Benzyl benzoate structure, properties, synthesis, uses

1253
David Holt

The Benzyl benzoate is an organic compound of formula C14H12ORtwo. It appears as a colorless liquid or as a white solid in the form of flakes, with a characteristic weak balsamic odor. This allows benzyl benzoate to be used in the perfume industry as a fixing agent for scents..

It was studied as a medicine for the first time in 1918, and has been on the World Health Organization list of essential medicines ever since..

Source: Jynto [CC0], from Wikimedia Commons

It is one of the most used compounds in the treatment of scabies or scabies. A skin infection caused by the mite Sarcoptes scabei, characterized by severe itching that intensifies at night and can cause secondary infections.

It is lethal to the scabies mite and is also used in pediculosis, a head and body lice infestation. In some countries it is not used as the treatment of choice for scabies due to the irritant action of the compound..

It is obtained by condensing benzoic acid with benzyl alcohol. There are other similar ways of synthesizing the compound. Likewise, it has been isolated in some species of plants of the genus Polyalthia.

Article index

  • 1 Structure of benzyl benzoate
    • 1.1 Interactions
  • 2 Physical and chemical properties
    • 2.1 Chemical name
    • 2.2 Molecular Weight
    • 2.3 Molecular formula
    • 2.4 Physical appearance
    • 2.5 Odor
    • 2.6 Flavor
    • 2.7 Boiling point
    • 2.8 Melting point
    • 2.9 Fire point
    • 2.10 Solubility in water
    • 2.11 Solubility in organic solvents
    • 2.12 Density
    • 2.13 Relative density with water
    • 2.14 Vapor density in relation to air
    • 2.15 Vapor pressure
    • 2.16 Stability
    • 2.17 Auto ignition
    • 2.18 Viscosity
    • 2.19 Heat of combustion
    • 2.20 pH
    • 2.21 Surface tension
    • 2.22 Refractive index
  • 3 Mechanism of action
  • 4 Synthesis
  • 5 Uses
    • 5.1 In the treatment of scabies
    • 5.2 In the treatment of spasms
    • 5.3 As an excipient
    • 5.4 In veterinary hospitals
    • 5.5 Other uses
  • 6 References

Structure of benzyl benzoate

The upper image depicts the structure of benzyl benzoate in a bar and sphere model. The dotted lines indicate the aromaticity of the benzene rings: one from benzoic acid (the left), and the other from benzyl alcohol (the right).

The Ar-COO and H bondstwoC-Ar rotate, causing the rings to rotate on those axes. Beyond these rotations, there are not many that can contribute (at first glance) with its dynamic characteristics; therefore, their molecules find fewer ways to establish intermolecular forces.

Interactions

Thus, it could be expected that the aromatic rings of neighboring molecules do not interact in an appreciable way, nor do these with the ester group due to their difference in polarity (that of the red spheres, R-CO-O-R)..

Also, there is no likelihood of hydrogen bonding on either side of its structure. The ester group could accept them, but the molecule lacks hydrogen donor groups (OH, COOH, or NHtwo) for such interactions to arise.

On the other hand, the molecule is slightly symmetric, which translates into a very low permanent dipole moment; therefore, their dipole-dipole interactions are weak.

And where would the region with the highest electron density be located? In the ester group, although not very pronounced due to the symmetry in its structure.

The intermolecular forces that predominate for benzyl benzoate are dispersion or London forces. These are directly proportional to the molecular mass, and by grouping several of these molecules together, it can be expected that the formation of instantaneous and induced dipoles will occur with greater probability..

All of the above is demonstrated by the physical properties of benzyl benzoate: it only melts at 21 ° C, but in a liquid state it boils at 323 ° C.

Physical and chemical properties

Chemical name

Benzyl benzoate, or benzoic acid methyl ester. In addition, numerous names are assigned due to the manufacturers of the medical product, receiving among them the following: Acarosan, Ascabiol, Benzanil, and Novoscabin.

Molecular weight

212.248 g / mol.

Molecular formula

C14H12ORtwo.

Physical appearance

Colorless liquid or white flake-shaped solid.

Odor

Has a mild balsamic scent.

Taste

Sharp, burning to taste.

Boiling point

323.5 ºC.

Melting point

21 ºC.

Burning point

148 ºC (298 º F).

Water solubility

It is practically insoluble in water (15.4 mg / L).

Solubility in organic solvents

Insoluble in glycerol, miscible with alcohol, chloroform, ether and oils. Soluble in acetone and benzene.

Density

1,118 g / cm3 at 25 ºC.

Relative density with water

1.1 (with a water density of 1 g / cm3).

Vapor density in relation to air

7.31 (air = 1).

Steam pressure

0.000224 mmHg at 25 ºC.

Stability

A 20% benzyl benzoate emulsion prepared in OS emulsifier and wool wax alcohol is stable. Maintains its effectiveness for approximately 2 years.

Auto ignition

480 ºC.

Viscosity

8,292 cPoise at 25 ºC.

