Caustic preparation

Caustic preparation begins with obtaining distilled water that has been boiled to remove dissolved carbon dioxide. Caustic solutions are prepared in 100 gram batches containing about 25% caustic by weight. The caustic (KOH,... 

RELATE CB is recommended for continuous caustic preparation to give an Improved base, and for continuous peroxide bleaching to give better whiteness. 

Versatility - stable and effective in both caustic preparation and peroxide bleaching. 

Several investigators have proposed using catalysts in the carbon such as platinum (Oita and Conway, 1954) or nickel (Kirsten, 1983) to lower the required pyrolysis temperature. The senior author has found that noncata-lyzed carbon at 1120°C has superior performance to catalyzed carbon. The pyrolysis gases are scrubbed, usually with caustic preparations, to remove interfering materials and the carbon monoxide is then determined. The carbon monoxide from the pyrolysis may be determined directly using a gas chromatographic separation prior to thermal conductivity, infrared absorption spectroscopy, or iodometry. Alternatively, the CO may be oxidized to CO2 and determined by gravimetry, coulometry, or one of the other methods discussed under carbon determinations. 

Usually prepared on the large scale by caustic soda fusion of sodium naphthalene-1-sulphonate, but can also be obtained by high-temperature alkaline digestion of... 

Obtained by K.OH fusion of many resins. Prepared by fusion of m-benzenedisulphonic acid with caustic soda, also obtained to some extent in the NaOH fusion of o-and p-ben-zenedisulphonic acids. 

C7H6O2 Oily liquid of aromatic odour b.p. 196°C. (t is prepared by the action of chloroform and caustic potash on phenol (the Reimer-Tiemann reaction) or by the oxidation of the glucoside salicin. It is easily reduced to salicyl alcohol or oxidized to salicylic acid. 

Aluminium is obtained on a large scale by the electrolysis of the oxide, dissolved in fused cryolite The oxide, occurring naturally as bauxite, AI2O3.2H2O, usually contains silica and iron(III) oxide as impurities. These must be removed first, since aluminium, once prepared, cannot be freed of other metals (which will be deposited on electrolysis) by refining it. The crude oxide is dissolved under pressure in caustic soda solution the aluminium oxide and silica dissolve and the ironflll) oxide is left ... 

The residue in the flask will contain the sodium (or potassium) salt of the acid together with excess of alkali. Just acidify with dilute sulphuric acid and observe whether a crystalline acid separates if it does, filter, recrystallise and identify (Section 111,85). If no crystaUine solid is obtained, the solution may be just neutralised to phenolphthalein and the solution of the alkali salt used for the preparation of a crystaUine derivative. This wiU confirm, if necessary, the results of hydrolysis by method 1. If the time factor is important, either method 1 or the product of the caustic alkali hydrolysis may be used for the identification of the acid. 

P Keto esters (t.g., ethyl ocetoacetate) are soluble in solutions of caustic alkalis but not in sodium carbonate solution. They give colours with freshly prepared ferric chloride solution a little alcohol should be added to bring the ester into solution. Sodium ethoxide solution reacts to yield sodio compounds, which usually crystallise out in the cold. Phenylhydrazine yields pyrazolones. They are hydrolysed by boiling sulphuric acid to the Corresponding ketones, which can be identified as usual (Section 111,74). 

Once the presence of a sulphonate group has been estabhshed (and, if possible, the phenol isolated), the compound may be characterised by the preparation of a derivative. It must be remembered that both sulphoxides RSOR and sulpJiones RSOjR yield sulphur dioxide on fusion with caustic alkali and acidification. 

Acetates may also be prepared by adding acetic anhydride to somewhat dilute solutions of compounds containing hydroxyl (or amino) groups in aqueous caustic alkahs. The amount of alkali used should suffice to leave the hquid shghtly basic at the end of the operation, so much ice should be added that a little remains unmelted, and the acetic anhydride should be added quickly. 

Nitrosomethylurea is conveniently prepared by treating acetamide (2 0 mols) with bromine (1 1 mols), followed by 10-25 per cent aqueous caustic alkali (2 0 mols) when acetylmethylurea is produced ... 

Ethyl Cellulose. Ethyl cellulose is prepared by reacting cellulose with caustic to form caustic cellulose, which is then reacted with chloroethane to form ethyl cellulose. Plastic-grade material contains 44 to 48% ethoxyl. 

Electrolytic Preparation of Chlorine and Caustic Soda. The preparation of chlorine [7782-50-5] and caustic soda [1310-73-2] is an important use for mercury metal. Since 1989, chlor—alkali production has been responsible for the largest use for mercury in the United States. In this process, mercury is used as a flowing cathode in an electrolytic cell into which a sodium chloride [7647-14-5] solution (brine) is introduced. This brine is then subjected to an electric current, and the aqueous solution of sodium chloride flows between the anode and the mercury, releasing chlorine gas at the anode. The sodium ions form an amalgam with the mercury cathode. Water is added to the amalgam to remove the sodium [7440-23-5] forming hydrogen [1333-74-0] and sodium hydroxide and relatively pure mercury metal, which is recycled into the cell (see Alkali and chlorine products). 

