Hypochlorite solution preparation

By electrolysis of a solution of sodium chloride the chlorine and sodium hydroxide can be formed in situ. I hey will then react immediately forming sodium hypochlorite solution. The first stage is the formation of Na+ ions at the cathode and Cl ions at the anode. The sodium immediately reacts with water forming sodium hydroxide and, if the anode and cathode are sufficiently close to each other, the chlorine will react with the sodium hydroxide and the result will be a sodium hypochlorite solution. The available chlorine, however, in sodium hypochlorite solutions prepared in this manner is considerably less than that obtained by the process previously described. 

To a stirred mixture of 40% sodium hydroxide solution (1 mL) and sodium hypochlorite solution, prepared from chlorine gas and sodium hydroxide (1.84 g) in ice water (15 mL), was added a solution of 3-acetyltropolone (820 mg, 5 mmol) in 6% NaOH solution (3 mL) with cooling in an ice water bath. The reaction mixture was stirred for 1 hr at 15 °C. The mixture was added to a solution of sodium hydrogensulfite (500 mg) in water (2 mL) to remove an excess of sodium hypochlorite. The mixture was carefully made slightly acidic with concentrated hydrochloric acid. The precipitate was collected and dissolved in hot water, the solution was made acidic with concentrated hydrochloric acid to give crystals which were recrystallized from methanol to give 3-carboxytropolone as yellow needles in a yield of 690 mg (85%), mp 217-218 °C IR (KBr) vmax 3212 (OH), 1718 (COOH), 1585 cm-1 (C=0) H NMR (deuteriochloroform) 8 7.05-7.8 (3H, m), 8.15 (1H, i,J= 10 Hz, H-4), 10.3 (2H, br, OH). 

Dichloramine-T. Dilute 80 ml, of freshly prepared 2N sodium hypochlorite soluticMi (preparation, p. 525) with 80 ml. of w ter, and then add with stirring 5 g. of finely powdered toluene-p-sulphonamide, a clear solution being rapidly obtained. Cool in ice-water, and then add about 50 ml. of a mixture of equal volumes of glacial acetic acid and water slowly with stirring until precipitation is complete the dichloro-amide separates at first as a fine emulsion, which rapidly forms brittle colourless crystals. Filter off the latter at the pump, wash well with... 

Iodoform reaction. To i ml. of the aldehyde solution, add 3 ml. of 10% KI solution and 10 ml. of freshly prepared sodium hypochlorite solution. Yellow crystals of iodoform, CHI3, soon separate. 

Lead dioxide. A convenient method of preparation is to oxidi.se a plumbous salt in an alkaline medium with a hypochlorite solution ... 

Anthranilic acid. This substance, the ortho amino derivative of benzoic acid, may be conveniently prepared by the action of sodium hypobromite (or sodium hypochlorite) solution upon phthalimide in alkaline solution at 80°. The ring in phthalimide is opened by hydrolysis to phthalamidic acid and the latter undergoes the Hofmann reaction (compare Section 111,116) ... 

Hypochlorite solutions are prepared in near quantitative yield by chlorination of dilute caustic or a lime slurry. 

High yields of NaOCl are obtained electrolyticaHy by oxidation of CT at dimensionally stable anodes (219). Sodium hypochlorite is prepared using small diaphragmless or membrane cells, with a capacity of 1—150 kg/d of equivalent CI2, which produce a dilute hypochlorite solution of 1—3 and 5—6 g/L from seawater and brine, respectively (see Chemicals from brine). They are employed in sewage and wastewater treatment and in commercial laundries, large swimming pools, and aboard ships. 

The hypochlorite solution also may be prepared conveniently from the calcium hypochlorite sold by the Mathieson Alkali Works under the trade name HTH and specified to contain not less than 65 per cent of available calcium hypochlorite. 

A 3-1., three-necked flask fitted with a mechanical stirrer, a dropping funnel, and a thermometer is then charged with an aqueous solution of 2.2 moles of calcium hypochlorite [Hypochlorous acid, calcium salt] (Note 3), and the piperidine acetate prepared above is placed in the dropping funnel. The hypochlorite solution is stirred and cooled to 0° to — 5° with a methanol-ice bath, and the piperidine acetate is added dropwise over a period of 1.25 hours while the temperature is maintained below 0°. After a further 15 minutes of stirring, equal portions of the mixture are placed in two 2-1. separatory funnels and extracted three times with a total of about 1300 ml. of ether. The ether extract is placed in a 2-1. flask and dried over anhydrous sodium sulfate in a cold room at 4° overnight. After filtration to remove inorganic material, the bulk of the ether is removed by boiling on a water bath maintained below 60° (Note 4). 

