Neutralization with zinc acetate

FIGURE 13.11 Schematic representation of ionomers prepared by neutralization of maleated ethylene-propylene copolymer (EPM) with zinc acetate. 

Zn2+ correlate can be obtained, as pyridinium salt, by reaction of corrole with zinc acetate in pyridine [25] in a procedure similar to that reported for the preparation of nickel and palladium complexes of corrole [11]. The zinc derivative is not paramagnetic and its formulation has been made on the basis of its proton NMR spectrum. Attempts to isolate the neutral zinc complex have been unsuccessful. 

Since thiosulphate is an intermediate oxidation product of sulphide in an alkahne or neutral medium, sulphide interferes with the determination of thiosulphate and, thus, any traces of sulphide should be removed by the precipitation of zinc sulphide with zinc acetate before the iodometric determination of thiosulphate. The solubility constant for ZnS has been given by Dyrssen and KremUng (1990). After precipitation of the zinc sulphide in a stoppered bottle full to the brim, a measured amount of the supernatant seawater sample is pipetted into a known amount of iodine. The latter oxidizes the thiosulphate to tetrathionate. The surplus iodine is then titrated by adding a thiosulphate solution of known concentration. 

Chemical Reactivity - Reactivity with Water No reaction Reactivity with Common Materials Corrosive to aluminum, zinc and tin. Contact with some metals can generate flammable hydrogen gas Stability During Transport Stable Neutralizing Agents for Acids and Caustics Dilute with water and rinse with dilute acetic acid Polymerization Not pertinent Inhibitor cf Polymerization Not pertinent. 

Apparently the role of methanol is to intercept unstable species which otherwise tend to polymerize or rearrange. The methoxy peroxide (72) can be isolated in crystalline form if desired, but it is preferable to treat the methylene dichloride solution at 0° with zinc dust and acetic acid until the mixture shows a negative potassium iodide test. The resulting crude seco-aldehyde (73) is then cyclized to (74) by stirring with neutral alumina in benzene at room temperature for 3 hr. ° Wechter has recently reported a number of transformations of a 5yS-hydroxy-6yS-formyl-B-norpregnane prepared in 8% yield by photolysis and hydrolysis of a 5a-hydroxy-6 -azidopregnane. 

The zinc bis(tetraseleno) anion, [Zn(Se4)2]2-, has been crystallized with a number of cations, synthesized by a variety of methods, and its reactivity studied.581-584 The compound (hexaseleno) (tetraseleno)zinc (64) was synthesized from zinc acetate in the presence of lithium polyselenide and structurally characterized, demonstrating seven-membered and flve-membered ZnSen rings.585 Mixed donor neutral monomers have also been formed with imidazole A-donor ligands, ZnSe4 (A-methylimidazole)2.553... 

Reduction of a,/3-unsaturated to saturated ketones was further achieved by electrolysis in a neutral medium using copper or lead cathodes (yields 55-75%) [766], with lithium in propylamine (yields 40-65%) [876], with potassium-graphite clathrate CgK (yields 57-85%) [807], and with zinc in acetic acid (yield 87%) [688]. Reduction with amalgamated zinc in hydrochloric acid (Clemmensen reduction) usually reduces both functions [877]. 

A mixture consisting of monochlorobenzene (33.1 g), /V-cthylcarbazole (0.11 mol), and zinc chloride (10 mmol) were heated at 80°C and treated with the dropwise addition of 4-fluoro-2-methylbenzoyl chloride (0.10 mol) and stirred for 1 hour. The mixture was cooled to ambient temperature and treated with -heptane (33.1 g) and then 16.5 ml of water added. The organic layer was isolated and neutralized with 8.30 ml of 1% aqueous sodium hydroxide and then washed with 40.0 ml of water in two portions. The mixture was concentrated to 50 ml and then treated with monochlorobenzene solution (90.0 g) and aluminum chloride (40.0 g) and cooled to 10°C. The solution was treated with acetyl chloride (0.13 mol), stirred at ambient temperature for 1 hour, and then poured into a mixture of dichloroethane (224 g) and 134 ml of ice water. The organic layer was collected and then treated with 40 ml 5% hydrochloric acid, 40 ml of water, and 40 ml 2% aqueous NaOH solution. It was and then concentrated, the residue recrystallized in -propyl acetate, and... 

The Step 4 product (l.OOg) dissolved in methyl alcohol was treated with NH4C1 (0.54 g) and zinc dust (4.5 g) and stirred 3 hours, then filtered through celite. The solution was concentrated and the residue was treated with 1 ml 10% acetic acid, then neutralized with NaHCOj. The solution was then extracted three times with 50 ml EtOAc, washed with 15 ml water, dried with Na2S04, reconcentrated, and 0.85 g product isolated. 

Dithizone test Dithizone (diphenyl thiocarbazone) forms complexes with a number of metal ions, which can be extracted with carbon tetrachloride. The zinc complex, formed in neutral, alkaline or acetic acid solutions, is red ... 

Neutralization with Various Levels of Zinc Acetate. A sulfonated CR-2504 containing about 33 meq sulfonic acid/100 g of sulfonated polymer was dissolved in hexane and 3 vol % methanol at a concentration of 100 g/L. Zinc acetate was added as a water/methanol solution at zinc acetate levels ranging from 0.5 to 6.0 equiv/equiv of sulfonic acid. The polymers were isolated as described previously. Zinc analyses were obtained on all products, and the data are given in Table II. Essentially all of the zinc that was added to the polymer was retained after workup. 

Dihydrate, crystallizes from di] acetic add faint, acetous odor astringent taste slightly efflorescent, d 1.735 mp 237. One gram dissolves in 2.3 ml water, 1.6 ml boiling water, 30 ml alcohol, about 1 ml boiling alcohol. The aq soln is neutral or slightly acid to litmus pH about 5-6. Keep in well-closed containers. Incompat. with zinc salts in general Acacia, alkalies and their carbonates, oxalates,... 

Cobalt(II) complexes (such as cob(II)alamin, formerly called B,2,) can be obtained by several methods including controlled potential reduction [14,15], anaerobic photolysis of some organocobalt species [16] (see Section 5.2(b)), partial oxidation of cobalt(I) complexes, in some cases acidification of solutions of cobalt(I) complexes (see below) and chemical reduction. Chemical reduction of cobalt(III) cobalamins to the +2 oxidation state has been achieved with hydrogen over platinum oxide [16], with neutral and acidic solutions of vanadium(III) [17], with chromous acetate at pH 3 [18] and with amalgamated zinc in 0.1 M aqueous perchloric acid [19]. All such cobalt(II) species are probably 5-coordinate, and are low spin d systems containing an unpaired electron and thus displaying an ESR spectrum [20]. 

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