Comment by no1uno
I honestly suspect that those latest compounds, the anthrecenes, may well avoid the application of the analogue acts, they are neither structurally similar to anything that is illegal, and NOBODY would be dumb enough to represent it as having similar properties, would they?
High-Yield Synthesis of Dimethyl Carbonate from Urea and Methanol Using a Catalytic Distillation Process
Mouhua Wang, Hui Wang, Ning Zhao, Wei Wei, and Yuhan Sun
Ind. Eng. Chem. Res. 2007, 46 (9), pp 2683–2687
DOI: 10.1021/ie061101u
Abstract
Reaction equilibrium for the dimethyl carbonate (DMC) synthesis from urea and methanol was calculated based on the Benson method, and results showed that the reaction was thermodynamically unfavorable. In addition, urea methanolysis was conformed to be a consecutive reaction. Major side reactions in the DMC synthesis included the thermal decomposition of DMC and reaction between methyl carbamate (MC) and DMC, which reduced the DMC yield in the batch process. A catalytic distillation technique was proposed in this study to minimize the side reactions and unfavorable equilibrium for DMC synthesis. The DMC yield reached 60?70% in the catalytic distillation reactor over a Zn-based catalyst.
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Modeling of the Catalytic Distillation Process for the Synthesis of Dimethyl Carbonate by Urea Methanolysis Method
Feng Wang, Ning Zhao, Junping Li, Wenbo Zhao, Fukui Xiao, Wei Wei, and Yuhan Sun
Ind. Eng. Chem. Res. 2007, 46 (26), pp 8972–8979
Abstract
A nonequilibrium model of the catalytic distillation was developed for the process of DMC synthesis by a urea methanolysis method over a solid base catalyst at the bench scale, and the Wilson model was used to account for the nonideality of the liquid phase. The superiority of the catalytic distillation on the removal of the products to restrain the reverse reaction was illustrated in the present work. Furthermore, the influence of total pressure and the reaction temperature on DMC yield and the sensitivity analysis to the reaction kinetics were discussed in detail. The results revealed that the catalytic distillation was appropriate for the process of DMC synthesis.
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Synthesis of dimethyl carbonate from urea and methanol using polyphosphoric acid as catalyst
Jianjun Suna, Bolun Yang, Xiaoping Wanga, Dongpeng Wanga and Hongye Lin
Journal of Molecular Catalysis A: Chemical Volume 239, Issues 1-2, 14 September 2005, Pages 82-86
Abstract
A new process was proposed for the synthesis of dimethyl carbonate (DMC) from urea and methanol in a batch operation. Polyphosphoric acid (PPA) was used as the catalyst and the absorbent for the ammonia, which was produced during the reaction. The effects of various operation conditions, such as reaction temperature, pressure, reaction time and the molar ratio of the reactants were investigated in the terms of DMC yield. The experimental results indicated that the optimal reaction conditions were the molar ratio of methanol/urea of 14, reaction time of 4 h, reaction temperature of 413 K, PPA/urea mass ratio of 1 and initial pressure of CO2 of 0.8 MPa, respectively. The DMC yield of 67.4% was obtained in the optimal reaction conditions. The by-product, ammonia was also used as a starting material of a useful fertilizer in the proposed process.
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Reactive rectifying for producing dimethyl carbonate
Xiaoping Wanga, Bolun Yang, Dongpeng Wanga and Xiaowei Zhai
Chemical Engineering JournalVolume 122, Issues 1-2, 1 September 2006, Pages 15-20[/i]
Abstract
A process for producing dimethyl carbonate (DMC) from methanol and urea, using polyphosphoric acid (PPA) as the catalyst, has been carried out by conducting the reaction continuously under reactive rectifying conditions on a laboratory scale. Several operational variables which have an influence on the yield of DMC, such as the total feed flow rate, bottom temperature, pressure, reflux ratio, mass ratio of the reactants, the concentration of the catalyst and the stirring speed, were investigated to achieve an optimum operation. Under these optimized settings, the highest yield of DMC obtained was 92.2%. A high concentration and purity of DMC in the overhead products, more than 17%, was gained in the reactive rectifying conditions
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Synthesis of dimethyl carbonate from urea and methanol catalyzed by the metallic compounds at atmospheric pressure
Bolun Yang, Dongpeng Wang, Hongye Lin, Jianjun Sun and Xiaoping Wang
Catalysis Communications Volume 7, Issue 7, July 2006, Pages 472-477 [/i]
Abstract
A novel route was proposed for producing dimethyl carbonate (DMC) at atmospheric pressure from urea and methanol catalyzed by the metallic compounds with a high boiling point electron donor compounds (polyethylene glycol dimethyl ether) (PGDE) as solvent. The effects of various operation conditions, such as methanol/urea initial molar ratio, catalyst concentration, urea/PGDE initial mass ratio, flow rate of circulating, reaction temperature, stirring speed and reaction time on DMC yield were investigated, respectively. Experimental results indicate that the using of PGDE as solvent enable this synthesis reaction to reach the requisite temperature and restrain the decomposition of urea and MC; removing the products, DMC and ammonia effectively from the reaction system in time is important to improve the yield of DMC. The DMC yield of 28.8% can be obtained in the optimal reaction conditions. This new process shows some advantages such as easily operating, effectively removing NH3 from the reaction system and lower cost.
The serotonin 5-HT2A receptor agonist TCB-2-a behavioral and neurophysiological analysis .pdf