Sodium hypochlorite systems

The reactor effluent, containing 1—2% hydrazine, ammonia, sodium chloride, and water, is preheated and sent to the ammonia recovery system, which consists of two columns. In the first column, ammonia goes overhead under pressure and recycles to the anhydrous ammonia storage tank. In the second column, some water and final traces of ammonia are removed overhead. The bottoms from this column, consisting of water, sodium chloride, and hydrazine, are sent to an evaporating crystallizer where sodium chloride (and the slight excess of sodium hydroxide) is removed from the system as a soHd. Vapors from the crystallizer flow to the hydrate column where water is removed overhead. The bottom stream from this column is close to the hydrazine—water azeotrope composition. Standard materials of constmction may be used for handling chlorine, caustic, and sodium hypochlorite. For all surfaces in contact with hydrazine, however, the preferred material of constmction is 304 L stainless steel. 

Precipitate formation can occur upon contact of iajection water ions and counterions ia formation fluids. Soflds initially preseat ia the iajectioa fluid, bacterial corrosioa products, and corrosion products from metal surfaces ia the iajectioa system can all reduce near-weUbore permeability. Injectivity may also be reduced by bacterial slime that can grow on polymer deposits left ia the wellbore and adjacent rock. Strong oxidising agents such as hydrogen peroxide, sodium perborate, and occasionally sodium hypochlorite can be used to remove these bacterial deposits (16—18). 

Sodium hypochlorite and calcium hypochlorite are chlorine derivatives formed by the reaction of chlorine with hydroxides. The appHcation of hypochlorite to water systems produces the hypochlorite ion and hypochlorous acid, just as the appHcation of chlorine gas does. 

Sodium Hypochlorite—Acid—Sodium Chlorite System. In this method, hydrochloric or sulfuric acid is added into a sodium hypochlorite [7681 -52-9] NaOCl, solution before reaction with the sodium chlorite (118). 

The pH of the chlorine dioxide reaction mixture must be maintained in the 2.8—3.2 pH range, otherwise decreased conversion yields of chlorite to chlorine dioxide are obtained with by-product formation of chlorate. Generator efficiencies of 93% and higher have been demonstrated. A disadvantage of this system is the limited storage life of the sodium hypochlorite oxidant solution. 

In comparison to N—S bond formation, O—N bond formation by essentially oxidative procedures has found few applications in the synthesis of five-membered heterocycles. The 1,2,4-oxadiazole system (278) was prepared by the action of sodium hypochlorite on A(-acylamidines (277) (76S268). The A -benzoylamidino compounds (279) were also converted into the 1,2,4-oxadiazoles (280) by the action of r-butyl hypochlorite followed by base. In both cyclizations A -chloro compounds are thought to be intermediates (76BCJ3607). 

Another two-phase system using phase-transfer catalysis for the oxidation of diaryl-iV-arylsulphonyl sulphilimines to sulphoximines has also been described188. In this reaction the oxidizing reagent is sodium hypochlorite and yields are in excess of 90% in most cases (equation 70). This reaction presumably occurs by initial attack by the nucleophilic hypochlorite ion on the sulphur atom followed by chloride ion elimination. 

Fueled by the success of the Mn (salen) catalysts, new forays have been launched into the realm of hybrid catalyst systems. For example, the Mn-picolinamide-salicylidene complexes (i.e., 13) represent novel oxidation-resistant catalysts which exhibit higher turnover rates than the corresponding Jacobsen-type catalysts. These hybrids are particularly well-suited to the low-cost-but relatively aggressive-oxidant systems, such as bleach. In fact, the epoxidation of trans-P-methylstyrene (14) in the presence of 5 mol% of catalyst 13 and an excess of sodium hypochlorite proceeds with an ee of 53%. Understanding of the mechanistic aspects of these catalysts is complicated by their lack of C2 symmetry. For example, it is not yet clear whether the 5-membered or 6-membered metallocycle plays the decisive role in enantioselectivity however, in any event, the active form is believed to be a manganese 0x0 complex <96TL2725>. 

