Sodium Ethoxide Concentrated Solution Synthesis at Ambient Temperature Using Sodium Hydroxide and Ethanol-90 in Excess

: Sodium ethoxide is a specific chemical product of synthesis used in laboratory, thus its presence at the suppliers stays very periodic and on order. It was in that sense that this project to synthesize a concentrated solution of sodium ethoxide got off at ambient temperature, under normal atmospheric pressure in an uncovered beaker using ethanol 90% of purity and sodium hydroxide 99% of purity seeing that the ethanol molecules were in excess in comparison with sodium hydroxide molecules which quantities were all soluble in ethanol. The initial calculated pH was equal to 15.23. In addition, not only an extraction procedure of the concentrated sodium ethoxide was done but also a titration procedure of the concentrated sodium ethoxide solution by hydrochloric acid HCl-0.1N was established and permitted to evaluate kinetic parameters of this synthesis reaction on these experimental conditions. The evaluated molar conversion from the initial quantities of sodium hydroxide was 88.49% after 3h25mn of reaction. It was noticed that the formation of sodium ethoxide was initially very important and very speed confirming the negativity of its standard molar enthalpies. Thus, the initial speed formation of synthesized sodium ethoxide was approximately equal to 0.013 [[mol×l -1 ×s -1 ]. Once synthesized, the total crystallization of the concentrated sodium ethoxide was tried with an evaluation of its porosity by immersion in dichloromethane giving a value in the order of 54.60%.


Introduction
In the first time, laboratory synthesis of concentrated solution of sodium ethoxide was done using an excess of ethanol (90% of purity) in comparison with sodium hydroxide which were completely soluble in the used ethanol volume. Laboratory materials and chemicals used during this synthesis were beaker-250ml, water bath Büchi B-480, rotavapor Büchi, magnetic stirrer-Fischer scientific, proofer, crystallizer, syringe, test tube-100ml, test tube-50ml, burette-50ml, thymol blue indicator dye, sodium hydroxide 99%, ethanol 90%. Then, the amount of sodium hydroxide molecules of the concentrated solution was determinated by titration with hydrochloric acid HCl-0.1N using a burette-50ml and indicator dye thymol blue according to a procedure described afterwards. Finally, a total crystallization of the synthesized concentrated solution of sodium ethoxide was tried and the crystallized sodium ethoxide porosity was evaluated by submerging 0.0174 [g] in 15 [ml] of dichloromethane during 150 minutes.

Experimental Conditions of Sodium Ethoxide-C 2 H 5 ONa Synthesis
The raw materials used to synthesize the sodium ethoxide (C 2 H 5 ONa) were ethanol 90° and sodium hydroxide 99% (NaOH) such as the ethanol was in excess compared to sodium ethoxide. Indeed, as shown in the following table 1, the molar ratio of ethanol divided by sodium hydroxide-NaOH was equal to 5.18. On this experimental conditions, all used NaOH-raw material were soluble in C 2 H 5 OH-90°-raw material during synthesis seeing that the sodium hydroxide solubility in ethanol was 139 [g/l] [1][2][3][4][5], so the raw materials collisions certainly increased efficiently. In addition, the calculated pH of the solution were 15.23 and the recorded pH of the solution after one minute of mixing were 11.48 seeing that it was composed with two strong bases such as the ethanol was in excess compared to sodium ethoxide [6][7]. Noticed that this pH=11.48 of the solution only after one minute of reaction (Table 1) was already in the vicinity of a sodium ethoxide-20% solution in ethanol pH for synthesis [8].  [9][10] seeing that the synthesis of sodium ethoxide using NaOH and alcohol-ROH (R=-C 3 H 7 , -C 4 H 9 , -C 5 H 11 ) was done by Vacek et al. at 1984 [11]. When the reaction time was achieved, remove the beaker-250 [ml] from the magnetic stirrer to put it over a water bath less than 288.15°C to freeze and to stop the reaction during 15 minutes. Then, a homogeneous oily solution like a detergent was obtained above with a constant refractive index 1.3765 superior than the refractive index at 20°C of the ethanol solution (100% concentration -w/w(%)) equals to 1.3614 at 100-w/w(%), 1.3425 at 14-w/w(%) and 1.3652 at 70-w/w(%) [12]. This oily solution slightly yellow in contact with a paper was a concentrated solution of sodium ethoxide-C 2 H 5 ONa synthesized which density was 0.88 [g.cm -3 ] [8]. Once synthesized, recorded the synthesized volume (V C2H5ONa ) which amount of sodium ethoxide was defined by titration with hydrochloric acid 0.1N inspired by bibliography [13]. Noticed that all the synthesis was at ambient temperature, under atmospheric pressure and the beaker wasn't covered up. After titration, the synthesized solution of sodium ethoxide-C 2 H 5 ONa was transferred in a glass sealed container, then maintained, decanted and crystallized in a freezer to increase the separation between water/non-transformed NaOH (at the bottom) and sodium ethoxide-C 2 H 5 ONa synthesized (upstairs) during approximately 24 hours. It was noticed that the solution became more slimy with formation of little sodium ethoxide-C 2 H 5 ONa crystals and may be eventually little unreacted NaOH crystals at the bottom. Finally, the slimy concentrated sodium ethoxide-C 2 H 5 ONa solution was transferred and separated from the bottom solution with the rest of the NaOH. The synthesized white slimy concentrated sodium ethoxide-C 2 H 5 ONa solution was stored in a freezer.

