Zinc Compounds chloride

The alternative product from pyridine-3,4-diamine and ethyl acetoacetate, compound 12, is obtained by the base-catalyzed cyclization of the ester 11, which is formed from the diamine and ethyl acetoacetate in the presence of zinc(II) chloride.298... 

A -( 1-Chloro- or bromoalkyl)amides are generally moisture-sensitive, unstable compounds, which are often directly used without further purification. Standard Lewis acids such as boron trifluoride-diethyl ether, aluminum(lll) chloride, zinc(II) chloride, tin(IV) chloride and titani-um(IV) chloride are used to generate the /V-acyliminium ion, although sometimes a catalyst is not necessary. 

There are a reasonable number of structurally characterized zinc compounds with bound THF molecules. For example, a six-coordinate zinc porphyrin complex with axial THF donors and a four-coordinate zinc center with two THF ligands and two phenolate ligands.341,357 Although less common there are other structural examples of ether solvents, such as diethyl ether, coordinated.358 The X-ray structure of zinc chloride with 1,4-dioxane ligands shows a monomeric four-coordinate zinc center with two 1,4-dioxane ligands.359... 

Reactions of allylzinc halides with carbon nucleophiles are rare examples of uncatalyzed transformations of organo-zinc compounds. Allylzinc bromide, formed in situ, reacted with a number of structurally diverse acyl chlorides furnishing the corresponding ketones 222 in high yields (Scheme 129).330 No isomerization to the corresponding a,(3-unsaturated ketones was observed under the conditions used (RT, 5min-6h). 

Injection of zinc chloride solution into the testes of 49 Syrian hamsters resulted in areas of necrosis occupying about 25% of each testis two embryonal carcinomas of the testis were found 10 weeks later at necropsy/ There is no evidence that zinc compounds are carcinogenic after administration by any other route/... 

The requisite hydroxylamine function for such cyclizations can also be generated from a precursor having a nitro group. This novel route has provided access to hitherto unknown l-hydroxy-6-allyl-, and -6,6-bisallyl-piperazine-2,5-diones (91UP1). The starting material is an W-nitroacetyl amino acid ester that can be either mono-or bis-allylated at the methylene adjacent to the nitro group. Reduction of the N02 to NHOH using zinc/ ammonium chloride, followed by cyclization, leads to the desired products (Scheme 76). Compound (215) is unique in that it possesses a chiral center at C-3 and a quaternary carbon at C-6 on a l-hydroxypiperazine-2,5-dione system. 

The filtered reaction mixtures from the zinc-ammonium chloride reductions of aromatic nitro compounds have been added to aqueous solutions of ferric chloride. Within 10-15 min the oxidation to nitroso compounds was completed. In the oxidation of nine different hydroxylamines, yields ranged from 30 to 60% [86a, b]. 

Ishihara and coworkers have reported that the reaction of 2-[(trimethylsilyl)methyl]-3-chloro-3,3-difluoropropene couples regioselectively with a variety of carbonyl compounds in the presence of zinc-copper chloride or silver acetate to give 2,2-difluoro-3-(trimethylsilyl)methyl-3-buten-l-ol derivatives (equation 87)81. Note again that the difluo-roallyl zinc species generated in situ reacts exclusively on the difluoromethylene terminus. 

Compound Name Ammonium Oxalate Ammonium Oxalate Ammonium Pentaborate Ammonium Pentaborate Zinc Ammonium Chloride Ammonium Perchlorate Ammonium Persulfate Ammonium Persulfate Ammonium Phosphate Ammonium Phosphate Ammonium Thiocyanate Ammonium Thiocyanate Ammonium Silicofluoride Ammonium Stearate Ammonium Sulfamate Ammonium Sulfate Ammonium Sulfide Ammonium Sulfide Ammonium Sulfide Ammonium Sulfite Ammonium Thiocyanate Ammonium Thiocyanate Ammonium Tartrate Ammonium Thiocyanate Ammonium Thiosulfate Zinc Ammonium Chloride Phosphorus, Red Ammonium Sulfamate Amyl Acetate Amyl Acetate N-Amyl Alcohol N-Amyl Alcohol Valeraldehyde Hexanol... 

