1: [3H]-2,4-Dichlorophenoxyacetic acid With benzotriazol-1-ol; N'-(3-dimethylaminopropyl)-N-ethylcarbodiimide in chloroform T=20°C; 0.5 h; Inert atmosphere; 2: tert-butyl alcohol With 4-(N,N-dimethlyamino)pyridine in chloroform 18 h; Inert atmosphereReflux;