Heat of combustion

-6.69 × 109 J / Kmol.

pH

Practically neutral when the pH is estimated by moistening the litmus paper in the compound.

Surface tension

26.6 dynes / cm at 210.5 ºC.

Refractive index

1.5681 at 21 ºC.

Mechanism of action

Benzyl benzoate has toxic effects on the Sarcoptes scabiei mite's nervous system, causing its death. It is also toxic to the mite's eggs, although the exact mechanism of action is unknown..

Benzyl benzoate would act by interrupting the function of voltage-gated sodium channels, causing a prolonged depolarization of the membrane potentials of nerve cells, and the interruption of the functioning of neurotransmitters..

It is pointed out that the selective neurotoxic effect of permethrin (a drug used in scabies) for invertebrates is due to structural differences between the sodium channels of vertebrates and invertebrates.

Synthesis

It is produced by the conjugation of benzyl alcohol and sodium benzoate in the presence of triethylamine. It is also produced by the transesterification of methylbenzoate, in the presence of benzyl oxide. It is a by-product of the synthesis of benzoic acid by oxidation with toluene.

In addition, it can be synthesized by the Tischenko reaction, using benzaldehyde with sodium benzylate (generated from sodium and benzyl alcohol) as a catalyst..

Applications

In the treatment of scabies

The compound has long been used in the treatment of scabies and also pediculosis, being used as a 25% benzyl benzoate lotion. In the treatment of scabies, the lotion is applied to the whole body from the neck down, after a previous cleaning.

When the first application is dry, apply a second coat of the lotion with benzyl benzoate. Its use is considered low risk for adult patients with scabies, and lethal for the mites that produce the disease, which are usually eliminated in five minutes. The use of benzyl benzoate in children is not recommended..

Typically two to three applications of the compound are required to cause skin irritation. An overdose of the compound can cause blisters, hives, or a rash..

There are no usable data on the percutaneous absorption of benzyl benzoate, there are studies that suggest this fact, but without quantifying its magnitude..

The absorbed benzyl benzoate is rapidly hydrolyzed to benzoic acid and benzyl alcohol. This is subsequently oxidized to benzoic acid. Subsequently, benzoic acid is conjugated with glycine to produce benzoylcholine (hipppuric acid), or with glucuronic acid to produce benzoylglucuronic acid..

In treating spasms

Benzyl benzoate has vasodilatory and spasmolytic effects, being present in many medications for the treatment of asthma and whooping cough.

Benzyl benzoate was initially used to treat many conditions that affected people's health, including excessive intestinal peristalsis; diarrhea and dysentery; intestinal colic and enteroespasm; pylorospasm; spastic constipation; biliary colic; renal or urethral colic; urinary bladder spasm.

Also, spasms associated with contraction of the seminal vesicle; uterine cramps in spastic dysmenorrhea; arterial spasm associated with high blood pressure; and bronchial spasm as in asthma. Currently it has been replaced in many of its uses by more effective drugs

As an excipient

Benzyl benzoate is used as an excipient in some testosterone replacement drugs (such as Nebido) in the treatment of hypogonadism..

In Australia, a case of anaphylaxis occurred in a patient under treatment with testosterone replacement drugs, associated with the use of benzyl benzoate.

The compound is used in the treatment of some skin conditions such as ringworm, mild or moderate acne, and seborrhea..

In veterinary hospitals

Benzyl benzoate has been used in veterinary hospitals as a topical miticide, scabicide, and pediculicide. At large doses, the compound can cause hyperarousal, loss of coordination, ataxia, seizures, and respiratory paralysis in laboratory animals..

Other uses

-It is used as repellants for chiggers, ticks and mosquitoes.

-It is a solvent for cellulose acetate, nitrocellulose and artificial musk.

-It is used as a flavoring agent in candy, confectionery, and in chewing gums. In addition, it finds use as an antimicrobial preservative agent..

-Benzyl benzoate is used in cosmetology in the treatment of dry lips, through the use of a cream that contains it in conjunction with petroleum jelly and a perfume.

-It is used as a substitute for camphor in celluloid compounds, plastics and pyroxylin.

-It is used as a dye carrier and plasticizer. Serves as a fragrance fixing agent. Although it is not an active fragrance ingredient, it helps to improve the stability and characteristic odor of the main ingredients..

References

  1. University of Hertfordshire. (May 26, 2018). Benzyl benzoate. Recovered from: sitem.herts.ac.uk
  2. Wikipedia. (2018). Benzyl benzoate. Recovered from: en.wikipedia.org
  3. PubChem. (2018). Benzyl benzoate. Recovered from: pubchem.ncbi.nlm.nih.gov
  4. Cosmetic, Medical and Surgical Dermatology. (2013). Scabies: a review. Recovered from: dcmq.com.mx
  5. Saludmedin.es. (June 30, 2018). Instructions for use benzyl benzoate: emulsion and ointment. Recovered from: saludmedin.es

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