Acetone zinc oxide

The results obtained in above experiments confirm the removal of chemisorbed particles in the process of immersion of the film with preliminary chemisorbed radicals in a liquid acetone. Note that at low pressures of acetone, the CHa-radicals absorbed on ZnO film could be removed only by heating the film to the temperature of 200 - 250°C. Moreover, if the film with adsorbed radicals is immersed in a nonpolar liquid (hexane, benzene, dioxane), or vapours of such a liquid are condensed on the surface of the film, then the effect of removal of chemisorbed radicals does not take place, as is seen from the absence of variation of electric conductivity of the ZnO film after it is immersed in liquid and methyl radicals are adsorbed anew onto its surface. We explain the null effect in this case by suggesting that the radicals adsorbed on the surface of the ZnO film in the first experiment remained intact after immersion in a nonpolar liquid and blocked all surface activity of the adsorbent (zinc oxide). 

Zinc. Next to sodium, zinc is the most used reductant. It is available in powder, dust, and granular (mossy) forms. Zinc gets coated by a l er of zinc oxide which must be removed to activate it before it can reduce effectively. It can easily be activated by shaking 3 to 4 min. in a 1% to 2% hydrochloric acid solution. This means for every 98 ml of water volume, add 2 ml of coned hydrochloric acid. Then wash this solution with water, ethatiol, acetone, and ether. Ot activation can be accomplished by washing zinc in a solution of anhydrous zinc chloride (a very small amount) in ether, alcohol, or tetrahydrofuran. Another way is to stir 180 g of zinc in a solution of 1 g copper sulfate pentahydrate. Personally, I like the HCl acid method. 

Zinc dust is frequently covered with a thin layer of zinc oxide which deactivates its surface and causes induction periods in reactions with compounds. This disadvantage can be removed by a proper activation of zinc dust immediately prior to use. Such an activation can be achieved by a 3-4-minute contact with very dilute (0.5-2%) hydrochloric acid followed by washing with water, ethanol, acetone and ether [/55]. Similar activation is carried out in situ by a small amount of anhydrous zinc chloride [156 or zinc bromide [157 in alcohol, ether or tetrahydrofuran. Another way of activating zinc dust is by its conversion to a zinc-copper couple by stirring it (180g) with a solution of 1 g of copper sulfate pentahydrate in 35 ml of water [/55]. 

Acetone-extracted pale crepe, 5 zinc oxide, 1 stearic acid, 1 phenyl-/3-naphthylamine, 0.7 Santocure, 2.5 sulfur 30 min at 140° C Methyl methacrylate 5 20 23 ... 

D-Galactose was converted by ethanethiol and hydrochloric acid into crystalline D-galactose diethyl dithioacetal, which was acetonated with acetone-zinc chloride. The product (15) was reduced to the L-fu-citol derivative (16) with Raney nickel. The overall yield of 16 was 29%, and it was characterized as the crystalline 6-p-toluenesulfonate 17. Oxidation of 16 by the Pfitzner-Moffatt reagent55 proceeded readily and, after O-deacetonation, and purification of the product by chromatography on a column of silica gel, L-fucose (18 13% overall yield from D-galactose) and L-fucitol (19 1% yield) were isolated (see Scheme 3). 

Mesityl oxide can also be produced by the direct condensation of acetone at higher temperatures. This reaction can be operated in the vapor phase over zinc oxide (182), or zinc oxide—zirconium oxide (183), or in the liquid phase over cation-exchange resin (184) or zirconium phosphate (185). Other catalysts are known (186). 

In the vapor phase, acetone vapor is passed over a catalyst bed of magnesium aluminate (206), zinc oxide—bismuth oxide (207), calcium oxide (208), lithium or zinc-doped mixed magnesia—alumina (209), calcium on alumina (210), or basic mixed-metal oxide catalysts (211—214). Temperatures ranging... 

Practical interest in high-molecular-weight poly (propylene oxide) centers in its potential use as an elastomer (19). Copolymerization of propylene oxide with allyl glycidyl ether gives a copolymer with double bonds suitable for sulfur vulcanization. Table IV shows the properties of elastomers made with a copolymer prepared with a zinc hexacyano-ferrate-acetone-zinc chloride complex. Also shown are the properties of elastomers made from partially crystalline copolymers prepared with zinc diethyl-water catalyst. Of particular interest are the lower room-... 

The equilibrium is more favorable to acetone at higher temperatures. At 325°C 97% conversion is theoretically possible. The kinetics of the reaction has been studied (23). A large number of catalysts have been investigated, including copper, silver, platinum, and palladium metals, as well as sulfides of transition metals of groups 4, 5, and 6 of the periodic table. These catalysts are made with inert supports and are used at 400 —600°C (24). Lower temperature reactions (315—482°C) have been successfully conducted using zinc oxide-zirconium oxide combinations (25), and combinations of copper-chromium oxide and of copper and silicon dioxide (26). 

Schultz (USA) 1995 Exposure of hospital emergency personnel during decontamination of chemically exposed patients Acetone, p-xylene, iron oxide, zinc oxide, total dust Breathing zone concentrations (ppm and mg/m )... 

Some 95% of the U.S. market for acetone (2-propanone) is now supplied by the cumene-phenol process (section 12.11.2), with the remainder produced mainly by dehydrogenation of isopropanol (over a copper or zinc oxide catalyst). In Europe, co-product acetone from HP s naphtha oxidation supplements that from cumene-phenol and isopropanol. 

Activators. Activators are chemicals that increase the rate of vulcanization hy reacting first with the accelerators to form rubber-soluhle complexes. These complexes then react with the sulfur to form sulfurating agents (eqs. 14,15). The most common activators are combinations of zinc oxide and stearic acid. Other fatty acids used include lauric, and oleic, acids. Soluble zinc salts of fatty acid such as zinc 2-ethylhexanoate are also used, and these rubber-soluble activators are effective in natural rubber to produce low set, low creep compoimds used in load-bearing applications. Weak amines and amino alcohols have also been used as activators in combination with the metal oxides. Natural rubber usually contains sufficient levels of naturally occurring fatty acids to solubihze the zinc salt. However, if these fatty acids are first extracted by acetone, the resultant clean natural rubber exhibits a much lower state of cime. Therefore, to ensme consistent cure rate, fatty acids are usually added. Synthetic rubbers, especially the solution polymerized elastomers, do not contain fatty acids and require their addition to the cure system. 

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