| Formation of Methylolureas Under Alkaline Condition: A Theoretical Study |
Tao Hong Li1,2, Xiao Guang Xie3 and Guan Ben Du1,* |
1College of Wood Science and Technology, Nanjing Forestry University, Nanjing 210037, P.R. China
2Southwest Forestry University, Kunming 650224, P.R. China
3Department of Chemistry, Yunnan University, Kunming 650091, P.R. China
*Corresponding author: Tel: +86 871 3863472; E-mail: dgb689@swfu.edu.cn |
| Abstract
The base-catalytic reactions between urea and formaldehyde were investigated by using theoretical methods of B3LYP and MP2 with solvent effects included. The urea anion H2NCONH– produced by the reaction of urea with OH– can react with two forms of formaldehyde, CH2O and CH2(OH)2, via nucleophilic addition and SN2 mechanisms, respectively. The addition mechanism is energetically more favourable. The calculated potential energy barriers for the formations of mono-methylolureas (MMU), di-methylolureas (DMU) and tri-methylolureas (TMU) are close, suggesting that the -NH2 and -HN- groups have close reactivity toward formaldehyde or substitutions of methylol groups on urea do not significantly decrease the reactivity of the left reactive positions. Statistical factor may explain the observed lower reactivity of methylolureas than free urea. The steric hindrance is the main factor that rationalizes the absence of tetra-methylolurea in experiment. |
| Keywords
Base-catalytic, Urea, Formaldehyde, Methylolurea, Theoretical. |
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