Titration Procedure of Sodium
Ethoxide-C 2 H 5 ONa Solution with Hydrochloric Acid 0.1N As said previously, the synthesized sodium ethoxide solution was decanted over a water bath less than 288.15°C to freeze and to stop the reaction during 15 The concentration of sodium ethoxide-C 2 H 5 ONa in the synthesized solution was The total moles-quantities in the synthesized volume V was The molar yields of this reaction compared with the initial moles-quantities of NaOH was

Progress Reaction and Kinetical Studies of This Sodium Ethoxide-C 2 H 5 ONa Solution Reaction Synthesis
As previously said in the introduction, the chemical equation of this sodium ethoxide-C 2 H 5 ONa solution synthesis was Thus, speed of this reaction equals to = C × C * H -OH × NaOH Yet, under this experimental condition, the ethanol moles-quantities was in excess compared with sodium hydroxide moles-quantities and assuming that the reactional volume was constant during the synthesis-reaction. Indeed Such as and α the reaction order Kinetically, As previously mentioned, it was assumed that this reaction synthesis occurred at constant reactional volume to facilitate its approximate speed constant calculations. Thus, The following table 2 showed the progress of this reaction, Incorporate X=( I? −∝) so Resolving this equation conducted to Such as K is a constant At initial time t=0, α=0. So, X= I? and K = -Ln( I? ) The equation (17)  and its slope gave the observed speed constant C Secondly, assuming that the reaction was the first order, the equation (12) In the other words, if this reaction is second order compared with sodium hydroxide-NaOH, the following equation (28) must be a straight line according to time t And its slope gave the observed speed constant C

Experimental Results and Discussions of This Sodium Ethoxide-C 2 H 5 ONa Solution Reaction Synthesis -Speed Constant Determination
The initial conversion was higher ( Figure 1) and confirmed not only the negative value of sodium alkoxides formation standard molar enthalpies [9][10] and consequently the observed exothermic and instantaneous of reaction between the raw materials NaOH and alcohol-ethanol in excess but also the efficacy of the experimental pH which was calculated in the vicinity of 15.23 and observed at 11.48 after one minute of reaction. Drawing the curves of Ln(   Seeing that the (R 2 ) of these figures 2 and 3 were in the vicinity of 0.60 and seeing also the conversion evolution ( Figure 1) such as the moles quantities of solvent-reagent ethanol molecules were in excess compared with sodium hydroxide molecules but noticed that the figure 3 have an interception with the origin \(0,0) higher (R 2 = 0.2922) than the figure 2 (R 2 = -0.453); it was more adequate to affirm that according these results and the experimental conditions (Table  1), this reaction between ethanol and sodium hydroxide was second order compared with the sodium hydroxide concentration ( Figure 2). Thus, the equation (  Noticed that, initially from zero second to 90 seconds, this concentration evolution could be equivalent to the following figure 5 from which it could be evaluated the initial concentration evolution of the synthesized sodium ethoxide in the solution with time reaction. In the other words, the initial speed formation of synthesized sodium ethoxide was equal to 0.013 [[mol×l -1 ×s -1 ].

Conclusion
The synthesis of the concentrated solution of sodium ethoxide in the order of 2.6 [mol.l -1 ] with 1.3765 refractive index was performed at ambient temperature, under normal atmospheric pressure and in open air from sodium hydroxide 99% and ethanol 90% in excess such as the molar ratio between these two raw materials were 5.18 and the initial calculated pH was equal to 15.23. The titration procedure of the sodium ethoxide using hydrochloric acid 0.1N was successful and permitted not only to draw the conversion evolution curve in accordance with time and but also to establish this synthesis kinetic parameters according to these experimental conditions such as the sodium hydroxide partial order was equals to one, the speed constant was equal to 1.28×10 -5 [s -1 ]. Finally, the total crystallization of the concentrated sodium ethoxide solution was tried in which instead of directly put under a rotavapor to remove ethanol, this solution was heated and agitated in a water bath at 323.15 [°K] during 3h30minutes in open air; it turned to yellow then brown with just maximally 2 [ml] volume diminution and its refractive index stayed 1.3760. Thereafter, it was stored with a hermetic box in a freezer for 16 hours and only now it was evaporated under pressure at 313. 15 [°K] using a rotavapor to remove ethanol. White and brown sodium ethoxide crystals were obtained and then dehydrated in a proofer during at least 15 hours. In addition, the sodium ethoxide crystals were stored in the proofer at 333. 15