Na2SO4 solution

Grafihoff [160] determined a from the bubble size distribution via the relative cumulative frequency of the surface area and found a/oo =/(P/V, c[Na2SO4]) independent of the stirrer type (oq - water value of a). The a/ao values increased at P/V = 1 kW/m almost directly proportionally with molarity in the concentration range of 0.03-0.12 M and then remained constant. For an aqueous 0.25 M Na2SO4 solution a/ao 9. 

Undoubtedly, the mercury/aqueous solution interface, was in the past, the most intensively studied interface, which was reflected in a large number of original and review papers devoted to its description, for example. Ref. 1, and in the more recent work by Trasatti and Lust [2] on the potentials of zero charge. It is noteworthy that in view of numerous measurements of the double-layer capacitance at mercury brought in contact with NaF and Na2SO4 solutions, the classical theory of Grahame [3] stiU holds [2]. According to Trasatti [4], the most reliable PZC value for Hg/HiO interface in the absence of specific adsorption equals to —0.433 0.001 V versus saturated calomel electrode, (SCE) residual uncertainty arises mainly from the unknown liquid junction potential at the electrolyte solution/SCE reference electrode boundary. 

Adsorption of a condensed 1-hydroxy-adamantane layer at the Hg elec-trode/(Na2SO4 or NaF) solution interface has been studied as a function of temperature by Stenina etal. [174]. Later, Stenina etal. [175] have determined adsorption parameters and their temperature dependence for a two-dimensional condensation of adamantanol-1 at a mercury electrode in Na2SO4 solutions. They have also studied coadsorption of halide (F , Cl , Br ) anions and 1-adamantanol molecules on Hg electrode [176]. More recently, Stenina etal. [177] have described a new type of an adsorption layer comprising organic molecules of a cage structure condensed at the electrode/solution interface. This phenomenon was discovered for adsorption of cubane derivatives at mercury electrode. 

A solution of 500 kg of Na2S04 in 2500 kg water is cooled from 333 K to 283 K in an agitated mild steel vessel of mass 750 kg. At 283 K, the solubility of the anhydrous salt is 8.9 kg/100 kg water and the stable crystalline phase is Na2SO4.10H2O. At 291 K, the heat of solution is —78.5 MJ/kmol and the specific heat capacities of the solution and mild steel are 3.6 and 0.5 kJ/kg deg K respectively. If, during cooling, 2 per cent of the water initially present is lost by evaporation, estimate the heat which must be removed. 

Ethyl cyclohexanecarboxylate [3289-28-9] M 156.2, b 76-77 /10mm, 92-93 /34mm, d 0.960, n 1.420. Washed with M sodium hydroxide solution, then water, dried with Na2SO4 and distd. 

Trimethylsilyl ethanol [2916-68-9] M 118.3, b 53-55 /llmm, 75 /41mm, 95 /100mm, 0.8254, np 1.4220. It the NMR spectrum is not clean then dissolve in Et2O, wash with aqueous NH4CI solution, dry (Na2SO4), evaporate and distil. The 3,4-dinitrobenzoyl deriv has m 66 (from EtOH). [NMR JACS 79 974 7957 Z Naturforsch 14b 137 7959],... 

To study these reactions use a 0-1m solution of sodiuip sulphate, Na2SO4.10H2O. 

To a cooled solution (0 °C) of the amino acid (193 mg, 1 mmol) and triethylamine (418 (iL, 3 mmol) in CH2CI2 (25 mL) was added POCI3 (460 mg, 3 imnol) dropwise, and the reaction mixture was stirred overnight at room temperature. The resulting solution was washed with saturated aqueous NaHCO3 (25 mL), brine (25 mL), and water (3 x 25 mL). Drying over anhydrous Na2SO4 and evaporation of the solvent yielded the p-lactam (145 mg, 83%). 

