Brine degassing

There are several crucial steps in the process of recycling hypochlorite solution. First, hypochlorite is formed in the chlorine destruction where chlorine reacts with the sodium hydroxide solution. This solution is added to the brine-degassing unit. Partial conversion to chlorate and bromate takes place, which continues in the anolyte... 

After extensive research and several tests, the option selected was recycling hypochlorite to the feed brine of the electrolysis cells. For this purpose, hypochlorite feed pipes were manufactured and the hydrochloric acid feed capacity to the brine degassing tanks was enlarged. 

There is some increase of sodium chlorate (100 mg kg-1) and sodium bromide (40 mg kg-1) in the cell-liquor. This is a result of the chlorate that is formed in brine degassing. Therefore, more chlorate is fed to the electrolysis cells. Since not all the chlorate is reduced at the cathode, an increase in chlorate in the cell-liquor is observed (see Fig. 14.4). 

An additional advantage of the hypochlorite recycling process is the chlorination of the feed brine in the brine-degassing unit. Organic and nitrogen-containing components are oxidised. The reaction products are removed via the vent-gas to the chlorine destruction unit. Less NCI3 is formed in the electrolysis cells because part of the... 

An additional advantage is the oxidation of all organic and nitrogen-containing components of the brine in the brine degassing tanks. These impurities are not fed to the electrolysis cells, but the products removed to the chlorine destruction unit and incinerator. Control of NCI3 concentrations in chlorine liquefaction has become easier. 

A degassed suspension of lhe halo compound 14 and an alkyne (1.2 equiv) in Et3N (0.1-0.2 mol) was stirred in the presence of dichlorobis(triphenylphosphane)palladium(II) (0.02 equiv) and coppcr(I) iodide (0.04 equiv) at 20 C for 20 h. EtOAc was added and the mixture was washed with H20 and brine the organic phase was dried (MgSOi) and evaporated to yield the product. 

Degassed water under ambient conditions has a relaxation time (T and T2) of about 4 s at 30 °C [11,12], However, air-saturated brines may have a relaxation time of about 2-3 s. Light hydrocarbons are even more sensitive to dissolved oxygen [10], For example, the relaxation time of deoxygenated pentane is 14 s while air-saturated pentane is about 3 s. The correlation for degassed alkanes between the relaxation time (Ti), viscosity (q) and temperature (T) is given by Eq. (3.6.1) [13]. 

The feed brine of the DEP contains a large quantity of carbonates. Therefore, at pH5 carbon dioxide is degassed. When hypochlorite is added, chlorate and bromate are formed in the feed of the electrolysis cells. These reactions have a slow velocity. The result of this is that conversion is only partial ... 

In addition, a vent-gas pipe leading from the degassing tanks to the chlorine destruction unit was put in place, since addition of hydrochloric acid to the brine (pH = 5) results in the evolution of carbon dioxide and some chlorine. 

To a solution of 5-chlorobicyclof3.2.0]heptan-6-one (50.1 mg, 0.35 mmol) in degassed acetone (2 mL) under N2 was added 1.35 M aq CrClz (1.25 mL. 1.68 mmol). The mixture was stirred for 1.5 h at 25 °C. Et2() was added, and the layers were separated. The Et20 layer was washed with H20 and brine, and the combined aqueous layers were reextracted with Et20. The combined organic phases were dried (MgS04) and the solvent was evaporated in vacuo to give the pure product yield 30.4mg (80%). 

The Step 1 product (4 mmol) dissolved in a mixture of 55 ml toluene and 20 ml ethyl alcohol was treated with 20 ml 0.8 M NaHC03 and the Step 2 product (4.8 mmol), then degassed 10 minutes and treated with Pd(PPh3)4 (0.4 mmol). The mixture was heated 2 hours at 95°C, then poured in brine, and extracted with CH2C12. The extract was dried with MgS04 and concentrated. The residue was purified by chromatography with silica gel using 250 ml EtOAc/hexanes, 1 9, and the product isolated in 81% yield as a white solid. 

In order to maintain reproducibility it is important to measure all volumes accurately. In a typical operation using 500 ml (one pint) cans, the procedure is to place 300 ml of degassed salt-water brine into the 500 ml can and add sediment until the can is filled to the brim, giving 200 ml of sediment and 300 ml of brine. The can is sealed and then zero-grade nitrogen is injected through a prepared septum to displace 100 ml of brine and leaving the can with a 2 2 1 mixture of 200 ml brine, 200 ml sediment, and 100 ml headspace. 

A somewhat different development involves use of ultrasonic equipment for the removal of volatiles (such as methane and ethane) from brine which is a by-product of the offshore drilling for crude oil [75]. The particular advantage in the use of ultrasound in this situation is that the volatiles can be degassed while the brine remains under pressure, thus it avoids the traditional methodology of depressurizing to atmospheric and subsequently boiling off. 

To a 100-mL, two-necked flask, is added a mixture of cyclohexanone (5.9 g, 60 mmol), o-iodoaniline (4.4 g, 20 mmol), and 1,4-diazabicyclo[2.2.2]octane (DABCO) (6.7 g, 60 mmol) in N,N-dimethylformamide (DMF) (60 mL). The mixture is degassed three times via nitrogen/vacuum, followed by the addition of palladium acetate (Pd(OAc)2) (2.24 mg, 0.1 mmol) (Note 1). The mixture is degassed twice and heated at 105°C for 3 hr or until completion of the reaction (Note 2). The reaction mixture is cooled to room temperature and partitioned between isopropyl acetate (150 mL) and water (50 mL). The organic layer is separated, washed with brine (50 mL), and concentrated under vacuum to dryness. The residue is chromatographed on 50 g of silica gel using 700 mL of ethyl acetate-heptane (1 6) as the eluent to give 2.22 g of 1,2,3,4-tetrahydrocarbazole (65%) as a pale brown solid (Note 3). 

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