Bases ammonium hydroxide

A monobasic base is one that will accept just one hydrogen ion per formula. Examples include sodium hydroxide, NaOH, a strong base ammonium hydroxide, NH4OH, a weak base and sodium bicarbonate, NaHC03, a weak base. A polybasic base is one that will accept two or more hydrogen ions per formula. Examples include sodium carbonate, Na2C03, a dibasic base, and sodium phosphate, Na3P04, a tribasic base. 

In order to produce the ions necessary for analysis, the pH of the mobile phase often has to be modified. Volatile organic acids (formic acid, acetic acid, and trifluoroacetic acid) and volatile bases (ammonium hydroxide) are used to provide this modification. With the analysis of basic compounds, a lower pH mobile... 

Similarly, in the reaction for a weak base, ammonium hydroxide NH4OH, or, more appropriately, aqueous ammonia NH3(aq) the dissociation is... 

Similar considerations can be applied to bases. Ammonium hydroxide (i.e. the aqueous solution of ammonia) dissociates according to the equation ... 

Carbonic Acid. — Carbon dioxide gas is often called carbonic acid gas, or simply carboiiic acid. It is believed that when carbon dioxide is passed into water it combines with the water and forms a weak, unstable acid. The case is analogous to the formation of the base ammonium hydroxide by the solution of ammonia gas in... 

Bases Ammonium hydroxide Quaternary amines, strong bases, generally triethyl-amine... 

Depending on their degree of ethoxylation, fatty alcohol ether sulfates are extremely complex mixtures, for which the separation efficiency of a polymer phase is not sufficient. Good separations are obtained with silica-based, chemically bonded reversed phases. The chromatographic conditions have to be adjusted accordingly. The free base ammonium hydroxide cannot be used as the ion-pair reagent because of the pH limitation of modified silica, so suppressor systems cannot be used for subsequent conductivity detection. Sodium acetate has proved to be a suitable ion-pair reagent for nonsuppressed conductivity... 

Primary solvents of water, methanol and acetonitrile modified with acids (formic or acetic acid) or bases (ammonium hydroxide or diethylamine) have been most widely used. With acid solvents the PA tertiary alkaloids elute before their PANOs, whereas in basic conditions this order is reversed. Basic solvents at high pH (10-11) often give good peak shapes but at the expense of longer retention times. Peak shapes are however also good with acid solvents and retention times are shorter [42]. 

As under acidic conditions, the hydrolysis of TEOS in basic media was a function of the catalyst concentration [51]. The order of the reaction was determined by comparing the times required to complete specific degrees of hydrolysis. In very dilute solutions, the hydrolysis reaction was found to be first-order in [NaOHj. However when the concentration of TEOS was increased, the reaction no longer followed a simple order but apparently became complicated by secondary reactions. The weaker bases, ammonium hydroxide and pyridine, produced measurable speeds of reaction only if they were present in large concentrations. Compared to acidic conditions, the hydrolysis kinetics were more strongly affected by the nature of the solvent. 

Further Ei eriments.—In the manner described above, one should also determine the heat of neutralization of a weak base (ammonium hydroxide) with a strong add (hydrochloric acid), and of a strong base (sodium hydroxide) with a weak acid (acetic add). Determine also the heat of neutralization of phosphoric acid using r, 2, and 3 moles of sodium hydroxide per mole of phosphoric acid. 

The base used is most often benzyltrimelhyl-ammonium hydroxide, but aqueous or ethano-lic alkali is suitable. In addition to compounds... 

Triton B Trade name for benzyltrimethyl-ammonium hydroxide usually as a 40% solution in methanol. A strong base, soluble in many solvents used as a catalyst. See phase transfer chemistry. 

Aqueous ammonia can also behave as a weak base giving hydroxide ions in solution. However, addition of aqueous ammonia to a solution of a cation which normally forms an insoluble hydroxide may not always precipitate the latter, because (a) the ammonia may form a complex ammine with the cation and (b) because the concentration of hydroxide ions available in aqueous ammonia may be insufficient to exceed the solubility product of the cation hydroxide. Effects (a) and (b) may operate simultaneously. The hydroxyl ion concentration of aqueous ammonia can be further reduced by the addition of ammonium chloride hence this mixture can be used to precipitate the hydroxides of, for example, aluminium and chrom-ium(III) but not nickel(II) or cobalt(II). 

