US EPA

7419206 

Journal Article 

Mechanism for Synthesis of Dibutyl Toluene-2,4-Dicarbamate via Urea Route Catalyzed by gamma-Al2O3 

Wang, G; Li, Xin; Wang, Y; Zhao, X 

2014 

Yes 

Industrial and Engineering Chemistry Research
ISSN: 0888-5885
EISSN: 1520-5045 

AMER CHEMICAL SOC 

WASHINGTON 

53 

6 

2130-2136 

English 

10.1021/ie403325j 

WOS:000331343600007 

https://pubs.acs.org/doi/10.1021/ie403325j
Exit
 

The reaction mechanism for synthesizing dibutyl toluene-2,4-dicarbamate (BTDC) catalyzed by gamma-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 gamma-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.