HMPA


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HMPA

(organic chemistry)
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Organic Yield [M.sub.w] [M.sub.n] [[eta].sub.red] solvent (%) (g/mol) * (g/mol) * [??] * (dL/g) ** DMSO 75.9 9,100 5,100 1.77 0.07 HMPA 70.4 9,300 5,600 1.65 0.09 DMA 64.7 16,900 8,600 1.97 0.14 DMI 75.6 18,500 9,500 1.93 0.15 NMP 90.8 26,600 13,300 1.99 0.17 * GPC in 0.1 M LiBr/DMF versus PMMA standards at a flow rate of 1.0 mL/min and 35[degrees]C.
They are stableenough on voltammetric time scale for furthermanipulations.The objective of this research is to investigate the solvent and temperature dependence of first reduction process, to study the protonation of the first reduction products of dinitrobenzene and to measure the heterogeneous electron transfer rate constants in HMPA solvent at different temperatures.The substrates are the three isomers of dinitrobenzenes and the protonating agents are benzoic acid and salicylic acid.
All the measurements were carried out in aprotic solvent Hexamethylphosphortriamide (HMPA) at four different temperatures 5oC, 15oC, 25oC and 35oC.
of dinitrobenzene in HMPA. (scan rate: 50 mV sec-1 and protonating agent: benzoic acid)
of dinitrobenzene in HMPA (scan rate: 50 mVsec-1 and protonating agent: salicylic acid)
Table-5: Thermodynamic parameters (H, G, S) calculated from disproportionation constants in HMPA
Table-6: Thermodynamic parameters (H, G, S) calculated from disproportionation constants in HMPA
Twenty-five percent NaOH (2.1 ml) was added to a solution of caffeic acid (2.00 g) in HMPA (150 ml), and the mixture was stirred for 1 h under [N.sub.2] at room temperature.