94-09-7 Usage
Description
Benzocaine, also known as ethyl p-aminobenzoate, is a lipophilic local anesthetic agent of the ester type with a short duration of action and poor solubility in water. It is used topically by itself or in combination with other ingredients in nonprescription dosage forms to relieve pain or irritation caused by various conditions.
Used in Pharmaceutical Industry:
Benzocaine is used as a local and topical anesthetic for products such as burn and sunburn remedies, hemorrhoidal creams, suppositories, creams for treatment of poison ivy, oral and gingival products, sore-throat sprays/lozenges, astringents, appetite suppressants, callus and wart remedies, athlete's-foot remedies, toothacheand denture-irritation products.
Used in Veterinary Medicine:
Benzocaine is used in cattle, sheep, swine, and horses for local and prolonged low epidural anesthesia. It is also used as a surface anesthetic in ointments for wounds and ulcerated surfaces in these animals, applied twice a day until healing.
Used in Topical Pain Relief:
Benzocaine is used as a commonly used topical pain reliever and as the main active ingredient in anesthetic ointments. It acts as a Na+ channel blocker, preventing the generation and conduction of nerve impulses by decreasing or preventing the large transient increase in the permeability of excitable membranes to Na+.
Used in Combination with Menthol or Phenol:
Benzocaine is used topically in combination with menthol or phenol in nonprescription dosage forms such as gels, creams, ointments, lotions, aerosols, and lozenges to provide pain or irritation relief caused by conditions like sunburn, insect bites, toothache, teething, cold sores or canker sores in or around the mouth, and fever blisters.
Indications and Usage
Benzocaine is a colorless trapezial crystal. Its melting point is 92℃ (88-90℃), boiling point is 183-184°C (1.87kPa). 1g of this drug is soluble in about 2500ml water, 5ml ethanol, 2ml chloroform, 4ml ether or 30-50ml almond oil and olive oil, and it is also soluble in dilute acid. It is stable in air, odorless, and slightly bitter.
Benzocaine is a lipid-soluble surface anesthetic, and it weaker than other local anesthetics such as lidocaine and tetracaine, so it will not cause any discomfort due to its anesthetizing effects when acting on mucosa. Benzocaine is a type of drug with relatively strong lipid-solubility and will bind with mucosa and the fatty layer of skin, but it will not easily penetrate into the body and cause poisoning. Benzocaine can be used as a precursor for Ossur imitation, orthocaine, and procaine. It is also used as a local anesthetic and can stop pain and itching. It is mainly used in pain and itch prevention on wounds, ulcer surfaces, mucous membrane surfaces and hemorrhoids. Its paste form can also lubricate and stop pain for the nasopharynx and endoscope. Benzocaine’s aural solution is used to alleviate acute congestion, concentrated otitis externa, and the pain and itching of swimming otitis. Benzocaine is also effective for toothaches, sore throat, oral ulcers, all kinds of hemorrhoids, anal fissures, and vulvar itching. Benzocaine can be used as a male sex organ numbing agent to slow ejaculation. It can also be used as a numbing lubricant for the pharynx and endoscope, and it can be used as a UV absorbing agent for cosmetics.
synthesis
Benzocaine is produced by reduction of ethyl 4-nitrobenzoate with iron or by the acid-catalyzed esterification of 4-aminobenzoic acid with ethanol:In a 5-mL round bottom flask, add 120 mg of 4-aminobenzoic acid (often called PABA for paminobenzoic acid), 1.5 mL of absolute ethanol (absolute ethanol is completely free of water and can be found on the hooded shevles), and 3 boiling chips. Heat this mixture on a sand bath until all the solid dissolves. Cool in ice and then add 0.25 mL of concentrated sulfuric acid dropwise. (One drop at a time.) A large amount of precipitate will form when the sulfuric acid is added, but this will dissolve during the reflux that follows. Attach an air condenser from the microscale kit, and reflux gently for 60- 75 min. Check periodically to be sure that the mixture is refluxing gently, and that the ring of condensation of solvent lies somewhere along the inner surface of the air condenser; loss of solvent will cause overheating and a significant decrease in yield.
Biological Functions
Benzocaine is a PABA derivative used primarily for
topical application to skin and mucous membranes. Its
low aqueous solubility allows it to stay at the site of application
for long periods. Its minimal rate of absorption
after topical administration is associated with a low incidence
of systemic toxicity. Benzocaine is contraindicated
in patients with known sensitivity to ester-linked
anesthetics or PABA-containing compounds.
Synthesis Reference(s)
Journal of the American Chemical Society, 71, p. 4154, 1949 DOI: 10.1021/ja01180a513Chemical and Pharmaceutical Bulletin, 29, p. 1443, 1981 DOI: 10.1248/cpb.29.1443
Biochem/physiol Actions
Benzocaine is the ethyl ester of p-aminobenzoic acid (PABA). Benzocaine acts to inhibit the voltage-dependent sodium channels (VDSCs) on the nerve membrane, stopping the propagation of the action potential.
Clinical Use
Benzocaine is used for endoscopy, bronchoscopy, and topicalanesthesia. Benzocaine is available as a 20% solution topicalspray, in a 1% gel for mucous membrane application, and a14% glycerin suspension for topical use in the outer ear.Toxicity to benzocaine can occur when the topical doseexceeds 200 to 300 mg resulting in methemoglobinemia.Infants and children are more susceptible to this and methemoglobinemiahas been reported after benzocaine lubricationof endotracheal tubes and after topical administration to treata painful diaper rash.
