Acid Acetic Hydriodic

Alternative procedure. The following method utilises a trace of copper sulphate as a catalyst to increase the speed of the reaction in consequence, a weaker acid (acetic acid) may be employed and the extent of atmospheric oxidation of hydriodic acid reduced. Place 25.0 mL of 0.017M potassium dichromate in a 250 mL conical flask, add 5.0 mL of glacial acetic acid, 5 mL of 0.001M copper sulphate, and wash the sides of the flask with distilled water. Add 30 mL of 10 per cent potassium iodide solution, and titrate the iodine as liberated with the approximately 0.1M thiosulphate solution, introducing a little starch indicator towards the end. The titration may be completed in 3-4 minutes after the addition of the potassium iodide solution. Subtract 0.05 mL to allow for the iodine liberated by the copper sulphate catalyst. 

Hydrobromic instead of hydriodic acid has also been used in quantitative work. Thus Larsson83 evaluated thionyl compounds with a hydrobromic acid/acetic acid reagent, then adding potassium iodide and titrating with thiosulphate. 

Reductions with hydriodic acid are usually accomplished by refluxing organic compounds with the azeotropic (57%) acid. Acetic acid is added to increase miscibility of the acid with the organic compound. If more energetic conditions are needed the heating has to be done in sealed tubes. This... 

The tinctura iodi of the British Pharmacopoeia is a soln. of half an ounce of iodine, and a quarter of an ounce of potassium iodide in a pint of rectified spirit. P. Wantig found the mol. ht. of soln. —1 941 Cals., and S. U. Pickering —1 714 per 880 mol. of ethyl alcohol. C. Lowig found that alcoholic tincture of bromine is slowly decomposed in darkness, rapidly in light. Alcoholic soln. of iodine, according to H. E. Barnard, are stable in light and in darkness, but according to J. M. Eder they decompose 1000 times more slowly than chlorine water under similar conditions T. Budde has shown that hydriodic acid, acetic ester, and aldehyde are formed, and the electrical conductivity of the soln. increases. J. H. Mathews and E. H. Archibald and W. A. Patrick found a freshly prepared AT-soln. to have an electrical conductivity of 2 4 XlO-6 reciprocal ohms and a sat. soln., 1 61 X10 4 reciprocal ohms at 25°. The decomposition is accelerated by the presence of platinum. The heat of soln. decreases with concentration from —7 92 to —7 42 cals, respectively for dilute and sat. soln. in methyl alcohol, and likewise from —4 88 to —5 22 cals, for similar soln. in ethyl alcohol. The solubility of iodine in aq. soln. of propyl alcohol is not very different from that in ethyl alcohol. 

With hydrobromic acid and hydriodic acid reduction may proceed to the trivalent state,9 and it has been shown that in the presence of acetic acid, hydrazine also produces vanadous oxide, V203, instead of hypovanadic oxide, V02 10... 

This compound is an inner anhydride of orthoarnidophenyl acetic acid, and is isomeric with indoxyl. It is formed by reduction of isatin with sodium amalgam [14], and of acetylorthoamidophenyl-glycollic acid with hydriodic acid [15]- It forms colourless needles, M.P. 120°, and exhibits simultaneously basic and acid properties. It reacts with nitrous acid, producing isatinoxime [24]. 

Further details about hydrolysis methods with particular reference to the use of formic acid, acetic acid, stannous chloride, sulphuric acid and hydriodic acid are to be found in the books of Hais and Macek and Linskens . 

Skelly, N.E. Separation of aliphatic and aromatic acids, aromatic sulfonates, quaternary ammonium compounds, and chelating agents on a reversed-phase column without ion pairing, J.Chromatogr.ScL, 2003, 41, 22-25. [nonoxynol-9 citric add benzenesulfonic acid phthsilic acid hydrobromic acid nitrUotriacetic acid oxalic acid nitric acid hydriodic acid glycolic acid formic add nitrous add cyanuric acid lactic acid acetic acid NTA benzalkonium EDTA]... 

Obtained by demethylation of 2-pheny-lacetyl-4-tert-butyl-anisole with a 47% hydrobromic acid/57% hydriodic acid mixture in refluxing acetic acid (63%) [4661]. 

