Research On Phosphorus Oxychloride-Catalyzed Aniline N-Alkylation

Alkylation of arylamines is one of the important technics to synthesize fine chemicals, there are many synthetic routes and methods. N-alkyl arylamines and there derivatives are important intermediates in the production of dyes, pharmaceuticals, pesticides, petrochemicals and so on. It currently still one of the hot direction of synthetic study. In this study, we have summarized previous work, in view of aniline can not completely transformed in the reaction system of"aniline + ethanol + phosphorus oxychloride", through the optimization of reaction process, make aniline completely transformed, eventually N-ethyl aniline and N, N-diethyl aniline were synthesized. In a certain extent, reduced the production cost and improved the economic benefit. In view of the above question, the main content of this paper is as follows:1. Establishment of reaction atmosphereAccording to a lot of literature reports, Aromatic amine N-alkylation reaction using alcohols compounds as alkylating agent always under reduction atmosphere, but the reaction system of"aniline + ethanol + phosphorus oxychloride"can not acquire well result. In consideration of the oxidability of phosphorus oxychloride, we adopted nitrogen as shielding gas, reacted under inert atmosphere. The result showed that inert atmosphere greatly improved aniline conversion. Therefore, this paper confirmed nitrogen as shielding gas for experiment.2. Synthesis of N-ethyl aniline and N, N-diethyl anilineUsing phosphorus oxychloride as a catalyst, aniline reacted with ethanol, the optimal reaction condition as follows: V (aniline) : V (ethanol) : V (phosphorus oxychloride) = 55 : 70 : 2, reaction temperature 493 K, N2 pr- essure 4.0 MPa, reaction time 8 h. N, N-diethyl aniline yield of 67.82% with the total yield of N-ethyl aniline and N, N-diethyl aniline of 95% was obtained while the conversion of aniline was 100%.3. Influence of different additives on the reactionThanks toγ-Al₂O₃ and ZSM-5 are good N-alkylating catalyst, so we addedγ-Al₂O₃ and ZSM-5 to the reaction system of"aniline + ethanol + phosphorus oxychloride"separately. Well reaction result was acquired uneder the optimal reaction condition as follows: V (aniline) : V (ethanol) : V (phosphorus oxychloride) : m(γ-Al₂O₃)= 55 : 70 : 2 : 3, reaction temp- erature 493 K, N2 pressure 4.0 MPa, reaction time 8 h. N-ethyl aniline yield of 79.26% with the total yield of N-ethyl aniline and N, N-diethyl aniline of 98% was obtained while the conversion of aniline was 100%.