Safety Profile
Poison by ingestion and
intraperitoneal routes. Human systemic
effects by rectal route:
methemoglobinemia/carboxyhemoglobinem
ia in infants. A skin irritant and a mild
sensitizer. Local contact may cause contact
dermatitis. Used as a topical anesthetic and
as a sun-screening agent. When heated to
decomposition it emits highly toxic fumes of
NOx. See also ETHYL ALCOHOL and
ESTERS
Synthesis
Benzocaine is the ethyl ester of 4-aminobenzoic acid (2.3.1). The classic,
optimal way of benzocaine synthesis is the reduction of the nitro group of the ethyl ester
of 4-nitrobenzoic acid to benzocaine by hydrogen, which generates directly in the reaction
medium by the reaction of iron filings with dilute acids [24–26].
Purification Methods
Crystallise Benzocaine from EtOH/H2O or EtOH (m 93-94o), and dry it in air. [Beilstein 14 H 422, 14 IV 1129.]
Structure and conformation
Ethyl aminobenzoate, a para-aminobenzoate derivative (PABA)
Check Digit Verification of cas no
The CAS Registry Mumber 94-09-7 includes 5 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 2 digits, 9 and 4 respectively; the second part has 2 digits, 0 and 9 respectively.
Calculate Digit Verification of CAS Registry Number 94-09:
(4*9)+(3*4)+(2*0)+(1*9)=57
57 % 10 = 7
So 94-09-7 is a valid CAS Registry Number.
InChI:InChI=1/C9H11NO2/c1-2-12-9(11)7-3-5-8(10)6-4-7/h3-6H,2,10H2,1H3/p+1
94-09-7Relevant articles and documents
Metal-free organic dyes containing thiadiazole unit for dye-sensitized solar cells: A combined experimental and theoretical study
Siva Kumar, Gangala,Srinivas, Kola,Shanigaram, Balaiah,Bharath, Dyaga,Singh, Surya Prakash,Bhanuprakash,Rao, V. Jayathirtha,Islam, Ashraful,Han, Liyuan
, p. 13172 - 13181 (2014)
We have designed and synthesized four new metal free D-A-π-A type dyes (9-12) with variations in their acceptor/anchor groups. The four dyes carry tert-butyl substituted triphenylamine as donor, thiadiazole as acceptor and bithiophene as π-spacer. Cyanoacetic acid, rhodanine-3-acetic acid, 2-(4-methoxyphenyl)acetic acid and 2-phenylacetic acid are used as acceptor/anchor groups, respectively in the dyes 9-12. The acceptor/anchor effect on their photophysical, electrochemical and photovoltaic properties was investigated. The dyes exhibited good power conversion efficiency ranging from 1.95-4.12%. Among the four dyes, 9 showed the best photovoltaic performance: short-circuit current density (Jsc) of 8.50 mA cm-2, open-circuit voltage (Voc) of 645 mV and fill factor (FF) of 0.75, corresponding to an overall conversion efficiency of 4.12% under standard global AM 1.5 solar light conditions. This journal is the Partner Organisations 2014.
Hydrogenation of ethyl p-nitrobenzoate on carbon-supported palladium-triphenylphosphine catalyst
Obraztsova,Efimov
, p. 511 - 512 (2004)
Hydrogenation of ethyl p-nitrobenzoate on carbon-supported palladium-triphenylphosphine catalyst at 40°C and atmospheric pressure of H2 was studied.
-
Gavrilin et al.
, (1968)
-
Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
supporting information, p. 1618 - 1629 (2021/01/25)
Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
Design, synthesis, in vitro and in vivo evaluation against MRSA and molecular docking studies of novel pleuromutilin derivatives bearing 1, 3, 4-oxadiazole linker
Liu, Jie,Zhang, Guang-Yu,Zhang, Zhe,Li, Bo,Chai, Fei,Wang, Qi,Zhou, Zi-Dan,Xu, Ling-Ling,Wang, Shou-Kai,Jin, Zhen,Tang, You-Zhi
, (2021/05/17)
A class of pleuromutilin derivatives containing 1, 3, 4-oxadiazole were designed and synthesized as potential antibacterial agents against Methicillin-resistant staphylococcus aureus (MRSA). The ultrasound-assisted reaction was proposed as a green chemistry method to synthesize 1, 3, 4-oxadiazole derivatives (intermediates 85–110). Among these pleuromutilin derivatives, compound 133 was found to be the strongest antibacterial derivative against MRSA (MIC = 0.125 μg/mL). Furthermore, the result of the time-kill curves displayed that compound 133 could inhibit the growth of MRSA in vitro quickly (- 4.36 log10 CFU/mL reduction). Then, compound 133 (- 1.82 log10 CFU/mL) displayed superior in vivo antibacterial efficacy than tiamulin (- 0.82 log10 CFU/mL) in reducing MRSA load in mice thigh model. Besides, compound 133 exhibited low cytotoxicity to RAW 264.7 cells. Molecular docking studies revealed that compound 133 was successfully localized in the binding pocket of 50S ribosomal subunit (ΔGb = -10.50 kcal/mol). The results indicated that these pleuromutilin derivatives containing 1, 3, 4-oxadiazole might be further developed into novel antibiotics against MRSA.