Reduction with hydriodic acid

HjO), a picrate, m.p. 253° (dec.) and furnishes a dibenzoate, whose sulphate has [a] ° + 52-1° (EtOH) and hydrochloride, B. HCl. 2H2O, m.p. 115° or 205° (dry), + 41-8° (dilute alcohol) and nitrate, B. HNO3, m.p. 197°. On reduction with hydriodic acid and red phosphorus the dihydroxytropane is converted into tropane and on treatment with phosphorus oxychloride it yields a base, CgHjgON, b.p. 188°/752 mm., picrate, m.p. 177° (dec.). This dihydroxytropane is probably represented by formula (XIII).The dibenzoyl-derivative has local ansesthetic properties. The wovaleryl ester is the alkaloid valeroidine found in Duboisia myoporoides (p. 90). 

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... 

Milder reductions with hydriodic acid can be accomplished by using more dilute hydriodic acid, or solutions of hydrogen iodide prepared from alkaline iodides and hydrochloric or acetic acid in organic solvents [22S],... 

The constitution of these acids was confirmed in 1908 by Leuchs and Felser, who converted them, by reduction with hydriodic acid, into proline. Their attempt to determine whether natural oxyproline was the active form of one of the synthetical compounds by converting the natural substance into its racemic form by heating with baryta to 200° C. was unsuccessful, since complete racemisation did not occur. As, however, all compounds containing one asymmetric carbon atom to which a carboxyl group is attached are easily racemised, the result led to the conclusion that oxyproline contains two asymmetric carbon atoms. Of the four possible formulae,... 

Further reduction of the pyrrolines to pyrrolidines is relatively easy both by catalytic hydrogenation and by metal-acid reduction (see Section 3.05.1.5). In contrast, further hydrogenation of the indolines can only be effected under extreme pressures and temperature to give the octahydroindole, and chemical reduction with hydriodic acid and phosphorus results in cleavage of the five-membered ring (72HC(25-l)i). 

The Wallach synthesis79 involves ring closure of an iV,jV -disubsti-tuted oxamide with PC15 to give a chlorine-containing compound, which, on reduction with hydriodic acid, yields a 1-substituted imidazole. The method has been adapted for the formation of halogen-substituted imidazoles.8 ° 8 2... 

The branched-chain structure of the acid is further confirmed through its reduction, with hydriodic acid and red phosphorus, to 2-methylbutyric acid. Oxidation of one mole of the isosaccharinic lactone with periodate produces approximately one molecular equivalent of formaldehyde. ... 

Confirmation of this structure for a -D-glucosaccharinic acid was obtained by Liebermann and Scheibler when they demonstrated that the known DL-(2-methylvaleric acid) [DL-(methylpropylacetic acid)] was also formed, in low yield, in the reduction of a -D-glucosaccharinic lactone to the 2-methylvalero-l,4-lactone. Moreover, under more strenuous conditions of reduction with hydriodic acid and red phosphorus (in a sealed tube at 200°), the DL-(2-methylvaleric acid) is the principal product. 

At this stage, the possible presence of a branched-chain saccharinic acid in Kiliani s preparation was supported only by (a) the properties of the barium salt of the hydroxyhexanoic acid obtained from it on reduction and (b) the reported oxidation of parasaccharinic acid with nitric acid to a tribasic acid. The latter evidence was retracted by Kiliani in his final report on the matter, when he stated that the previous identification of hydroxycitric acid was in error and that this tribasic acid is, in fact, ( — )-tartaric acid. In addition, he now observed that oxidation of parasaccharinic acid with nitric acid, followed by reduction with hydriodic acid and red phosphorus, gives a low yield of adipic acid. 

The hypothesis of the existence of the branched-chain parasaccharinic acid now depended solely on the identity of the reduction product, hydroxyhexanoic acid. To support his previous contention that the barium salt of this acid is, indeed, barium 2-ethyl-4-hydroxybutyrate, Kiliani also prepared the calcium salt and found that it, too, closely resembled the corresponding salt of 2-ethyl-4-hydroxybutyric acid. As emphasized by Kiliani, neither the reductions with hydriodic acid and red phosphorus nor the oxidations with nitric acid proceed in good yield to single products. Accordingly, Kihani remained firm in his conviction that his preparation, although it was apparently a mixture, nevertheless contained the branched-... 

The ozonides (which are explosive) were decomposed by reduction with hydriodic acid the dicarbonyl compounds formed were determined as p-nitrophenylosazones. 

At a temperature of —20° C. and in chloroform solution, the y-pyrones take up 2 molecules of ozone. This means that only the C=C bonds react with ozone, which was also found when ozone reacted with other heterocyclic rings, such as pyridine, pyrrole, and furan. The ozonides were decomposed by reduction with hydriodic acid, whereby carbonyl compounds are formed, as well as acetic acid and in some cases formic acid. By reacting the carbonyl compounds with p-nitrophenylhydrazine, the corresponding nitrophenylhydrazones or p-nitrophenylosazones are formed. The separation of the mixture of hydrazones and osazones is carried out by a chromatographic method. The quantitative determination of the separated nitrophenylosazones (or hydrazones) is carried out by means of spectrographic measurements. 

Benzoin and its analogues are derivatives of the hydrocarbon dibenzyl, C6Hj. CH2. CH2. CeHj, and in feet benzoin on reduction with hydriodic acid is converted into this hydrocarbon. 

Acidify to pH 3 with HCl clean-up on activated Sep-Pak C g cartridge column reduction with hydriodic acid... 

Ellington and Purves applied a cyanohydrin synthesis to oxystarch (obtained by oxidizing starch with chromium trioxide) and were able, after reduction with hydriodic acid, to isolate the lactone of 4-hydroxy-2-... 

Oxidation of coniine with chromic acid produces butyric acid (115, 124), while dehydrogenation of the alkaloid with silver acetate converts it to abase, conyrine (125), which is also obtained from coniine hydrochloride by distillation with zinc dust (126). Conyrine, CgHnN, is a colorless, fluorescent oil, b.p. 166-168°, which forms a chloroplatinate and an aurichloride it can be converted back to coniine by reduction with hydriodic acid, it behaves on methylation like a pyridine base, and further, it gives rise on oxidation to a-pyridinecarboxylic acid. Therefore, conyrine is a 2-propylpyridine (XCIV) while coniine is a 2-propylpiperidine (XCV) (126), in which the side chain is normal since conyrine is not identical with 2-isopropylpyridine (127). 

Karrer and Ehrenstein (1926) treated a-benzoyl(+)omithine, which had been obtained from natural arginine, with nitrous acid hydrolysis and reduction with hydriodic acid at 120-140° gave impure and insufficiently characterized (—)proline. These experiments suggest that (-b)arginine and (-b)omithine are related to (—)proline, and therefore to l(- -) alanine. 

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