Another limitation is seen when extra strain is included in the compound to be reduced. Dehalogenation of 3,3-dichlorobicyclo[2.2.0]hexan-2-one with zinc/ammonium chloride in methanol gave, at best, a 25% yield of 3-chlorobicyclo[2.2.0]hexan-2-one (14) together with cyclohexenone and 6-chlorohex-5-enoic acid.128 The best results were achieved with the zinc/ acetic acid system, while addition of water, silver-promoted zinc reduction in methanol, tri-butyltin hydride reduction or hydrogenolysis with palladium in methanol did not result in formation of 14, but various other ring-opened products. 

As far as equilibrium constant is concerned, differences between metal ions are perhaps more important than those between ligands. Thus, in the solvent chlorobenzene (41), the equilibrium constant [Eq. (7)] for MC12 and pyridine favors the octahedral configuration for Ni(Il) over that for Co(II) y a factor of 1500 to 2000. In the same solvent, there is no clear evidence that any octahedral zinc compound is formed. The Ni-Co difference cited is actually less than the difference between chloride and thiocyanate against... 

Pure solutions of zinc sulfate can only be used for the preparation of lithopone having a low (up to 30%) percentage of zinc sulfide. Additional zinc compound must be added for the preparation of lithopone having a higher concentration of ZnS. Most often that compound is zinc chloride. One can either use a mixture of sulfuric and hydrochloric acid for the dissolution of zinc-containing raw materials, or direcdy mix separately prepared solutions of zinc sulfate and zinc chloride. The precipitation of 60% of the lithopone can be approximated by the following reaction ... 

Fluorine is simultaneously eliminated with other halogens if it is the only halogen vicinal to iodine, bromine or chlorine. The elimination tendency decreases in the series IF > BrF > C1F. The group CF2CHFX is relatively stable towards elimination and requires stronger reaction conditions. The dehalogenation of saturated fluorohalo compounds with zinc dust or zinc/ copper and zinc/silver couples is one of the most useful methods for the preparation of fluoroalkenes (see Table 8). Zinc/zinc(II) chloride has also been used instead of zinc alone. 

Organovanadium reagents, 219 Phenylmagnesium bromide-Vanadi-um(III) chloride, 219 Vanadium(III) chloride, 219 Vanadyl acetylacetonate, 54 Vanadyl trichloride, 289 Zinc Compounds Bis(acetylacetonate)zinc(II), 33... 

Metal-containing compounds, Zinc Compounds (Continued) (Carboethoxyalkyl)zinc iodide, 220 (Carboethoxyethyl)zinc iodide, 220 (Carboethoxypropyl)zinc iodide, 220 Chlorotrimethylsilane-Zinc, 82 (Cyanomethyl)zinc bromide, 221 Dibromomethane-Zinc-Copper(I) chloride, 93... 

Zinc-Ammonium Chloride (ZnCla,2NH3).—This compound is formed by passing a current of dry ammonia gas into molten zinc chloride. It can also be obtained by passing the gas over pulverised anhydrous zinc chloride. This compound gives up ammonia on heating and is used in place of the concentrated solution in certain reactions. 

Uses Zinc (Zn) is one of the most common elements in the Earth s crust. Metal zinc was first produced in India and China during the Middle Ages. Industrially important compounds of zinc are zinc chloride (ZnCl2), zinc oxide (ZnO), zinc stearate (Zn (Ci6H3502)2), and zinc sulfide (sphalerite, ZnS). It is found in air, soil, and water, and is present in all foods. Pure zinc is a bluish-white shiny metal. Zinc has many commercial uses, as coatings to prevent rust, in dry cell batteries, and mixed with other metals to make alloys like brass and bronze. Zinc combines with other elements to form zinc compounds. Zinc compounds are widely used in industry to make paint, rubber, dye, wood preservatives, and ointments.109-112... 

Treatment of 2-carboxyphenyl aryl tellurium compounds with zinc(II) chloride in butyl dichloromethyl ether at 100° converted the carboxylic acids to the acid chlorides7 and subsequently isomerized the thus formed 2-chlorocarbonylphenyl aryl tellurides to 2-arylcarbonylphenyl tellurium chlorides1. 

