Moreau, Jean et al. published their research in Journal of Labelled Compounds in 1974 | CAS: 20637-09-6

Methyl 4-(4-aminophenyl)butanoate (cas: 20637-09-6) belongs to esters. Esters are also usually derived from carboxylic acids. It may also be obtained by reaction of acid anhydride or acid halides with alcohols or by the reaction of salts of carboxylic acids with alkyl halides. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are common in organic chemistry and biological materials.Computed Properties of C11H15NO2

Synthesis of carbon-14-labeled p-[N,N-bis(2-chloroethyl)aminophenyl]butyric acid was written by Moreau, Jean;Madelmont, Jean C.. And the article was included in Journal of Labelled Compounds in 1974.Computed Properties of C11H15NO2 This article mentions the following:

p-(ClCH2CH2)2-NC6H4(CH2)3CO2H is labeled with 14C on 3 different positions: on the carbon bearing the carboxylic function by means of K14CN; uniformly on the 4 carbons of the 2 chloroethyl groups by means of labeled ethylene oxide; on the vicinal carbon of the carboxylic function by means of K14CN. In the experiment, the researchers used many compounds, for example, Methyl 4-(4-aminophenyl)butanoate (cas: 20637-09-6Computed Properties of C11H15NO2).

Methyl 4-(4-aminophenyl)butanoate (cas: 20637-09-6) belongs to esters. Esters are also usually derived from carboxylic acids. It may also be obtained by reaction of acid anhydride or acid halides with alcohols or by the reaction of salts of carboxylic acids with alkyl halides. Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are common in organic chemistry and biological materials.Computed Properties of C11H15NO2

Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics