Reactions with alkalis

Fiber-Reactive Dyes. These dyes can enter intu chemical reaction with the fiber and form a covalent bond to become an integral part of the liber polymer. They therefote have exceptional wetfastness. Their main use is oil eellulosie fibers where they are applied neutral and then chemical reaction is initialed by the addition of alkali. Reaction with the cellulose can be by either nucleophilic substitution, using, for example, dyes containing activated halogen substituents, or by addition to the double bond in. for example, vinyl sulfone. -SCfCH=CH2, groups. 

Oxazoles give acylamino ketones 232 by acid-catalyzed ring scission, although they are somewhat more stable than furans. The oxazole ring is also moderately stable to alkali reaction with hydroxide ions is facilitated by electron-withdrawing substituents and fused benzene rings. 

Phase diagrams are extremely useful in determining the reactions that occur when alkali oxides react with many common ceramics. Most scientists and engineers are easily able to evaluate binary phase diagrams that correspond to an alkali reaction with single oxide ceramics however, when multi-oxide ceramics such as mullite are involved, multi-component phase diagrams are not fully used and extremely time-consuming experimentation is unnecessarily conducted. 

If the solution is clear up to this salinity, any problem mentioned previously would not appear because the solution will be more stable after mixing with the oil in situ. If the solution is hazy or any precipitation appears, chemicals must be reselected. Such a test is an aqueous stability test. Generally, the salinity limit in an aqueous stability test is close to the optimum salinity of microemulsion. When an alkali is added for screening ASP formula, sometimes precipitation is seen. This result is probably due to an alkali reaction with the glass tube so that silicate forms (Sheng et al., 1994). Figure 7.5 shows an example of an aqueous stability test. 

The preceding four types of consumption mnst be determined experimentally in the laboratory and upscaled to field scales. The experimental conditions should be as close to the field conditions as possible. Field oil and water samples can be obtained, and experiments shonld be condncted at the held temperature. Ideally, reservoir rocks should be used. In practice, we may not be able to conduct all the necessary experiments becanse of the cost, available resources, and limited time. An approximation mnst be made to estimate the consumption for each type. For example, the consnmption for alkali reaction with crude oil can be estimated from Eq. 10.12, assnming all the acidic components are consumed to react with the alkali. The alkali consumption ACo in meq/mL is the same as the soap generated. ACo is generally a small fraction of the total consumption. Because these consumptions involve complex chemical reactions, efforts have been made to collect some published experimental data and were presented earlier. A general rule is 0.05 to 2% alkali concentration and 0.1 to 0.23 PV injection volnme. Note that alkali addition in an ASP system can rednce snrfactant and polymer adsorption. However, addition of snrfactant and/or polymer does not affect alkali consumption (Li, 2007). This is probably because the alkali molecules are smaller than the surfactant or polymer molecules, thus the existence of snrfactant and polymer molecnles will not affect the adsorption of alkali molecnles, nor will their existence affect alkahne reactions. 

Injected alkali reaction with formation brine (precipitation) and minerals (dissolution and ion exchange)... 

Heat of crystallization and heat of evaporation Heat of combustion and heat of formation Heat of nitration Chemical properties Reactions with acids and alkalis Reaction with inorganic substances Effect of heat Effect of light... 

Fiber Cellulose Salt, alkali Reaction with Salt... 

The corrosive alkalis are strong basic (caustic) substances that can attack tissues, other organic substances, and metals, although alkali reactions with metals are considerably slower than reactions with adds. Corrosive alkalis are generally classified as materials with a pH of 11.5 or greater however, as with acids, the pH of an alkaline compound in itself cannot reliably indicate its relative hazard. Even very dilute alkalis can produce severe bums. A 3.8 percent sodium hydroxide solution can produce a necrosis of the mucosa and submucosa of the esophageal wall. 

The change from non-metallic to metallic properties of the Group V elements as the atomic mass of the element increases is shown in their reactions with alkalis. 

Copper(II) ions in aqueous solution are readily obtained from any copper-containing material. The reactions with (a) alkali (p. 430), (b) concentrated ammonia (p 413) and (c) hydrogen sulphide (p. 413) provide satisfactory tests for aqueous copper(II) ions. A further test is to add a hexacyanoferrate(II) (usually as the potassium salt) when a chocolate-brown precipitate of copper(II) hexacyanoferrate(II) is obtained ... 

The above simple experiments illustrate the more important properties of the anhydrides of aliphatic acids. For their characterisation, the reaction with aniline or p-toluidine is frequently employed. Alternatively, the anhydride may be hydrolysed with dilute alkali as detailed under Acid Chlorides, Section 111,88, and the resulting acid characterised as in Section 111,85. 

