Neutralization of Alkalies

Puri and collaborators (3d, 59) found that the amount of CO2 given off on heating to 1200° was always equivalent to the Ba(OH)2 or NaOH neutralization. Evolution of COj was complete between 750 and 900°. Samples oxidized in liquid medium evolved more COg in relation to CO on heating than did samples treated with oxygen (3d, 55). Puri and Bansal (59) suggested that the neutralization of alkali was caused by carbon dioxide chemisorbed on the carbon surface ( COg complex ). If carboxyl groups were responsible, 1 mole of COg should be formed for each equivalent of alkali consumed. The author of this article thinks, as will be shown below, that very likely carboxyl groups of different environment are responsible for bicarbonate and carbonate neutralization as well as COg evolution. 

It is evident from the above equations that the quantity of H2SO4 required in both the stages of neutralization of NagCOg is the same. The second stage of neutralization of Na2COg (i.e. the neutralization of NaHCOg) can be indicated by methyl orange which can also indicate complete neutralization of alkali carbonate or bicarbonate. Thus phenolphthalein and methyl... 

For the production of precipitated silicas, sols, and gels, sodium silicate of ratio about 3.3 is usually used rather than lower ratios, since less acid is required for neutralization of alkali per unit of silica, and this ratio is available at low cost because such large volumes are produced. However, the 3.8 ratio may be used to some further advantage if acid consumption is an important factor in cost. 

Anthraquinone can be brominated, chlorinated directly to the tetrachloro (I, 4, 5, 8-) stage, nitrated easily in the 1-position, but gives the 1,5-and 1,8-dinitro-derivalives on prolonged nitration the nitro groups in these compounds are easily displaced by neutral solutions of alkali sulphites yielding the corresponding sulphonic acids. Sulphonation with 20-30 % oleum gives the 2- 2,6- and 2,7-derivatives in the presence of Hg the 1- 1,5- and 1,8- derivatives are formed. 

The characteristic property of aliphatic nitrocompounds of the type RCHiKOj and RjCHNO, is that they are pseiido cids, I. e., whereas they are neutral in the normal form (A), they are able by tautomeric change under the influence of alkali to give the acidic hydroxy form (B) which thus in turn gives the sodium salt (C). When this sodium salt is treated with one equivalent of hydrochloric acid, the acid form (B) is at once regenerated, and then more slowly reverts to the more stable normal form (A). 

Ferric chloride reaction. For the success of this reaction it is important that the solution should be neutral. Excess of acid usually inhibits the production of colour or precipitate, and excess of alkali gives a reddish-brown precipitate of ferric hydroxide. A neutral solution may be made as follows ... 

Since the silver salts of the carboxylic acids are usually soluble in dilute nitric acid, they must be prepared by treating an aqueous solution of a neutral salt of the acid (and not the free acid itself) with silver nitrate solution. It is not practicable to attempt to neutralise the acid with sodium or potassium hydroxide solution, because the least excess of alkali would subsequently cause the white silver salt to be contaminated with brown silver oxide. The general method used therefore to obtain a neutral solution j to dissolve the acid in a small excess of ammonia solution, and then to boil the solution until all free... 

The sweet water from continuous and batch autoclave processes for splitting fats contains tittle or no mineral acids and salts and requires very tittle in the way of purification, as compared to spent lye from kettle soapmaking (9). The sweet water should be processed promptly after splitting to avoid degradation and loss of glycerol by fermentation. Any fatty acids that rise to the top of the sweet water are skimmed. A small amount of alkali is added to precipitate the dissolved fatty acids and neutralize the liquor. The alkaline liquor is then filtered and evaporated to an 88% cmde glycerol. Sweet water from modem noncatalytic, continuous hydrolysis may be evaporated to ca 88% without chemical treatment. 

The common impurities found in amines are nitro compounds (if prepared by reduction), the corresponding halides (if prepared from them) and the corresponding carbamate salts. Amines are dissolved in aqueous acid, the pH of the solution being at least three units below the pKg value of the base to ensure almost complete formation of the cation. They are extracted with diethyl ether to remove neutral impurities and to decompose the carbamate salts. The solution is then made strongly alkaline and the amines that separate are extracted into a suitable solvent (ether or toluene) or steam distilled. The latter process removes coloured impurities. Note that chloroform cannot be used as a solvent for primary amines because, in the presence of alkali, poisonous carbylamines (isocyanides) are formed. However, chloroform is a useful solvent for the extraction of heterocyclic bases. In this case it has the added advantage that while the extract is being freed from the chloroform most of the moisture is removed with the solvent. 

The anodically produced acid is neutralized by the alkaline mortar (CaO). Corrosion is then possible only if the supply of alkali at the steel surface is consumed and the steel becomes active. This process is possible only under certain circumstances after a very long incubation period. Apparently in steel-concrete foundations the possible current densities are so small that this case never arises. The possibility of danger has to be verified with thin outer coatings where deliming has been noticed on the steel surface. 

