXY;DTXCID70152;Benzyl alcohol (Benzenemethanol);E-1519;EC 202-859-9;4-06-00-02222 (Beilstein Handbook Reference);185532-71-2;NCGC00091865-01;BENZYL ALCOHOL (II);BENZYL ALCOHOL [II];MBN;BENZYL ALCOHOL (MART.);BENZYL ALCOHOL [MART.];Alcool benzylique (INN-French);BENZYL ALCOHOL (USP-RS);BENZYL ALCOHOL [USP-RS];benzyl alcohol (ring-13c6);Alcohol bencilico (INN-Spanish);Alcoholum benzylicum (INN-Latin);BENZYL ALCOHOL (EP MONOGRAPH);BENZYL ALCOHOL [EP MONOGRAPH];phenylmethan-1-ol;CAS-100-51-6;Ulesfia (TN);Benzyl alcohol [USAN:INN:JAN];enzylalcohol;Protocoxil;phenyl carbinol;benzene-methanol;Benzyl Alcohole;a-Hydroxytoluene;a-Toluenol;Alcohol benzilico;Benzyl alcohol [INN:JAN:NF];Hydroxymethyl resin (200-400 mesh);PhCH2OH;Bn-OH;Benzyl alcohol (Standard)
Benzyl alcohol is useful as a solvent for its polarity, low toxicity, and low vapor pressure. Benzyl alcohol has moderate solubility in water (4 g/100 mL) and is miscible in alcohols and diethyl ether. The anion produced by deprotonation of the alcohol group is known as benzylate or benzyloxide. Benzyl alcohol is produced naturally by many plants and is commonly found in fruits and teas. Benzyl alcohol is also found in a variety of essential oils including jasmine, hyacinth and ylang-ylang. Benzyl alcohol is also found in castoreum from the castor sacs of beavers. Benzyl esters also occur naturally. Phenylcarbinol is also known as benzyl alcohol. Benzyl alcohol’s chemical formula is C6H5CH2OH and its density is 1.045 g/mL at 25 ° C (lit). Benzyl alcohol is one of the simplest fatty alcohol containing phenyl. Benzyl alcohol can be seen as benzene substituted by hydroxymethyl, or methyl alcohol substituted by phenyl.
Benzyl alcohol is a colorless transparent sticky liquid with faint aroma. Sometimes benzyl alcohol is placed for a long time, it will smells like bitter almond flavor because of oxidation. Polarity, low toxicity and low steam, so it is used as alcohol solvent. Benzyl alcohol is combustible, and slightly soluble in water (about 25ml of water soluble 1 gram of benzyl alcohol). Benzyl alcohol is miscible with ethanol, ethyl ether, benzene, chloroform and other organic solvents. Benzyl alcohol mainly exists in the form of free or ester in essential oil, such as jasmine oil, ylang-ylang oil, jasmine oil, hyacinth oil, sesame oil, hyacinths balsam, peru balsam and tolu balsam, which all contain this ingredient. Benzyl alcohol should not be stored for a long time. Benzyl alcohol can be slowly oxidized to benzaldehyde and anisole in the air. Therefore benzyl alcohol products often smell like almond aroma with characteristic of benzaldehyde. In addition, benzyl alcohol is also easily oxidized to benzoic acid by many kinds of antioxidants such as nitric acid. Benzyl alcohol is an aromatic alcohol that consists of benzene bearing a single hydroxymethyl substituent. Benzyl alcohol has a role as a solvent, a metabolite, an antioxidant and a fragrance.
An aromatic primary alcohol. Phenylmethanol is synthesized by Cannizzaro’s reaction, which involves the simultaneous oxidation and reduction of benzenecarbaldehyde (benzaldehyde) by refluxing in an aqueous solution of sodium hydroxide: 2C6H5CHO → C6H5CH2OH + C6H5COOH Phenylmethanol undergoes the reactions characteristic of alcohols, especially those in which the formation of a stable carbonium ion as an intermediate (C6H5CH2 +) enhances the reaction. Substitution onto the benzene ring is also possible; the -CH2OH group directs into the 2- or 4-position by the donation of electrons to the ring.
