SciELO - Scientific Electronic Library Online

 
vol.13 número2Asymmetric Synthesis of exo-Isobrevicomin and exo-Brevicomin via Conjugated Addition of Primary Alkyl Iodides to alpha,beta-Unsaturated KetonesGround-State Diffuse Reflectance and Laser-Induced Luminescence on the Evaluation of Total PAHs in Urban Air Particulate Matter from Rio de Janeiro City in Brazil índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Journal of the Brazilian Chemical Society

versão impressa ISSN 0103-5053

Resumo

BERTRAN, Celso A.; CIRINO, José J. V.  e  FREITAS, Luiz C. G.. Theoretical Studies of Concentrated Aqueous Urea Solutions Using Computacional Monte Carlo Simulation. J. Braz. Chem. Soc. [online]. 2002, vol.13, n.2, pp. 238-244. ISSN 0103-5053.  http://dx.doi.org/10.1590/S0103-50532002000200016.

Monte Carlo simulations were carried out for concentrated aqueous urea solutions at 4, 5, 6, 7 and 8 mol L-1 in the NpT ensemble at 298 K and 1 atm. The potential energy surfaces were represented by the sum of Coulomb and Lennard-Jones potentials in which pair-wise additivity was considered. Water was described by the TIP4P model, while urea was described by the OPLS planar model and also by a proposed non-planar model. The simulation results for both urea models showed that urea does not induce any significant changes in the structure of water over all the concentrations studied. However, it was noted that the number of hydrogen bonds between the water molecules decrease as the concentration increases. The simulation results of the OPLS planar model suggest the formation of urea dimers in the more concentrated solutions. The simulations with the non-planar model showed several features similar to those of the OPLS planar model.

Palavras-chave : urea; Monte Carlo; liquid simulation.

        · resumo em Português     · texto em Inglês     · pdf em Inglês