Hydrazine, NH2NH2, is an oily, colorless liquid. It is prepared by the gentle oxidation of ammonia with alkaline hypochlorite solution ... 

At low pH the existence of HOCl is favoured over OCl" (hypochlorite ion). The relative microbiocidal effectiveness of these forms is of the order of 100 1. By lowering the pH of hypochlorite solutions the antimicrobial activity increases to an optimum at about pH 5 however, this is concurrent with a decrease in stability of the solutions. This problem may be alleviated by addition of NaOH (see above equation) in order to maintain a high pH during storage for stability. The absence ofbuffer allows the pH to be lowered sufficiently for activity on dilution to use-strength. It is preferable to prepare use-dilutions of hypochlorite on a daily basis. 

Rate of admission of chlorine into the alcohol during preparation of fert-butyl hypochlorite must be regulated to keep the temperature below 20°C to prevent explosion [1], A safer and simpler preparation uses hypochlorite solution in place of chlorine [2],... 

A. Sodium hypochlorite solution. A solution of sodium hypochlorite 2 is prepared immediately before it is to be used. A mixture of 50 g. (1.25 moles) of sodium hydroxide and 200 ml. of water is swirled until the solid dissolves. The solution is cooled to 0°, and 100 g. of crushed ice is added. The flask is then placed in an ice bath, and chlorine gas from a tank is bubbled through the solution until 41 g. (0.58 mole) is absorbed. An excess of chlorine should be avoided. The solution of sodium hypochlorite is kept in the dark at 0° until needed. 

A solution was prepared by mixing an aqueous solution of sodium hydro-genphosphate (0.05 M, 10 mL) and a solution prepared with concentrated bleach (sodium hypochlorite, 5mL) in water (20 mL). The pH of the resulting solution was adjusted to 11.25 by addition of few drops of hydrogen chloride 1 M or sodium hydroxide 1M. 

In preparing smaller amounts of either STB (supertropical bleach) or HTH (calcium hypochlorite) solution, the following mixture would apply. For a 5 percent solution, mix... 

M of ring substituted styrene or propenylbenzene in 30 ml tetrahydrofuran in V2L flask. Flush with N2 and add 33 ml 1 M borane in tetrahydrofuran (see procedure below for preparation). Stir one hour, add 3 ml water and 50 ml 3N NaOH, and then 215 ml 0.31 M fresh chloramine solution (prepared by treating dilute aqueous NH4OH with Na hypochlorite at 0° see BER 40,4586 (1907)). Keep at room temperature one hour, acidify with HCI, extract with ether, basify with NaOH and extract with ether and dry, evaporate in vacuum (or just basify and extract with ether and dry, evaporate in vacuum) to get the amine. 

The acid, referred to as tetra acid , is prepared as follows In a Friedel-Crafts reaction, acenaphthene 72 is reacted with malonic dinitrile and aluminum chloride. The resulting condensation product 75 is oxidized with sodium chlorate/hy-drochloric acid to form the dichloroacenaphthindandione 76. Oxidation with sodium hypochlorite solution/sodium permanganate affords naphthalene tetracar-boxylic acid 68, mostly existing as the monoanhydride 68a. The dianhydride, on the other hand, evolves only after drying at approx. 150°C. 

If no fresh bleaching powder is available, a hypochlorite solution is prepared by passing chlorine into an ice-cooled solution of 15 g. of sodium hydroxide in 250 c.c. of water, until the increase in weight is 14 g. 

In the preparation of the sodium hypochlorite solution it is quite necessary that the mixture be kept cold and be alkaline to red litmus paper at the end of the reaction, if good yields of hydrazine are to be obtained. 

A normal solution of sodium hypochlorite is prepared as follows in a 5-I. round-bottom flask are placed 1800 g. of sodium hydroxide solution (300 g. of sodium hydroxide to 1500 g. of water) and 1500 g. of ice. Chlorine gas is then passed into the solution until it has gained in weight approximately 213 g. During this addition, the solution must be kept thoroughly cooled with ice, in order that chlorates will not be formed. After all the chlorine has been passed in, it is necessary to be certain that the mixture is slightly alkaline, since any excess of free chlorine in the solution prevents the formation of hydrazine. 

The sodium hypochlorite solution was prepared by passing chlorine, with stirring and cooling, into 1.51. of aqueous I AM sodium hydroxide solution held at 0-5°. 

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