Benzyl alcohol Chemical Properties Melting point: -15 °C Boiling point: 205 °C Density: 1.045 g/mL at 25 °C(lit.) Vapor density: 3.7 (vs air) Vapor pressure: 13.3 mm Hg ( 100 °C) Refractive index: n20/D 1.539(lit.) FEMA: 2137 | BENZYL ALCOHOL Fp: 201 °F Storage temp.: Store at +2°C to +25°C. Solubility H2O: 33 mg/mL, clear, colorless Form: Liquid pka: 14.36±0.10(Predicted) Color: APHA: ≤20 Relative polarity: 0.608 Odor: Mild, pleasant. Odor Type: floral Explosive limit: 1.3-13%(V) Water Solubility: 4.29 g/100 mL (20 ºC) Merck: 14,1124 JECFA Number: 25 BRN: 878307 Henry’s Law Constant: <2.70 x 10-7 at 25 °C (thermodynamic method-GC/UV, Altschuh et al., 1999) Exposure limits: No exposure limit is set. Because of its low vapor pressure and low toxicity, the health hazard to humans from occupational exposure should be very low. Dielectric constant: 13.1（20℃） InChIKey: WVDDGKGOMKODPV-UHFFFAOYSA-N LogP: 1.05 at 20℃ CAS DataBase Reference: 100-51-6(CAS DataBase Reference) NIST Chemistry Reference: Benzyl alcohol(100-51-6) EPA Substance Registry System: Benzyl alcohol (100-51-6)
Benzyl alcohol has a characteristic pleasant, fruity odor and a slightly pungent, sweet taste; the note tends to become similar to that of benzyl aldehyde on aging. Slightly soluble in water, and miscible with alcohol, ether, chloroform and so on. Benzyl alcohol occurs in many essential oils and foods. Benzyl alcohol is a colorless liquid with a weak, slightly sweet odor. Benzyl alcohol can be oxidized to benzaldehyde, for example, with nitric acid. Dehydrogenation over a copper-magnesium oxide-pumice catalyst also leads to the aldehyde. Esterification of benzyl alcohol results in a number of important fragrance and flavor materials. Diphenylmethane is prepared by a Friedel-Crafts reaction of benzyl alcohol and benzene with aluminum chloride or concentrated sulfuric acid. By heating benzyl alcohol in the presence of strong acids or strong bases, dibenzyl ether is formed.
Reactions Like most alcohols, Benzyl alcohol reacts with carboxylic acids to form esters. In organic synthesis, benzyl esters are popular protecting groups because they can be removed by mild hydrogenolysis. Benzyl alcohol reacts with acrylonitrile to give N-benzylacrylamide. This is an example of a Ritter reaction:
C6H5CH2OH + NCCHCH2 → C6H5CH2N(H)C(O)CHCH2
Applications Benzyl alcohol is used as a general solvent for inks, waxes, shellacs, paints, lacquers, and epoxy resin coatings. Thus Benzyl alcohol can be used in paint strippers, especially when combined with compatible viscosity enhancers to encourage the mixture to cling to painted surfaces. Benzyl alcohol is a precursor to a variety of esters and ethers, used in the soap, perfume, and flavor industries. E.g. benzyl benzoate, benzyl salicylate, benzyl cinnamate, dibenzyl ether, benzyl butyl phthalate. Benzyl alcohol can be used as a local anesthetic, especially with epinephrine. As a dye solvent, Benzyl alcohol enhances the process of dying wool, nylon, and leather. Esters of benzyl alcohol are used in makingperfume, soap, flavoring, lotion, and ointment. Benzyl alcohol finds application in color photography;the pharmaceuticals industry, cosmetics,and leather dyeing; and as an insect repellent.
Benzyl alcohol occurs in natural products such as oils ofjasmine and castoreum. Benzyl alcohol is widely used as a solvent for the dielectrophoretic reconfiguration of nanowires, inks, paints, lacquers and epoxy resin coatings and as a precursor to a variety of esters used in soaps, perfumes and flavoring. Benzyl alcohol is employed as a local anesthetic which reduces the pain associated with lidocaine injection. Benzyl alcohol has a various applications in baby products, bath products, soaps and detergents, eye makeup, blushers, cleansing products, make up products as well as hair, nail and skin care products. Benzyl alcohol is a preservative against bacteria, used in concentrations of 1 to 3 percent. Benzyl alcohol can cause skin irritation.
Benzyl alcohol is a colorless clear oily liquid; its odor type is floral and its odor at 100% is described as ‘floral rose phenolic balsamic’. Benzyl alcohol is used in cosmetics as afragrance component, preservative, solvent and diluting agent for perfumes and flavors, and viscosity-decreasing agent. Benzyl alcohol is used as a solvent for surface-coating materials, cellulose esters and ethers, alkyd resins,acrylic resins, fats, dyestuffs,casein (when hot), gelatin, shellac and waxes. Benzyl alcohol is added in small amounts to surface-coating materials to improve their flow and gloss. In the textile industry, benzyl alcohol is used as anauxiliary in the dyeing of wool, polyamides, and polyesters. In pharmacy Benzyl alcohol is used as a local anesthetic ingredient in over-the-counter anorectal, oral healthcare and topical analgesic drug products and, because of its antimicrobial effect, as an ingredient of ointments and other preparations. Benzyl alcohol is also a starting material for the preparation of numerous benzyl esters that are used as odorants, flavors, stabilizers for volatile perfumes, and plasticizers and is also employed in the extractive distillation of m- and p-xylenes and m- and p-cresols. Other uses include or have included heat-sealing of polyethylene films,in color photography as a development accelerator and in microscopy as embedding material.