Many studies on the direct reaction of methyl chloride with silicon-copper contact mass and other metal promoters added to the silicon-copper contact mass have focused on the reaction mechanisms.7,8 The reaction rate and the selectivity for dimethyldichlorosilane in this direct synthesis are influenced by metal additives, known as promoters, in low concentration. Aluminum, antimony, arsenic, bismuth, mercury, phosphorus, phosphine compounds34 and their metal complexes,35,36 Zinc,37 39 tin38-40 etc. are known to have beneficial effects as promoters for dimethyldichlorosilane formation.7,8 Promoters are not themselves good catalysts for the direct reaction at temperatures < 350 °C,6,8 but require the presence of copper to be effective. When zinc metal or zinc compounds (0.03-0.75 wt%) were added to silicon-copper contact mass, the reaction rate was potentiated and the selectivity of dimethyldichlorosilane was enhanced further.34 These materials are described as structural promoters because they alter the surface enrichment of silicon, increase the electron density of the surface of the catalyst modify the crystal structure of the copper-silicon solid phase, and affect the absorption of methyl chloride on the catalyst surface and the activation energy for the formation of dimethyldichlorosilane.38,39 Cadmium is also a structural promoter for this reaction, but cadmium presents serious toxicity problems in industrial use on a large scale.41,42 Other metals such as arsenic, mercury, etc. are also restricted because of such toxicity problems. In the direct reaction of methyl chloride, tin in... 

Hybridization can also help explain the existence and structure of many inorganic molecular ions. Consider, for example, the zinc compounds shown here. At the top is shown the electron configuration of atomic zinc, and just below it, of the divalent zinc ion. Notice that this ion has no electrons at all in its 4-shell. In zinc chloride, shown in the third row, there are two equivalent chlorine atoms bonded to the zinc. The bonding orbitals are of sp character that is, they are hybrids of the 4s and one 4p orbital of the zinc atom. Since these orbitals are empty in the isolated zinc ion, the bonding electrons themselves are all contributed by the chlorine atoms, or rather, the chlor ide ions, for it is these that are the bonded species here. Each chloride ion possesses a complete octet of electrons, and two of these electrons occupy each sp bond orbital in the zinc chloride complex ion. This is an example of a coordinate covalent bond, in which the bonded atom contributes both of the electrons that make up the shared pair. 

Toxicity and health effects Exposure to high concentrations of fumes of zinc compounds such as zinc chloride and zinc oxide causes poisoning among industrial workers. The symptoms include but are not limited to headache, blurred vision, low back pain, vomiting, fever, chills, muscle ache, dry throat, cough, weakness, exhaustion, metallic taste in the mouth, chest tightness, respiratory distress, and decreased pulmonary function. The clinical... 

Organozinc addition reactions to unsaturated systems lead to an intermediate zinc compound which is in most cases further hydrolyzed to give the corresponding protonated organic compound. This intermediate can also be trapped by reaction with electrophiles (see Electrophile) (E+) such as aldehydes, acyl chlorides, organic halides, silyl halides, and so on. Depending on the nature of the electrophile (see... 

In Volume V of this series, syntheses were presented for coordination compounds of 2,2 -iminodipyridine [di-2-pyridylamine, NH(C6H4N)2] with copper(II) and cobalt-(II). Nickel(II) has also been shown to coordinate with this ligand. A similar behavior is exhibited by zinc salts, which form 1 1 derivatives if a 1 1 mol ratio of reactants is used. The specific choice of a solvent medium for synthesis is dictated by the solubility of the zinc compound. Either acetone or methanol may be used with zinc chloride, methanol with zinc acetate, and pyridine with zinc cyanide. 

Thietane is a superior inhibitor of corrosion of iron in 10% hydrochloric acid and its effectiveness is said to be due to partial polymerization on the surface of the iron. Addition of chloride ion reduces the inhibition, possibly by inducing ringopening with the formation of sulfhydryl groups. The cyclic sulfide also has been considered as an odorant for natural gas and its absorption by organic soil and clay have been determined. Stabilization of methylchloroform and trichloroethylene by thietane, 2-methylthietane, 3-hydroxythietane, and two spirothietane derivatives has been claimed. Phosphorus and tin derivatives of 3,3-bis-hydroxy-methylthie-tane are reported to be light stabilizers for poly(vinyl chloride), and the dibutyl-tin derivative is a catalyst for the polymerization of aliphatic isocyanates. Mercury and zinc compounds derived from phenylmercury or phenylzinc hydroxide and 3-... 

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