Anion exchange resins of the quaternary ammonium hydroxide type (e.g., De-Acidlte FF, IRA-400 or Dowex I) are strong bases and are useful cataly s for the cyanoethylatlon of alcohols and possibly of other active hydrogen compounds. 

The Hofmann elimination route, of which many versions exist, can be carried out at much lower temperatures in conventional equipment. The PX is generated by a 1,6-Hofmaim elimination of amine from a quaternary ammonium hydroxide in the presence of a base. This route gives yields of 17—19%. Undesired polymeric products can be as high as 80% of the product. In the presence of a polymerization inhibitor, such as phenothiazine, DPXN yields can be increased to 50%. 

Ammonia—Gas-Cured Flame Retardants. The first flame-retardant process based on curing with ammonia gas, ie, THPC—amide—NH, consisted of padding cotton with a solution containing THPC, TMM, and urea. The fabric was dried and then cured with either gaseous ammonia or ammonium hydroxide (96). There was Httle or no reaction with cellulose. A very stable polymer was deposited in situ in the cellulose matrix. Because the fire-retardant finish did not actually react with the cellulose matrix, there was generally Httle loss in fabric strength. However, the finish was very effective and quite durable to laundering. 

Pentafluoroaniline. Pentafluoroaniline [771 -60-8] i2is been prepared from amination of hexafluoroben2ene with sodium amide inbquid ammonia or with ammonium hydroxide in ethanol (or water) at 167—180°C for 12—18 h. It is weakly basic (p = 0.28) and dissolves only in concentrated acids. Liquid crystals have been prepared from Schiff bases derived from pentafluoroaniline (230). 

The nitro alcohols available in commercial quantities are manufactured by the condensation of nitroparaffins with formaldehyde [50-00-0]. These condensations are equiUbrium reactions, and potential exists for the formation of polymeric materials. Therefore, reaction conditions, eg, reaction time, temperature, mole ratio of the reactants, catalyst level, and catalyst removal, must be carefully controlled in order to obtain the desired nitro alcohol in good yield (6). Paraformaldehyde can be used in place of aqueous formaldehyde. A wide variety of basic catalysts, including amines, quaternary ammonium hydroxides, and inorganic hydroxides and carbonates, can be used. After completion of the reaction, the reaction mixture must be made acidic, either by addition of mineral acid or by removal of base by an ion-exchange resin in order to prevent reversal of the reaction during the isolation of the nitro alcohol (see Ion exchange). 

Idemitsu Process. Idemitsu built a 50 t x 10 per year plant at Chiba, Japan, which was commissioned in Febmary of 1989. In the Idemitsu process, ethylene is oligomerised at 120°C and 3.3 MPa (33 atm) for about one hour in the presence of a large amount of cyclohexane and a three-component catalyst. The cyclohexane comprises about 120% of the product olefin. The catalyst includes sirconium tetrachloride, an aluminum alkyl such as a mixture of ethylalurninumsesquichloride and triethyl aluminum, and a Lewis base such as thiophene or an alcohol such as methanol (qv). This catalyst combination appears to produce more polymer (- 2%) than catalysts used in other a-olefin processes. The catalyst content of the cmde product is about 0.1 wt %. The catalyst is killed by using weak ammonium hydroxide followed by a water wash. Ethylene and cyclohexane are recycled. Idemitsu s basic a-olefin process patent (9) indicates that linear a-olefin levels are as high as 96% at C g and close to 100% at and Cg. This is somewhat higher than those produced by other processes. 

In general, polycarbonate resins have fair chemical resistance to aqueous solutions of acids or bases, as well as to fats and oils. Chemical attack by amines or ammonium hydroxide occurs, however, and aUphatic and aromatic hydrocarbons promote crazing of stressed molded samples. Eor these reasons, care must be exercised in the choice of solvents for painting and coating operations. Eor sheet appHcations, polycarbonate is commonly coated with a sihcone—sihcate hardcoat which provides abrasion resistance as well as increased solvent resistance. Coated films are also available. 

