Sodium iodide reducing agent

Citronellal, an aldehyde with a trisubstituted double bond, was hydrogenated to citronellol over a ruthenium catalyst poisoned with lead acetate in 90-100% yields (eq. 5.22)46 or over chromium-promoted Raney Ni in 94% yield in methanol at 75°C and about 0.31 MPa H2.47 Court et al. studied the selective hydrogenation of citral (1, eq. 5.24) to citronellol over unsupported Nij. o catalysts, prepared by reduction of mixtures of metal iodides with naphthalene-sodium as reducing agent, in cyclohexane and in 2-propanol at 80°C and 1.0 MPa H2.48 Higher yields of citronellol were obtained in 2-propanol than in cyclohexane, primarily via citronellal as the predominant intermediate. The yields of citronellol for the overall hydrogenation in 2-propanol over Mo-promoted catalysts were Mo0 03 96%, Mo0 06 98%, and Mo012 96%. 

Iodide ion, a moderately effective reducing agent, is used extensively for the deterrnination of oxidants. In such appHcations, the iodine Hberated by reaction between the analyte and the unmeasured excess of potassium iodide is ordinarily titrated with a standard solution of sodium thiosulfate. The reaction is as foHows ... 

Self-Test K.3B When sulfuric acid reacts with sodium iodide, sodium iodate and sulfur dioxide are produced. Identify the oxidizing and reducing agents in this reaction. 

Trimethylsilyl iodide can be substituted for the trimethylsilyl triflate catalyst in the reactions of aliphatic aldehydes. TMSI can be generated conveniently in situ either from trimethylsilyl chloride and sodium iodide in acetonitrile314 or from hexamethyldisilane and iodine in dichloromethane334 or pentane.338 It is noted that neither triisopropylsilane nor PMHS is an effective reducing agent for this purpose when used with TMSI under these conditions.314,334... 

Tetra-n-butylammonium triborono-octahydride, which can be obtained by metathesis from the sodium salt and tetra-n-butylammonium iodide, is a mild reducing agent with a selectivity similar to that of the tetrahydride, but with a much lower overall activity [l]. For example, acid chlorides are reduced five-times more readily than are aldehydes, which are ten-times more susceptible to reduction than acyclic... 

Chlorine gas may be identified readdy by its distinctive color and odor. Its odor is perceptible at 3 ppm concentration in air. Chlorine may be measured in water at low ppm by various titrimetry or colorimetric techniques (APHA, AWWA and WEF. 1999. Standard Methods for the Examination of Water and Wastewater, 20th ed. Washington DC American Pubhc Health Association). In iodometric titrations aqueous samples are acidified with acetic acid followed by addition of potassium iodide. Dissolved chlorine liberates iodine which is titrated with a standard solution of sodium thiosulfate using starch indicator. At the endpoint of titration, the blue color of the starch solution disappears. Alternatively, a standardized solution of a reducing agent, such as thiosulfate or phenylarsine oxide, is added in excess to chlorinated water and the unreacted reductant is then back titrated against a standard solution of iodine or potassium iodate. In amperometric titration, which has a lower detection limit, the free chlorine is titrated against phenyl arsine oxide at a pH between 6.5 and 7.5. 

Sodium thiosulfate is a common reducing agent. It reduces iodine to iodide anion forming sodium tetrathionate. This reaction is utilized in the so-called iodometric titration ... 

Sodium triacetoxyborohydride, 283 Other reducing agents Dichlorotris(triphenylphosphine)-ruthenium(II), 107 Dicyclopentadienyldihydrido-zirconium, 108 Samarium(II) iodide, 270 Sodium-Alcohol, 277 Tributyl tin hydride, 316 Reagents which can be used to reduce cyclic ketones to axial (less stable) alcohols... 

PROBLEM 6.22 Bromine reacts with sodium iodide to yield iodine and sodium bromide. Identify the oxidizing and reducing agents, and write the balanced equation. 

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