Anhydrous acids

To prepare pure acetic acid (glacial acetic acid), the crude aqueous product is converted into the sodium salt, the latter dehydrated by fusionf and then heated with concentrated sulphuric acid anhydrous acetic acid, b.p. 118°, distils over. Only the preparation of aqueous acetic acid and of crystalline copper acetate is described below. 

Organic acids Anhydrous sodium, magnesium or calcium sulphate. 

Ammonia, anhydrous Mercury, halogens, hypochlorites, chlorites, chlorine(I) oxide, hydrofluoric acid (anhydrous), hydrogen peroxide, chromium(VI) oxide, nitrogen dioxide, chromyl(VI) chloride, sulflnyl chloride, magnesium perchlorate, peroxodisul-fates, phosphorus pentoxide, acetaldehyde, ethylene oxide, acrolein, gold(III) chloride... 

The acid occurs both as colorless triclinic prisms (a-form) and as monoclinic prisms ( 3-form) (8). The P-form is triboluminescent and is stable up to 137°C the a-form is stable above this temperature. Both forms dissolve in water, alcohol, diethyl ether, glacial acetic acid, anhydrous glycerol, acetone, and various aqueous mixtures of the last two solvents. Succinic acid sublimes with partial dehydration to the anhydride when heated near its melting point. 

The tri-, tetra-, penta-, and hexahydrates of boron phosphate have been reported. AH of these decompose rapidly in water to give solutions of the parent acids. Anhydrous boron phosphate hydroly2es in a similar fashion, though the reaction proceeds quite slowly for material that has been ignited at high temperatures. 

Hydrogen chloride or a few drops of hydrochloric acid cataly2e the conversion of //-butyraldehyde iato the trimer, parabutyraldehyde, C22H24O2, (2,4,6-tripropyl-l,3,5-trioxane [56769-26-7] (1). The reaction is reversed by heating the parabutyraldehyde ia the presence of acid. Anhydrous hydrogen chloride at —40°C converts //-butyraldehyde iato l,l -dichlorodibutyl ether, (2) ia 70—75% yield (10). 

Oxychlorination of Hydrocarbons. Methane was oxychlorinated with HCl and oxygen over a 4 3 3 CuCl—CUCI2—KCl molten mixture to give a mixture of chlorinated methanes, 60 mol % of which was carbon tetrachloride (28). Aqueous 20% HCl was used in the multistep process as the source of the acid. Anhydrous HCl is more typically used. Other oxychlorination processes can be made to yield high percentages of carbon tetrachloride starting from any of several hydrocarbon feeds (29—31). The typical reaction temperature is 400—600°C (see Chlorocarbons and chlorohydrocarbons. Methyl cm oRiDE Methylene cphoride and Cphoroform). 

Citric acid, anhydrous, crystallizes from hot aqueous solutions as colorless translucent crystals or white crystalline powder. Its crystal form is monoclinic holohedra. Citric acid is dehquescent in moist air. Some physical properties are given in Table 1 (1 3). The solubiUty of citric acid in water and some organic solvents is given in Table 2. The pH and specific gravity of aqueous solutions of citric acid are shown in Table 3. 

Table 1. Physical Properties of Citric Acid, Anhydrous...

Xanthopterin monohydrate (2-amino-4,6-dihydroxypteridine, 2-amino-pteridin-4,6(lff,5ff)-dione) [5979-01-1 (H2O), 119-48-8 (anhydr)] M 197.2, m <300", pK, 1.6 (basic), pKj 6.59 (acidic), PK3 9.31 (acidic)(anhydrous species), and pKj 1.6 (basic), pK2 8.65 (acidic), PK3 9.99 (acidic)(7,8-hydrated species). Purification as for isoxanthopterin. Crystd by acidifying an ammoniacal soln, and collecting by centrifugation followed by washing with EtOH, ether and drying at 100° in vacuo. Paper chromatography Rp 0.15 ( -PrOH, 1% aq NH3, 2 1), 0.36 ( -BuOH,AcOH, H2O, 4 1 1) and 0.47 (3% aq NH3). [Inoue and Perrin J Chem Soc 260 7962 Inoue Tetrahedron 20 243 I964 see also Blakley Biochemistry of Folic Acid and Related Pteridines North Holland Publ Co, Amsterdam 1969.]... 

