Behavior Of Glycerol Nitration Reaction At Hydro-Dynamically Stable Condition

Title:

Behavior Of Glycerol Nitration Reaction At Hydro-Dynamically Stable Condition

Budi Santoso¹⁾, ING Wardana¹⁾, Akhmad Sabarudin²⁾, Nurkholis Hamidi ¹⁾

¹⁾ Department of Mechanical Engineering, Faculty of Engineering, Brawijaya University, Jl. Veteran Malang, Jawa-Timur, Indonesia

²⁾ Department of Chemistry, Faculty of Science, Brawijaya University, Jl. Veteran Malang, Jawa-Timur, Indonesia

^*To whom correspondence should be addresses:

E-mail: wardana@ub.ac.id (ING Wardana)

Phone:+62-341-551430

ABSTRACT

The behavior of glycerol nitration reaction due to the different reactant fluid density was observed in the hele-shaw cell (HSC). The experiment was conducted in three procedures of hydrodynamically stable reactants by altering their positions. The molar ratio of reactants was fixed as follows: C₃H₅(OH)₃ : HNO₃ : H₂SO₄  = 3.33 :10 :18.01. For the procedure 1, HNO₃ was placed in the upper and the mixture of C₃H₅(OH)₃-H₂SO₄ was in the lower part, whereas in the procedure 2,  the mixture of C₃H₅(OH)₃-HNO₃ was conceived in the upper part and H₂SO₄ was in the lower part,  and in the procedure 3, C₃H₅(OH)₃ was in the upper and the mixture of H₂SO₄-HNO₃ was in the lower part.

The result showed that the reaction mechanism is mainly determined by the relative density of the product to reactant, and the formation of a radical ion as well as a reactive intermediate. When the density of the product is smaller than the reactant in lower part of HSC, but larger than the reactant in upper part as in the procedure 2, the product formed at the boundary of two reactant positions hinders further reaction, preventing a complete reaction. However, when the density of product is heavier than the reactant in lower part of HSC, the product moves downward and induces natural convection, which accelerate reaction rate through two mechanisms. The first mechanism is dealing with the formation of reactive intermediate of C₃H₅(OSO₃H)₃ in lower part of HSC as in the procedure 1. This intermediate generates fast reaction, which is indicated by hastily propagation of the reaction front following the downward motion of the product. The second mechanism is through the formation of NO₂⁺ (nitronium ion) and water in the lower part of HSC as in the procedure 3. The existence of water reduces effectiveness of NO₂⁺ along with the dilution of an upper reactant, resulting in slow reaction rate with unclear reaction front. Such result reveals that the formation of C₃H₅(OSO₃H)₃ intermediate is more effective than NO₂⁺ for glycerin nitration reaction.

Keywords: glycerol nitration, hele-shaw cell, nitronium ion, hydrodynamics