Semidry Scrubbers The advantage of semidry scrubbers is in that they remove contaminants by way of a solid waste that is easier to dispose of (less expensive). Initially, the scrubbing medium is wet (such as a lime or soda ash slurry). Then a spray dryer is used to atomize the slurry into the gas which evaporates the water in the droplets. As this takes place, the acid in the gas neutralizes the alkali material and forms a fine white solid. Most of the white solids are removed at the bottom of the scrubber while some are carried into the gas stream and have to be removed by a filter or electrostatic precipitator (discussed later). Although semidry systems cost 5-15% more than wet systems, when combined with a fabric filter, they can achieve 90-95% efficiencies. Dry scrubbers are sometimes used in a very similar fashion, but without the help of gas-liquid-solid mass transfer, these systems use much higher amounts of the solid alkali materials. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Attacks copper and copper alloys these metals should not be used. Penetrates leather, so contaminated leather shoes and gloves should be destroyed. Attacks aluminum in high concentrations Stability During Transport Stable Neutralizing Agents for Acids and Caustics Not pertinent Polymerization May occur spontaneously in absence of oxygen or on exposure to visible light or excessive heat, violently in the presence of alkali. Pure ACN is subject to polymerization with rapid pressure development. The commercial product is inhibited and not subject to this reaction Inhibitor of Polymerization Methylhydroquinone (35 - 45 ppm). 

The alkali metal cyanides MCN are produced by direct neutralization of HCN they crystallize... 

Other uses of HCI are legion and range from the purification of fine silica for the ceramics industry, and the refining of oils, fats and waxes, to the manufacture of chloroprene mbbers, PVC plastics, industrial solvents and organic intermediates, the production of viscose rayon yam and staple fibre, and the wet processing of textiles (where hydrochloric acid is used as a sour to neutralize residual alkali and remove metallic and other impurities). 

The free base of either optical isomer may be obtained by addition to the d-tartrate in the case of the levo isomer and the d-bitartrate in the case of the dextro isomer of alkali in excess, as, for example, by the addition of an aqueous solution of caustic soda, which will cause the base to separate as an oil which may be recovered and purified by any well-known procedure. The base is exactly neutralized with sulfuric acid to give the sulfate. 

A mixture of 100 g of 5,5-dimethylacridan, 20 g of pulyerized sodium amide and 6.5 g of 1 -chloro-3-dimethylaminopropane in 50 ml of xylene is heated at reflux with stirring for one hour. To the cooled reaction mixture is added one yolume of water. The organic layer is separated and extracted several times with diluted lactic acid. The acidic extracts are combined, washed with ether and neutralized by alkali. The crude 10-(3 -dimethylaminopropvl)-5,5-dimethylacridan is isolated by ether extraction and purified by distillation in a high vacuum. The yield is 6,4 g BP 170°-1 B0°C/0.005 mm. n = 1.5990. 

To a solution of 20 parts of thiamine hydrochloride in 30 parts of water is added an aqueous solution of sodium hydroxide (7.2 parts of NaOH in 30 parts of water), and the mixture is cooled with water. The mixture is allowed to stand for 30 minutes, 60 parts of chloroform is added, followed by a solution of 30 parts of crude sodium tetrahydrofurfurylthiosulfate in 30 parts of water, and the whole is stirred for 30 minutes. The chloroform layer is separated and the aqueous layer is extracted twice with 20 parts of chloroform. All the chloroform solutions are combined and shaken with 50 parts of 5% hydrochloric acid. The acid solution is decolorized and neutralized with alkali carbonate, whereupon thiamine tetrahydrofurfuryl disulfide separates out in the resinous state but soon solidifies [MP 129 (decomp.)]. The yield is 16 parts. Recrystallization from ethyl acetate gives colorless prisms melting at 132°C (decomp.). 

Pectin is a collective name for heteropolysaccharides, which consist essentially of polygalacturon acid. Pectin is soluble in water only after a partial neutralization with alkali or ammonium hydroxide [18]. 

Titanium is almost invariably resistant towards neutral salts, particularly halides, at temperatures up to 100°C, and in respect of the latter environments it is significantly more resistant than stainless steel. In strong solutions of caustic alkalis, on the other hand, titanium tends to form soluble titanates, and it is not as resistant as say, nickel. While at low or moderate concentrations of alkali there is no significant attack, the metal has appreciable solubility in concentrated or molten caustic alkali. Titanium is however resistant to attack by aqueous ammonia at all concentrations and temperatures and to anhydrous ammonia . 

Studies on hot water tank enamelsin media of varying pH demonstrate a minimum corrosion rate at pH value of 4. In citric acid (pH 2), IR measurements indicate that ion exchange is the principal mode of corrosion. Distilled water (pH 7) showed evidence of a bulk dissolution mechanism with no silica enrichment of the surface layer. In neutral solutions, the first stage of attack is leaching of alkali ions, raising the pH of solution, which subsequently breaks down the glass network of the acidic oxides. 

In some of the details which follow, reference is made to the addition of a buffer solution, and in all such cases, to ensure that the requisite buffering action is in fact achieved, it is necessary to make certain that the original solution has first been made almost neutral by the cautious addition of sodium hydroxide or ammonium hydroxide, or of dilute acid, before adding the buffer solution. When an acid solution containing a metallic ion is neutralised by the addition of alkali care must be taken to ensure that the metal hydroxide is not precipitated. 

Determination of oxalate as calcium oxalate and as calcium carbonate or calcium oxide Discussion. The neutral solution of alkali oxalate is acidified with acetic (ethanoic) acid, heated to boiling, and precipitated with boiling calcium chloride solution. After standing for 12 hours, the precipitate is filtered off, washed with hot water, and weighed either as calcium oxalate, or after heating, as calcium carbonate, CaC03, or as calcium oxide, CaO. Further details are given in Section 11.22. 

---