Ttinitroparaffins can be prepared from 1,1-dinitroparaffins by electrolytic nitration, ie, electrolysis in aqueous caustic sodium nitrate solution (57). Secondary nitroparaffins dimerize on electrolytic oxidation (58) for example, 2-nitropropane yields 2,3-dimethyl-2,3-dinitrobutane, as well as some 2,2-dinitropropane. Addition of sodium nitrate to the anolyte favors formation of the former. The oxidation of salts of i7k-2-nitropropane with either cationic or anionic oxidants generally gives both 2,2-dinitropropane and acetone (59) with ammonium peroxysulfate, for example, these products are formed in 53 and 14% yields, respectively. Ozone oxidation of nitroso groups gives nitro compounds 2-nitroso-2-nitropropane [5275-46-7] (propylpseudonitrole), for example, yields 2,2-dinitropropane (60). 

Tire usual commercial method of preparation of gibbsite is by cry staUization from a supersaturated caustic aluminate, Na A102, solution. Seed gibbsite crystals are used. 

Manufacture. Several methods have been described for the preparation of -hydroxyben2oic acid. The commercial technique is similar to that of salicylic acid, ie, Kolbe-Schmitt carboxylation of phenol. The modification includes the use of potassium hydroxide in place of caustic (51). The dried potassium phenate is heated under pressure, 270 kPa (2.7 atm) or more, with dry carbon dioxide at 180—250°C. The potassium salt [16782-08-4] of Nhydroxyben2oic acid forms almost quantitatively and can be converted to free acid by using a mineral acid. 

Solutions of anhydrous stannous chloride are strongly reducing and thus are widely used as reducing agents. Dilute aqueous solutions tend to hydrolyze and oxidize in air, but addition of dilute hydrochloric acid prevents this hydrolysis concentrated solutions resist both hydrolysis and oxidation. Neutralization of tin(II) chloride solutions with caustic causes the precipitation of stannous oxide or its metastable hydrate. Excess addition of caustic causes the formation of stannites. Numerous complex salts of stannous chloride, known as chlorostannites, have been reported (3). They are generally prepared by the evaporation of a solution containing the complexing salts. 

Amorphous Sb2S2 can be prepared by treating an SbQ solution with 442S or with sodium tliiosulfate, or by heating metallic antimony or antimony trioxide with sulfur. Antimony trisulfide is almost iasoluble ia water but dissolves ia concentrated hydrochloric acid or ia excess caustic. In the absence of air, Sb2S2 dissolves ia alkaline sulfide solutions to form the tliioantimonate(III) ion [43049-98-5], SbS 2, in the presence of air the tetratliioantimonate(V) ion [17638-29-8], SbS , is formed. The lemon-yellow crystalline salt, Na SbS 94420, known as Schhppe s salt [1317-86-8], contains the tetrahedral tetratliioantimonate(V) ion. 

Formation of Ethers. Very high ether yields can be obtained from alcohols and phenols with dialkyl sulfates in CH2CI2 and concentrated NaOH—tetrabutylammonium chloride at room temperature or slightly elevated temperature within 1—5 h (18). Using excess aqueous caustic—N(C4H2)4HS04, unsymmetrical aUphatic ethers can be prepared with alkyl chlorides at 25—70°C in 3—4 h (19) (see Ethers). 

Carbene Reactions. The best procedure for preparing dihalocarbene adducts of olefins consists in stirring a haloform—methylene chloride solution with an excess of concentrated aqueous caustic soda in the presence of hen 2y1triethy1 amm onium chloride. Even stericahy hindered and electronically deactivated compounds give excellent yields (32). Mixed dihalocarbenes, CXY (X,Y = E, Cl, Br, I), except for CE2, can be prepared. 

Oxazolidinones. 3-Chloro-4,4-dimethyl-2-oxa2ohdinone [58629-01-9] (10) has been extensively evaluated as a disiafectant (157). It is prepared by phosgenation of (CH2)2CH(NH2)CH20H followed by chlorination ia the presence of caustic. It is a white crystalline soHd with a theoretical av CI2 of... 

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

Lime slurry is chlorinated in the presence of Ca(OCl)2 mother Hquor, NaOH, and NaOCl (185). After concentration, the resulting slurry of Ca(OCl)2 2H20 is filtered and the cake dried. A portion of the filtrate is treated with caustic, the recovered lime is recycled, and the mother Hquor used to prepare the requited NaOCl solution in an evaporator—chlorinator, which after separation of salt, is sent to the main reactor. In a slightly modified version, a lime purification step is added (186). 

Several modifications of the preparation of neutral Ca(OCl)2 2H20 do not involve intermediates. In a continuous process, lime slurry containing caustic and Ca(OCl)2 mother Hquor is chlorinated under reduced pressure to remove the heat of reaction, and the resulting slurry is separated in a classifier into Ca(OCl)2— and NaCl-rich regions from which slurry is withdrawn to obtain Ca(OCl)2 filter cake and soHd salt (204). 

Virtually all of the organo derivatives of CA are produced by reactions characteristic of a cycHc imide, wherein isocyanurate nitrogen (frequendy as the anion) nucleophilically attacks a positively polarized carbon of the second reactant. Cyanuric acid and ethylene oxide react neady quantitatively at 100°C to form tris(2-hydroxyethyl)isocyanurate [839-90-7] (THEIC) (48—52). Substitution of propylene oxide yields the hydroxypropyl analogue (48,49). At elevated temperatures (- 200° C). CA and alkylene oxides react in inert solvent to give A/-hydroxyalkyloxazohdones in approximately 70% yield (53). Alternatively, THEIC can be prepared by reaction of CA and 2-chloroethanol in aqueous caustic (52). THEIC can react further via its hydroxyl fiinctionahty to form esters, ethers, urethanes, phosphites, etc (54). Reaction of CA with epichlorohydrin in alkaline dioxane solution gives... 

---