Reduction solid-state

The practical applications of NaBH4 reductions on mineral surfaces for in situ generated SchifFs bases have been successfully demonstrated. The solid-state reductive amination of carbonyl compounds on various inorganic solid supports such as alumina, clay, silica etc. and especially on K 10 clay surface rapidly afford secondary and tertiary amines [126]. Clay behaves as a Lewis acid and also provides water from its interlayers thus enhancing the reducing ability of NaBH4 [22],... 

The reaction mechanism for the solid state reduction is the same as that described above for the hydrogen reduction of haematite, namely the formation of a porous iron product which results from the penetration of pores in the reacting pellets by reducing gases, and the migration of the reaction products, C02 and H20 through these pores back into the gaseous phase. 

There are numerous preparatively useful solid-state reductions with potential for quantitative conversion and yield [ 142]. It appears, however, that these have not been tried under more favorable conditions in ball-mills. The stereospecific reductions of 447 to give 448 used enormous excessive amounts of reducing... 

Solid-state reductions of sulfoxides such as 449 have been performed with potassium iodide andp-toluenesulfonic acid monohydrate [144]. Dibenzothi-ophene (450) or similarly bis-4-tolylsulfide (451) are obtained with 100% yield. 

Until recently no anhydrous iodites were known. In 1965 Harmelin and Duval3 reported a general method for the preparation of iodites the solid-state reduction of iodates by metallic lead. Since the reaction occurs without loss of weight, it was postulated to occur according to... 

Solid state Reduction in surface free energy Solid-state diffusion... 

For the solid-state reduction techniques, crystals are grown containing trivalent ions, as in the photoreduction process, but the divalents produced are now stabilized. One of these techniques involves heating the trivalent crystal with the appropriate alkaline earth metal. A convenient way of doing this is to heat the crystal with the alkaline earth metal in a vacuum so that the crystal is baked in metal vapor (11). The reduction can also be carried out by solid-state electrolysis 4,7). An electric field is applied to the crystal at an elevated temperature such as above 600°C. for calcium fluoride or above 400°C. for strontium chloride. If the reduction is carried out below these temperatures, nonuniform results are obtained. 

In light of the work of Ure (23) showing the conductivity of calcium fluoride being mainly caused by the motion of fluoride ion, the solid state reduction reactions have been interpreted in terms of a model which allows reduction to occur by diffusion of the interstitial, charge compensating ion out of the crystal while an electron is injected to reduce the trivalent lanthanide. Under these conditions there is no hole or electron deficiency remaining in the crystal, as in the case of radiation reduction hence the divalent species is stable. 

Solid state reduction of alkyl aryl ketone 8 in an inclusion complex with the chiral host 10 with borane-ethylenediamine complex 2BH3-NH2CH2CH2NH2 gave optically active alcohol 9 in the optical and chemical yields summarized in Table 15-3 [7],... 

Finally, electrocatalysis can proceed via adduct formation between immobilized sites and species in solution and subsequent solid-state reduction of that adduct species. For the case where the substrate is in solution and the catalyst is immobilized, this situation can be represented as (Figure 3.6) ... 

Rj - solid state reduction in inert media (n-octane)... 

Solid state reduction of (metal, typ. iron) oxides into the metallic state. 

The solid-state reduction of carbonyl compounds has been accomplished by mixing them with NaBH4 and storing the reaction mixture in a dry box for five days which is too long for it to be of any practical utility [124]. In a first example of its kind under solvent-free conditions to be accelerated by MW irradiation, Varma and coworkers have reported a simple method for the expeditious reduction of aldehydes and ketones that uses alumina-supported NaBH4 and proceeds in the solid state [125]. 

The diamagnetic cobalt(ii) corrin complex, iodo-cobalt(ii)-cobyrinic acid-heptamethylester (78), dissolves in benzene or toluene to give monomeric paramagnetic complexes which form 1 1 adducts with molecular oxygen in fast and reversible reactions. Reaction of [Co Pc] (Pc = phthalocyanine) with thionyl chloride or bromine yields C0PCX2 (X = Cl or Br). Physical and chemical measurements on the compounds indicate they contain a phthalocyanine radical and a cobalt(iii) ion. This is the first report of the isolation of a phthalocyanine radical in the solid state. Reduction of [Co"Pc] with sodium in THF or by electrochemical means leads to the formation of five... 

Sodium tetrahydridoborate Sec. alcohols from ketones Solid-state reduction... 

Sodium borohydride has been extensively used as a reducing agent. The solid state reduction with NaBH requires longer time and use of solvents slow down the reaction. A microwave irradiation reaction has been developed for the reduction of aldehydes and ketones using alumina supported NaBH (Scheme 23). 

A. CRYSTALLINE TUNGSTEN TETRACHLORIDE BY SOLID-STATE REDUCTION... 

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