Zinc oxide acetylenes

Tsai et al. have also used RAIR to investigate reactions occurring between rubber compounds and plasma polymerized acetylene primers deposited onto steel substrates [12J. Because of the complexities involved in using actual rubber formulations, RAIR was used to examine primed steel substrates after reaction with a model rubber compound consisting of squalene (100 parts per hundred or phr), zinc oxide (10 phr), carbon black (10 phr), sulfur (5 phr), stearic acid (2 phr). 

Methyl ethyl ketone may also he produced hy the catalyzed dehydrogenation of sec-hutanol over zinc oxide or brass at about 500°C. The yield from this process is approximately 95%. MEK is used mainly as a solvent in vinyl and acrylic coatings, in nitrocellulose lacquers, and in adhesives. It is a selective solvent in dewaxing lubricating oils where it dissolves the oil and leaves out the wax. MEK is also used to synthesize various compounds such as methyl ethyl ketone peroxide, a polymerization catalyst used to form acrylic and polyester polymers and methyl pentynol by reacting with acetylene ... 

Nearly quantitative yields of acetonitrile can be obtained by passing mixtures of NH3 and acetylene over zircon at 400-500°C [225], over CviOy on Y-alumina at 360°C [226] or by passing mixtures of NH, acetylene and hydrogen at 400-420°C over a mixture of zinc and thorium oxides on silica [227] or at 300-450°C over zinc oxide or zinc sulfate or zinc chloride on silica [228, 229], In such reactions, the role of traces of water has often been questioned. However, acetonitrile could be obtained under rigorously anhydrous conditions, thus demonstrating the direct amination of acetylene with NH,. It was also reported that ethyUdeneimine can be obtained in up to 26% yield [225], However, in the Ught of more recent work [230, 231] the product was most probably 2,4,6-trimethyl-l,3,5-hexahydrotriazine. 

Studies of the interaction of acetylenes with zinc oxide clearly provide a very interesting avenue for more detailed study. Results to date, though still very fragmentary, suggest that the view that reactions of unsaturated hydrocarbons over zinc oxide occur via proton abstraction to form a species with considerable anionic character has considerable merit. 

The ratio, Nj/N0, can therefore be calculated. For the relatively easily excited alkali metal sodium, it is 9.9 x 10 6 at 2000 °K and 5.9 x 10 4 at 3000 °K this latter temperature is about the highest commonly obtained with flames used for atomic absorption or emission work. Hence, only about 1(T3 % of the sodium atoms are excited at 2000 ° and 6 x 1(F2 % at 3000°. For an element such as zinc,Nf/N0 is 5.4 x 10"10 at 3000 and so only 5 x 10"8% is excited. In spite of the small fraction excited, good sensitivities can be obtained for many elements by flame photometry if a high temperature flame is used, because the difference between zero and a small but finite number is measured. For example, seventy elements can be determined by flame photometry using the nitrous oxide-acetylene flame 1H. 

CH2 CH.OOC.CH(C2H5).C4H9 mw 170.25 liq, sp gr 0.8751 at 20/20° fr p -90°, bp 185.2°, fl p 165°F insol in w. It can be prepd from acetylene, 2-ethylhexanoic acid, zinc oxide and Raney nickel heated under pressure. Used in polymers and emulsi-fying paints... 

Flame methods are the conventional atomization sources used in MS for industrial hygiene (Table I). Air/acetylene at 2150-2400°C is used for the easily atomized elements like lead, cadmium, and zinc. Refractory metals such as tungsten or vanadium require hotter nitrous oxide/acetylene atomization at 2600-2800 C. The need for greater sensitivity and multielement analysis from a single filter has increased the use of electrothermal atomization for tin, vanadium, nickel, and other difficult elements. Formation of hydrides combined with flame atomization has been used in some cases to increase sensitivity. 

Aluminium 309.3 nitrous oxide/ acetylene Add 2000Mg ml-1 potassium to sample solutions to suppress ionisation. Use a standard additions procedure to avoid interference from the zinc matrix... 

Copper 327.4 nitrous oxide/ acetylene The nitrous oxide/acetylene flame is used to minimise the effect of the high zinc/copper ratio... 

Zinc is used in ointments and eye-lotions and is a constituent of different forms of insulin. In the former type of applications zinc oxide, zinc stearate and zinc undecanoate may be encountered in a variety of creams, ointments and pastes. Moody and Taylor [104] dissolved the residue from such samples after ether extraction (lg in 5 ml ether) in concentrated hydrochloric acid. After dilution, the determination can be completed at 213.9 nm in the air/acetylene flame where interferences are not normally encountered. Various analytical techniques for determining zinc in insulin injections have been critically compared [105] atomic absorption was preferred as being accurate, fast and precise. Spielhotz and Toralballa [106] reported a method capable of determining low levels of zinc in insulin. The sample (5 mg) was suspended in water (10 ml), 1 drop of 6M hydrochloric acid was added to effect dissolution. After making up to 50 ml the determination was completed using an air/acetylene flame. Alternatively protamine insulin solution (1 ml) may be diluted to 50 ml after the addition of 1 drop of acid. 

