Nitrogen atmospheric evolution

Hydrolysis. Heating 1,2-dichloroethane with excess water at 60°C in a nitrogen atmosphere produces some hydrogen chloride. The rate of evolution is dependent on the temperature and volume of the aqueous phase. Hydrolysis at 160—175°C and 1.5 MPa (15 atm) in the presence of an acid... 

To a stirred slurry of 35 mg (0.87 mmol) of sodium hydride in 5 mL of THF under a nitrogen atmosphere at OX is added 225 mg (0.80 mmol) of ethyl [4-oxo-1-(2-propenyl)-2-cyclohexenyl]methylpropanedioatein 3 mL of THF. After the evolution of hydrogen ceases the cooling bath is removed and the mixture is stirred for 2.5 h at 25 °C. The mixture is poured into cold 0.1 N aq HCI and then extracted three times with 10 mL of CH2n2. The combined extracts are washed with aq NaHCO, and water. After drying and evaporation of the solvent the crude product is recrystallized yield 197 mg (87%) mp 83-84 C (diethyl ether). 

Under a nitrogen atmosphere a solution of 18.0 g (88 mmol) of (4.S ,5.5 )-2-cthyl-4,5-dihydro-4-hydroxymethyl-5-phenyIoxazole in 150 mL of dry THE is added dropwise at 20 C to a stirred heterogeneous solution of 2.53 g (105.3 mmol) of sodium hydride (oil removed by washing with 50 mL of dry benzene) at a rate to maintain a mild evolution of hydrogen. When the addition is complete, the mixture is heated at 50-60 °C for 1.5 h, cooled to r.L. and a solution of 16.2 g (114 mmol) of iodomethane in 10 mL of dry THF is added dropwise. The reaction mixture is stirred for 2 h and slowly poured into. 300 mL of ice water, then extracted with two 200-mL portions of diethyl ether. The combined extract is dried over Na2S04 and concentrated to give an oil, which is distilled in vacuo, yield 87% bp 91-93 °C/0.25 Torr [at] 4 —84.2 (r = 10.1, CHC13). 

Polymerization of PO initiated with the (TPP)AlCl (l,X=Cl)-2-propanol (2-PrOH) system in the presence of methylaluminum bis(2,6-di-tert-butyl-4-meth-ylphenolate) (3e) was carried out by the addition of a mixture of PO and 2-PrOH to a CH2CI2 solution of a mixture of 1 (X=C1) and 3e at room temperature in a nitrogen atmosphere (Fig. 36). For example, when a mixture of 200 equiv of PO and 9 equiv of 2-PrOH was added to the solution of 1 containing 0.3 equiv of 3e (0.15 mol% with respect to PO), the color of the solution immediately turned from dark reddish purple to bright reddish purple, characteristic of the alcoho-latealuminum porphyrin family. The polymerizations proceeded very rapidly with heat evolution to attain 57% monomer conversion in 3 min (A). In contrast, the polymerization without 3e under similar conditions proceeded rather... 

H.3 Write balanced chemical equations for the following reactions (a) Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide, (b) The reaction of sodium oxide, Na20, and water produces sodium hydroxide, (c) Hot lithium metal reacts in a nitrogen atmosphere to produce lithium nitride, Li3N. (d) The reaction of calcium metal with water leads to the evolution of hydrogen gas and the formation of calcium hydroxide, Ca(OH)2. 

Measuring Methods. Chlorine content was determined by the oxygen flask method (2) on a polymer purified by precipitation from the solution in cyclohexanone. Thermal stability, as HC1 evolution, was determined according to ASTM method D-793-49, determining the quantity of HC1 evolved by the polymer maintained at 180 °C in a nitrogen atmosphere. From the slope of the straight line for the amount of HC1 evolved with time, the constant K for the dehydrochlorination rate (DHC) is deduced. 

Differential Thermal Analysis. A sample of film pressed in air at 200°C was heated at the rate of 10°C/minute from 25°-500°C in a nitrogen atmosphere. The Tg and the temperatures for the onset of HC1 evolution and the peak endotherm were determined from the DTA plot. 

A solution of 4-[2-(5-ethyl-2-pyridyl)ethoxy]nitrobenzene (60.0 g) in methanol (500 ml) was hydrogenated at room temperature under one atmospheric pressure in the presence of 10% Pd-C (50% wet, 6.0 g). The catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. The residual oil was dissolved in acetone (500 ml)-methanol (200 ml). To the solution was added a 47% HBr aqueous solution (152 g). The mixture was cooled, to which was added dropwise a solution of NaN02 (17.3 g) in water (30 ml) at a temperature not higher than 5°C. The whole mixture was stirred at 5°C for 20 min, then methyl acrylate (112 g) was added thereto and the temperature was raised to 38°C. Cuprous oxide (2.0 g) was added to the mixture in small portions with vigorous stirring. The reaction mixture was stirred until nitrogen gas evolution ceased, and was concentrated under reduced pressure. The concentrate was made alkaline with concentrated aqueous ammonia, and extracted with ethyl acetate. The ethyl acetate layer was washed with water and dried (MgS04) The solvent was evaporated off to leave methyl 2-bromo-3- 4-[2-(5-ethyl-2-pyridyl)ethoxy]phenyl propionate as a crude oil (74.09 g, 85.7%). 

Vinogradov (1964) divides the history of the atmosphere into three phases (Table 1) ancient (water vapor), transitional (nitrogen atmosphere), and present (oxysphere). Apparently the Precambrian BIF were deposited at the boundary of the transitional atmosphere and the oxysphere. Therefore, it is of particular interest to examine the evolution of the nitrogen atmosphere and its individual components, mainly nitrogen and carbon. 

Vinogradov has pointed out that with the appearance of the biosphere somewhere on the verge of 3-10 yr ago, there was a major upheaval in the evolution of the Earth. Oxidizing processes were abruptly accelerated, a nitrogen atmosphere arose in which carbon dioxide predominated over methane, and free carbon was oxidized to CO2. After the carbon was oxidized or at the same time as that process, there began oxidation of divalent iron (at — 10 ), which led to subsequent wholesale deposition of the sediments of the Precambrian BIF. Free carbon in equilibrium with the atmosphere appeared only after complete oxidation of ferrous iron compounds in the hydrosphere and on the land surface. 

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