Some fabrication processes, such as continuous panel processes, are mn at elevated temperatures to improve productivity. Dual-catalyst systems are commonly used to initiate a controlled rapid gel and then a fast cure to complete the cross-linking reaction. Cumene hydroperoxide initiated at 50°C with benzyl trimethyl ammonium hydroxide and copper naphthenate in combination with tert-huty octoate are preferred for panel products. Other heat-initiated catalysts, such as lauroyl peroxide and tert-huty perbenzoate, are optional systems. Eor higher temperature mol ding processes such as pultmsion or matched metal die mol ding at temperatures of 150°C, dual-catalyst systems are usually employed based on /-butyl perbenzoate and 2,5-dimethyl-2,5-di-2-ethyIhexanoylperoxy-hexane (Table 6). 

Choline base [123-41 -17, [(CH2)3NCH2CH20H] 0H, triniethyl(2-hydroxyethyl)-ammonium hydroxide, derives its name from bile (Greek chole from which it was first obtained. This so-called free-ch oline is a colorless, hygroscopic Hquid with an odor of trimethyl amine. The quaternary ammonium compound (1) choline [62-49-7] or a precursor is needed in the diet as a constituent of certain phosphoHpids universally present in protoplasm. 

Choline is not usually encountered as the free base but as a salt, most commonly, the chloride, [(CH2)3N(CH2CH20H)] C1 . As a quaternary ammonium hydroxide, choline reacts with hydrochloric acid to form the chloride and water, whereas primary, secondary, and tertiary amines combine with hydrochloric acid to form hydrochlorides. 

Pla.tinum, Platinum plating has found appHcation in the production of platinised titanium, niobium, or tantalum anodes which are used as insoluble anodes in many other plating solutions (see Metalanodes). Plating solutions were often based on platinum "P" salt, which is diamminedinitroplatiniim (IT). A dinitroplatinite sulfate—sulfuric acid bath has been used to plate direcdy onto titanium (129). This bath contains 5 g/L of the platinum salt, pH adjusted to 2.0 with sulfuric acid. The bath is operated at 40°C at 10—100 A/m. Other baths based on chloroplatinic acid have been used in both acid and alkaline formulations the acid bath uses 20 g/L of the platinum salt and 300 g/L hydrochloric acid at 65° C and 10—200 A/m. The alkaline bath uses 10 g/L of the platinum salt, 60 g/L of ammonium phosphate and ammonium hydroxide to give a pH of 2.5—9.0. The alkaline bath can be plated directly onto nickel-base alloys acid baths require a gold strike on most metals. 

The most common plafing bath uses fluoride to complex the fin. A typical solution contains 45 g/L staimous chloride, 300 g/L nickel chloride hexahydrate, and 55 g/L ammonium bifluofide. It is operated at pH 2.0—2.5 usiag ammonium hydroxide temperature is 65—75°C and current about 200 A/m. The bath has excellent throwing power. Air agitation is avoided. The deposit is bright without additives. Anodes are cast nickel, and the fin is replenished by additions of staimous chloride. AHoy anodes of 72% fin have been used to a much lesser extent. Tia-nickel deposits are covered by ASTM (136) and ISO (137) specifications. One other bath based on pyrophosphate has appeared ia the Hterature, but does not seem to be ia commercial use. 

The procedure for preparing 6-hydroxynicotinic acid is also based on a method described by von Pechmann. 6-Hydroxynico-tinic acid has also been prepared by decarboxylation of 6-hy-droxy-2,3-pyridinedicarboxylic acid by heating 6-hydra-zinonicotinic acid or its hydrazide with hydrochloric acid by the action of carbon dioxide on the sodium salt of a-pyridone at 180-200 and 20 atmospheres by heating the nitrile of 6-chlo-ronicotinic acid with alcoholic sodium hydroxide or hydrochloric acid from 6-aminonicotinic acid and by the prolonged action of concentrated ammonium hydroxide on methyl cou-malate. ... 

The first two are very soluble in water but the last is less so. Weaker bases inelude ammonium hydroxide where X is NH4. In faet every aeid ean generate a base by loss of a proton and the definition now ineludes any eompound eapable of donating eleetron pairs, e.g. amines. Bases turn litmus paper blue and show eharaeteristie effeets on other indieators. They are soluble in water, tarnish in air, and in eoneentrated form are eorrosive to the toueh. Common examples are given in Table 3.5. ... 

Bases (Caustics)—Sodium Hydroxide. Ammonium Hydroxide. Calcium Hydroxide... 

Recently Gadamer s view > has been widely accepted. He postulates for these compounds a tautomeric system of three components, in which the quaternary ammonium hydroxide, the pseudo base (or... 

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