To a solution of 15.3 g (37.5 mmol) of the alcohol in 150 mL of hexanes was added 60 g of activated Mn02. The reaction mixture was stirred at 22 °C overnight and filtered, and the solid residue was washed with 30% EtOAc in hexanes solution. The combined filtrates were dried (Na2SO4) and concentrated in vacuo. The residue was purified by chromatography on SiO2 (EtOAc hexanes, 1 10) to give 13.7 g (90%) of the ketone as a colorless oil. 

To a mixture of pyridinium chlorochromate (PCC 339 mg, 1.57 mmol), ammonium acetate (215 mg, 2.62 mmol), and 4 A molecular sieves (610 mg) in CI FCP (33 mL) was added a solution of the alcohol (208 mg, 1.05 mmol) in CH2CI2 (14 mL) under argon at 0 °C over a period of 10 min. After the mixture had been stirred at room temperature for 3 h, diethyl ether (200 mL) was added and the mixture was filtered through a short pad of Florisil. The filtrate was washed successively with water (100 mL) and brine (100 mL), dried with Na2SO4, and concentrated. The residue was purified by chromatography on silica gel (hexane 70%, Et2O 30%) followed by distillation to give the aldehyde as a colorless oil (132 mg, 63%). 

Dimethylsulfoxide (1.25 mL, 17.6 mmol) was added to a solution of 2,4,6-trichloro-[l,3,5]-triazine (TCT, 0.66 g, 3.6 mmol) in THF (20 mL), stirred, and maintained at -30 °C. After 30 min, A-benzyloxycarbonyl-2-amino-3-phenylpropan-l-ol, (0.86 g, 3 mmol) in THF (10 mL) was added slowly at -30 °C with stirring, and after an additional 30 min, NEts (2 mL, 14.3 mmol) was added. After 15 min, the mixture was warmed to room temperature, the solvent evaporated in vacuo, and I T O (50 mL) added to the resulting solid. The mixture was quenched with 1 N HCl, and the organic phase washed with 15 mL of a saturated solution of NaHCOs, followed by brine. The organic layer was dried (Na2SO4) and the solvent evaporated to yield pure A-benzyloxycarbonyl-2-amino-3-phenylpropionaldehyde (0.77 g, 90%). 

To a stirred solution of the sulfide (8.11 g, 15.5 mmol) in CH2CI2 (150 mL) was added 90% m-CPBA (2.97 g, 15.5 mmol) at -78 °C. The reaction mixture was stirred at -78 °C for 4 h, warmed to -20 °C, and quenched with saturated aqueous Na2CO3. The solution was washed with saturated aqueous NaiCC)., brine, and dried over anhydrous Na2SO4. Removal of solvent and recrystallization from EtOAc and hexane gave the sulfoxide (7.00 g, 13.0 mmol, 84%). 

To a solution of the P-hydroxy-/V-methyl-O-methylamide (0.272 g, 1.55 mol) in tetrahydrofuran (THF) (30 mL) were added carbon disulfide (6.75 mL, 112 mmol) and iodomethane (6.70 mL, 108 mmol) at 0 °C. The mixture was stirred at this temperature for 0.25 h, and then sodium hydride (60% suspension in mineral, 136.3 mg, 3.4 mmol) was added. After 20 min at 0 °C, the reaction was quenched by slow addition to 60 g of crushed ice. (Caution hydrogen gas evolution ). The mixture was raised to room temperature and separated, and the aqueous layer was extracted with CH2CI2 (4x15 mL). The combined organic extracts were dried (Na2SO4), concentrated in vacuo, and purified (SiO2, 5% EtOAc in hexanes) to afford 0.354 g (86%) of the xanthate. To a solution of the xanthatc (2.95 g, 11.1 mmol) in toluene (100 mL) was added tributyltin hydride (15.2 mL, 56.6 mmol) and 2,2 -azobisisobutyronitrilc (AIBN, 0.109 g, 0.664 mmol). The reaction mixture was then heated to reflux for 1 h. The mixture was cooled, concentrated in vacuo, and purified (SiO2, 100% hexanes to remove tin byproducts, followed by 10% EtOAc in hexanes to elute product) to afford 1.69 g (96%) of the/V-methyl-O-methylamide. 

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