Solid acid salts

But this is not necessarily so. Carboxy-acids are often much less soluble in water than are their salts. In such a case the ternary diagram will have the lop-sided appearance represented in Fig. 1(c) when a solid acid salt exists, the lop-sidedness may lead to the effect shown in... 

The infrared spectrum of this (solid) acid salt (24, 25, 26) will be discussed in section XX B. Here we simply state that it is anomalous without explanation of the term. 

The weakly basic 2-aminothiazoles are most readily diazotized in concentrated solutions of oxygen containing acids such as sulfuric acid, 40 to 50% (322-326) fiuoroboric phosphoric acids (589) phosphoric acid (327, 328) and mixtures of phosphoric and nitric acid (74. 322, 323. 329-331). From strong acid solutions, solid diazonium salts can be isolated (34, 332. 333). 

Ammonium formate [540-69-2] M 63.1, m 116 , 117.3 , d 1.280. Heat solid in NH3 vapour and dry in vacuum till NH3 odour is faint. Recryst from abs EtOH and then keep in a desiccator over 99% H2SO4 in vacuo. It is very hygroscopic. Exists in two forms, stable needles and less stable plates. Also forms acid salts, i.e. HCO2NH4.3HCO2H and HCO2NH4.HCO2H. [J Am Chem Soc 43 1473 1921 63 3124 1941. ]... 

Dissolve in distilled H2O and acidify with dilute HCl to pH 3.5. Filter off the solid acid and wash well with H2O. Redissolve ca lOg in 300mL H2O containing 12g of NaOAc. Ppte again by adding HCl, filter and wash with H2O. Add the solid to 200mL of EtOH stir for Ih and filter. Repeat the EtOH wash and dry the bright yellow solid in a vacuum. This acid decomposes on heating at ca 180°. See below for the prepn of the Na salt. [Anal Chem 28 882 1956]. 

The apparatus employed in the preceding experiment is used. To 600 g of 98% sulfuric acid at O " (ice-salt bath) is added about 3 ml of 88 % formic acid. When the rapidly stirred solution becomes foamy with evolution of carbon monoxide, 50 g of decahydro-2-naphthol and 100 g of 88% formic acid are added from two dropping funnels over 3 hours. During the addition, the temperature is kept below 5° the mixture continues to foam. Work-up as for the cis acid gives about 85% of solid acid, predominantly trans. After three recrystallizations from acetone, about 7 g of the pure acid is obtained, mp 135-136°. 

A mixture of 2.33 g of bismuth oxide (BijOa), 3.71 g of anhydrous sodium carbonate, and 7.64 g of triglycollamic acid and 40 cc of water was heated at B0°C on the water bath until all was dissolved. The solution was avaporated on the water bath to a syrup. The syrup was allowed to cool, during which time partial solidification occurred. It was then triturated with 300 cc of alcohol, and the solid anhydrous salt was collected on a filter, washed with alcohol, ground fine, and dried in a vacuum desiccator. This substance has a water solubility at 25°C of 31 S% by weight. It decomposes on heating in the melting point bath. 

This crude product is dissolved in 100 ml of dilute hydrochloric acid, the acid solution is extracted with ether, and the aqueous layer is made basic with sodium hydroxide solution (3N) in the presence of ether (approximately 250 ml). The ether layer Is separated, dried over potassium hydroxide and evaporated to a white solid. Additional purification by repeating the formation of the hydrochloric acid salt and reprecipitation of the base is carried out. When purified in this manner, followed by drying at 80°C in vacuo over phosphorus pentoxide, 2-chloro-11-(4-methyl-1-piperazinyl)dibenz[b,f] [1,4]oxazepine, li/IP 109° to 111°C, is obtained. 

The organic acid salts, such as EDTA and heptonate, are included for water softening properties, and to assist in the removal of solid particles. Gluconate and heptonate, in particular, are effective in the highly alkaline solutions used for etching aluminium and prevent the precipitation of aluminium hydroxide scale and sludge. 

In most cases diazonium salts are not isolated, but are converted into products by reactions that can be carried out in situ. Moreover, it is actually recommended not to isolate these salts, not even for purification purposes, as many of them have a tendency to explode. In addition, the high solubility of most diazonium salts in water makes precipitation from this medium difficult. Therefore, to obtain solid diazonium salts the recommended method for many decades was to carry out diazotizations in ethanol followed by precipitation with ether. As inorganic salts of nitrous acid are scarely soluble in ethanol, Knoevenagel recommended alkyl nitrites (ethyl or isopentyl nitrite) as diazotization reagents as long ago as 1890. Various other solvents have subsequently been used for diazotizations with alkyl nitrites (see Saunders and Allen, 1985, p. 23 ff.), but as a method for obtaining solid diazonium salts this has been superseded by the isolation of diazonium tetrafluoroborates and, to a lesser degree, of hexafluorophosphates. 

There have been many studies of the reduction of oxides and of oxy-acid salts with elemental carbon, some of which are of great technological importance. Although both reactants may be solids... 

Unsymmetrical as well as symmetrical anhydrides are often prepared by the treatment of an acyl halide with a carboxylic acid salt. The compound C0CI2 has been used as a catalyst. If a metallic salt is used, Na , K , or Ag are the most common cations, but more often pyridine or another tertiary amine is added to the free acid and the salt thus formed is treated with the acyl halide. Mixed formic anhydrides are prepared from sodium formate and an aryl halide, by use of a solid-phase copolymer of pyridine-l-oxide. Symmetrical anhydrides can be prepared by reaction of the acyl halide with aqueous NaOH or NaHCOa under phase-transfer conditions, or with sodium bicarbonate with ultrasound. 