Most aromatic acid chlorides impart a strongly acid reaction when shaken with water (compare Section 111,88). All are completely hydrolysed by boiling with solutions of caustic alkalis and yield no product volatile from the alkaline solution (compare Eaters, Sections 111,106 and IV, 183). They may be distinguished from acids by their facile reactions with alcohols (compare Section 111,27), phenols (compare Section IV,114), and amines (compare Sections 111,123 and IV.lOO). 

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). 

MetaUic ions are precipitated as their hydroxides from aqueous caustic solutions. The reactions of importance in chlor—alkali operations are removal of magnesium as Mg(OH)2 during primary purification and of other impurities for pollution control. Organic acids react with NaOH to form soluble salts. Saponification of esters to form the organic acid salt and an alcohol and internal coupling reactions involve NaOH, as exemplified by reaction with triglycerides to form soap and glycerol,... 

Reaction with nitrous acid can be used to differentiate primary, secondary, and tertiary mononitroparaffins. Primary nitroparaffins give nitrolic acids, which dissolve in alkali to form bright red salts. 

Reaction with Aldehydes and Ketones. Formaldehyde combines with primary and secondary alkanolamines in the presence of alkali to give methylol derivatives. For the reaction of monoethanolamine with formaldehyde (12), the reaction scheme shown in Figure 1 occurs. 

Organometalhcs. Halosilanes undergo substitution reactions with alkali metal organics, Grignard reagents, and alkylaluininums. These reactions lead to carbon—siUcon bond formation. 

Metallic Antimonides. Numerous binary compounds of antimony with metallic elements are known. The most important of these are indium antimonide [1312-41 -0] InSb, gallium antimonide [12064-03-8] GaSb, and aluminum antimonide [25152-52-7] AlSb, which find extensive use as semiconductors. The alkali metal antimonides, such as lithium antimonide [12057-30-6] and sodium antimonide [12058-86-5] do not consist of simple ions. Rather, there is appreciable covalent bonding between the alkali metal and the Sb as well as between pairs of Na atoms. These compounds are useful for the preparation of organoantimony compounds, such as trimethylstibine [594-10-5] (CH2)2Sb, by reaction with an organohalogen compound. 

Manufacture. MethylceUulose is manufactured by the reaction of alkali cellulose with methyl chloride (76). 

Chloroform can be manufactured from a number of starting materials. Methane, methyl chloride, or methylene chloride can be further chlorinated to chloroform, or carbon tetrachloride can be reduced, ie, hydrodechlorinated, to chloroform. Methane can be oxychlorinated with HCl and oxygen to form a mixture of chlorinated methanes. Many compounds containing either the acetyl (CH CO) or CH2CH(OH) group yield chloroform on reaction with chlorine and alkali or hypochlorite. Methyl chloride chlorination is now the most common commercial method of producing chloroform. Many years ago chloroform was almost exclusively produced from acetone or ethyl alcohol by reaction with chlorine and alkali. 

The dye is initially linked to a ballasted thiazoUdine, which reacts with silver to form a silver iminium complex. The alkaline hydrolysis of that complex yields an alkali-mobile dye. Concomitantiy the silver ion is immobilized by reaction with the ballasted aminoethane thiol formed by cleavage of the thiazolidine ring. 

Pyrrole and alkylpyrroles can be acylated by heating with acid anhydrides at temperatures above 100 °C. Pyrrole itself gives a mixture of 2-acetyl- and 2,5-diacetyl-pyrrole on heating with acetic anhydride at 150-200 °C. iV-Acylpyrroles are obtained by reaction of the alkali-metal salts of pyrrole with an acyl halide. AC-Acetylimidazole efficiently acetylates pyrrole on nitrogen (65CI(L)1426). Pyrrole-2-carbaldehyde is acetylated on nitrogen in 80% yield by reaction with acetic anhydride in methylene chloride and in the presence of triethylamine and 4-dimethylaminopyridine (80CB2036). 

Pyrroles do not react with alkyl halides in a simple fashion polyalkylated products are obtained from reaction with methyl iodide at elevated temperatures and also from the more reactive allyl and benzyl halides under milder conditions in the presence of weak bases. Alkylation of pyrrole Grignard reagents gives mainly 2-alkylated pyrroles whereas N-alkylated pyrroles are obtained by alkylation of pyrrole alkali-metal salts in ionizing solvents. 

Pyrrolethiols, readily obtained from the corresponding thiocyanates by reduction or treatment with alkali, rapidly oxidize to the corresponding disulfides. They are converted into thioethers by reaction with alkyl halides in the presence of base. Both furan- and thiophene-thiols exist predominantly as such rather than in tautomeric thione forms. 

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