Other metals can also be used as a catalytic species. For example, Feringa and coworkers <96TET3521> have reported on the epoxidation of unfunctionalized alkenes using dinuclear nickel(II) catalysts (i.e., 16). These slightly distorted square planar complexes show activity in biphasic systems with either sodium hypochlorite or t-butyl hydroperoxide as a terminal oxidant. No enantioselectivity is observed under these conditions, supporting the idea that radical processes are operative. In the case of hypochlorite, Feringa proposed the intermediacy of hypochlorite radical as the active species, which is generated in a catalytic cycle (Scheme 1). 

Cyanide oxidation consists of a reaction with sodium hypochlorite under alkaline conditions in either a batch or continuous system. A complete system includes reactors, sensors, controls, mixers, and... 

Method Cyanide is destroyed by reaction with sodium hypochlorite under alkaline conditions. System component Reaction tanks, a reagent storage and feed system, mixers, sensors, and controls two identical reaction tanks sized as the above-ground cylindrical tank with a retention time of 4 h. Chemical storage consists of covered concrete tanks to store 60 d supply of sodium hypochlorite and 90 d supply of sodium hydroxide. 

Attempts have been made to exploit the intrinsic C2 symmetry of the phenolate-based dinickel core in enantioselective catalytic reactions. Therefore, enantiomerically pure C2-symmetric ligands such as (736a) and the corresponding dinickel systems (736b) have been prepared ( Equation (27)),1890 and (736b) was tested in the epoxidation of unfunctionalized alkenes with sodium hypochlorite as the oxidant. The catalytic reaction was found to be highly pH dependent with an optimum at a pH of 9. While the complex is catalytically active, significant enantioselectivity was not achieved. 

Oxidation of oxime 422 with aqueous sodium hypochlorite has been used to synthesize the central piperidine ring of the tricyclic system 423 in moderate yield, which presumably proceeds via an intramolecular 1,3-diploar cycloaddition of the intermediate nitrile oxide (Equation 114) <2000EJ0645>. 

Figure 9 CL response curves from the oxidation of H202 with sodium hypochlorite in the presence of fluorescein and surfactants. (1) Aqueous system without fluorescein (2) aqueous system (3) CSDS = 2.0 X 1(L2 M (4) CBrij.35 = 4.2 X 1CT3 M (5) Chtac = 3.0 X lO"3 M CH2o2 = 1.5 X 10-4 M CNa0a = 2.0 X KT3 M Cfluolescdn = 2.7 X KT4 M Cnsoh — 0.05 M. (From Ref. 39 with permission.)...

The reduction in the numbers of incinerators and the limitations of autoclaves have created the need for alternative medical waste treatment systems. Currently, there are over 40 such technologies available from greater than 70 manufacturers within the United States, Europe, the Middle East, and Australia. While these systems vary in their treatment capacity, the extent of automation, and overall volume reduction, all alternative technologies utilize one or more of the following methods (1) heating the waste to a minimum of 90 to 95°C by means of microwaves, radio waves, hot oil, hot water, steam, or superheated gases (2) exposing the waste to chemicals such as sodium hypochlorite (household bleach) or... 

A typical manganese-salen complex (27)[89] is capable of catalysing the asymmetric epoxidation of (Z)-alkenes (Scheme 18) using sodium hypochlorite (NaOCl) as the principle oxidant. Cyclic alkenes and a, (3-unsaturated esters are also excellent starting materials for example indene may be transformed into the corresponding epoxide (28) with good enantiomeric excess1901. The epoxidation of such alkenes can be improved by the addition of ammonium acetate to the catalyst system 911. 

For a similar series of chalcone derivatives the use of aqueous sodium hypochlorite in a two phase system (with toluene as the organic solvent) and the quinine derivative (32) as a chiral phase-transfer catalyst, produces epoxides with very good enantiomeric excesses and yields1981. 

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