Ethyl N-phenylformimidate

ETHYL N-PHENYLFORMIMIDATE (Forxnimidic acid, N-phenyl-, ethyl ester) 

Submitted by Royston M. Roberts and Paul J. Vogt.1 Checked by T. L. Cairns and J. J. Drysdale. 

A 500-ml. flask is equipped with a capillary through a side opening, and 94 g. (1.01 moles) of aniline and 1 ml. of concentrated hydrochloric acid are added. A 12-in. glass-helix-packed column is attached (Note 1), and the water introduced with the acid is removed by boiling about 1 ml. of aniline is collected after the water has distilled. The flask and its contents are then cooled to room temperature, and 222 g. (1.50 moles) of ethyl orthoformate is added. The column is reattached, and ethanol (Note 2) is distilled as it is produced the theoretical amount (92 g., 116 ml.) is obtained in about 2.25 hours. 

A Vigreux column may also be used since it is not difficult to separate the ethanol from ethyl orthoformate, the next most volatile component present. A total reflux, partial take-off head was used. Heat was supplied by an electric mantle the column was heated with a glass-covered heating tape during the distillation of excess ethyl orthoformate and product. 

A small amount (5-10 ml.) of lower-boiling material usually comes over before the ethanol this is probably ethyl formate, produced by hydrolysis of the ethyl orthoformate. 

---

Ethyl N-phenylformimidate has been prepared from silver formanilide and ethyl iodide,4 and from aniline and ethyl orthoformate.3 This method incorporates the discovery2 of the necessity of acid catalysis for satisfactory yields by the latter process. 

Ethylphenyldichlorophosphine, 31, 89 Ethyl N-phenylformimidate, 35, 65 Ethyl phenylpropiolate, 32, 75 Ethyl phosphite, 31, 111 Ethyl pyruvate, 31, 59 Ethyl stearate, 34,13 1-Ethynylcyclohexanol, 35, 2... 

Reaction with primary arylamines. Investigations of Wichelhaus and of Claisen of the reaction of aniline with triethyl orthoformate were later clarified by Roberts and Vogt, who showed that by adjustment of the catalyst and the experimental conditions it is possible to produce in good yield any one of three products from the two reactants. The initial product in each use is ethyl N-phenylformimidate (1). 

Ethyl N-phenylformimidate heated with 2 moles of y ,7-dimethylallyl alcohol while the ethanol formed is distilled off through a glass helices-packed column -> / ,y-dimethylallyl N-phenylformimidate. Y 83%. F. e. s. R. M. Roberts and F. A. Hussein, Am. Soc. 82, 1950 (1960). 

Dihydroresorcinol and ethyl N-phenylformimidate heated 1 hr. at 130° then 10 min. at 140-150° with continuous distillation of the resulting alcohol 2-(N-phenylformimidoyl) cyclohexane-1,3-dione (Y 85%) refluxed 1.5 hrs. with phenylhydrazine in ethanol 2-phenylhydrazonomethylcyclohexane-1,3-dione (Y 81%) refluxed 1 hr. with a little p-toluenesulfonic acid in benzene with azeotropic water entrainment 4-oxo-l-phenyl-4,5,6,7-tetrahydroindazole (Y 86%) (startg. m. f. 924). F. e. s. G. Lehmann, H. Wehlan, and G. Hilgetag, B. 100, 2967 (1967). 

---