Selective neutralization, sodium carbonate

The aqueous sodium naphthenate phase is decanted from the hydrocarbon phase and treated with acid to regenerate the cmde naphthenic acids. Sulfuric acid is used almost exclusively, for economic reasons. The wet cmde naphthenic acid phase separates and is decanted from the sodium sulfate brine. The volume of sodium sulfate brine produced from dilute sodium naphthenate solutions is significant, on the order of 10 L per L of cmde naphthenic acid. The brine contains some phenolic compounds and must be treated or disposed of in an environmentally sound manner. Sodium phenolates can be selectively neutralized using carbon dioxide and recovered before the sodium naphthenate is finally acidified with mineral acid (29). Recovery of naphthenic acid from aqueous sodium naphthenate solutions using ion-exchange resins has also been reported (30). 

The acidic functional groups can be characterized by their neutralization reactions with a selection of bases differing in their pK values. The usual reagents are sodium hydroxide, sodium carbonate, sodium bicarbonate and, for very weak acids, sodium ethoxide in alcohol. An additional dimension of information can be obtained by pretreating the carbon prior to neutralization analysis [156]. 

Cross-dyeing mixtures of protein and cellulosic fibres, which involves imparting two distinct colours, is not often practised. The best method is to dye the wool or silk first with an acid, acid mordant, or premetallized dyestuff, and then rinse till free from acid, preferably having previously neutralized with ammonia or sodium carbonate. The cellulosic component is next dyed with a selected direct dye in the presence of 1 to 6 per cent of Tanninol VR or Katanol W at 40° to 60°C (104° to 140°F). The addition... 

Isoxazolo[4,5-c]pyridines have been converted into thiazolo[5,4-(>]pyridines by three methods. Catalytic hydrogenation of compound (616) using palladium on carbon (10%) in aqueous sodium hydroxide at 50 psi followed by neutralization with HC1 to selectively cleave the isoxazole ring afforded 6-chloro-3-(l-iminoethyl)-4-hydroxypyridine-2-thione (617) (57%) <90JCS(P1)1477>. Animation of the thione moiety of the imine (617) with hydroxyamine-Osulfonic acid and subsequent cyclization affords 6-chloro-4-hydroxy-3-methylisothiazolo[5,4-<5 pyridine (618) (57%) (Scheme 78). 

The cross-coupling reaction of organoboron compounds with organic halides or triflates proceeds selectively in the presence of a base, such as sodium or potassium carbonate, phosphate, hydroxide, and alkoxide [11, 45], The bases can be used in aqueous solution, or in suspension in dioxane or DMF. In contrast, the cross-coupling reaction with certain electrophiles, such as allylic acetates [45], 1,3-butadiene monoxide [49], and propargyl carbonates [50], occurs under neutral conditions without any assistance from a base. The transmetallation of organoboron compounds with palladium halides under basic or neutral conditions can be considered to involve three routes, 1, 2, and 3 (Schemes 2-18, 2-20, and 2-23, below). 

Precipitation. The clear sodium aluminate liquor is cooled down, diluted with the water from the red-mud wash, and acidified by bubbling carbon dioxide (CO ) gas through the solution. Carbon dioxide forms a weak acid solution of carbonic acid, which neutralizes the sodium hydroxide from the first treatment. This neutralization selectively precipitates the aluminum hydroxide [AlfOH),] but leaves the remaining traces of silica in solution the precipitation or the crystallization of the hydrate is also called decomposition. The liquor is... 

A large number of flow schemes for inorganic carbon analysis are based on conductometric detection. The inherent selectivity provided by the membrane separation process makes it possible. When NaOH is used as acceptor solution, an electrical conductivity decrease is recorded with increase in TIC concentration owing to the neutralization of the sodium hydroxide. On the contrary, a raise of the conductance signal is measured when either deionized water or weak bases such as tris(hydroxymethylamino)methane or sodium acetate are present in the receptor phase. 

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