II Chloride — Sulfuric Acid Reagent

Manganese(II) Chloride — Sulfuric Acid Reagent 335 Cyclohexane — diethyl ether (1 +1). 

Some of these effects are illustrated in the experimental curves of Figures 15-1 and 15-2. In the titration of Fe(II), before the end point the shapes are independent of the nature of the oxidant. The value of El is highest with perchloric acid, because hydrolysis of Fe(III) is largely suppressed and the perchlorate ion has little tendency to form complexes. With sulfuric acid and with Ce(IV) as titrant, the two effects of hydrolysis and complex formation tend to counteract each other. In the presence of phosphoric acid, complex formation predominates, and El is distinctly lower. The shape of the curve beyond the end point is determined primarily by the properties of the oxidant. For Ce(TV) in various media the value of El is different, and the potential varies correspondingly. The reasons for these effects are qualitatively the same as for the Fe(III)-Fe(II) couple. Note that three of the experimental curves with Ce(IV) in Figure 15-1 closely resemble the expected shapes the distortion of the curve for hydrochloric acid after the end point is due to the gradual oxidation of chloride by the excess Ce(IV). For further details see the discussion of Ce(TV) as a reagent (Chapter 18). 

The action of the Z-R reagent is first to supply an adequate concentration of Mn(II), which reacts with local excesses of permanganate and ensures the reduction of intermediate oxidation states of manganese to Mn(III). The Mn(II) also depresses the potential of the reversible Mn(III)-Mn(II) couple. Phosphoric acid (and to a lesser extent, sulfuric acid) also lowers the Mn(III)-Mn(II) potential, so that Mn(III) is reduced by Fe(II) rather than by chloride. Schleicher S stressed the importance of the Mn(III)-Mn(II) couple and maintained that five Mn(II) ions should be present locally for each Mn(VII) ion, to ensure that no manganese oxidation state higher than Mn(III) can exist. For this purpose four Mn(II) ions should suflBce ... 

Vitamin E compounds can be detected (about 20 /tg) as dark spots in UV light. They appear violet and detection is appreciably more sensitive (0.02 /tg) on layers that contain 0.02% Na-fluorescein. Moreover, these are visible in daylight as reddish spots (limit of detection 2 fig). The same effect is produced by spraying with fluorescein or dichlorofluorescein reagent. Nonspecific visualization procedures for tocopherols and tocotrienols are based on spraying with sulfuric acid, molybdophosphoric add, antimony(V) chloride, dipyridyl-iron reagent, nitric add, and copper(II) sulfate-phosphoric add [1-4]. 

The Pictet-Spengler cyclization of )VA -dimethyltryptamine (V-oxide (66) to the tetrahydrocarboline (78) using sulfur dioxide in anhydrous formic acid and the selective (V-dealkylation of the morphinan iV-oxide (79) using catalytic quantities of iron(II) chloride (equations 19 and 20) illustrate the advantages of using these activating reagents in the Polonovski reaction. 

Sulfinic acids are generally prepared by reduction of the readily available sulfonyl chlorides with zinc in neutral or basic aqueous solution.2 The reduction may also sometimes be achieved by treatment with tin(II) chloride or sodium sulfite (Scheme 1). Another route involves reaction of a Grignard reagent with sulfur dioxide (Scheme 1). 

Deposits were formed in dilute cupric sulfate to avoid rapid attak of the substrate by cupric ion. The basic solution was 0.01 M CuSO j 1.0 M H SO. O.lmM or 2.0 mM chloride as HCl was added to two of the solutions. Two solutions without added chloride were prepared, one with reagent grade materials and another with Aesar Puratronic cupric sulfate and sulfuric acid. All of the solutions were made with demineralized water which was doubly distilled and passed through a Nanopivre II filtration system. Copper single crystal disks of orientation 100 and 110 were obtained from Monocrystals Incorporated. They were polished with 0.05 nm alumina on an irrigated wheel and then electropolished in orthophosphoric acid. After polishing, the samples were rinsed sequentially in 10 % nitric acid, 10 % sulfuric acid and water. 

Sample preparation 500 p-L Plasma + 100 p.L 200 p,g/mL tridecanoic acid in ethylene chloride + 200 xL 600 mM sulfuric acid + 3 mL isooctane isopropanol 95 5, extract. Remove the organic layer and evaporate it to dryness, reconstitute the residue in 1 mL 2.4 mg/mL 2-etho y-l-ethoxycarbonyl-l,2-dihydroquinoline (EEDQ) in ethylene chloride, add 5 mL reagent, reflux for 10 min, dilute with 10 mL ethylene chloride, wash with an equal volume of 200 mM NaOH, wash with an equal volume of 1 M HCl, wash with an equal volume of water. Remove the organic layer and diy it over sodium sulfate, evaporate to diyness, reconstitute the residue in mobile phase, ii ject an aliquot. (Prepare reagent by dissolving 5 mg p-nitrobenzylamine hydrochloride in 5 mL 200 mM NaOH, extract... 

Evaluation reagents I ethanolic sulfuric acid, 2 tetrazolium blue, 3 antimony(III)chloride, 4 chloramine T. 5 xanihidrol, 6 phosphoric acid, 7 iodine, 8 hydrochloric acid, 9 Dragendorff reagent, 10 phosphomolybdic acid, II p-acelylaminobcnzaldehydc scmicarbazonc, 12 1,4-dihydrazinophtalazine. 

The fluorination of acid chlorides with other reagents, e. g. arsenic fluoride, zinc fluoride,217 -219 and antimony fluoride,220 222 has been reported. Zinc fluoride reacts under mild conditions giving the desired acyl fluorides in good yield, while antimony(III) fluoride gives aromatic acyl fluorides in good yield, e.g. 2,220 but aliphatic systems in only moderate yield, e. g. 3.222 Other reagents which are used include mercury(II) fluoride,223 thallium fluoride,134 alkali metal fluorosulfinates224 and sulfur tetrafluoride.225... 

---