Dichloride reduction

This reaction was also studied with a more complicated nitro ketoester starting material [10]. hi this example, the nucleophilic addition occurs intramolecularly to form a 15-membered macrocycle. Zinc/ammonium chloride reduction to form the hydroxyindole 16 followed by cyclization provided a better yield of 17 (40% over both steps) than the direct tin dichloride reduction of 15 to macrocycle 17 (10%). 

Other Reductions. Ductile, pure zirconium has been made by a two-stage sodium reduction of zirconium tetrachloride (68) in which the tetrachloride and sodium are continuously fed into a stirred reactor to form zirconium dichloride [13762-26-0], heating with additional sodium yields zirconium metal. Leaching with water removes the sodium chloride from the zirconium. Bomb reduction of pure zirconium tetrafluoride with calcium also produces pure metal (69). 

It is not possible to use zinc for reductive debromination in the presence of (x-halo ketones and for transformations involving these intermediates, sodium iodide has been used. ° In some instances, e.g. 5,6-dihalo-3-ketones, iodide does not always give a completely halogen-free product, and zinc does not give clean debromination. The use of chromous chloride has proved advantageous in such cases and is the reagent of choice for vicinal dichlorides, which are inert to iodide ... 

An interesting bridged-sulfur compound, which is a natural constituent of Iranian oil, has been synthesized 478) by the reaction of a bicyclic bis-enamine with sulfur dichloride and subsequent Wolff-Kishner reduction of an initial sulfur-bridged diketone. Sulfur dichloride has also been added to a number of vinylogous amides 479). 

The stereochemical course of reduction of imonium salts by Grignard reagents was found to depend on the structure of the reagent 714). Hydro-boration of enamines and oxidation with hydrogen peroxide led to amino-alcohols (7/5). While aluminum hydrogen dichloride reacted with enamines to yield mostly saturated amines and some olefins on hydrolysis, aluminum hydride gave predominantly the unsaturated products 716). 

The metallocene dichloride of zirconium and hafnium 20b and 20c were also prepared and underwent reduction with potassium to give monomeric metallocene monochloride complexes 21b and 21c (Eq. 8) [39b]. The structure of the zirconocene complex 21 b in the crystal showed a conformation which suggests a less steric strain as compared to 21a due to zirconium s larger atomic size. As a consequence of the coordinative unsaturation an unusually short Zr —Cl bond length was found. 

This means, in practice, that when employing a polar solvent with n-heptane (or any other paraffin for that matter) to reduce the retention, there will be a dramatic reduction in retention over the concentration range of about 0-2%w/v. However, subsequent changes in solute retention with polar solvent concentration will be relatively small. This will be true for any polar solute and was experimentally verified by Scott and Kucera for solutions of ethyl acetate, tetrahydrofuran and n-propanol in n-heptane. The very sensitive relationship between solvent concentration and retention at very low concentrations makes the phase system very difficult to make reproducible. This problem is one of the factors that deter analysts from using silica gel as a stationary phase for the separation of polar solutes. It is very satisfactory, however, for the separation of polarizable and weakly polar substances that can be eluted by paraffin/methylene dichloride or similar types of solvent mixtures. 

Though the usual product of epoxide reductions is the alcohol (10-85), epoxides are reduced all the way to the alkane by titanocene dichloride and Et3SiH-BH3. ... 

Reduction of carboxylic esters with titanocene dichloride... 

Animal data consistently show dibutyltin dichloride to cause dose-dependent developmental toxicity, such as fetal deaths, birth defects, and reductions in fetal weight. 

Miller Scott (1985) reported marked reduction in thymus weight in rats fed dioctyltin dichloride for 8 or 12 weeks at a level of 75 mg/kg diet. Numbers of lymphocytes together with T cell subpopulations were reduced in treated rats, but no difference was seen in antibody response to sheep red blood cells in vivo. No evidence was foimd of in vitro cytocidal effects of dioctyltin dichloride on blood lymphocytes. Evans et al. (1986) dosed pregnant and non-pregnant rats for 3 weeks at 75 mg/kg diet and reported severe thymic atrophy and extensive vacuolation of reticuloendothelial cells in pregnant animals only. 

Cathodic reduction of mixtures of benzil imines 58 and N-arylcarbonimidoyl dichlorides 59 produces 3,4,5-triaryl-2-(arylimino)-4-oxazolines 60 <95T10375>. Carbodiimides 61... 

When a reducible compound (that is not directly attacked by the free radicals) is present in the solution, the stored electrons may react with it. Stored electrons may be transferred pairwise to the solute. The reduction of the aqueous solvent and of the solute compete with each other. A typical example is shown in Fig. 3. Methylene dichloride was the solute here, the product of its reduction being the Cl ion. It is seen that the H2 yield decreases as that of Cl increases with increasing CH2CI2 concentration. For each H2 molecule not formed, one Cl anion is produced. As two electrons are necessary to produce one molecule, one has to conclude that methylene... 

Chromium (II) salts reduce water into hydrogen. This gradual transformation at ambient temperature has been responsible for accidents of the same nature. A glass bottle, in which chromium dichloride was stored for several years, detonated spontaneously. A sealed tube, in which there was chromium (II) sulphate heptahydrate and water in excess, detonated after being stored in darkness for a year. In both cases the accidents were interpreted as the result of water reduction, forming hydrogen whose pressure eventually caused the explosion of the containers. 

The conversion of a higher chloride to a lower chloride by hydrogen reduction has been mentioned earlier in connection with the formation of the relatively less volatile ferrous chloride from ferric chloride. This type of reaction is more general and is widely used. Vanadium trichloride can be reduced to the dichloride by hydrogen at temperatures higher than 500 °C ... 

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