While in Europe most limit tests use the method of standard additions, the United States Pharmacopoeia [84] requires that an aliquot of the test element equal to the set limit be added to the sample. If the response of the sample solution is less than the difference between the sample solution and sample plus aliquot (control) solution, it passes the test. Such a test may be used to limit sodium in other alkali salts. Atomic absorption spectrometry using the air/acetylene flame has been shown to be sufficient to test lead contamination in bismuth subcarbonate [114] and in zinc oxide and carbonate [115]. Miller [88] has reviewed such applications. 

Many paints require vigorous pre-treatment before the matrix can be destroyed. Even after considerable oxidation it may be necessary to filter off titanium dioxide. Some paints are, however, more amenable to acid dissolution. Eider [147] reported that it was possible to determine barium, cadmium, calcium, cobalt, lead, magnesium, manganese, mercury, tin, zinc and zirconium in vinyl additives and paint (1 g) by dissolution in hot concentrated nitric acid (10 ml). The mixture was filtered and made up to 100 ml. Liquid samples were again dissolved in MIBK (lg in 100 ml). Air/ acetylene and nitrous oxide/acetylene flames were used to complete the analysis as appropriate. Porter [148] reported losses of lead during the dry ashing of alkyd and latex paints and therefore recommended dissolution in either nitric/perchloric acids or nitric acid alone. 

Metal salts may be used in the treatment of wool. Flame methods for the determination of aluminium [185], barium, chromium, copper, mercury, strontium, tin, zinc [186] and zirconium [187] in wool have been published. Standard additions to wool cleaned by soaking and washing it with disodium EDTA (800 ml of 0.5 M for 30g wool with soaking for 3 days and double washing) was used as the calibration technique. This compensated for interferences from hydrochloric acid and amino-acids. The samples were equilibrated to a constant humidity for 24 h and then 0.3 g sealed with 5 ml of constant boiling point hydrochloric acid in a glass tube. The tubes were placed in an oven at 110UC for 20 h. The nitrous oxide/acetylene flame was used for the determination of aluminium and zirconium. Sulphate, phosphate, citrate and silicate have been found to interfere in the determination of titanium and zirconium in fire-proofed wool [188], These flame... 

Acetylene is condensed to vinylacetylene and divinylacetylene by cuprous chloride and ammonium chloride. Similar additions of other compounds containing an active hydrogen atom occur in the presence of various catalysts. Mercury salts ate most effective in the vapor-phase reaction of acetylene with hydrogen chloride to give vinyl chloride (100%). Basic catalysts such as potassium hydroxide, potassium ethoxide, or zinc oxide are used for the vinylation of alcohols, glycols, amines, and acids. Most of these reactions involve the use of acetylene under pressure, and few have been described as simple laboratory procedures. Chloroacetic acid, however, reacts with acetylene at atmospheric pressure in the presence of mercuric oxide to yield vinyl chloro-acetate (49%). ... 

Alumina catalysts activated by additions of dehydrogenating catalysts, e.g., nickel oxide, copper oxide or sulfide, zinc oxide or sulfide, cobalt selenide, zinc phosphate, cadmium tungstate, mixtures of the oxides of zinc and tungsten, of cadmium and molybdenum, etc., are claimed to be superior in the formation of acetaldehyde from mixtures of steam and acetylene at 350° to 400° C.l-la Zinc oxide catalysts may be activated in a similar way by the addition of small amounts of molybdates or molybdic acid, and are effective at 300° to 350° C.121b... 

CHLOROMETHANE (74-87-3) CH3CI Highly flammable gas [explosion limits in air (vol %) 8.1 to 17.2 flashpoint <32°F/<0°C autoignition temp 1170°F/632°C Fire Rating 4]. Moisture causes decomposition. Violent reaction with strong oxidizers, acetylene, anhydrous aluminum trichloride, ammonia, amines, ethylene, fluorine, interhalogens magnesium, potassium, powdered aluminum or zinc, sodium, and... 

Liquid- and vapor-phase processes have been described the latter appear to be advantageous. Supported cadmium, zinc, or mercury salts are used as catalysts. In 1963 it was estimated that 85% of U.S. vinyl acetate capacity was based on acetylene, but it has been completely replaced since about 1982 by newer technology using oxidative addition of acetic acid to ethylene (2) (see Vinyl polymers). In western Europe production of vinyl acetate from acetylene stiU remains a significant commercial route. 

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