Hydrolysis of the azlactone leads to the acylaminooinnamic acid the latter may be be reduced catal3rtlcally (Adams PtOj catalyst 40 lb. p.s.i.) and then hydrolysed by hydrochloric acid to the amino acid. Alternatively, the azlactone (say, of a-benzylaminocinnamic acid) may undergo reduction and cleavage with phosphorus, hydriodic acid and acetic anhydride directly to the a-amino acid (d/ p phenylalanine). 

A mild procedure which does not involve strong adds, has to be used in the synthesis of pure isomers of unsymmetrically substituted porphyrins from dipyrromethanes. The best procedure having been applied, e.g. in unequivocal syntheses of uroporphyrins II, III, and IV (see p. 251f.), is the condensation of 5,5 -diformyldipyrromethanes with 5,5 -unsubstituted dipyrromethanes in a very dilute solution of hydriodic add in acetic acid (A.H. Jackson, 1973). The electron-withdrawing formyl groups disfavor protonation of the pyrrole and therefore isomerization. The porphodimethene that is formed during short reaction times isomerizes only very slowly, since the pyrrole units are part of a dipyrromethene chromophore (see below). Furthermore, it can be oxidized immediately after its synthesis to give stable porphyrins. 

Pentaerythrityl bromide has been prepared by the action of phosphorus tribromide on pentaerythritol, - and of an acetic acid solution of hydrobromic acid on pentaerythritol tetraacetate. The iodide has been prepared by the action of red phosphorus and hydriodic acid on pentaerythritol and by treating the bromide with sodium iodide in acetone. ... 

Constitution. When coniine is distilled with zinc dust or heated with silver acetate/ a new base, coiiyrine, CgH N, differing from coniine by six atoms of hydrogen, is formed. This on oxidation yields pyridine-2-carboxylic acid and, since it is not identical with 2-isopropylpyridine, must be 2-propylpyridine (I). When coniine is heated with hydriodic acid at 300° it yields w-octane (II). These and other observations due mainly to A. W. Hofmann, made it clear by 1885 that coniine was probably a-propylpiperidine (III), and this has been amply confirmed by other reactions of the alkaloid and by syntheses. Thus, Wolffenstein showed that on oxidation with hydrogen peroxide, coniine is converted into amino-w-propylvaleraldehyde (IV) ... 

Hydriodic acid at low concentration in acetic acid will also effect the reduction of a,j5-epoxy ketones to a,jS-unsaturated ketones ... 

D-homosteroids, 382 Hydrazoic acid, 27, 145 Hydriodic acid, 172 Hydroboration, 165, 166 Hydrogen peroxide, 221 Hydrogen transfer, 239 17 i3-Hydroxy-2-acety l-5a-androstan-3 -one acetate, 342... 

Preparation of 3 5-diiodo-4-(4 -hydroxyphenoxy)phenylacetic acid (diac) A solution of ethyl 3 5-diiodo-4-(4 -methoxyphenoxy)phenyl acetate (9.5 g) in acetic acid (60 ml) was heated under reflux with hydriodic acid (SG 1.7, 50 ml) and red phosphorus (0.5 g) for 1 hour. The hot solution was filtered and the filtrate concentrated at 50°C and 15 mm of mercury to above 20 ml. The residue was treated with water (70 ml) containing a little sodium thiosulfate to decolorize the product. The solid was collected by filtration and purified by the method of Harington and Pitt-Rivers [Biochem. J. (1952), Vol. 50, page 438]. Yield 8,36 g (95%). After crystallization from 70% (v/v) acetic acid it melted at 219°C. 

Neutralisation reactions. The equivalent of an acid is that mass of it which contains 1.008 (more accurately 1.0078) g of replaceable hydrogen. The equivalent of a monoprotic acid, such as hydrochloric, hydrobromic, hydriodic, nitric, perchloric, or acetic acid, is identical with the mole. A normal solution of a monoprotic acid will therefore contain 1 mole per L of solution. The equivalent of a diprotic acid (e.g. sulphuric or oxalic acid), or of a triprotic acid (e.g. phosphoric( V) acid) is likewise one-half or one-third respectively, of the mole. 

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