Acids, also

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

When the reaction is complete, heat the stirred mixture carefully under reflux over a Bunsen burner and asbestos gauze for I hour if the mixture becomes too thick for efficient stirring, add up to 15 mL of acetic acid. Now decant the hot mixture into 500 ml. of vigorously-stirred ice-cold water wash the residual zinc thoroughly with glacial acetic acid (2 portions each of I -2 ml.), decanting the acid also into the stirred water. 

The relatively concentrated hydrochloric acid is employed so that with ordinary use of the apparatus, spent liquor does not accumulate very rapidly the concentrated acid also ensures a brisk and delicately controlled flow of gas. When the generator is replenished with acid, marble or both, the de-aeration procedure detailed above is repeated until a sufficiently air-free gas supply is obtained. 

Phenylethylbarbituric acid (also termed luminal and phenobarbitone) may be prepared by condensing ethyl phenyletUylmalonate with urea in the presence of sodium methoxide ... 

Group III. Carboxylic and sulphonic acids (also sym.-tribromophenol, 2 4-dinitrophenol and picric acid) are also soluble in dilute sodium bicarbonate solution. 

Lactones, which may be regarded as cyclic or inner esters, react similarly. Anhydrides of carboxylic acids also react with hydroxylamine to form hydroxamic acids ... 

Acids are not limited to liquid (or gaseous) systems. Solid acids also play a significant role. Acidic oxides such as silica, silica-alumina, etc. are used extensively as solid acid catalysts. New solid acid systems that are stronger than those used conventionally are frequently called solid superacids. 

The chemist can try to separate the two isomers by careful fractional distillation but it will be next to impossible to do because both the cis and the trans have practically the same boiling point. There are a few things that the chemist can do or hope for to get rid of that cis isomer. The cis configuration is less stable than the trans and may switch over to the trans configuration with a little help. The chemist can gently heat the isosafrole oil to about 150°C for an hour or so. She can also try the same heating except have the oil mixed with some acetic acid. Also, the isosafrole can be fractionally distilled to ultra purity and then be allowed to simply sit for a couple of days. Trans isosafrole may spontaneously crystalize out while the cis form remains as an oil. They can then be separated by filtration. 

Polyprotic bases, like polyprotic acids, also have more than one base dissociation reaction and base dissociation constant. 

TBP and nitric acid also tend to form a complex with each other, but at sufftcientiy high uranyl nitrate concentrations the nitric acid is mainly displaced into the aqueous phase. 

The esters of monofluorophosphoric acid are of great interest because of their cholinesterase inhibiting activity which causes them to be highly toxic nerve gases and also gives them medical activity (see Enzyme inhibitors). The most studied is the bis(l-methylethyl)ester of phosphorofluoridic acid also known as diisopropyl phosphorofluoridate [155-91 DFP (5), and as the ophthalmic ointment or solution Isoflurophate USP. It is used as a... 

Of the water-soluble vitamins, intakes of nicotinic acid [59-67-6] on the order of 10 to 30 times the recommended daily allowance (RE)A) have been shown to cause flushing, headache, nausea, and moderate lowering of semm cholesterol with concurrent increases in semm glucose. Toxic levels of foHc acid [59-30-3] are ca 20 mg/d in infants, and probably approach 400 mg/d in adults. The body seems able to tolerate very large intakes of ascorbic acid [50-81-7] (vitamin C) without iH effect, but levels in excess of 9 g/d have been reported to cause increases in urinary oxaHc acid excretion. Urinary and blood uric acid also rise as a result of high intakes of ascorbic acid, and these factors may increase the tendency for formation of kidney or bladder stones. AH other water-soluble vitamins possess an even wider margin of safety and present no practical problem (82). 

Petfluotoalkanesulfonic acids also show high acidity. The parent trifluoromethanesulfonic acid (triflic acid), CF SO H, is commercially prepared by electrochemical fluorination of methanesulfonic acid (214). It has an value of —14.1 (215,216). The higher homologues show slightly decreasing acidities. 

Gravimetric methods more suitable for general use involve the precipitation of metallic gold from tetrachloraurate solutions by reduction with oxaUc acid, SO2, or hydroquinone. Formaldehyde, hydrazine, ferrous sulfate, and hypophosphorous acid also have been used but are considered less efficient (40). 

Glycohc acid also undergoes reduction or hydrogenation with certain metals to form acetic acid, and oxidation by hydrogen peroxide ia the presence of ferrous salts to form glyoxylic acid [298-12A], HCOCOOH, and ia the presence of ferric salts ia neutral solution to form oxaHc acid, HOOCCOOH formic acid, HCOOH and Hberate CO2 and H2O. These reduction and oxidation reactions are not commercially significant. 

R, R -Tartaric acid also can be produced by racemization of (R-R, R -tartaric acid in the presence of y j O-tartaric acid (85). In this process, formation of y j O-tartaric acid during racemization does not occur. 

The term naphthenic acid, as commonly used in the petroleum industry, refers collectively to all of the carboxyUc acids present in cmde oil. Naphthenic acids [1338-24-5] are classified as monobasic carboxyUc acids of the general formula RCOOH, where R represents the naphthene moiety consisting of cyclopentane and cyclohexane derivatives. Naphthenic acids are composed predorninandy of aLkyl-substituted cycloaUphatic carboxyUc acids, with smaller amounts of acycHc aUphatic (paraffinic or fatty) acids. Aromatic, olefinic, hydroxy, and dibasic acids are considered to be minor components. Commercial naphthenic acids also contain varying amounts of unsaponifiable hydrocarbons, phenoHc compounds, sulfur compounds, and water. The complex mixture of acids is derived from straight-mn distillates of petroleum, mosdy from kerosene and diesel fractions (see Petroleum). 

Devarda s Method. Nitrogen in nitrates or nitric acid also may be deterrnined by the Kjeldahl method or by Devarda s method. The latter is both convenient and accurate when no organic nitrogen is present. The nitrate is reduced by Devarda s alloy to ammonia in an alkaline solution. The ammonia is distilled and titrated with standard acid. 

Sulfite is oxidized rapidly (/t = 1 X 10 ) to sulfate by ozone (39). Bisulfite ion and sulfurous acid also are oxidized rapidly (to bisulfate and sulfuric acid) with k values of 3.2 X 10 and 2 X 10 , lespectively. 

Cyanide Wastes. Ozone is employed as a selective oxidant in laboratory-scale synthesis (7) and in commercial-scale production of specialty organic chemicals and intermediates such as fragrances, perfumes (qv), flavors, antibiotics (qv), hormones (qv), and vitamins (qv). In Japan, several metric tons per day (t/d) of piperonal [120-57-0] (3,4-methylenedioxybenzaldehyde) is manufactured in 87% yield via ozonolysis and reduction of isosafrole [93-16-3], Piperonal (or heHotropine [120-57-0]) has a pleasant odor and is used in perfumery. Oleic acid [112-80-1/, CH3(CH2 )7CH—CH(CH2 ). C02H, from tall oil (qv) is ozonated on a t/d scale to produce pelargonic, GgH2yG02H, and azelaic, H02G(GH2)yG02H, acids. Oleic acid also is ozonated in Japan... 

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