Benzocaine, 4-aminobenzoic acid ethyl ester

Ethyl o-aminobenzoate. See Ethyl anthranilate Ethyl-p-aminobenzoate CAS 94-09-7 EINECS/ELINCS 202-303-5 Synonyms 4-Aminobenzoic acid ethyl ester p-Aminobenzoic acid ethyl ester Benzocaine Benzoic acid, 4-amino-, ethyl ester Benzoic acid, p-amino-, ethyl ester 4-Carbethoxyaniline 4-(Ethoxycarbonyl) aniline Ethylaminobenzoate Ethyl-4-aminobenzoate Ethyl p-aminophenylcarboxylate Ethyl PABA (INCI)... 

SYNS AMERICAINE p-AMINOBENZOIC ACID ETHYL ESTER 4-AMINOBENZOIC ACID ETHYL ESTER ANESTHESIN ANESTHONE BENZOCAINE ETHYL AMINOBENZOATE ETHYL-p-AMNOBENZOATE KELOFORM NORCAIN ORTHESIN PARATHESIN TOPCAINE... 

A chance observation made some time prior to the full structural elucidation of cocaine in fact led to one of the more important lasses of local anesthetics. It was found that the simple ethyl e. ter of p-aminobenzoic acid, benzocaine (25), showed activity. 1-. a local anesthetic. It is of interest to note that this drug, I 1rst introduced in 1903, is still in use today. Once the struc-iiire of cocaine was established, the presence of an alkanolamine iiiniety in cocaine prompted medicinal chemists to prepare esters "I aminobenzoic acids with acyclic alkanolamines. Formula 26 11 presents the putative relationship of the target substances with cocaine. 

A. Ethyl 4-Amino-3-(methylthiomethyl)benzoate [Benzoic acid, 4-amino-3-[(methylthio)methyl]-]. A 1-1., three-necked, round-bottomed flask is fitted with a mechanical stirrer, a condenser topped with a gas-inlet tube, and a two-neckcd adapter holding a low-temperature thermometer and a 100-ml., pressure-equalizing dropping funnel. The flask is charged with 10.50 g. (0.10 mole) of ethyl p-aminobenzoate [Benzocaine Benzoic acid, 4-amino-, ethyl ester] (Note 1), 300 ml. of acetonitrile, and 100 ml. of dichloromethane, is flushed with nitrogen, and is then immersed in a 40% aqueous methanol-dry ice bath maintained between... 

Benzocaine 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]. 

Benzocaine (ethyl / -aminobenzoate), which has a very simple structure, is used as a mild topical anesthetic in ointments for burns, insect bites, and open wounds. Note that procaine and benzocaine are different esters of the same acid, p-aminobenzoic acid. 

It should be mentioned that several more drastic simplifications of cocaine appeared on the scene even earlier. The only survivor is ethyl p-aminobenzoate (benzocaine, Table 13-6, No. 5). The others of interest were methyl p-amino-m-hydroxybenzoate (ortho-form), which, like benzocaine, was nontoxic, highly insoluble, and therefore not suitable for parenteral administration. Orthoform has no activity on intact skin, but it was useful as a powder on painful wounds. It was superseded commercially by the position isomer p-hydroxy-m-aminobenzoate methyl ester for reasons of cost since large-scale production of orthoform (as the pure, correct isomer) presented difficulties at the time. It should be pointed out that water-soluble hydrochlorides of the aminobenzoates can be prepared however, their solutions are much too acidic to inject. 

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