Note 4). It is possible to obtain 80-90 g. (63-70 per cent of the theoretical amount) of the pure tf-base-f-acid (anhydrous acid salt). 

Chemical Designations - Synonyms Hydrobromic acid, anhydrous Hydrogen bromide, anhydrous Chemical Formula HBr. 

Chemical Designations - Synonyms Hydrochloric acid, anhydrous Chemical Formula Hcl. Observable Characteristics - Physical State (asslipped) Compressed liquefied gas Color Colorless to slightly yellow Odor Sharp, pungent, irritating. 

DuPont, 19 Hydrofluoric Acid, Anhydrous - Technical, Properties, Uses, Storage and Ha ing, undated bulletin, E.I. duPont de Nemours Company, Wilmington, DL,. 

Heavily fluonnated aminobenzenes, pyridines, and pyrimidines are diazotized in strong-acid media Solid sodium nitrite added directly to the fluonnated amine dissolved in 80% hydrofluonc acid, anhydrous hydrogen fluoride, or (1 1 wt/wt) 98% sulfuric acid in (86 14 wt/wt) acetic and propionic acids affords the electrophilic fluoroarenediazonium ion Addition of an electron rich aromatic to the resultant diazonium solution gives the fluoroareneazo compound [10 II] (equa tions 9 and 10)... 

In contrast to other acids, anhydrous hydrogen fluoride does not cause hydroly SIS and decarboxylation of the malonic acid residues in these reactions [5]. It is a good reagent for the cyclization of a-benzamidoacetophenones to 2,5 diphenyl-oxazoles [6] (equation 7) The same reaction with concentrated sulfuric acid gives cyclic product with only a 12% yield [6]... 

Commercial acetic acid is manufactured fiom pyroligneous acid obtained in the destructive distillation of wood. The latter is neutralised with lime, and separated by distillation from wood-spirit and acetone. The crude calcium acetate, which has a dark colour, is then distilled with the requisite quantity of concentrated hydrochloric acid. Anhydrous or glacial acetic acid is obtained by distilling fused sodium acetate with concentrated sulphuric acid. 

Hydrochloric acid, anhydrous Production Absorbers, coolers, strippers, chlorine burners, complete plants... 

For uses of oxalic acid, see under oxalic - acid, anhydrous, below Refs 1) Beil 2, 505, (219), (475] 1534 2) Merck (1968), 771-2 3) CondChemDict... 

Oxalic Acid, Anhydrous (Ethanedioic Acid, Aethandisaure or Kleesaure in Ger). H02C.C02H, mw 90,04, orthorhombic crysts from glac acet ac mp, 189.5° dec, subl best at 157° d 1.9g/cc. 

By a similar argument we calculate for /3-oxalic acid (anhydrous), which contain finite strings18 of molecules... 

Hydrofluoric acid, anhydrous Ammonia, aqueous or anhydrous... 

Induced dissolution is also a well known phenomenon and frequently applied in chemical analysis. To dissolve platinum easily it was suggested by Ropp that the sample should be alloyed with silver or copper, the alloys being easily soluble even in dilute acids. Anhydrous chromic chloride, insoluble in water and dilute acids, becomes easily soluble by adding metallic magnesium or zinc to the dilute acid . In this case the chromium(III) compound is reduced to chro-mium(II), which will be oxidized by the solvent to water-soluble chromium(III)... 

A final group of reactions are those involving water. A wide variety of materials such as the alkali metals light metals and their hydrides strong acids, such as sulphuric acid anhydrous metal oxides anhydrous metal halides and non-metal oxides ail react vigorously or violently with water under various circumstances. 

Chlorine dioxide Copper Fluorine Hydrazine Hydrocarbons (benzene, butane, propane, gasoline, turpentine, etc) Hydrocyanic acid Hydrofluoric acid, anhydrous (hydrogen fluoride) Hydrogen peroxide Ammonia, methane, phosphine or hydrogen sulphide Acetylene, hydrogen peroxide Isolate from everything Hydrogen peroxide, nitric acid, or any other oxidant Fluorine, chlorine, bromine, chromic acid, peroxide Nitric acid, alkalis Ammonia, aqueous or anhydrous Copper, chromium, iron, most metals or their salts, any flammable liquid, combustible materials, aniline, nitromethane... 

---