Incidentally, 31 contributes more to the hybrid than 32, as shown by bond-distance measurements. In benzenediazonium chloride, the C—N distance is 1.42 A, and the N—N distance 1.08 A, which values lit more closely to a single and a triple bond than to two double bonds (see Table 1.5). Even aromatic diazonium salts are stable only at low temperatures, usually only below 5°C, though more stable ones, such as the diazonium salt obtained from sulfanilic acid, are stable up to 10 or 15°C. Diazonium salts are usually prepared in aqueous solution and used without isolation, though it is possible to prepare solid diazonium salts if desired (see 13-20). The stability of aryl diazonium salts can be increased by crown ether complexion. ... 

Photocopies of journal articles relating to the Unipet process for the recycling of PETP developed by United Resource Recovery Corp. Details are given of the process which enables contaminated PETP to be recycled by the use of caustic soda which reacts with the PETP to yield ethylene glycol and terephthalic acid, followed by heating and evaporation of the EG which reduces organic impurities to carbon dioxide and water and leaves solid terephthalic salt. Its implications for the industry are also discussed. 

Catalysts can be metals, oxides, sulfides, carbides, nitrides, acids, salts, virtually any type of material. Solid catalysts also come in a multitude of forms and can be loose particles, or small particles on a support. The support can be a porous powder, such as aluminium oxide particles, or a large monolithic structure, such as the ceramics used in the exhaust systems of cars. Clays and zeolites can also be solid catalysts. 

Since the values of the unit cell parameter of the acidic salts were not intermediate between those of the neutral salts and of the parent acid (ao = 1.216 and 1.217 nm, respectively, for H3PWX2O40 and H4SiWi204o), one may propose that there is no formation of solid solutions but rather a mixture of the neutral salt and of the acid highly dispersed on the neutral salt. 

During the last decade many industrial processes shifted towards using solid acid catalysts (6). In contrast to liquid acids that possess well-defined acid properties, solid acids contain a variety of acid sites (7). Sohd acids are easily separated from the biodiesel product they need less equipment maintenance and form no polluting by-products. Therefore, to solve the problems associated with liquid catalysts, we propose their replacement with solid acids and develop a sustainable esterification process based on catalytic reactive distillation (8). The alternative of using solid acid catalysts in a reactive distillation process reduces the energy consumption and manufacturing pollution (i.e., less separation steps, no waste/salt streams). 

C. (+)- and (-)-a-(Isopropylideneaminooxy) propionic acid-(-)-ephedrine salts. A solution of 36.6 g. (0.200 mole) of (— )-ephedrine monohydrate (Note 7) in 800 ml. of ethyl acetate containing 6% of ethanol (Note 8) is placed in a 2-1. beaker, d,l-a-(Isopropylideneaminooxy)propionic acid (29.0 g., 0.200 mole) is dissolved in this solution by stirring (Note 9). The beaker is covered securely with a rubber dam, cooled for a short period in an ice bath, placed in a refrigerator at 0-5°, and allowed to remain undisturbed for 8-16 hours after crystallization has begun (Note 10). The solid mass of crystals is filtered by suction, and the funnel is covered with a rubber dam to remove most of the solvent. The solid product is placed in a 500-ml. beaker, 250 ml. of ethyl acetate is added (Note 11), and the mixture is heated until all the solid has dissolved. The solution is cooled, placed in a refrigerator for several hours, and filtered the crystalline precipitate is dried in air. The yield of the (—)-ephedrine-(+)-a-(isopropylideneaminooxy)propionic acid salt is 22-25 g. (71-81%) m.p. 115-119° (Notes 12 and 13) [ ]2°d -4.2° (c 1.5, chloroform). 

The combined filtrates are diluted with an equal volume of petroleum ether (b.p. 30-60°), placed in a refrigerator for 8-16 hours, and filtered. The solid product is recrystallized from ethyl acetate (10 ml. per gram of the salt). The yield of the monohydrate of the (—)-ephedrine-(—)-a-(isopropylideneami-nooxy)propionic acid salt is 19-26 g. (58-79%) m.p. 88-90° [a]20D —57° (c 1.5, chloroform) (Notes 13 and 14). 

The two diastereoisomeric salts can be readily distinguished from each other. The (—)-ephedrine-(+)-acid salt is formed as cottony crystals that grow in the solution and eventually become a solid, white opaque mass. The monohydrate of the (—)-ephedrine-(—)-acid salt consists of clear, chunky crystals that grow from, and adhere to, the bottom and sides of the flask. 

The esters of nitrous acid are characterised by their high velocities of formation and hydrolysis. They are almost instantaneously decomposed by mineral acids and in the method of preparation given this has been taken into account. The slightest excess of hydrochloric acid must be avoided. Advantage is taken of this property of the alkyl nitrites in all cases where it is desired to liberate nitrous acid in organic solvents (in which metallic nitrites are insoluble). Examples addition of N203 to olefines, preparation of solid diazonium salts (p. 286), production of isonitroso-derivatives from ketones by the action of HN02. This synthesis is often also carried out in the manner of the acetoacetic ester synthesis, with ketone, alkyl nitrite, and sodium ethylate the sodium salt of the isonitrosoketone is formed (cf. in this connexion p. 259) ... 

Most of the work on chiral recognition has been carried out with amino-acid ester salts. The limited number of available data of similar experiments with amino-acid salts point to an increased enantiomeric differentiation (Table 69 Peacock and Cram, 1976). The reason might be the higher -acidity of the carboxyl group (vide ir fra). In solid-liquid chromatography (see Table 68) the difference between amino-acid salts and amino-acid ester salts is not consistent and not always in favour of the amino-acid salts. However, it should be... 

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