The reaction mechanism for synthesizing dibutyl toluene-2,4-dicarbamate (BTDC) catalyzed by γ-Al₂O₃ from toluene-2,4-diamine, urea, and n-butyl alcohol has been investigated by means of Fourier transform infrared spectroscopy, liquid chromatograph–mass spectrometry, and experimental observations. The results show that (1) the nitrogen atom of C═NH in the tautomer of urea is absorbed on the acidic site of γ-Al₂O₃, causing the carbon atom to be charged more positively; (2) toluene-2,4-diamine as a nucleophilic reagent attacks the positively charged carbon atom of C═NH to produce an intermediate, 3-amino-4-methyl phenylurea or 2-methyl-5-amino phenylurea (TU); (3) a nucleophilic C₄H₉O^– coming from an n-butyl alcohol molecule attacks the ureido carbon atom in a TU molecule to generate another intermediate, butyl 3-amino-4-methyl-N-phenyl carbamate or butyl 2-methyl-5-amino-N-phenyl carbamate (TMC); and (4) another −NH₂ group in a TMC molecule follows the same steps as mentioned above, and then BTDC is obtained.

中文翻译：

---

机构用于经由尿素路线催化二丁基甲苯-2,4-二氨基甲酸酯的合成的γ-Al ₂ ö ₃

通过催化的γ-Al合成二丁基甲苯-2,4-二氨基甲酸酯（BTDC）的反应机理₂ ö ₃从甲苯-2,4-二胺，脲和Ñ丁基醇已由变换红外光谱的傅立叶方法研究，液相色谱-质谱和实验观察。结果表明：（1）C═NH的尿素的互变异构体的氮原子被吸收上的酸性部位的γ-Al ₂ ö ₃，使其得到多个带正电荷的碳原子; （2）甲苯-2,4-二胺作为亲核试剂攻击C═NH的带正电荷的碳原子，生成中间体3-氨基-4-甲基苯基脲或2-甲基-5-氨基苯基脲（TU）；（3）亲核的C ₄ H₉ ø ^-从一个未来Ñ丁基醇分子攻击的脲基的碳原子在一个TU分子，以产生另一个中间，丁基3-氨基-4-甲基- ñ -苯基氨基甲酸酯或丁基2-甲基-5-氨基- ñ -氨基甲酸苯酯（TMC）; （4）TMC分子中的另一个-NH ₂基团按照与上述相同的步骤，得到BTDC。