Pharmaceutical Applications Benzyl alcohol is an antimicrobial preservative used in cosmetics, foods, and a wide range of pharmaceutical formulations, including oral and parenteral preparations, at concentrations up to 2.0% v/v. The typical concentration used is 1% v/v, and Benzyl alcohol has been reported to be used in protein, peptide and small molecule products, although its frequency of use has fallen from 48 products in 1996, 30 products in 2001, to 15 products in 2006. In cosmetics, concentrations up to 3.0% v/v may be used as a preservative. Concentrations of 5% v/v or more are employed as a solubilizer, while a 10% v/v solution is used as a disinfectant. Benzyl alcohol 10% v/v solutions also have some local anesthetic properties, which are exploited in some parenterals, cough products, ophthalmic solutions, ointments, and dermatological aerosol sprays. Although widely used as an antimicrobial preservative, benzyl alcohol has been associated with some fatal adverse reactions when administered to neonates. Benzyl alcohol is now recommended that parenteral products preserved with benzyl alcohol, or other antimicrobial preservatives, should not be used in newborn infants if at all possible.
Use in health care Benzyl alcohol is used as a bacteriostatic preservative at low concentration in intravenous medications, cosmetics, and topical drugs. 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. 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 lice in people 6 months of age and older. Benzyl alcohol 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. Benzyl alcohol is used effectively for treating lice infestations as the active ingredient in lotion shampoo with 5% benzyl alcohol. 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. Benzyl alcohol is a common ingredient in a variety of household products.
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. 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.
Production Method 1.Benzyl chloride with potassium or sodium is heated for a long timg, and hydrolyzes to yield benzyl alcohol. 2.Benzaldehyde in methanol and sodium hydroxide solution react to benzyl alcohol at 65~75 ℃. The product has high purity. 3.Using benzyl chloride as raw materials, it is heated and hydrolyzes to yield benzyl alcohol in the presence of the sodium catalyst. Specification of spices benzyl alcohol(QB792-81): the relative density of 1.041-1.046; refractive index of 1.538-1.541; boiling range 203-206℃ and distillate volume more than 95%; dissolving completely in 30 volumes of distilled water; containing more than 98 percent of alcohol; chlorine test (NF) as the side reaction. Raw material consumption quota: benzyl chloride 1600kg/t; soda ash 1000kg/t. 4.Benzyl alcohol exists naturally in orange flower, ylang-ylang, jasmine, gardenia, acacia, lilac and hyacinth. Benzyl chloride or benzaldehyde is used as raw materials to prepare benzyl alcohol in the industry. 5.Add chlorobenzyl to 12% sodium carbonate solution, heat to 93 ℃ and stir for 5h. Then warm the mixture to 101~103℃ and react for 10h. After the reaction, cool Benzyl alcohol to the room temperature, and add salt to saturation. After still standing for stratification, take the upper liquid and get crude products through pressure distillation. Then refine to gain the target products. The yield is 70%～72%.
C6H5CH2Cl+H2O[Na2CO3]→C6H5CH2OH+NaCl+CO2↑ In the presence of sodium hydroxide, formaldehyde and benzaldehyde react to produce benzyl alcohol by disproportionation reaction. C6H5CHO+HCHO[NaOH]→C6h5CH2OH+HCOONa
Preparation Benzyl alcohol is prepared commercially by the distillation of benzyl chloride with potassium or sodium carbonate. Benzyl alcohol may also be prepared by the Cannizzaro reaction of benzaldehyde and potassium hydroxide.
Reactivity Profile Acetyl bromide reacts violently with alcohols or water. Mixtures of alcohols with concentrated sulfuric acid and strong hydrogen peroxide can cause explosions. Example: an explosion will occur if dimethylbenzylcarbinol is added to 90% hydrogen peroxide then acidified with concentrated sulfuric acid. Mixtures of ethyl alcohol with concentrated hydrogen peroxide form powerful explosives. Mixtures of hydrogen peroxide and 1-phenyl-2-methyl propyl alcohol tend to explode if acidified with 70% sulfuric acid. Alkyl hypochlorites are violently explosive. They are readily obtained by reacting hypochlorous acid and alcohols either in aqueous solution or mixed aqueous-carbon tetrachloride solutions. Chlorine plus alcohols would similarly yield alkyl hypochlorites. They decompose in the cold and explode on exposure to sunlight or heat. Tertiary hypochlorites are less unstable than secondary or primary hypochlorites. Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence.
